Download Chapter 5 Test Answers

Chapter 5 Test
Membranes are composed of:____________________with embedded and attached proteins in a
structure called a______________
In animal cell membranes, cholesterol helps: stabilize____________at warm temp, and
keep_________________ at lower temperature
Membrane proteins perform many functions: Some membrane proteins:
-maintain cell shape through attachment to________________and ___________________
- function as____________for chemical messengers from other cells
- function as__________
- Membrane glycoproteins are involved on the intercellular junctions that attach_____________to each
other
- Membranes may exhibit_______________, allowing some substances to cross more easily than others
Phospholipids, the key ingredient of___________, spontaneously self-assemble into________________
The formation of membrane-enclosed collections of molecules was a critical step in the evolution of the
___________
_______________is diffusion across a membrane with no energy investment
Diffusion –________________________________________________________________
This means that particles diffuse down their__________________________
Eventually the particles reach_________________where the concentration is the same throughout
Diffusion across a cell membrane does not require__________so it is called passive transport
The concentration gradient itself represents___________________for diffusion
Osmosis- ____________________________________________________________________
If a membrane permeable to water (but not to a solute) separates 2 solutions with different
concentrations of solute:
-
Water will cross the______________
Moving down its own_____________________________
Until the solute concentration on both sides is_________
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Water balance btwn cells and their surroundings is crucial to organisms
Tonicity - ______________________________________________________________________
Tonicity mostly depends on concentration of a____________on both sides of the______________
Isotonic Solution – the concentration of solute is ________________of the membrane and cell volume
___________ change
Hypotonic Solution – solute concentration is _________outside cell, water molecules move______ cell,
and the cell will _______________
Hypertonic Solution – solute concentration is _________outside of cell, so water molecules
move________of cell and the cell will __________
For an animal cell to survive in a hypotonic or hypertonic solution environment, it must engage in
Osmoregulation- __________________________
Hydrophobic substances_________diffuse across membrane
Polar or charged molecules do not easily cross cell membranes, and instead move across membranes
with the help of________________in process called Facilitated Diffusion which:
-
Does not require_____________
And relies on the_____________
Channel Proteins: proteins that function by becoming a______________for passage of ions or other
molecules
Carrier proteins: proteins that __________________________________________________________
In both of these situations that protein is specific for the substrate which can be sugars, amino acids,
ions, and even water
Because water is________, its diffusion through a membrane’s hydrophobic interior is relatively_______
The very rapid diffusion of water into and out of certain cells is made possible by a protein channel
called an_______________
Cells expend _________in the active transport of a ____________
In active transport, a cell: must expend _______to move a solute against its___________________
A cell uses 2 mechanisms to move large molecules across membranes
Exocytosis – ______________________________________________________________________
Endocytosis – _____________________________________________________________________
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In both cases, material to be transported is packaged w/in a___________ that fuses with the membrane
3 kinds of endocytosis:
Phagocytosis – engulfment of a particle by______________________________, forming a___________
Pinocytosis – is the same thing except that____________are taken into small vesicles
Receptor –Mediated Endocytosis: uses___________in a receptor-coated pit to interact with a specific
protein, initiating the formation of a_____________
Cells are small units, a chemical factory, housing thousands of chem reactions
Cells use these chem reactions for:
-Cell______________________
-Manufacture of________________
-And______ replication
Energy- _________________________________________________________________
2 kinds of energy:_________________and_________________________
Heat: type of__________energy; associated with random movement of_______________________
Light: type of_______________energy; can be harnessed to power___________________
Thermodynamics: study of energy______________________ that occur in____________
-
Law 1: energy in universe is____________
Law 2: energy conversions increase___________of universe
Entropy: measure of__________________
5.11 chem reactions either release or store energy
Cells use oxygen in reactions that____________ energy from fuel molecules
In_________________________, the chemical energy stored in organic molecules is converted to a form
that the cells can use to perform work
Chemical reactions either:
Release energy (________________Reactions)
Require input of energy and store energy (____________________Reactions)
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Exergonic Reactions:
Release energy in _________________bonds of the____________________
-
Burning wood releases energy in Glucose as _________ and ____________
Cellular Respiration :
o Involves many steps
o Releases energy__________
o Uses some of released energy to produce_____
Endergonic Reactions:
Requires________________________; Yields products rich in __________________________
Begins with reactant molecules that contain little _______________________
End with products that contain more_________________________
Photosynthesis:
Type of __________________________________process
Energy-__________ reactants, ______ and H2O are used
Energy is absorbed from ______________
Energy-rich _____________________________ are produced
Energy-Coupling:
Uses the: Energy released from exergonic reactions to drive_______________________________
Usually using energy stored in______________________
5.12 ATP drives cellular work by coupling________________ and ___________________ reactions
ATP (________________________) powers___________________
Consists of:
- Nitrogenous base__________
- 5 Carbon sugar ___________and
- 3 _________________
Hydrolysis of ATP releases energy by__________________________________________________to
some other molecules in a process called Phosphorylation
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Most cellular work depends on ATP energizing molecules by ______________________________
Is ATP renewable or non-renewable?
