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416 Cards in this Set
- Front
- Back
Six levels of organization
|
chemical
cellular tissue organ organ system organismal |
|
The five parts of the chemical level of organization
|
subatomic particles
atom molecule macromolecule organelle |
|
**The cell represents the ___ level of organization in the human body.
|
second
|
|
The cell is the smallest ___ unit we know of.
|
living
|
|
To understand the cell is to understand the ___.
|
body
|
|
**___ has been the rate-limiting step in determining what we know about cells.
|
technology
|
|
T/F: We cannot see, hear or touch cells.
|
true
|
|
Broad categories of techniques used in cell biology
|
microscopy
cell culture methods that separate part of the cell manipulation of DNA |
|
___ can solidify observations obtained through other techniques.
|
microscopy
|
|
Electron microscopes enlarge up to ___ times.
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1 million
|
|
___ may be the single most valuable tool used in studying cells.
|
cell culture
|
|
In cell cultures, cultures of a ___ can be maintained.
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single cell
|
|
Examples of processes that can be studied in a cell culture
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cell division
cell movement membrane function |
|
By ___, cellular organelles can be isolated and studied, e.g., macromolecules making up the cell can be separated by weight, electrical charge
|
separating components of the cell (cell fractionation)
|
|
___ is various techniques in which a mixture of dissolved components are separated while moving through a porous matrix.
|
chromatography (a technique for separating components of the cell)
|
|
The central theme in ___ is the use of bacteria and viruses and their natural enzymes.
|
DNA manipulation
|
|
Used in DNA manipulation of bacteria to cut DNA at specific sites
|
restriction endonucleases
|
|
Used in DNA manipulation of viruses to build DNA from RNA
|
reverse transcriptase
|
|
Manipulating DNA allows some intriguing possibilities, such as reconstructing (recombining) DNA to observe the ___ of key segments.
|
function
|
|
We can cut DNA into specific segments and then produce ___ of that segment (used in genetic testing).
|
large quantities
|
|
___ = cleave human DNA with restriction nuclease, get millions of genomic DNA fragments; DNA fragments are inserted into plasmids; these plasmids can be introduced into bacteria
|
DNA recombination (recombinant DNA molecules are now part of those plasmids)
|
|
The building block of all organisms
|
the cell
|
|
All organisms are composed of one or more ___.
|
cells
|
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Cells can only arise by division from a ___.
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preexisting cell
|
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The cell is the smallest ___ unit we know of.
|
living
|
|
T/F: Cells may subsist outside of their organism of origin
|
true (e.g., cell culture)
|
|
First example of isolating cells (early 50's), still using this cell line today
|
HeLa cells
|
|
Properties of cells:
1. very ___, very ___ 2. contain our genetic ___ 3. can ___ themselves 4. acquire and utilize ___ 5. carry out ___ reactions 6. engage in ___ activities 7. self-___ |
1. complex, organized
2. blueprint (DNA) 3. reproduce 4. energy 5. chemical 6. mechanical 7. regulate |
|
T/F: Every cell contains the entire genetic blueprint of the organism
|
true
|
|
Every cell on earth stores its genetic blueprint as ___.
|
DNA
|
|
Cells acquire and utilize energy in order to maintain ___.
|
cellular organization
|
|
___ serves as directions for reproducing and running the organism.
|
DNA
|
|
T/F: Cells can repair themselves and can even kill themselves
|
true
|
|
Two basic classes of cells
|
prokaryotic
eukaryotic |
|
The two basic classes of cells are distinguished on the basis of ___ and ___.
|
size
internal structures (organelles) |
|
Generally, ___ cells are larger and more complex.
|
eukaryotic
|
|
Class of cell without a (membrane-bound) nucleus
|
prokaryote
|
|
Class of cell with a (membrane-bound) nucleus
|
eukaryote
|
|
___ contain much more genetic information because they have a membrane-bound nucleus.
|
eukaryotes
|
|
Example of a prokaryotic cell
|
bacterium
|
|
___ lack organelles (ER, mitochondria, etc.)
|
prokaryotes
|
|
Plant and animal cells = ___ cells
|
eukaryotic
|
|
There are around ___ cells in the human body.
|
75 trillion
|
|
There are about ___ different cell types in the human body.
|
250
|
|
The various cell types differ greatly in terms of ___, ___, and ___.
|
shape
size function |
|
A cell that stores nutrients
|
fat
|
|
___ lay down extracellular matrix.
|
fibroblasts
|
|
Examples of cells that move organs and body parts
|
fibroblasts
erythrocytes epithelial skeletal muscle smooth muscle |
|
Cell that fights disease
|
macrophage
|
|
Cell that gathers information and controls body functions
|
nerve
|
|
Cell of reproduction
|
sperm
|
|
Cells performing a common function aggregate to form ___.
|
tissues
|
|
Four tissue types
|
epithelial
connective muscle nervous |
|
Although tissues will contain many cell types, each tissue will usually be composed of a ___ cell type.
|
predominant
|
|
RBCs are an example of ___ tissue.
