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267 Cards in this Set
- Front
- Back
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What are the levels of organization for the heirarchy of life?
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-biosphere
-ecosystem -community -population -organism -organs and organ systems -tissue -cell -organelle -molecule |
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What is the lowest level of organization that perform all activities required for life?
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the cell
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What characteristics do ALL cells share?
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-are all enclosed by a membrane
-all use DNA as genetic information -all have cytoplasm -all have ribosomes |
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eukaryotes
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those subdivided by internal membranes into various membrane-enclosed organelles (nucleus, Gogli body, etc)
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prokaryotes
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those that lack the kinds of membrane-enclosed organelles found in eukaryotic cells
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system
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a combination of components that form a more complex organization
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Each step upward in the heirarchy of biological order reveals emergent properties...what are emergent properties?
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new properties that "emerge" as complexity increase
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reductionism
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"reducing" a system to its simpler components
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systems biology
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seeks to create models of the dynamic behavior of whole biological systems
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What is the goal of systems biology?
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to predict how a change in one part of a system will affect the rest of the system
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What are the classifications of life?
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-Domain
-Kingdom -Phylum -Class -Order -Family -Genus -Species |
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What are the three domains?
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-Eukarya
-Archaea -Bacteria |
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Natural Selection
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proposed by Darwin as the mechanism for evolutionary adaption of populations to their environment
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Natural Selection-
Population of Organisms splits into... |
1.Hereditary Variation
2.Overproduction and Struggle for Existence |
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Hereditary Variation and Overproduction and Struggle for Existence join back together into...
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Differences in Reproductive Success
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Differences in Reproductive Success goes to...
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Evolution of Adaptions in the Population
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When energy is absorbed does the atom expand energy shells or lose energy shells?
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expand energy shells
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When energy is lost does the atom expand energy shells or lose energy shells?
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loses energy shells
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Which electron transition represents a gain of energy?
a.2nd to 3rd shell b.2nd to 1st shell c.3rd to 2nd shell d.3rd to 1st shell |
a.2nd to 3rd shell
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The reactivity of an atom arises from...
a.the existence of unpaired electrons in the valence or outer electron shell b.the average distance of the outermost electron shell from the nucleus c.the potential energy of the valence shell d.the sum of the potential energies of all the electron shells |
a.the existence of unpaired electrons in the valence or outer electron shell
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What are the three types of chemical bonds?
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-covalent
-ionic -hydrogen |
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covalent bonds
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-a strong bond
-the sharing of valence electrons |
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compound
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a fixed ratio of two or more kinds of elements
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molecule
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two or more atoms covalently bonded together
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single bond
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the sharing of one pair of valence electrons
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double bond
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the sharing of two pairs of valence electrons
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triple bond
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the sharing of three pairs of valence electrons
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ionic bonds
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-a strong bond
-the attraction of cations and anions to each other |
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hydrogen bonds
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-a weak bond
-the attraction of hydrogen atoms on one molecule to partially negative areas of another molecule |
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electronegativity
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the relative ability of an atom to attractive electrons, compared to other atoms
-the stronger atoms "pull" electrons from the weaker atoms -it depends on the number of valence electrons and the size of the atom |
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solubility
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Like dissolves like
-polar liquids dissolve polar compounds and non-polar liquids dissolve non-polar compounds |
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If the electronegativity is equal, what kind of bond is formed?
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non-polar covalent
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If the electronegativity difference is between 0 and 2, what kind of bond is formed?
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polar covalent
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If the electronegativity difference is 2 or greater, what kind of bond is formed?
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ionic
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When is chemical equilibrium reached?
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when the forward reaction rate = the reverse reation rate
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How much of a difference does each pH unit represent for differences in H+ and OH- concentrations?
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tenfold difference for each pH unit
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What is the neutral solutions pH?
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pH=7
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What side is acidic and what side is basic?
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Acidic is less than 7 while basic is greater than 7
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acid
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a substance that increases in hydrogen ion concentration in a solution
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base
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any substance that reduces the hydrogen ion concentration
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Strong acids and bases _______ completely in water.
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dissociate
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What helps to maintain the normal pH value of most biological fluids near 7?
