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267 Cards in this Set

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What are the levels of organization for the heirarchy of life?
-biosphere
-ecosystem
-community
-population
-organism
-organs and organ systems
-tissue
-cell
-organelle
-molecule
What is the lowest level of organization that perform all activities required for life?
the cell
What characteristics do ALL cells share?
-are all enclosed by a membrane
-all use DNA as genetic information
-all have cytoplasm
-all have ribosomes
eukaryotes
those subdivided by internal membranes into various membrane-enclosed organelles (nucleus, Gogli body, etc)
prokaryotes
those that lack the kinds of membrane-enclosed organelles found in eukaryotic cells
system
a combination of components that form a more complex organization
Each step upward in the heirarchy of biological order reveals emergent properties...what are emergent properties?
new properties that "emerge" as complexity increase
reductionism
"reducing" a system to its simpler components
systems biology
seeks to create models of the dynamic behavior of whole biological systems
What is the goal of systems biology?
to predict how a change in one part of a system will affect the rest of the system
What are the classifications of life?
-Domain
-Kingdom
-Phylum
-Class
-Order
-Family
-Genus
-Species
What are the three domains?
-Eukarya
-Archaea
-Bacteria
Natural Selection
proposed by Darwin as the mechanism for evolutionary adaption of populations to their environment
Natural Selection-

Population of Organisms splits into...
1.Hereditary Variation

2.Overproduction and Struggle for Existence
Hereditary Variation and Overproduction and Struggle for Existence join back together into...
Differences in Reproductive Success
Differences in Reproductive Success goes to...
Evolution of Adaptions in the Population
When energy is absorbed does the atom expand energy shells or lose energy shells?
expand energy shells
When energy is lost does the atom expand energy shells or lose energy shells?
loses energy shells
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
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
What are the three types of chemical bonds?
-covalent
-ionic
-hydrogen
covalent bonds
-a strong bond
-the sharing of valence electrons
compound
a fixed ratio of two or more kinds of elements
molecule
two or more atoms covalently bonded together
single bond
the sharing of one pair of valence electrons
double bond
the sharing of two pairs of valence electrons
triple bond
the sharing of three pairs of valence electrons
ionic bonds
-a strong bond
-the attraction of cations and anions to each other
hydrogen bonds
-a weak bond
-the attraction of hydrogen atoms on one molecule to partially negative areas of another molecule
electronegativity
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
solubility
Like dissolves like
-polar liquids dissolve polar compounds and non-polar liquids dissolve non-polar compounds
If the electronegativity is equal, what kind of bond is formed?
non-polar covalent
If the electronegativity difference is between 0 and 2, what kind of bond is formed?
polar covalent
If the electronegativity difference is 2 or greater, what kind of bond is formed?
ionic
When is chemical equilibrium reached?
when the forward reaction rate = the reverse reation rate
How much of a difference does each pH unit represent for differences in H+ and OH- concentrations?
tenfold difference for each pH unit
What is the neutral solutions pH?
pH=7
What side is acidic and what side is basic?
Acidic is less than 7 while basic is greater than 7
acid
a substance that increases in hydrogen ion concentration in a solution
base
any substance that reduces the hydrogen ion concentration
Strong acids and bases _______ completely in water.
dissociate
What helps to maintain the normal pH value of most biological fluids near 7?
buffers
buffer
accepts hydrogen ions from the solution when they are in excess and donate hydrogen ions when they have been depleted
What makes up a buffer?
normally a weak acid and its corresponding base
pK value
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
When does a buffer have the greatest capacity to maintain its pH?
around its pK value
cohesiveness
from constantly forming and breaking hydrogen bonds in liquid water
high specific heat
it takes one calorie to raise one gram of water one degree Celsius
high heat of vaporization
it takes 540 calories to evaporate one gram of water
freezing point
water is densest at 4 degrees Celsius
-at 0 degrees Celsius, hydrogen bonds take up more space, making "solid" water less dense
Why is water an effective solvent?
it so readily forms hydrogen bonds with charged ions and polar covalent molecules
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
All cells have:

a.mitochondria
b.a cell wall
c.ribosomes
d.a nucleus
c.ribosomes
Organisms in the same class must also be in the same:

a.genus
b.order
c.family
d.phylum
e.species
d.phylum
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
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
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
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
Which of the following molecules is most capable of forming hydrogen bonds?