|
connective
|
|
The three main parts of the eukaryotic cell
|
plasma membrane
cytoplasm nucleus |
|
Boundary of the eukaryotic cell
|
plasma membrane
|
|
The ___ of the eukaryotic cell contains various organelles.
|
cytoplasm
|
|
The ___ of the eukaryotic cell contains chromosomal DNA.
|
nucleus
|
|
Much of what we know about the cell has been obtained from a limited number of ___.
|
representative organisms
|
|
Advantages of learning about a cell from representative organisms
|
consistency
efficiency experimental ease |
|
Disadvantage of learning about a cell from representative organisms
|
certain findings could be organism-specific
|
|
The ___ cell has been crucial in learning about manipulating DNA.
|
E. coli
|
|
The nude mouse has been useful in research because ___
|
no thymus, therefore no T cells, and therefore doesn't reject lots of stuff
|
|
Cells are almost always ___ in size.
|
microscopic
|
|
Bacterial (prokaryotic) cells are typically ___ micrometers in length; eukaryotic cells are typically ___ micrometers.
|
1 - 5
10 - 30 |
|
The science concerned with the atomic composition of substances and their interactions
|
chemistry
|
|
___ considers the composition of substances and how they change.
|
chemistry
|
|
The properties of cells and organelles derive directly from the ___.
|
activities of their constituent molecules
|
|
Atoms can be subdivided into ___, ___, and ___ (but not through normal reactions).
|
neutrons
electrons protons |
|
___ are the simplest form of matter to have unique chemical properties.
|
atoms
|
|
T/F: Subatomic particles are not unique.
|
true
|
|
A proton from a carbon atom is ___ to a proton from an oxygen atom. However, ___ are unique.
|
identical
atoms (e.g., gold is different from silver, etc.) |
|
**The uniqueness of atoms is based on the ___ of neutrons, electrons and protons they contain.
|
number
|
|
Atoms contain a ___ consisting of ___ and ___.
|
central nucleus
protons neutrons |
|
Because protons have a positive charge and neutrons have no charge (neutral), an atom's nucleus is ___ charged.
|
positively
|
|
Protons and neutrons have about the same ___.
|
mass
|
|
___ are tiny particles which orbit the nucleus.
|
electrons
|
|
Electrons have a negative charge which ___ the positive charge of protons.
|
equals
|
|
Atoms have an equal number of protons and electrons, but the number of ___ may vary.
|
neutrons
|
|
Electrons have ___ the mass of protons/neutrons.
|
1/2000th
|
|
Each form of an atom is known as an ___.
|
element
|
|
Each element has unique ___ and ___ properties.
|
physical
chemical |
|
**___ are the smallest forms of matter that possess unique physical and chemical properties.
|
elements (atoms)
|
|
___ properties are detected with senses or measurement (e.g., color, texture, boiling/freezing points)
|
physical
|
|
___ differences of elements pertain to bonding behavior (iron rusts, gasoline combusts, animals digest, etc.).
|
chemical
|
|
**The uniqueness of any given element is solely due to this one factor
|
different elements contain different numbers of neutrons, electrons and protons
|
|
The ___ of an atom refers to the number of protons in its nucleus.
|
atomic number
|
|
The atomic number of an atom refers to the number of ___.
|
protons in its nucleus
|
|
The number of protons always equals the number of ___.
|
electrons
|
|
T/F: Since the number of protons always equals the number of electrons, the atomic number will also tell us the number of electrons in the atom.
|
true
|
|
The ___ of an atom refers to the total number of protons and neutrons in its nucleus.
|
mass number
|
|
The mass number of an atom refers to the ___.
|
total number of protons and neutrons in its nucleus
|
|
There are about ___ elements that have a normal physiological role in the body.
|
24
|
|
There are about ___ natural elements.
|
92
|
|
The four most important elements in the human body
|
oxygen
carbon hydrogen nitrogen |
|
Electrons are organized concentrically around the nucleus in ___.
|
electron shells (or energy levels)
|
|
Most atoms combine with other atoms to form ___.
|
molecules
|
|
Two basic types of molecules
|
molecules of an element
molecules of a compound |
|
Two or more atoms of the same element combine; cannot be broken down by chemical means
|
element (e.g., O + O = O2; H + H = H2)
|
|
Two or more different kinds of elements combine
|
compound (e.g., H2 + O = H2O)
|
|
In a ___, individual atoms lose their properties and assume its own properties (e.g., NaCl)
|
compound
|
|
A ___ is a relationship between electrons of interacting (reacting) atoms
|
chemical bond
|
|
T/F: Electrons are organized around the nucleus of an atom in concentric shells
|
true
|
|
There are ___ possible energy (concentric) shells that can organize around a nucleus.
|
seven
|
|
T/F: The first energy shell must be filled before the second, the second before the third, etc.
|
true
|
|
It is electrons in the ___ shell of one atom that will react with the electrons in the ___ shell of another atom.
|
outermost
outermost |
|
**A chemical reaction will occur when the ___ is incomplete.
|
outer shell
|
|
In ___ bonding, outer shell electrons are shared between reacting atoms.