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buffers
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buffer
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accepts hydrogen ions from the solution when they are in excess and donate hydrogen ions when they have been depleted
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What makes up a buffer?
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normally a weak acid and its corresponding base
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pK value
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the pH at which the ratio of a weak acid to its corresponding base is one
-this is the pH at which the weak acid is half ionized |
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When does a buffer have the greatest capacity to maintain its pH?
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around its pK value
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cohesiveness
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from constantly forming and breaking hydrogen bonds in liquid water
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high specific heat
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it takes one calorie to raise one gram of water one degree Celsius
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high heat of vaporization
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it takes 540 calories to evaporate one gram of water
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freezing point
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water is densest at 4 degrees Celsius
-at 0 degrees Celsius, hydrogen bonds take up more space, making "solid" water less dense |
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Why is water an effective solvent?
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it so readily forms hydrogen bonds with charged ions and polar covalent molecules
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The statement "If you show your dog affection then your dog will seek your affection" is an example of:
a.a statement that can be tested b.a prediction c.deductive reasoning d.a statement derived from a hypothesis e.all of the above |
e.all of the above
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All cells have:
a.mitochondria b.a cell wall c.ribosomes d.a nucleus |
c.ribosomes
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Organisms in the same class must also be in the same:
a.genus b.order c.family d.phylum e.species |
d.phylum
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An atom with atomic number 12 is most likely to form which kind of chemical bond?
a.polar covalent b.non-polar covalent c.ionic d.hydrogen |
c.ionic
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The type of logic that describes various specific observations leading to a generalized explanation is called:
a.inductive logic b.deductive logic |
a.inductive logic
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Which of these is a "divalent" cation?
a.sodium ion b.calcium ion c.sulfate ion d.chlorate ion e.hydroxide ion |
b.calcium ion
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Based on electron configuration, which of these elements would behave most like an oxygen atom?
a.6C b.1H c.7N d.16S e.11Na |
d.16S
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Which of the following molecules is most capable of forming hydrogen bonds?
a.CH4 b.NaCl c.NH3 d.H2 |
c.NH3
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Of the following, which atomic number describes the least reactive element?
a.1 b.8 c.12 d.16 e.18 |
e.18
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True of False: If an acid is defined as anything that increases the hydrogen ion concentration in a solution, then a base must be anything that reduces the hydrogen ion concentration in a solution.
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True
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solution
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consists of a solute dissolved in a solvent
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molarity
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moles of solution per liter of solution
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osmolarity
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a method of expressing solution concentration based on the number of particles in a solution
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osmolarity(osmol) =
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molarity * (number of particles/molecule)
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organic chemistry
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the study of carbon compounds
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What are the most versatile building blocks of molecules?
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carbon atoms
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hydrocarbons
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molecules consisting of only carbon and hydrgen
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isomers
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molecules with the same molecular formula but different structures and properties
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What are the three types of isomers?
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structural, geometrical, and enantiomers
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functional groups
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the chemically reactive groups of atoms within an organic molecule
-are the parts of molecules involved in chemical reactions -give organic molecules distinctive chemical properties |
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hydroxyl
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-OH
-alcohOL |
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carbonyl
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-CHO
-ALdehyde -ketONE |
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carboxyl
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-COOH
-acid |
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amino
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-NH2
-amine |
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sulfhydryl
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-SH2
-thiol |
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phosphate
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-PO4
-phosphate |
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monosacchrides
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-may be linear
-can form rings |
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disacchrides
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-consist of two monosacchrides
-are joined by a glycosidic linkage -form by a dehydration reaction |
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polysacchrides
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-polymers of sugar
-have basically two different functions in organisms - energy storage and structure |
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starch
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a polymer consisting entirely of glucose monomers
-is the major storage form of glucose in plants |
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glycogen
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-consists of glucose monomers
-is the major storage form of glucose in animals |
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cellulose
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a polymer of glucose
-has different glycosidic linkages than starch -is a major component of the tough walls that enclose plant cells -difficult to digest |
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chitin
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-found in the exoskeleton of arthropods
-can be used as surgical thread |
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What is the basic elemental composition of carbohydrates?