a.CH4
b.NaCl
c.NH3
d.H2
c.NH3
Of the following, which atomic number describes the least reactive element?

a.1
b.8
c.12
d.16
e.18
e.18
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.
True
solution
consists of a solute dissolved in a solvent
molarity
moles of solution per liter of solution
osmolarity
a method of expressing solution concentration based on the number of particles in a solution
osmolarity(osmol) =
molarity * (number of particles/molecule)
organic chemistry
the study of carbon compounds
What are the most versatile building blocks of molecules?
carbon atoms
hydrocarbons
molecules consisting of only carbon and hydrgen
isomers
molecules with the same molecular formula but different structures and properties
What are the three types of isomers?
structural, geometrical, and enantiomers
functional groups
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
hydroxyl
-OH
-alcohOL
carbonyl
-CHO
-ALdehyde
-ketONE
carboxyl
-COOH
-acid
amino
-NH2
-amine
sulfhydryl
-SH2
-thiol
phosphate
-PO4
-phosphate
monosacchrides
-may be linear
-can form rings
disacchrides
-consist of two monosacchrides
-are joined by a glycosidic linkage
-form by a dehydration reaction
polysacchrides
-polymers of sugar
-have basically two different functions in organisms - energy storage and structure
starch
a polymer consisting entirely of glucose monomers
-is the major storage form of glucose in plants
glycogen
-consists of glucose monomers
-is the major storage form of glucose in animals
cellulose
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
chitin
-found in the exoskeleton of arthropods
-can be used as surgical thread
What is the basic elemental composition of carbohydrates?
carbon, hydrogen, and oxygen
What are the key functional groups of carbohydrates?
hydroxyl and carbonyl groups
condensation reaction
forms glycosidic linkages between monomers to form dimers, and polymers of carbohydrates
What determines whether polysacchrides function as energy sources or as structural material?
linkages of polysacchrides
hydrolysis reaction
breaks down polysacchrides into monosacchride subunits
What is the most common monomer of polysacchrides?
glucose
lipids
-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
triglyceride (i.e. fat) =
fatty acid + glycerol
fatty acid =
long chain hydrocarbons + a carboxyl group at one end
essential fatty acid
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
How do you name unsaturated fatty acids?
indicated the position of the first double bond counting from the opposite end of the carboxyl group
omega carbon atom
the terminal carbon atom
saturated fatty acid
"saturated" with hydrogen atoms covalently bonded to carbon atoms
-no more can be added
-packed close together
-solid at room temperature
unsaturated fatty acid
have less hydrogen atoms because of one or more double bonds betwee carbon atoms
-"flow" at room temperature
monounsaturated
one double bond
polyunsaturated
more than one double bond
hydrogenated
converting unsaturated oils back back to saturated by adding hydrogen atoms
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
Why are trans fats bad for you?
trans fats are neither required nor beneficial for health
-increase the risk of coronary heart disease by raising bad cholesterol and lowering good cholesterol
fats
constructed from two types of smaller molecules, a single glycerol and three fatty acids
phospholipids =
2 fatty acids + glycerol + phosphate + organic group
wax
organic compounds formed from ester linkages between very long chain fatty acids and long chain fatty alcohols
True or False: Cholesterol and the steriods are fat-soluble molecules with a tetracyclic base structure.
True
What is the biological role of carbohydrates?
structure and energy molecules
What is the biological role of fats (lipids)?
structure and energy molecules
What is the biological role of phospholipids?
membrane structure
What is the biological role steriods/sterols?
membrane structure-hormones
plasma membrane
-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
Proteins in the plasma membrane...
can drift within the bilayer
What two factors affect the fluidity of the plasma membrane?
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
peripheral proteins
appendages loosely bound to the inner surface of the membrane
integral proteins
penetrate the hydrophobic core of the lipid bilayer
-are often transmembrane proteins, completely spanning the membrane
phospholipid
the primary molecular structure of the cell's boundary...makes a permeability barrier between aqueous regions, a matrix for functional proteins
cholesterol
reinforcement of phospholipid bilayer, facilitates fluidity at both high and low temperatures
glyco groups
the cell's identification molecules
proteins
a variety of functions
-signal transduction
-transport of molecules
-attachment points (to ECM/cytoskeletal fibers)
-cell recognition
-intercellular junctions
-enzymatic activity
amino acids
organic molecules possessing both carboxyl and amino groups
-differ in their properties due to differing side chains, called R groups
polypeptides
polymers of amino acids
protein
consists of one or more polypeptides
Four Levels of Protein Structure