|
covalent
|
|
In covalent bonding, outer shell electrons are ___ between reacting atoms.
|
shared
|
|
Outer shell electrons are shared between reacting atoms in ___ bonding.
|
covalent
|
|
In covalent bonding, the bonding between both atoms will fill the ___ of each atom.
|
outer electron shell
|
|
The benefit of covalent bonding for both atoms is that they will be ___.
|
stable
|
|
An ionic bond occurs following a ___ between atoms.
|
transfer of electrons
|
|
An ___ bond occurs following a transfer of electrons between atoms.
|
ionic
|
|
In ionic bonding, one atom ___ an electron and one atom ___ an electron.
|
loses
gains |
|
In ionic bonding, the ___ atom loses an electron; the ___ atom gains an electron.
|
donor
acceptor |
|
The donor atom that loses an electron in ionic bonding is now a(an) ___ charged ion.
|
positively
|
|
The acceptor atom that gains an electron is now a(an) ___ charged ion.
|
negatively
|
|
A positively charged ion is a(an) ___.
|
cation
|
|
A negatively charged ion is a(an)___.
|
anion
|
|
The cation and anion will attract each other because of ___ charges.
|
opposite
|
|
**The ___ bond results from the opposite-charge attraction between cation and anion.
|
ionic
|
|
Compounds, such as NaCl, dissociate in water to produce ions, which are called ___.
|
electrolytes
|
|
Important ions in the body involved in such things as nerve conduction, muscle contraction, enzyme function
|
electrolytes
|
|
The weakest of the three types of bonds
|
hydrogen
|
|
___ bonds are more like attractions and are not as strong as covalent and ionic bonds.
|
hydrogen
|
|
___ bonds form between slightly positive hydrogen atoms and other atoms, which are slightly negative.
|
hydrogen
|
|
___ is an excellent example of hydrogen bonds at work.
|
water
|
|
Water is a ___ molecule.
|
polar
|
|
A ___ occurs whenever chemical bonds are formed, broken, or rearranged.
|
chemical reaction
|
|
Chemical reactions can be written as ___.
|
equations (reactants --> product)
|
|
T/F: Many chemical reactions are reversible.
|
true
|
|
Most chemical reactions will exhibit a ___ (e.g., of synthesis, decomposition or exchange reaction)
|
pattern
|
|
Reaction which results in the formation of a larger, more complex molecule
|
synthesis
|
|
Type of reaction: A + B --> AB
|
synthesis
|
|
Reaction in which a molecule is broken down
|
decomposition
|
|
Type of reaction: AB --> A + B
|
decomposition
|
|
Reaction in which reactant molecules exchange 'partners'
|
exchange
|
|
Type of reaction: AB + CD --> AD + CB
|
exchange
|
|
One particular type of chemical reaction that is critical in living systems, the basis for which is a loss or gain of electrons in the reactants
|
redox reaction
|
|
A process by which a molecule loses one or more electrons and releases energy
|
oxidation
|
|
In oxidation when a molecule loses an electron, there will always be another molecule to accept that electron, usually ___.
|
oxygen
|
|
A process in which a molecule gains one or more electrons and gains energy
|
reduction
|
|
**The oxidation of one molecule is always accompanied by the ___ of another.
|
reduction
|
|
**The ___ of one molecule is always accompanied by the reduction of another.
|
oxidation
|
|
LEO the lion says GER
|
lose electron = oxidation
gain electron = reduction |
|
Oxidation-reduction reactions
|
redox
|
|
Redox reactions are ___ reactions.
|
decomposition
|
|
___ reactions are the basis for obtaining energy from food.
|
redox (i.e. decomposition)
|
|
The food we eat is broken down (digested) into small molecules which are then ___.
|
oxidized
|
|
Glucose is ___ to provide energy.
|
oxidized
|
|
The study of the chemistry of living organisms
|
biochemistry
|
|
The two classes of chemicals in the body
|
organic
inorganic |
|
The main inorganic compounds in the body
|
water
salts many acids and bases |
|
Compounds which contain carbon, are covalently bonded; many are large
|
organic
|
|
Organic compounds contain ___ and are ___ bonded.
|
carbon
covalently |
|
The most important and abundant inorganic compound in living material
|
water
|
|
___ is the major constituent of our bodily fluids.
|
water
|
|
Humans are more than half ___.
|
water
|
|
Five properties of water
|
1. high heat capacity
2. high heat of vaporization 3. polar solvent properties 4. reactivity 5. cushioning |
|
The high heat capacity of water is good for ___.
|
absorbing heat from muscular activity
|
|
The polar solvent properties of water are important because ___ must happen in solution.
|
biochemical reactions
|
|
___ uses heat from muscular activity.
|
evaporation (sweat)
|
|
Ionic compounds containing cations other than H+ and anions other than OH- (hydroxyl ion)
|
salts
|
|
Common salts in the body
|
NaCl (sodium chloride)
Ca2Co3 (calcium carbonate) KCl (potassium chloride) |
|
Salts dissociate into their ___ constituents in water.