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carbon, hydrogen, and oxygen
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What are the key functional groups of carbohydrates?
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hydroxyl and carbonyl groups
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condensation reaction
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forms glycosidic linkages between monomers to form dimers, and polymers of carbohydrates
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What determines whether polysacchrides function as energy sources or as structural material?
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linkages of polysacchrides
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hydrolysis reaction
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breaks down polysacchrides into monosacchride subunits
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What is the most common monomer of polysacchrides?
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glucose
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lipids
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-diverse
-basically composed of carbon, hydrogen, oxygen, and one type has phosphorus -are the one class of large biological molecules that do not consist of polymers -are hydrophobic |
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triglyceride (i.e. fat) =
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fatty acid + glycerol
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fatty acid =
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long chain hydrocarbons + a carboxyl group at one end
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essential fatty acid
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fatty acids that are required in the human diet
-they cannot be synthesized by the body from other fatty acids and must be obtained from food |
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How do you name unsaturated fatty acids?
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indicated the position of the first double bond counting from the opposite end of the carboxyl group
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omega carbon atom
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the terminal carbon atom
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saturated fatty acid
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"saturated" with hydrogen atoms covalently bonded to carbon atoms
-no more can be added -packed close together -solid at room temperature |
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unsaturated fatty acid
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have less hydrogen atoms because of one or more double bonds betwee carbon atoms
-"flow" at room temperature |
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monounsaturated
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one double bond
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polyunsaturated
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more than one double bond
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hydrogenated
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converting unsaturated oils back back to saturated by adding hydrogen atoms
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In hydrogenation, plant oils are exposed to hydrogen at high temperature and in the presence of a catalyst.
What two things result? |
1.some double bonds are converted in single bonds
2.other double bonds are converted from cis to trans configuration -both of these effects straighten out the molecules so they can lie closer together and become solid at room temperature |
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Why are trans fats bad for you?
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trans fats are neither required nor beneficial for health
-increase the risk of coronary heart disease by raising bad cholesterol and lowering good cholesterol |
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fats
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constructed from two types of smaller molecules, a single glycerol and three fatty acids
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phospholipids =
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2 fatty acids + glycerol + phosphate + organic group
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wax
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organic compounds formed from ester linkages between very long chain fatty acids and long chain fatty alcohols
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True or False: Cholesterol and the steriods are fat-soluble molecules with a tetracyclic base structure.
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True
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What is the biological role of carbohydrates?
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structure and energy molecules
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What is the biological role of fats (lipids)?
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structure and energy molecules
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What is the biological role of phospholipids?
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membrane structure
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What is the biological role steriods/sterols?
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membrane structure-hormones
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plasma membrane
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-the cell's boundary to the outside
-selectively permeable (the "gatekeeper") -a fluid-like bilayer of phospholipids with a mosaic of embedded proteins -held together primarily by hydrophobic interactions |
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Proteins in the plasma membrane...
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can drift within the bilayer
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What two factors affect the fluidity of the plasma membrane?
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1.the type of hydrocarbon tails in phospholipids
-unsaturated tails enhance fluidity by not packing so closely together 2.cholesterols presence has different effects on membrane fluidity at different temperatures -at warm temperatures the cholesterol molecules help stabilize the membrane by interfering with movements of phospholipid molecules -at cool temperatures cholesterol molecules help protect the membrane by resisting solidifaction |
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peripheral proteins
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appendages loosely bound to the inner surface of the membrane
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integral proteins
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penetrate the hydrophobic core of the lipid bilayer
-are often transmembrane proteins, completely spanning the membrane |
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phospholipid
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the primary molecular structure of the cell's boundary...makes a permeability barrier between aqueous regions, a matrix for functional proteins
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cholesterol
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reinforcement of phospholipid bilayer, facilitates fluidity at both high and low temperatures
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glyco groups
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the cell's identification molecules
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proteins
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a variety of functions
-signal transduction -transport of molecules -attachment points (to ECM/cytoskeletal fibers) -cell recognition -intercellular junctions -enzymatic activity |
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amino acids
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organic molecules possessing both carboxyl and amino groups
-differ in their properties due to differing side chains, called R groups |
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polypeptides
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polymers of amino acids
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protein
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consists of one or more polypeptides
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Four Levels of Protein Structure
Primary Structure: |
the unique sequence of amino acids in a polypeptide
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Four Levels of Protein Structure
Secondary Structure: |
the folding or coiling of the polypeptide into a repeating configuration
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Four Levels of Protein Structure
Tertiary Structure: |
results from interactions between amino acids and R groups
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Four Levels of Protein Structure
Quaternary Structure: |
the overall protein structure that results from the aggregation of two or more polypeptide subunits
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chaperonins
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protein molecules that assist in the proper folding of other proteins
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denaturation
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when a protein unravels and loses it native conformation
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nucleic acids
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-composed of carbon, hydrogen, oxygen, phosphorus, and nitrogen
-monomer subunits: nucleotides -functions: genetic information storage (DNA), protein synthesis (RNA) |
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What are the two major types of nucleic acids?