List the 3 main types of cellular work:________________________________________________
What drives all three of these types of work?
5.13 enzymes speed up cell’s chem reactions by lowering _____________
Although biological molecules possess much__________energy, it is not released spontaneously
An______________ must be overcome before a chem reaction can begin
This energy is called the ____________________(EA)
Enzymes
Function as biological ___________ by lowering _______needed for reaction to begin
Increase the __________________without being consumed by the reaction and
Are usually____________, although some ___________molecules can function as enzymes
An Enzyme:
-
Is very selective on the _______________it catalyzes
Has a shape that determines enzyme’s ______________
The specific reactant that an enzyme acts on is called the enzyme’s __________
A (previous answer) __________fits into a region of the enzyme called the _______________
Enzymes are specific because their ______________fits only specific _________molecules (HINT: both
blanks are previous answers)
An enzyme’ optimal temp produces the ___________rate of contact btwn the reactants and enzyme’s
________________
The optimal pH for most enzymes is ________________________
Cofactors - ______________________________________________________________________
-
Bind to _______________
Function in _______________
If a cofactor is an organic molecule, such as most______________, it is called a ________________
Inhibitor - ___________________________________________________________________
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Competitive Inhibitors
- block substrates from entering _______________
- reduce enzyme’s _____________________
Non - Competitive Inhibitors
-
Bind to enzyme somewhere other than active site
- Change _________ of active site
- Prevent __________ from binding
Chapter 5 Test Answers
Membranes are composed of: a bilayer of phospholipids with embedded and attached proteins in a
structure called a fluid mosaic
In animal cell membranes, cholesterol helps: stabilize membranes at warm temp, and keep membrane
fluid at lower temperature
Membrane proteins perform many functions: Some membrane proteins:
-maintain cell shape through attachment to cytoskeleton and extracellular matrix
- function as receptors for chemical messengers from other cells
- function as enzymes
- Membrane glycoproteins are involved on the intercellular junctions that attach adjacent cells to each
other
- Membranes may exhibit selective permeability, allowing some substances to cross more easily than
others
Phospholipids, the key ingredient of biological membranes, spontaneously self-assemble into simple
membranes
The formation of membrane-enclosed collections of molecules was a critical step in the evolution of the
first cells
Passive Transport is diffusion across a membrane with no energy investment
Diffusion – tendency of particles to spread out evenly in an available space
This means that particles diffuse down their concentration gradient
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Eventually the particles reach equilibrium where the concentration is the same throughout
Diffusion across a cell membrane does not require energy so it is called passive transport
The concentration gradient itself represents potential energy for diffusion
osmosis- diffusion of water across a selectively permeable membrane
If a membrane permeable to water (but not to a solute) separates 2 solutions with different
concentrations of solute:
-
Water will cross the membrane
-
Moving down its own concentration gradient
-
Until the solute concentration on both sides is equal
Water balance btwn cells and their surroundings is crucial to organisms
Tonicity – term that describes the ability of a solution to cause a cell to gain or lose water
Tonicity mostly depends on concentration of a solute on both sides of the membrane
Isotonic Solution – the concentration of solute is the same on both sides of the membrane and cell
volume won’t change
Hypotonic Solution – solute concentration is lower outside cell, water molecules move into cell, and the
cell will expand and may burst
Hypertonic Solution – solute concentration is higher outside of cell, so water molecules move out of cell
and the cell will shrink
For an animal cell to survive in a hypotonic or hypertonic solution environment, it must engage in
Osmoregulation- the control of water balance
Hydrophobic substances easily diffuse across membrane
Polar or charged molecules do not easily cross cell membranes, and instead move across membranes
with the help of specific transport proteins in process called Facilitated Diffusion which:
-
Does not require energy
-
And relies on the concentration gradient
Channel Proteins: proteins that function by becoming a hydrophilic tunnel for passage of ions or other
molecules
Carrier proteins: proteins that bind passenger, change shape, and release their passenger on other side
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In both of these situations that protein is specific for the substrate which can be sugars, amino acids,
ions, and even water