|
ionic
|
|
Ions such as Ca++, Na+, Cl-, etc. are also known as ___.
|
electrolytes
|
|
Like salts, ___ and ___ are ionic compounds which dissociate in water.
|
acids
bases |
|
An ionic compound that releases a proton, or hydrogen ion (H+)
|
acid (sour taste)
|
|
An ionic compound that accepts a hydrogen ion (H+)
|
base (tastes bitter)
|
|
Many ___ are ionic compounds that dissociate to release OH- (NaOH --> Na+ + OH-). The hydroxyl ion then accepts H+ to form ___.
|
bases
water |
|
Another definition of salt: any compound that results from the chemical interaction of ___.
|
an acid and a base
|
|
Chemical interaction of an acid and a base
|
neutralization reaction
|
|
A classic ___ reaction:
HCl + NaOH --> NaCl + H2O (acid + base --> salt + water) |
neutralization
|
|
The pH scale was originally devised to measure the acidity of ___.
|
beer
|
|
pH is a measure of the ___ concentration of a solution.
|
hydrogen ion (i.e., acidity)
|
|
The greater the H+ concentration of a solution, the ___ the acidity.
|
higher
|
|
The lower the H+ concentration of a solution, the ___ the acidity.
|
lower
|
|
pH is a ___ logarithm
|
negative
|
|
lower acidity = ___ alkalinity
|
higher
|
|
The greater the H+ concentration, the ___ the pH value.
|
lower
|
|
The lower the H+ concentration, the ___ the pH value.
|
higher
|
|
Two exceptions to the rule that inorganic compounds don't contain carbon
|
CO
CO2 |
|
___ is the defining element of life.
|
carbon
|
|
Carbon is so essential to life because of its ___.
|
structure
|
|
Carbon never ___ or ___ electrons; it ___ them.
|
gains
loses shares |
|
Because carbon never gains or loses electrons (it shares them), it can form multiple ___ bonds with other atoms and other carbons.
|
covalent
|
|
Carbon is the basis of what four main categories of macromolecules
|
carbohydrates
lipids proteins nucleic acids |
|
**Carbohydates, lipids, proteins, and nucleic acids are all composed of at least some variation of ___, ___, and ___.
|
hydrogen
oxygen carbon |
|
T/F: Carbohydrates are hydrophobic
|
false (they are hydrophilic)
|
|
Water loving
|
hydrophilic
|
|
general chemical formula of carbohydrates
|
(CH2O)n
|
|
Most familiar carbohydrates are ___ and ___.
|
sugars
starches |
|
Carbohydrates are classified according to size: ___, ___ and ___.
|
monosaccharide (one sugar)
disaccharide (two sugars) polysaccharide (many sugars) |
|
three functions of carbohydrates
|
source of fuel
structure signaling |
|
T/F: Lipids are hydrophilic organic compounds
|
false (they are hydrophobic)
|
|
fear of water
|
hydrophobic
|
|
T/F: Lipids do not dissolve in water
|
true
|
|
Lipids have a high ratio of ___ to ___.
|
hydrogen
oxygen |
|
Three different types of lipids in the body
|
triglycerides (fats)
phospholipids (cell membranes) steroids (formed from cholesterol) |
|
Function of triglycerides (fats)
|
energy storage
|
|
Function of phospholipids
|
cell membranes
|
|
Steroids are formed from ___ and play a role in ____.
|
cholesterol
hormones |
|
All amino acids contain a central ___ atom, an ___ group and a ___ group.
|
carbon
amine carboxyl |
|
Number of common types of amino acids
|
20
|
|
T/F: All 20 common types of amino acids are identical except for the R group
|
true
|
|
There are ___ essential amino acids.
|
eight
|
|
Amino acids can __ or ___ a hydrogen atom.
|
accept
donate |
|
Proteins are made up of ___.
|
chains of amino acids
|
|
___ have the most varied functions of any molecule in the body.
|
proteins
|
|
___ are the basic structural material of the body.
|
proteins
|
|
___ accelerate chemical reactions (catalysts).
|
proteins
|
|
___ are used in communication within and between cells.
|
proteins
|
|
Three functions of proteins
|
1. basic structural material of the body
2. accelerate chemical reactions (catalysts) 3. used in communication within and between cells |
|
The structure of a protein will be determined by its constituent ___.
|
amino acids
|
|
**For proteins to function properly, a ___ is required.
|
precise structure
|
|
Secondary structure of protein is described by ___.
|
the three-dimensional structure (conformation) of sections of the polypeptide backbone (think beta sheet)
|
|
Primary structure of a protein is described by the ___.
|
amino acid sequence of a polypeptide (think chain)
|
|
Tertiary structure of protein is described by the ___.
|
conformation of the entire polypeptide
|
|
Quaternary structure of a protein is described by the arrangement of its ___.
|
subunits
|
|
The four structural levels of a protein
|
primary
secondary tertiary quaternary |
|
Enzymes are proteins that act as ___.