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-DNA
-RNA |
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nucleotide monomers
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made up of nucleosides and phosphate groups
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In DNA, what forms the hydrogen bonds in the complementary fashion?
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the nitrogenous bases
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carbohydrate:
-monomer (unit molecule) -large biomolecules (generic) -specific examples of biomolecules -linkage |
-monosacchrides (glucose)
-polysacchrides -amylose (starch), glycogen, amylopectin, cellulose -glycosidic |
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lipids:
-monomer (unit molecule) -large biomolecules (generic) -specific examples of biomolecules -linkage |
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-triglycerides, phospholipids, and waxes -fats, oils -ester |
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proteins:
-monomer (unit molecule) -large biomolecules (generic) -specific examples of biomolecules -linkage |
-amino acids (20 varieties)
-polypeptides, proteins -structural proteins, enzymes -peptide |
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nucleic acids:
-monomer (unit molecule) -large biomolecules (generic) -specific examples of biomolecules linkage |
-nucleotides (adenosine, thymosine, guanosine, cytosine, uracil)
-polynucleotides: DNA and RNA -DNA, mRNA, tRNA, rRNA, snRNA, ribozymes -phosphodiester |
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Miller-Urey Experiment
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tested the Oparin-Haldane hypothesis
-explains how simple inorganic molecules could react to form more complex organic molecules |
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abiotic replication of RNA
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1.RNA monomers
2.formation of short RNA polymers 3.assembly of a complementary RNA chain 4.complementary chain serves as template for making copy of original "gene" |
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protobiont
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an aggregate of molecules (abiotically produced) surrounded by a "membrane"
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generally prokaryotes are:
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-microscopic
-ubiquitous -unicellular -genetically very diverse |
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prokaryotic cell shapes:
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-rod (bacilli)
-spherical (cocci) -spiral |
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cell wall of prokaryotes
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maintains cell shape, provides physical protection, and prevents the cell from bursting in a hypotonic environment
-covered by a capsule |
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Gram positive
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have a cell wall with large amounts of peptidoglycan
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Gram negative
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have less peptidoglycan, and is located in a layer between the plasma membrane and an outer membrane
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capsule
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a sticky layer of polysacchride or protein
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fimbriae and pili
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allow prokaryotes to stick to their substrate or other individuals in a colony
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flagella
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the way that bacteria propel themselves
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Many prokaryotes form endospores...
