Bio Test1

Front 1

permeable

Back 1

allows substances to pass through

Front 2

hydrophobic

Back 2

"water fearing" molecules - usually non-polar molecules which have lower free energy when clustered together than when exposed to aqueous environments

Front 3

hydrophillic

Back 3

"water loving" molecules - water soluable - usually polar or charged

Front 4

integral proteins

Back 4

membrane proteins that penetrate the phospholipid bilayer

Front 5

peripheral proteins

Back 5

membrane proteins that associate only with surfaces of membranes

Front 6

diffusion

Back 6

random kinetic movement of molecules that results in net movement of particle from areas of high concentration to areas of low concentration

Front 7

osmosis

Back 7

movement of water across semi-permeable membranes, from areas of low-osmotic concentration to areas of high osmotic concentration

Front 8

hypotonic

Back 8

solution with lower osmotic concentration relative to another solution

Front 9

hypertonic

Back 9

solution with higher osmotic concentration relative to another solution

Front 10

isotonic

Back 10

solutions with same osmotic concentration

Front 11

amphipathic

Back 11

describes a molecule that has both hydrophillic and hydrophobic regions

Front 12

electrochemical gradient

Back 12

Diffusion gradient resulting from the combined effects of membrane potential and concentration gradient

Front 13

membrane potential

Back 13

the charge difference between the cytoplasm and fluid outside of the cell due to a differential distribution of ions

Front 14

cotransport

Back 14

the coupling of the facilitated diffusion of one substance to
the transport by active process of another substance against the
concentration gradient

Front 15

saturated

Back 15

Fatty acids with carbons joined by a single bond.

Front 16

unsaturated

Back 16

Fatty acids with some carbons joined by double bonds.

Front 17

List the function(s) of "integral proteins"

Back 17

communication between extracellular and intracellular
compartments

examples :
1) ion channels
2) nuclear pores
3) transport proteins
4) gap junctions

Front 18

List the function(s) of "phospholipid portion of the membrane"

Back 18

1) provide structural integrity 2) serve as barrier between cell and environment

Front 19

List the function(s) of "membrane carbohydrates"

Back 19

important in cell recognition events

Front 20

List the differences of plasma membranes between prokaryotes and eukaryotes

Back 20

1) Prokaryotic membranes do not contain cholesterol
2) Types of membrane proteins differ between eukaryotic and prokaryotic cell

Front 21

What are 3 ways of getting substances across membranes in both eukaryotic and prokaryotic cells?

Back 21

1) exocytosis / endocytosis
2) simple diffusion
3) facilitated diffusion
4) active transport

Front 22

How can you tell the difference between simple and facilitated diffusion?

Back 22

Simple:
the rate of diffusion is directly proportional to concentration

Facilitated:
the rate of diffusion will eventually reach a maximal rate, dictated by membrane protein concentration.

Front 23

What do endocytosis, receptor-mediated endocytosis, pinocytosis, phagocytosis, and exocytosis have in common?

Back 23

Are all membrane mediated events - involving encapsulation of particles within membrane bound vesicle, fusion of membranes

Front 24

Match appropriate letters.

Lipid Bilayer
Membrane Proteins
Glycolipids
Glycoproteins

A) Cellular communication
B) Permeability barrier
C) Membrane transport
D) Accelerate reactions
E) Molecule recognition

Back 24

Lipid Bilayer - B
Membrane Proteins - A,C,D,E
Glycolipids - A
Glycoproteins - A

Front 25

What will happen to a animal if immersed in the solutions:
Hypotonic
Hypertonic
Isotonic

Back 25

Hypotonic - burst (lyse)
Isotonic - shrivel
Isotonic - normal

Front 26

What will happen to a plant if immersed in the solutions:
Hypotonic
Hypertonic
Isotonic

Back 26

Hypotonic - stable (turgid)
Isotonic - shrivel (plasmolysis)
Isotonic - wilt (flaccid)