|
biological catalysts
|
|
Catalysts ___ reactions, but they ___ create reactions.
|
speed up
do not |
|
Enzymes ___ the activation energy required to make a reaction occur.
|
lower
|
|
Enzymes are/are not changed by the reaction
|
are not
|
|
nucleic acids
|
DNA
RNA |
|
Nucleic acids are so named because they are acids found in the ___ of cells.
|
nucleus
|
|
DNA = ___
|
deoxyribonucleic acid
|
|
RNA = ___
|
ribonucleic acid
|
|
**DNA and RNA are derived from the sugar ___.
|
ribose
|
|
**In DNA the sugar is called ___ since it is missing one oxygen.
|
deoxyribose
|
|
The nucleic acids are made up of ___.
|
nucleotides
|
|
The ___ molecule is referred to as a double-helix.
|
DNA
|
|
DNA, a double-helix molecule, is essentially a ___ of nucleotides.
|
double chain
|
|
The nucleotides of DNA are arranged in such a way as to create a ___ structure.
|
helical
|
|
The DNA double-helix contains a person's ___.
|
genetic code
|
|
The two fundamental roles of DNA
|
1. replicates itself before a cell divides
2. contains the blueprint required to make every protein in the body |
|
DNA ___ itself before a cell divides.
|
replicates
|
|
DNA contains the blueprint required to make every ___ in the body.
|
protein
|
|
Our bodies break down food into its smallest components to release energy, which is captured in the bonds of the molecule ___.
|
ATP
|
|
ATP uses the energy captured from the breakdown of food to drive ___.
|
cellular processes
|
|
The membrane that encompasses the cell
|
plasma membrane (cell membrane)
|
|
Protects, segregates the inside from the outside of the body
|
skin
|
|
T/F: Life would not be possible without membranes
|
true
|
|
___ enclose and sequester.
|
membranes
|
|
The plasma membrane is crucial to establishing vital differences between the ___ and the ___.
|
cytosol
extracellular environment |
|
the fluid inside the cell
|
cytosol
|
|
The cell (plasma) membrane is only about ___ wide.
|
5-10 nm
|
|
In electron micrographs all membranes share a common ___ appearance.
|
tri-laminar
|
|
Membranes are ___, ___ sheets. Thus membranes ___ areas.
|
continuous
unbroken enclose |
|
Compartmentalization of areas by membranes allows for ___.
|
specialization
|
|
The membrane provides an architectural foundation, or ___, for the cell.
|
scaffolding
|
|
The scaffolding provided by the cell membrane enables the ___ of mechanical signals between intra- and extra-celular structures and a means for ___ to take place.
|
transmission
biochemical reactions |
|
If you tug on any one "stick," you'll affect another part; the tug reverberates.
|
tensegrity
|
|
___ prevent the unrestricted movement of molecules from cytosol to extracellular space (and vice-versa).
|
membranes
|
|
Membranes are a ___ barrier.
|
selectively permeable
|
|
Passage across the cell membrane is ___; thus the internal environment of the cell is also ___.
|
controlled
controlled |
|
Cell membranes respond to external stimuli via structures on/in the membrane called ___.
|
receptors
|
|
the capacity to transform one type of energy into another
|
transduction
|
|
___ have the capacity to transform one type of energy into another (transduction).
|
membranes
|
|
In eukaryotes, transduction takes place in ___.
|
cytoplasmic membranes
|
|
In eukaryotes, transduction takes place in the cytoplasmic membranes by/in ___ and ___.
|
chloroplasts
mitochondria |
|
The concept of a ___ was proposed in 1925 using red blood cells.
|
lipid bilayer
|
|
The lipid bilayer is composed of ___.
|
phospholipids
|
|
Phospholipids provide two biochemically distinct groups: ___ and ___.
|
hydrophilic polar heads
hydrophobic lipid tails |
|
In phospholipids, the ___ interacts with the cytoplasm or extracellular fluid (water).
|
hydrophilic polar heads
|
|
Water and lipid ___ each other.
|
repel
|
|
Hydrophobic interactions are energy ___.
|
favorable
|
|
In hydrophobic interactions of water and lipids, non-polar molecules are forced into ___.
|
aggregates (the tails group together and polar heads face outward)
|
|
Membranes contain ___ in addition to lipids.
|
proteins
|
|
The term "___" derives from the fact that the membrane is not a solid and movement in the membrane is possible, and that the plasma membrane is composed of many different types of molecules.
|
fluid mosaic model
|
|
**The membrane is not a solid; it is a ___.
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fluid
|
|
T/F: Movement in the plasma membrane is possible.
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true
|
|
The plasma membrane is composed of many different types of molecules - it is a ___.