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which can remain viable in harsh conditions for centuries
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photoautotroph:
-energy source -carbon source -types of organisms |
-light
-carbon dioxide -photosynthetic prokaryotes, plants, certain protists |
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chemoautotrophs
-energy source -carbon source -types of organisms |
-inorganic chemicals
-carbon dioxide -certain prokaryotes |
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photoheterotroph
-energy source -carbon source -types of organisms |
-light
-organic compounds -certain prokaryotes |
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chemoheterotroph
-energy source -carbon source -types of organisms |
-organic compounds
-organic compounds -many prokaryotes and protists, fungi, animals, and some parasitic plants |
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Archaea
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share some traits with bacteria and with eukaryotes
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size of prokaryote cells
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1 to 10 micrometers
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size of eukaryote cells
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10 to 100 micrometers
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resolving power
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the smallest separation at which two separate objects can be distinguished
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SEM
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3-D image
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TEM
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internal ultrastructure of cells
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Nucleus
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-Nuclear envelope: double membrane enclosing the nucleus; perforated b pores; continuous with ER
-Nucleolus: nonmembranous organelle involved in production of ribosomes; a nucleus has one or more nucleoli -Chromatin: material consisting of DNA and proteins; visible as individual chromosomes in a dividing cell |
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Plasma membrane
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membrane enclosing the cell
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Ribosomes
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nonmembranous organelles that make proteins; free in cytoplasm or bound to rough ER or nuclear envelope
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Golgi apparatus
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organelle active in synthesis, modification, sorting, and secretion of cell products
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Lysosome
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digestive organelle where macromolecules are hydrolyzed
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Mitochondrion
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organelle where cellular respiration occurs and most ATP is generated
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Peroxisome
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organelle with various specialized metabolic functions; produces hydrogen peroxide
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Microvilli
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projections that increase the cell’s surface area
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Microtubules:
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-Structure: hollow tubes; wall consists of 13 columns
-Diameter: 25 nanometers with 15 nanometers of lumen -Protein subunits: tubulin, consisting of alpha-tubulin and beta-tubulin -Main functions: -Maintenance of cell shape (compression – resisting “girders”) -Cell motility (as in cilia or flagella) -Chromosome movements in cell division -Organelle movements |
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Intermediate filaments:
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-Structure: fibrous proteins supercoiled into thicker cables
-Diameter: 8 to 12 nanometers -Protein subunits: one of several different proteins of the keratin family, depending on cell type -Main functions: -Maintenance of cell shape (tension-bearing elements) -Anchorage of nucleus and certain other organelles -Formation of nuclear lamina |
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Microfilaments:
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-Structure: two intertwined strand of actin, each a polymer of actin subunits
-Diameter: 7 nanometers -Protein subunits: actin -Main functions: -Maintenance of cell shape (tension – bearing elements) -Changes in cell shape -Muscle contraction -Cytoplasmic streaming -Cell motility (as in pseudopodia) -Cell division (cleavage furrow formation) |
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Cytoskeleton:
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reinforces cell’s shape, functions in cell movement; components are made of protein
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Centrosome:
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region where the cell’s microtubules are initiated; in an animal cell, contains a pair of centrioles (function unknown)
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Flagellum:
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locomotion organelle present in some animal cells; composed of membrane-enclosed microtubules
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Endoplasmic reticulum:
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network of membranous sacs and tubes; active in membrane synthesis and other synthetic and metabolic processes; has rough (ribosome-studded) and smooth regions
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Nucleus:
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nuclear envelope, nucleolus, and chromatin
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Centrosome:
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region where the cell’s microtubules are initiated; lacks centrioles in plant cells
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Cell wall:
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outer layer that maintains cell’s shape and protects cell from mechanical damage; made of cellulose, other polysaccharides, and protein
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Plasmodesmata:
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channels through cell walls that connect the cytoplasms of adjacent cells
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Chloroplast:
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photosynthetic organelle; converts energy of sunlight to chemical energy stored in sugar molecules
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Tonoplast:
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membrane enclosing the central vacuole
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Central vacuole:
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prominent organelle in older plant cells; functions include storage, breakdown of waste products, hydrolysis of macromolecules; enlargement of vacuole is a major mechanism of plant growth
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What does the endomembrane system contain?