Primary Structure:
the unique sequence of amino acids in a polypeptide
Four Levels of Protein Structure

Secondary Structure:
the folding or coiling of the polypeptide into a repeating configuration
Four Levels of Protein Structure

Tertiary Structure:
results from interactions between amino acids and R groups
Four Levels of Protein Structure

Quaternary Structure:
the overall protein structure that results from the aggregation of two or more polypeptide subunits
chaperonins
protein molecules that assist in the proper folding of other proteins
denaturation
when a protein unravels and loses it native conformation
nucleic acids
-composed of carbon, hydrogen, oxygen, phosphorus, and nitrogen
-monomer subunits: nucleotides
-functions: genetic information storage (DNA), protein synthesis (RNA)
What are the two major types of nucleic acids?
-DNA
-RNA
nucleotide monomers
made up of nucleosides and phosphate groups
In DNA, what forms the hydrogen bonds in the complementary fashion?
the nitrogenous bases
carbohydrate:
-monomer (unit molecule)
-large biomolecules (generic)
-specific examples of biomolecules
-linkage
-monosacchrides (glucose)
-polysacchrides
-amylose (starch), glycogen, amylopectin, cellulose
-glycosidic
lipids:
-monomer (unit molecule)
-large biomolecules (generic)
-specific examples of biomolecules
-linkage
-
-triglycerides, phospholipids, and waxes
-fats, oils
-ester
proteins:
-monomer (unit molecule)
-large biomolecules (generic)
-specific examples of biomolecules
-linkage
-amino acids (20 varieties)
-polypeptides, proteins
-structural proteins, enzymes
-peptide
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
Miller-Urey Experiment
tested the Oparin-Haldane hypothesis
-explains how simple inorganic molecules could react to form more complex organic molecules
abiotic replication of RNA
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"
protobiont
an aggregate of molecules (abiotically produced) surrounded by a "membrane"
generally prokaryotes are:
-microscopic
-ubiquitous
-unicellular
-genetically very diverse
prokaryotic cell shapes:
-rod (bacilli)
-spherical (cocci)
-spiral
cell wall of prokaryotes
maintains cell shape, provides physical protection, and prevents the cell from bursting in a hypotonic environment
-covered by a capsule
Gram positive
have a cell wall with large amounts of peptidoglycan
Gram negative
have less peptidoglycan, and is located in a layer between the plasma membrane and an outer membrane
capsule
a sticky layer of polysacchride or protein
fimbriae and pili
allow prokaryotes to stick to their substrate or other individuals in a colony
flagella
the way that bacteria propel themselves
Many prokaryotes form endospores...
which can remain viable in harsh conditions for centuries
photoautotroph:

-energy source
-carbon source
-types of organisms
-light
-carbon dioxide
-photosynthetic prokaryotes, plants, certain protists
chemoautotrophs

-energy source
-carbon source
-types of organisms
-inorganic chemicals
-carbon dioxide
-certain prokaryotes
photoheterotroph

-energy source
-carbon source
-types of organisms
-light
-organic compounds
-certain prokaryotes
chemoheterotroph