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mosaic
|
|
The plasma membrane is held together by ___ interactions.
|
hydrophobic
|
|
The two main roles of lipids in the plasma membrane
|
1. structural backbone
2. barrier to (most) polar molecules |
|
The three macromolecules of the plasma membrane
|
lipids
proteins carbohydrates |
|
containing both hydrophilic and hydrophobic regions
|
amphipathic
|
|
All lipids in the cell membrane are ___ (i.e., contain both hydrophilic and hydrophobic regions)
|
amphipathic
|
|
The three main categories of membrane lipids
|
phosphoglycerides
sphingolipids cholesterol |
|
T/F: Different cell membranes (and other membranes) have different lipid components; some may contain hundreds of chemically distinct lipids.
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true
|
|
The lipid profile of the membrane has important effects on the biological properties of the membrane, i.e., the ___ of the membrane and the ___ of membrane proteins.
|
physical state
function |
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T/F: The hydrophobic hydrocarbon tails of the membrane never interact with water.
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true
|
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T/F: The cell membrane has no free edge; it is continuous.
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true
|
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The implications of membrane continuity: formation of ___ in the cell.
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networks
|
|
The lipid bilayer provides the necessary flexibility to allow ___ (fluidity of the membrane)
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deformation
|
|
___ of the membrane is crucial during locomotion or cell division.
|
deformability
|
|
The lipid bilayer is thought to facilitate membrane ___ and ___.
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fusion (e.g., fertilization)
budding |
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T/F: The lipid bilayer has the ability to self-assemble.
|
true
|
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Membrane ___ can be demonstrated in vitro when phospholipids dispersed in aqueous solution will assemble into spherical vesicles (liposomes).
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self-assembly
|
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Liposomes have been used in various studies, such as vehicles for ___.
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drug delivery
|
|
Plasma membranes of eukaryotic cells contain carbohydrates - between ___ and ___% by weight.
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2
10 |
|
Most carbohydrate (about 90%) in the plasma membrane of eukaryotic cells is covalently linked to ___.
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proteins (glycoproteins)
|
|
About 10% of the carbohydrate in the plasma membrane is covalently linked to ___.
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lipids (glycolipids)
|
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All carbohydrate chains face ___ into extracellular space.
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outward
|
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Carbohydrate chains in the plasma cell membrane serve as ___.
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markers (recognition tags)
|
|
The two main purposes for glycoprotein carbohydrate chains
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1. extracellular interactions
2. intracellular protein trafficking |
|
T/F: Glycolipids' function is little known, yet it is likely important.
|
true
|
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T/F: Cells interact with their environment; cells must recognize each other and be able to work together.
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true
|
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Two examples of cells working together and recognizing each other
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1. immune system (e.g., blood typing)
2. fusion of sperm and egg |
|
Carbohydrate chains ensure that newly synthesized proteins reach the appropriate ___.
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destination
|
|
___ give the membrane its functional characteristics; ___ give the physical structure.
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proteins
lipid |
|
The amount and type of ___ in a membrane is highly variable.
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protein
|
|
Myelin sheath has about ___% protein by mass; mitochondrial membrane has about ___% protein by mass.
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25
75 |
|
Three distinct ways proteins are associated with the cell membrane
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integral proteins
peripheral proteins lipid-anchored proteins |
|
How a protein interacts with the lipid bilayer will reflect the ___ of the protein.
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function
|
|
Integral membrane proteins are also called ___ proteins.
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transmembrane (i.e., span entire membrane)
|
|
T/F: Transmembrane proteins span the entire bilayer and may span the bilayer more than once.
|
true
|
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Facts about integral proteins and their attachment:
1. They are ___ (have polar and non-polar regions). 2. The hydrophobic portions of the protein interact with the ___. 3. The protein is sealed into the lipid bilayer by ___ interactions. |
1. amphipathic
2. inner bilayer 3. van der Walls |
|
In van der Walls interactions that seal an integral protein into the lipid bilayer of the cell membrane, the relative ___ of the bilayer is maintained.
|
impermeability
|
|
Van der Waals forces refer to the momentary/weak ___.
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attraction of atoms to each other
|
|
T/F: Macromolecules with complementary surfaces can establish multiple van der Waals interactions.
|
true
|
|
Three functions transmembrane proteins perform on either side of the bilayer
|
1. receptors
2. channels or transporters 3. involved in energy transduction |
|
___ proteins are located entirely outside of the lipid bilayer.
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peripheral
|
|
T/F: Peripheral proteins are found on either side of the lipid bilayer.
|
true
|
|
Peripheral proteins associate via ___ interactions.
|
non-covalent
|
|
Peripheral proteins often form a membrane ___.
|
skeleton (e.g., spectrin in RBC)
|
|
The peripheral protein skeleton ___ the membrane and provides an ___ for integral proteins.
|
supports
attachment point |
|
T/F: Peripheral proteins have a dynamic relationship with the membrane.
|
true
|
|
Lipid-anchored proteins:
1. located ___ the lipid bilayer 2. found on both ___ and ___ sides 3. are ___ bonded to a lipid |
1. outside
2. cytosolic, extracellular 3. covalently |
|
Membrane fluidity implies that ___ and ___ molecules may move about in the membrane.
|
lipid
protein |
|
Membrane fluidity/movement generally occurs in the ___ plane.
|
horizontal
|
|
Membranes are fluid because their constituent molecules interact via ___ bonds.
|
non-covalent
|
|
___ interactions are key in membrane fluidity.
|
hydrophobic
|
|
Lipid movement is generally restricted to ___ of the bilayer.
|
one leaflet
|
|
T/F: With respect to lipid movement in the membrane, flip-flopping is possible but energetically unfavorable.
|
true
|
|
T/F: Within a leaflet of the bilayer, lipid movement is very slow.