Because water is polar, its diffusion through a membrane’s hydrophobic interior is relatively slow
The very rapid diffusion of water into and out of certain cells is made possible by a protein channel
called an aquaporin
Cells expend energy in the active transport of a solute
In active transport, a cell: must expend energy to move a solute against its concentration gradient
A cell uses 2 mechanisms to move large molecules across membranes
Exocytosis – used to export bulky molecules such as proteins or polysaccharides
Endocytosis – used to import substances useful to the livelihood of the cell
In both cases, material to be transported is packaged w/in a vesicle that fuses with the membrane
3 kinds of endocytosis:
Phagocytosis – engulfment of a particle by wrapping cell membrane around it, forming a vacuole
Pinocytosis – is the same thing except that fluids are taken into small vesicles
Receptor –Mediated Endocytosis: uses receptors in a receptor-coated pit to interact with a specific
protein, initiating the formation of a vesicle
Cells are small units, a chemical factory, housing thousands of chem reactions
Cells use these chem reactions for:
-Cell maintenance
-Manufacture of cellular parts
-And cell replication
Energy- capacity to cause change or to perform work
2 kinds of energy: kinetic and potential
Heat: type of kinetic energy; associated with random movement of atoms or molecules
Light: type of kinetic energy; can be harnessed to power photosynthesis
Thermodynamics: study of energy transformation that occur in matter
-
Law 1: energy in universe is constant
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-
Law 2: energy conversions increase disorder of universe
Entropy: measure of disorder or randomness
5.11 chem reactions either release or store energy
Cells use oxygen in reactions that release energy from fuel molecules
In cellular respiration, the chemical energy stored in organic molecules is converted to a form that the
cells can use to perform work
Chemical reactions either:
Release energy (Exergonic Reactions)
Require input of energy and store energy (Endergonic Reactions)
Exergonic Reactions:
Release energy in covalent bonds of the reactants
- Burning wood releases energy in Glucose as heat and light
- Cellular Respiration :
o
o
o
Involves many steps
Releases energy slowly
Uses some of released energy to produce ATP
Endergonic Reactions:
Requires input of energy; Yields products rich in potential energy
Begins with reactant molecules that contain little potential energy
End with products that contain more chemical energy
Photosynthesis:
Type of endergonic process
Energy-poor reactants, CO2 and H2O are used
Energy is absorbed from sunlight
Energy-rich sugar molecules are produced
Energy-Coupling:
Uses the: Energy released from exergonic reactions to drive essential endergonic reactions
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Usually using energy stored in ATP molecules
5.12 ATP drives cellular work by coupling exergonic and endergonic reactions
ATP (adenosine triphosphate) powers nearly all forms of cellular work
Consists of:
- Nitrogenous base adenine
- 5 Carbon sugar Ribose and
- 3 Phosphate Groups
Hydrolysis of ATP releases energy by transferring its 3rd phosphate from ATP to some other molecules in
a process called Phosphorylation
Most cellular work depends on ATP energizing molecules by phosphorylating them
Is ATP renewable or non-renewable? Renewable
List the 3 main types of cellular work: Chemical; Mechanical; Transport
What drives all three of these types of work? ATP
5.13 enzymes speed up cell’s chem reactions by lowering energy barriers
Although biological molecules possess much potential energy, it is not released spontaneously
An energy barrier must be overcome before a chem reaction can begin
This energy is called the activation energy (EA)
Enzymes:
Function as biological catalysts by lowering EA needed for reaction to begin
Increase the rate of a reaction without being consumed by the reaction and
Are usually proteins, although some RNA molecules can function as enzymes
An Enzyme:
-Is very selective on the reaction it catalyzes
-Has a shape that determines enzyme’s specificity
The specific reactant that an enzyme acts on is called the enzyme’s substrate
A (previous answer) substrate fits into a region of the enzyme called the active site
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Enzymes are specific because their active site fits only specific substrate molecules (HINT: both blanks
are previous answers)
An enzyme’ optimal temp produces the highest rate of contact btwn the reactants and enzyme’s active
site
The optimal pH for most enzymes is near neutrality
Cofactors – non-protein helpers of enzymes
-
Bind to active site
Function in catalysts
If a cofactor is an organic molecule, such as most vitamins, it is called a coenzyme
Inhibitor - A chemical that interferes with an enzyme’s activity
Competitive Inhibitors
-
block substrates from entering active site
- reduce enzyme’s productivity
Non - Competitive Inhibitors
-
Bind to enzyme somewhere other than active site
- Change shape of active site
- Prevent substrate from binding
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