-energy source
-carbon source
-types of organisms
-organic compounds
-organic compounds
-many prokaryotes and protists, fungi, animals, and some parasitic plants
Archaea
share some traits with bacteria and with eukaryotes
size of prokaryote cells
1 to 10 micrometers
size of eukaryote cells
10 to 100 micrometers
resolving power
the smallest separation at which two separate objects can be distinguished
SEM
3-D image
TEM
internal ultrastructure of cells
Nucleus
-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
Plasma membrane
membrane enclosing the cell
Ribosomes
nonmembranous organelles that make proteins; free in cytoplasm or bound to rough ER or nuclear envelope
Golgi apparatus
organelle active in synthesis, modification, sorting, and secretion of cell products
Lysosome
digestive organelle where macromolecules are hydrolyzed
Mitochondrion
organelle where cellular respiration occurs and most ATP is generated
Peroxisome
organelle with various specialized metabolic functions; produces hydrogen peroxide
Microvilli
projections that increase the cell’s surface area
Microtubules:
-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
Intermediate filaments:
-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
Microfilaments:
-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)
Cytoskeleton:
reinforces cell’s shape, functions in cell movement; components are made of protein
Centrosome:
region where the cell’s microtubules are initiated; in an animal cell, contains a pair of centrioles (function unknown)
Flagellum:
locomotion organelle present in some animal cells; composed of membrane-enclosed microtubules
Endoplasmic reticulum:
network of membranous sacs and tubes; active in membrane synthesis and other synthetic and metabolic processes; has rough (ribosome-studded) and smooth regions
Nucleus:
nuclear envelope, nucleolus, and chromatin
Centrosome:
region where the cell’s microtubules are initiated; lacks centrioles in plant cells
Cell wall:
outer layer that maintains cell’s shape and protects cell from mechanical damage; made of cellulose, other polysaccharides, and protein
Plasmodesmata:
channels through cell walls that connect the cytoplasms of adjacent cells
Chloroplast:
photosynthetic organelle; converts energy of sunlight to chemical energy stored in sugar molecules
Tonoplast:
membrane enclosing the central vacuole
Central vacuole:
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
What does the endomembrane system contain?
-the nuclear membrane
-endoplasmic reticulum
-Golgi structures
-lysosomes
-vacuoles
What is the function of the endomembrane system?
regulates protein traffic and performs diversified metabolic functions in the cell
Endoplasmic Reticulum
-continuous with the nuclear envelope
-a network of tubules and sac-like foldings called "cisternae" having an interior - the lumen
-rough and smooth ER
RER
-ER with ribosomes attached
-produces secretory proteins
-produces membrane
SER
-ER without ribosomes attached
-synthesizes lipids
-metabolizes carbohydrates
-stores calcium
-detoxifies poisons
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
Lysosomes
Structure:
-a membranous sac of hydrolytic enzymes
Functions:
-digests all kinds of macromolecules
How do lysosomes carry out intracellular digestion?
phagocytosis
food vacuole
formed by phagocytosis
contractile vacuoles
pumps excess water out of protist cells
central vacuole
-found in plant cell
-holds reserves of water, ions, metabolic wastes, pigments, and protective compounds
mitochondrion
site of cellular respiration
chloroplast
site of photosynthesis
peroxisome
-breakdown of excess purines and fatty acids
-participates in the synthesis of cholesterol, bile acids, and lipids used to make myelin
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
passive transport
happens spontaneously, without an input of energy
-substances move down their concentration gradient
active transport
requires an addition of energy
-substances move against their concentration gradient
transport proteins
allow hydrophilic substances across the membrane
diffusion
the tendency for molecules of any substance to spread out evenly into the available space
facilitated diffusion
passive transport aided by proteins
-transport proteins speed the movement of molecules across the plasma membrane
What are the types of transmembrane proteins?
channel proteins and carrier proteins
osmosis
the net movement of water across a semipermeable membrane
What affects osmosis?
the concentration gradient of dissolved substances
tonicity
the ability of a solution to cause a cell to gain or lose water
-has a great impact on cells without walls
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
If a solution is hypertonic...
-the concentration of solutes is greater than inside the cell
-the cell will lose water
If a solution is hypotonic...
-the concentration of solutes is less than inside the cell
-the cell will gain water
turgid
rigid cell wall
flaccid
limp cell wall
-isotonic or hypertonic environment
sodium-potassium pump
-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
membrane potential
the voltage difference across a membrane
What two forces cause the electrochemical gradient?
-chemical - the ion's concentration gradient
-electrical - the effect of membrane potential on the movement of ions