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-the nuclear membrane
-endoplasmic reticulum -Golgi structures -lysosomes -vacuoles |
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What is the function of the endomembrane system?
|
regulates protein traffic and performs diversified metabolic functions in the cell
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Endoplasmic Reticulum
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-continuous with the nuclear envelope
-a network of tubules and sac-like foldings called "cisternae" having an interior - the lumen -rough and smooth ER |
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RER
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-ER with ribosomes attached
-produces secretory proteins -produces membrane |
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SER
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-ER without ribosomes attached
-synthesizes lipids -metabolizes carbohydrates -stores calcium -detoxifies poisons |
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Golgi apparatus
|
Structure:
-consists of flattened membranous sacs called cisternae Functions: -receives transport vesicles coming from RER -modifies the products produced in and shipped from RER -makes certain kinds of marcomolecules -sends finished products to intracellular and intercellular destinations |
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Lysosomes
|
Structure:
-a membranous sac of hydrolytic enzymes Functions: -digests all kinds of macromolecules |
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How do lysosomes carry out intracellular digestion?
|
phagocytosis
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food vacuole
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formed by phagocytosis
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contractile vacuoles
|
pumps excess water out of protist cells
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central vacuole
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-found in plant cell
-holds reserves of water, ions, metabolic wastes, pigments, and protective compounds |
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mitochondrion
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site of cellular respiration
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chloroplast
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site of photosynthesis
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peroxisome
|
-breakdown of excess purines and fatty acids
-participates in the synthesis of cholesterol, bile acids, and lipids used to make myelin |
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What are the six major functions of the membrane protein?
|
-transport
-enzymatic activity -signal transduction -cell-cell recognition -intercellular joining -attachment to the cytoskeleton and extracellular matrix |
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passive transport
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happens spontaneously, without an input of energy
-substances move down their concentration gradient |
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active transport
|
requires an addition of energy
-substances move against their concentration gradient |
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transport proteins
|
allow hydrophilic substances across the membrane
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diffusion
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the tendency for molecules of any substance to spread out evenly into the available space
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facilitated diffusion
|
passive transport aided by proteins
-transport proteins speed the movement of molecules across the plasma membrane |
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What are the types of transmembrane proteins?
|
channel proteins and carrier proteins
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osmosis
|
the net movement of water across a semipermeable membrane
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What affects osmosis?
|
the concentration gradient of dissolved substances
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tonicity
|
the ability of a solution to cause a cell to gain or lose water
-has a great impact on cells without walls |
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If a solution is isotonic...
|
-the concentration of solutes is going to be the same as it is inside the cell
-there will be no net movement of water |
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If a solution is hypertonic...
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-the concentration of solutes is greater than inside the cell
-the cell will lose water |
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If a solution is hypotonic...
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-the concentration of solutes is less than inside the cell
-the cell will gain water |
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turgid
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rigid cell wall
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flaccid
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limp cell wall
-isotonic or hypertonic environment |
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sodium-potassium pump
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-active transport
1.cytoplasmic sodium ions bind to the sodium potassium pump 2.sodium ion binding stimulates phosphorylation by ATP 3.potassium ions are released and sodium ion sites are receptive again; the cycle repeats 4.phosphorylation causes the protein to change its conformation, expelling sodium ions to the outside 5.loss of the phosphate restores the protein's original conformation 6.extracellular potassium ions bind to the protein, triggering release of the phosphate group |
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membrane potential
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the voltage difference across a membrane
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What two forces cause the electrochemical gradient?
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-chemical - the ion's concentration gradient
-electrical - the effect of membrane potential on the movement of ions |
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electrogenic pump
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a transport protein that generates the voltage across a membrane
-proton pump |
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cotransport
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active transport driven by a concentration gradient
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exocytosis
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transport vesicles migrate to the plasma membrane, fuse with it, and release their contents
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endocytosis
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the cell takes in macromolecules by forming new vesicles from the plasma membrane
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What are the three types of endocytosis?
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phagocytosis, pinocytosis, and receptor-mediated endocytosis
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resting potential
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the membrane potential of a neuron that is not transmitting a signal
-it is -70 inside the cell |
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hyperpolarization
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the membrane potential becomes more negative
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depolarization
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the membrane potential becomes less negative
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action potential
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a graded depolarization reaches a certain membrane voltage, the threshold
-brief all-or-none depolarization of a neuron's plasma membrane -the type of signal that carries information along axons |
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What are the steps of action potential?