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false (it's very rapid)
|
|
A single lipid may cross a bacterial membrane in ___, whereas a flip-flop could take ___.
|
1 second
days |
|
T/F: Within the bilayer, movement is generally restricted.
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false (it's generally unrestricted)
|
|
Although movement is generally unrestricted within the bilayer, parts of the membrane may be ___.
|
compartmentalized (fenced in)
|
|
The "fence" that compartmentalizes parts of the membrane may consist of ___.
|
integral proteins
|
|
T/F: Compartments in a membrane speed up lipid travel.
|
false (they slow travel)
|
|
Two general patterns of protein movement observed in the membrane
|
random
non-random (directed) |
|
Patterns of protein movement are likely dependent on the ___.
|
nature of the protein
|
|
Restrictions on membrane protein movement:
1. Some do not move - they are considered ___. 2. Some are crowded by other proteins - they have ___ movement. 3. Compartmentalized proteins have ___ movement. |
1. immobilized
2. reduced 3. somewhat restricted |
|
Membrane proteins are inhibited by ___ materials.
|
extracellular
|
|
A technique to show integral protein movement within the membrane in which specific proteins are labeled with a fluorescent dye and a small portion of the cells are irradiated, creating a bleached circle
|
FRAP (fluorescence recovery after photobleaching)
|
|
The cell must precisely regulate the ___ of the membrane in order to carry out specific activities.
|
fluidity (or the inverse, viscosity)
|
|
T/F: Cell processes could simply not occur in too rigid or too fluid a membrane.
|
true
|
|
The fluidity of a membrane is based primarily on ___ and ___.
|
lipid composition
external temperature |
|
With respect to membrane fluidity, it is important to understand that ___ can mitigate the effects of temperature.
|
lipid composition
|
|
The cell attempts to maintain a given membrane fluidity in the face of changing external conditions (mainly temperature) by appropriately modifying the ___ of the membrane. (cellular homeostasis)
|
lipid composition
|
|
As the body temperature is lowered below the normal body temp (37 degrees C) to a ___ temperature, the tails become more rigid and overall membrane fluidity is lowered.
|
transition
|
|
The temperature below which the movement of membrane molecules is greatly restricted
|
transition temperature
|
|
Transition temperature of the bilayer depends on the ability to pack individual ___ molecules together.
|
lipid
|
|
Tightly packed lipid molecules in the bilayer will have a ___ transition temperature.
|
higher
|
|
The membrane will assume ___ configuration at warmer temperatures.
|
crystalline gel
|
|
Saturated fatty acids are ___ rods; unsaturated fatty acids have ___ at the site of double bonds.
|
straight flexible rods
kinks |
|
The kinks in unsaturated fatty acids make it more ___ to pack these fatty acids together.
|
difficult
|
|
The ___ the unsaturation of fatty acids, the ___ the transition temperature.
|
greater
lower |
|
___ lipid hydrocarbon tails lower the transition temperature and reduce the tendency of the tails to interact with each other.
|
shorter
|
|
Three methods of adjusting membrane fluidity (keeping it more fluid)
|
1. more cis double bonds (i.e., more unsaturated fatty acids)
2. shorter chain length 3. more cholesterol molecules |
|
T/F: Shorter chain length reduces the tendency of tails to interact with each other, so less likely for chains to be packed together
|
true
|
|
T/F: Cholesterol is found in relatively high amounts in eukaryotic cells
|
true
|
|
T/F: Cholesterol molecules keep hydrocarbon tails from interacting (packing together) and results in a lower transition temperature.
|
true
|
|
T/F: The function of each leaf of the lipid bilayer is considerably different
|
true
|
|
___ are microdomains of the membrane composed of specific phospholipids that float within the less "ordered" lipid membrane.
|
lipid rafts
|
|
Lipid rafts are thought to serve as platforms for ___ performing a common task.
|
proteins
|
|
T/F: There is debate as to whether lipid rafts occur in a natural cell environment.
|
true
|
|
The two primary purposes of the plasma (cell) membrane
|
1. retain cell contents
2. selectively allow passage of substances into and out of the cell |
|
The bilayer must contain ___ permitting controlled passage of molecules.
|
proteins
|
|
T/F: Almost anything can cross a lipid bilayer given time.
|
true
|
|
A molecule's ability to cross the lipid bilayer is based on its ___ and ___.
|
size
polarity |
|
Which size molecular crosses the lipid bilayer faster - smaller or larger?
|
smaller
|
|
Which molecule crosses the lipid bilayer faster - polar or non-polar?