electrogenic pump
a transport protein that generates the voltage across a membrane
-proton pump
cotransport
active transport driven by a concentration gradient
exocytosis
transport vesicles migrate to the plasma membrane, fuse with it, and release their contents
endocytosis
the cell takes in macromolecules by forming new vesicles from the plasma membrane
What are the three types of endocytosis?
phagocytosis, pinocytosis, and receptor-mediated endocytosis
resting potential
the membrane potential of a neuron that is not transmitting a signal
-it is -70 inside the cell
hyperpolarization
the membrane potential becomes more negative
depolarization
the membrane potential becomes less negative
action potential
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
What are the steps of action potential?
1.resting potential
2.threshold
3.depolarization
4.repolarization
5.undershoot
gated channel proteins
the channel responds to external stimuli that either permit or stop the flow of ions by opening or closing
ligand gated channel
the stimulus is a specific chemical
voltage gated channel
the stimulus is a change in the membrane potential
stretch gated channel
the stimulus is mechanical
depolarization of action potential
-sodium channels open
-sodium ions enter the cell
-entry of sodium into the cytoplasm depolarizes the cell membrane further, thereby opening more sodium channels
When the action potential reaches a terminal...
the final result is the release of neurotransmitters into the synaptic cleft
A neuron that is not transmitting signals...
contains many open potassium channels and fewer open sodium channels in its plasma membrane
-the membrane is selectively permeable to potassium ions
collagen fibers
embedded in a web of proteoglycan complexes
fibronectin
attaches the ECM to the integrins embedded in the plasma membrane
proteoglycan complex
consists of hundreds of proteoglycan molecules attached noncovalently to a single long polysacchride molecule
integrins
membrane proteins that are bound to the ECM on one side and to associated proteins attached to microfilaments on the other
extracellular matrix
support, adhesion, and transmembrane signaling
tight junctions
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
desmosomes
anchoring junctions
-fasten cells together into strong sheets
gap junctions
communicating junctions
-provide cytoplasmic channels from one cell to an adjacent cell
plasmodesmata
analogous to gap junctions in animal cells
-in plant cells
signal transduction pathway
convert signals on a cell's surface into cellular responses
local signaling
have cell junctions that directly connect the cytoplasm of adjacent cells
-animal cells may communicate via direct contact or using local regulators
paracrine signaling
a secreting cell acts on nearby cells by discharging molecules of a local regulator into the extracellular fluid
synaptic signaling
a nerve cell releases neurotransmitter molecules into a synapse, stimulating the target cell
What are the three stages of cell signaling?
-reception
-transduction
-response
protein phosphorylation
when a phosphate functional group is added to a protein to regulate the activity of that protein
protein kinase
the enzyme that adds phosphates to proteins
protein dephosphorylation
when a phosphate functional group is removed from a protein
protein phosphatase
the enzyme that removes phosphates from a protein
hormonal signaling
-long-distance signaling
-specialized endocrine cells secrete hormones into body fluids
-may reach all body cells
reception
a signal molecule (ligand) binds to a receptor protein, causing it to change shape
What are three types of membrane receptors?
-ion channel receptors
-G-protein-linked receptors
-receptor tryosine kinase
cAMP
a second messenger in a G-protein-signaling pathway
pathway branching and "cross-talk"...
further help the cell coordinate incoming signals
scaffolding proteins
can increase the signal transduction efficiency
How are signal responses terminated quickly?
by the reversal of ligand binding
1st Law of Thermodynamics
Energy is neither created nor destroyed
2nd Law of Thermodynamics
Entropy increases with a spontaneous reaction.
exergonic reaction
proceeds with a net release of free energy and is spontaneous
endergonic reaction
one that absorbs free energy from its surroundings and is nonspontaneous
competitive inhibition
an inhibitor blocks the binding site for the substrate
-overcome this by increasing the amount of substrate present
non-competitive inhibition
an inhibitor binds to the binding site and it makes the binding site for the substrate change shapes to not allow binding to occur
allosteric enzyme
an allosteric effector molecule binds to the enzyme and either activates or deactivates the binding site for the substrate
feedback inhibition
a reaction occurs and triggers the inhibitor to bind to the starting site of the reaction stopping the reaction from occuring
light energy goes in...
heat energy comes out
redox reactions
the transfer of "high energy" electrons in oxidation and reduction reactions
During cellular respiration, glucose is (oxidized,reduced) and oxygen is (oxidized,reduced).
-oxidized
-reduced
What are the three stages of cellular respiration?
-glycolysis
-citric acid cycle (krebs cycle)
-oxidative phosphorylation