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1.resting potential
2.threshold 3.depolarization 4.repolarization 5.undershoot |
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gated channel proteins
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the channel responds to external stimuli that either permit or stop the flow of ions by opening or closing
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ligand gated channel
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the stimulus is a specific chemical
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voltage gated channel
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the stimulus is a change in the membrane potential
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stretch gated channel
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the stimulus is mechanical
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depolarization of action potential
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-sodium channels open
-sodium ions enter the cell -entry of sodium into the cytoplasm depolarizes the cell membrane further, thereby opening more sodium channels |
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When the action potential reaches a terminal...
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the final result is the release of neurotransmitters into the synaptic cleft
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A neuron that is not transmitting signals...
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contains many open potassium channels and fewer open sodium channels in its plasma membrane
-the membrane is selectively permeable to potassium ions |
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collagen fibers
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embedded in a web of proteoglycan complexes
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fibronectin
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attaches the ECM to the integrins embedded in the plasma membrane
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proteoglycan complex
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consists of hundreds of proteoglycan molecules attached noncovalently to a single long polysacchride molecule
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integrins
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membrane proteins that are bound to the ECM on one side and to associated proteins attached to microfilaments on the other
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extracellular matrix
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support, adhesion, and transmembrane signaling
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tight junctions
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the membranes of neighboring cells are very tightly pressed against each other, bound together by specific proteins
-prevent leakage of extracellular fluid across a layer of epithelial cells |
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desmosomes
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anchoring junctions
-fasten cells together into strong sheets |
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gap junctions
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communicating junctions
-provide cytoplasmic channels from one cell to an adjacent cell |
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plasmodesmata
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analogous to gap junctions in animal cells
-in plant cells |
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signal transduction pathway
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convert signals on a cell's surface into cellular responses
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local signaling
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have cell junctions that directly connect the cytoplasm of adjacent cells
-animal cells may communicate via direct contact or using local regulators |
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paracrine signaling
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a secreting cell acts on nearby cells by discharging molecules of a local regulator into the extracellular fluid
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synaptic signaling
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a nerve cell releases neurotransmitter molecules into a synapse, stimulating the target cell
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What are the three stages of cell signaling?
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-reception
-transduction -response |
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protein phosphorylation
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when a phosphate functional group is added to a protein to regulate the activity of that protein
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protein kinase
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the enzyme that adds phosphates to proteins
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protein dephosphorylation
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when a phosphate functional group is removed from a protein
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protein phosphatase
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the enzyme that removes phosphates from a protein
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hormonal signaling
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-long-distance signaling
-specialized endocrine cells secrete hormones into body fluids -may reach all body cells |
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reception
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a signal molecule (ligand) binds to a receptor protein, causing it to change shape
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What are three types of membrane receptors?
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-ion channel receptors
-G-protein-linked receptors -receptor tryosine kinase |
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cAMP
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a second messenger in a G-protein-signaling pathway
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pathway branching and "cross-talk"...
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further help the cell coordinate incoming signals
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scaffolding proteins
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can increase the signal transduction efficiency
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How are signal responses terminated quickly?
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by the reversal of ligand binding
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1st Law of Thermodynamics
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Energy is neither created nor destroyed
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2nd Law of Thermodynamics
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Entropy increases with a spontaneous reaction.
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exergonic reaction
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proceeds with a net release of free energy and is spontaneous
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endergonic reaction
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one that absorbs free energy from its surroundings and is nonspontaneous
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competitive inhibition
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an inhibitor blocks the binding site for the substrate
-overcome this by increasing the amount of substrate present |
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non-competitive inhibition
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an inhibitor binds to the binding site and it makes the binding site for the substrate change shapes to not allow binding to occur
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allosteric enzyme
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an allosteric effector molecule binds to the enzyme and either activates or deactivates the binding site for the substrate
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feedback inhibition
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a reaction occurs and triggers the inhibitor to bind to the starting site of the reaction stopping the reaction from occuring
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light energy goes in...
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heat energy comes out
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redox reactions
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the transfer of "high energy" electrons in oxidation and reduction reactions
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During cellular respiration, glucose is (oxidized,reduced) and oxygen is (oxidized,reduced).
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-oxidized
-reduced |
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What are the three stages of cellular respiration?
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-glycolysis
-citric acid cycle (krebs cycle) -oxidative phosphorylation |