|
non-polar (hydrophobic)
|
|
Because a lipid bilayer alone would be too restrictive for the passage of many substances, the cell needs ___ to 'circumvent' the bilayer and allow substances to pass through.
|
membrane proteins
|
|
The two ways movement of substances across the cell membrane is accomplished
|
passively (not requiring energy)
actively (requiring energy) |
|
Three forms of diffusion across the cell membrane (passive movement)
|
1. simple
2. channel-mediated 3. facilitated |
|
In ___, substances pass directly through the lipid bilayer.
|
simple diffusion
|
|
In ___, substances pass through the lipid bilayer via a channel
|
channel-mediated diffusion
|
|
In ___, substances pass through the lipid bilayer via a carrier.
|
facilitated diffusion
|
|
Active movement of a substance through the lipid bilayer occurs via a ___.
|
transport protein
|
|
In active transport, the transport protein undergoes a ___.
|
configurational change
|
|
Passive movement of a substance across cell membranes is accomplished by ___ and ___.
|
diffusion
filtration |
|
In ___, molecules move randomly at very high speeds until they are evenly distributed.
|
diffusion
|
|
The net effect of movement through diffusion is that molecules will move from an area of ___ to an area of ___ until equilibrium is achieved.
|
higher concentration
lower concentration |
|
Molecules are said to move down their ___.
|
concentration gradient
|
|
The diffusion of water is referred to as ___.
|
osmosis
|
|
T/F: Water diffuses rapidly across cell membranes.
|
true
|
|
T/F: Even though the lipid bilayer is hydrophobic, water is able to cross it directly -individual water molecules may slip in between phospholipids.
|
true
|
|
___ are protein channels that permit a more rapid diffusion of water into/out of cells.
|
aquaporins
|
|
Water diffuses through the membrane of certain cells more rapidly than predicted for a simple lipid bilayer due to the presence of ___.
|
aquaporins
|
|
Aquaporins = ___ diffusion
|
channel-mediated
|
|
___ make possible the movement of ions across the membrane.
|
ion channels
|
|
T/F: Lipid membranes are considered highly impermeable to charged molecules (Na+, K+, etc.) even though the rapid movement of ions across the cell membrane is crucial.
|
true
|
|
Ion channels are ___ proteins.
|
integral (transmembrane)
|
|
Ion channels contain a central ___.
|
aqueous pore
|
|
The two main categories of ion channels
|
open (leak)
gated |
|
Three main types of gated ion channels
|
1. voltage-gated
2. ligand-gated 3. mechano-gated |
|
___ (ion) channels respond to voltage differences across the membrane.
|
voltage-gated
|
|
___ (ion) channels respond to binding of a specific molecule.
|
ligand-gated
|
|
___ (ion) channels respond to mechanical forces.
|
mechano-gated
|
|
Although ion-gated channels must allow extremely rapid movement of ions through the central pore, the channels must remain ___.
|
selective
|
|
Gated channels selectively allow ions through by use of a ___.
|
selectivity filter
|
|
The selectivity filter for an ion channel permits both ___ and ___ of ion passage.
|
speed
selectivity |
|
In order to get the ion of choice through an ion channel, the channel ___ the energy barrier.
|
lowers (energy required to get through fast)
|
|
For substances that do not cross the membrane or use a channel, an ___ that facilitates passage is necessary.
|
integral membrane protein (a facilitative transporter)
|
|
___ are often used by polar molecules such as glucose or amino acids to facilitate passage through the membrane.
|
facilitative transporters
|
|
T/F: Facilitative transporters can move solutes in either direction (depends on the concentration gradient).
|
true
|
|
Facilitative transporters assume a particular ___ to accept a specific molecule.
|
conformation
|
|
In facilitated diffusion, once the molecule is bound, the transporters change ___ to allow release of the molecule on the other side of the membrane.
|
configuration/confirmation
|
|
In order for diffusion to occur through a plasma membrane, the membrane must be ___.
|
semi-permeable
|
|
___ is a process in which substances travel down a concentration gradient.
|
diffusion
|
|
___ is used when passive transport is not possible.
|
active transport
|
|
In active transport, substances are being moved ___ the concentration gradient.
|
against (up)
|
|
T/F: Active transport is used for substances too large for channels or carriers (vesicular transport).
|
true
|
|
Active transport requires the energy of ___.
|
ATP
|
|
The sodium-potassium pump is an example of ___.
|
active transport
|
|
The concentration of ___ is much higher outside the cell.
|
Na+
|
|
The concentration of Na+ is much ___ outside the cell than inside.
|
higher
|
|
The concentration of ___ is much higher inside the cell.
|
K+
|
|
The concentration of K+ is much ___ inside the cell.
|
higher
|
|
The normal condition of a higher Na+ concentration outside the cell and a higher K+ concentration inside the cell is necessary for an ___ to take place (i.e., necessary for proper cellular function).
|
action potential
|
|
Cellular ionic concentration gradients would be rapidly lost if not for the action of the ___.
|
Na+/K+ pump
|
|
The Na+/K+ pump burns ___ of our daily calories.
|
half
|