Front 27

What will happen to a bacterium if immersed in the solutions:
Hypotonic
Hypertonic
Isotonic

Back 27

Hypotonic - stable (turgid)
Isotonic - shrivel (plasmolysis)
Isotonic - wilt (flaccid)

Front 28

What will happen to a fungi if immersed in the solutions:
Hypotonic
Hypertonic
Isotonic

Back 28

Hypotonic - stable (turgid)
Isotonic - shrivel (plasmolysis)
Isotonic - wilt (flaccid)

Front 29

Compare and contrast the role of the plasma membrane of a cell with the skin of an animal

Back 29

Similarities:
Both serve as protective barrier, Both allow nonspecific passage of lipid soluble molecules

Difference:
Skin (outer dead layer) does not have active transport mechanisms

Front 30

What are some of the major ways in which a cell membrane controls interactions with the environment?

Back 30

1) Regulates traffic of molecules into and out of cell
2) Mediates cell-cell recognition events
3) Receives and transduces environmental stimuli via receptors

Front 31

Compare and contrast facilitated diffusion and active transport

Back 31

Similarities:
Involve transmembrane (integral) carrier proteins / require specific
recognition phenomenon

Differences:
Facilitated is passive, substances move down concentration gradient
Active requires energy, moves substances against concentration gradient

Front 32

What role does the Na-K pump play in transport?

Back 32

1) Serves to maintain elevated extracellular [Na+] and low intracellular [K+]
2) Sets up Na+ gradient that can be used to do work (like move glucose into cell
against gradient)

Front 33

A particular membrane is said to be permeable to water and sodium, but impermeable to sucrose. How can you explain this difference?

Back 33

Most membranes are permeable to water, Na+ passes thru ion channels, no transport protein available for sucrose and sucrose too large (also polar) to cross lipid bilayer via simple diffusion.

Front 34

What is the cross sectional width of a typical plasma membrane

Back 34

8 nanometers
8 * 10^9

Front 35

What is the chemical formula for Glucose

Back 35

C6H12O6

Front 36

How does an enzyme function to facilitate chemical reactions? (2 answers)

Back 36

a) couples endergonic and exergonic reactions
b) decreases activation energy

Front 37

What do Km and Vmax mean to an enzyme reaction?

Back 37

Km = affinity between enzyme and substrate
Vmax = maximum velocity of enzyme-catalyzed reaction (velocity at enzyme saturation)

Front 38

How do temperature, pH, amount of enzyme and substrate concentration affect enzyme reactions?

Back 38

Temperature and pH:
affect enzyme activity levels

Amount of enzyme:
affects Vmax (as amount of enzyme, ( Vmax)

Substrate concentration: affects rate of reaction (as ( [S], ( rate of reaction til
reach enzyme saturation

Front 39

What is feedback inhibition in allosteric reactions? Give examples.

Back 39

Feedback inhibition refers to a form of metabolic regulation in which the end products of a metabolic pathway inhibit an enzyme that catalyzes one of the steps in the pathway, thus turning down the rate at which that pathway produces
product.
(Figure 6.16)

Front 40

Catalyst

Back 40

chemical substance that accelerates the rate at which a reaction occurs without itself being consumed during the reaction. Catalysts act by lowering the activation energy.

Front 41

activation energy

Back 41

energy barrier that must be overcome before reactions can proceed (the energy that must be put in to get the reaction to go)

Front 42

enzyme

Back 42

biological catalyst, typically a protein (although there are examples of RNA enzymes, called ribozymes)

Front 43

substrate

Back 43

reactant molecule recognized (bound by) an enzyme

Front 44

active site

Back 44

region (site) within the enzyme molecule where the substrate binds and where catalysis occurs

Front 45

allosteric site

Back 45

region (site) separate and distinct from the active site where allosteric effector (or
egulator) molecules bind to the enzyme

Front 46

inhibitor

Back 46

molecule that binds to the enzyme and in so doing, reduces its catalytic activity
(decreases the rate of the reaction)

Front 47

metabolism

Back 47

all the chemical reactions that take place within a living organism

Front 48

catabolic pathways

Back 48

degradative processes in which complex molecules are broken down into simpler molecules to release energy
(example: polymers are broken down to monomers
via hydrolysis reactions)

Front 49

potential energy

Back 49

energy with the potential to be released

Front 50

kinetic energy

Back 50

the energy of motion, which is directly related to the speed of that motion. Moving matter does work by transferring some of its kinetic energy to other
matter that it interacts with.

Front 51

energy

Back 51

the capacity to do work

Front 52

energy

Back 52

the capacity to do work

Front 53

1st and 2nd laws of thermodynamics

Back 53

the laws that govern energy transformations in organisms and other collections of
matter.

1st law of thermodynamics states that "energy can be transformed and
transferred, but it can be neither created nor destroyed".

2nd law of
thermodynamics states that "every energy transfer or transformation increases the
entropy of the universe", usually in the form of heat.

Front 54

free energy

Back 54

the portion of a system's energy that is available to do work

Front 55

equilibrium

Back 55

with respect to a chemical reaction, the point when there is no further change in
the concentration of products and reactants;

also refers to the point in a reaction when the free energy is lowest (as move towards equilibrium, free energy decreases; as move away from equilibrium, the free energy increases).

Front 56

cooperativity

Back 56

a mechanism for increasing enzyme activity that is observed only in enzymes
comprised of 2 or more subunits, each of which has an active site: binding of one
substrate molecule alters the conformation of the enzyme so that it more readily
binds additional substrate molecule
(FIGURE 6.15)

Front 57

What is the role of enzymes in biochemical reactions?

Back 57

a) increase the rate of exergonic reactions
b) to couple exergonic reactions and endergonic reactions

Front 58

List factors that may alter the activity of an enzyme.

Back 58

pH, temperature, [substrate], [enzyme], presence/absence of inhibitors, allosteric effectors

Front 59

Explain the induced fit theory of enzyme activity

Back 59

The binding of substrate to the active site of the enzyme induces a slight change in
the conformation (shape) of the enzyme such that there is a better fit between the
substrate and the enzyme

Front 60

Distiniguish between a competitive and non-competitive inhibitor. (in regard to rate of reaction, Km, Vmax)

Back 60

Competitive:
binds to the active site, Km increases; at low [substrate], inhibitor
↓
reaction rate; however, this inhibition can be overcome at high [substrate], Vmax is
the same

Noncompetitive:
binds to enzyme at site other than the active site inducing a
change in the conformation of the enzyme molecule. In most cases Km remains the same. The rate is decreased at low [substrate]. There is a lower Vmax;
inhibition cannot be overcome by high [substrate],

Front 61

Explain how feedback inhibition works. Why is allosteric regulation important?

Back 61

Feedback inhibition refers to a form of metabolic regulation in which the endproducts of a metabolic pathway inhibit an enzyme that catalyzes one of the steps in the pathway, thus turning down the rate at which that pathway produces
product. (see figure 6.16 in your text for an example). Allosteric regulation is
important because it prevents the cell from wasting resources (prevents cell from
making products it has sufficient quantities of); also prevents the potentially toxic
buildup of products in the cell.

Front 62

The 1st law tells us that energy can be incoverted but not destroyed, while the 2nd law says there is always a price to pay in conversion.

What is the that price and how does it relate to biological processes?

Back 62

The price to pay is energy lost in every chemical reaction in the form of heat (entropy). This is relevant to biological systems because it means that chemical
reactions in cells are not 100% efficient, and that energy must be continually put into an organism to replace the energy lost in the form of heat.

Front 63

Discuss this statement, "Life is an endergonic process." If this is true where do most ibological organisms get their energy?

Back 63

Ultimately all energy used in by biological organisms comes from light (via
photosynthesis); living organisms must also obtain energy from potential energy
stored in chemical bonds.
Light energy → chemical energy → work