Cell Membrane, Transport, Enzymes & Tonicity

Question 1

Diffusion Definition

Answer 1

Movement of molecules from greater concentration to lower concentrated areas.

Question 2

Diffusion Transport in Cells

Answer 2

across bilayer, does not require ATP, small non-charged molecules.

Question 3

Factors that affect rate of diffusion

Answer 3

difference in concentration: greater concentration diffuses faster
temperature: heat increases diffusion speed
Mass of Molecules: heavier molecules diffuse slower

Question 4

Osmosis

Answer 4

water molecules from higher concentration move to lower concentration through a selective membrane

Question 5

Osmosis in Cell Membrane Transport

Answer 5

Across bilayer or through channels, no ATP requireed

Question 6

Osmotic Pressure

Answer 6

A force that pulls water from where its more concentrated to where its less concentrated. Salt pulls water.

Question 7

Semipermeable/Selective Membrane in Osmosis

Answer 7

prevents salt and other molecules from entering

Question 8

Tonicity

Answer 8

ability of a solution to make water move in or out of a cell by osmosis

Question 9

Isotonic

Answer 9

solution outside cell has same solute concentration as inside the cell

Question 10

Hypertonic

Answer 10

solution outside of cell has a higher solute concentration than inside the cell

Question 11

Hypotonic

Answer 11

outside cell has a lower solute concentration than inside the cell

Question 12

Homeostasis

Answer 12

process that maintains stability of an internal environment in response to changing external conditions

Question 13

Factors of membrane fluidity

Answer 13

temperature, fatty acid composition, cholesterol temperature

Question 14

Affects of Temperature on Membrane Fluidity

Answer 14

high temp disorders membrane and cell won’t hold shape
low temp makes membrane rigid and may break

Question 15

Saturated Fatty Acids & Membrane Fluidity

Answer 15

Saturated FAs in phospholipid bilayer means tails are straight and easy to pack, decreasing membrane fluidity

Question 16

Unsaturated Fatty Acids & Membrane Fluidity

Answer 16

tails have kinks and are harder to pack, increased membrane fluidity

Question 17

Channel Proteins

Answer 17

create holes in the membrane.
gated channel proteins require a molecule to bind before opening a gate.

Question 18

Carrier Proteins

Answer 18

bind a molecule on side of membrane and deliver it to other side of membrane through a change in conformation

Question 19

Cell Recognition Proteins

Answer 19

glycoproteins with carbon chains on the outside
provide information to other cells about cell type and identity and enable immune cells to identify and attack pathogens

Question 20

Receptor Proteins

Answer 20

molecules outside of the cell can bind to the receptor protein, changing its conformation and triggering a chain reaction inside the cell that signals to initiate a function

Question 21

Enzymatic Proteins

Answer 21

catalyze specific reactions at cell membrane

Question 22

Facilitated Diffusion

Answer 22

molecules move from high to low concentration with the help of a carrier or channel protein

Question 23

Facilitated Diffusion: Channel vs Carrier

Answer 23

Channels: transport molecules more quickly
Carriers: more specific, increase selectivity of membrane

Question 24

Active Transport

Answer 24

Requires ATP to move molecules against the concentration gradient (low to high)

Question 25

Bulk Transport

Answer 25

large molecules (polysaccharides and polypeptides) move in and out of cell by vesicle formation

Question 26

Exocytosis

Answer 26

In bulk transport, vesicles fuse with membrane as secretion occurs (leave cell)

Question 27

Endocytosis

Answer 27

I’m bulk transport, vesicles form to take substances in the cell. Includes phagocytosis (large solid molecules) and pinocytosis (small liquid molecules)

Question 28

Cellular Metabolism

Answer 28

the sum of all chemical reactions in a cell

Question 29

catabolism

Answer 29

breaking down of molecules large molecule -> small molecules + energy

Question 30

anabolism

Answer 30

building of molecules small molecules + energy -> large molecules

Question 31

Metabolic Pathway

Answer 31

series of reactions that occur in a step by step manner

Question 32

Substrates

Answer 32

reactants in enzyme reactions

Question 33

Enzymes

Answer 33

special proteins that speed up reactions in the body (catalysts)

Question 34

Active Site

Answer 34

Space on an enzyme that substrates bind to

Question 35

Lock and Key Model

Answer 35

outdated model that states enzymes and substrates fit together like a lock and key

Question 36

Induced Fit Model

Answer 36

enzymes undergo a conformational change to allow for binding of substrates

Question 37

delta G

Answer 37

the change in free energy as system goes from reactants to products. Gfinal - Ginitial

Question 38

Activation Energy

Answer 38

amount of energy needed for a reaction to occur

Question 39

Enzyme Functions

Answer 39

lower activation energy by bringing substances closer together, speeding up reactions

Question 40

exergonic reactions

Answer 40

release energy (delta G < 0)

Question 41

endergonic

Answer 41

require energy (delta G > 0)

Question 42

amylase

Answer 42

produced in mouth, breaks starch (complex sugars) into maltose

Question 43

maltase location and function

Answer 43

secreted by intestines, converts maltose to glucose

Question 44

pepsin location and function

Answer 44

produced in stomach, breaks down proteins into amino acids

Question 45

Lactase

Answer 45

digests lactose into glucose

Question 46

Lipase

Answer 46

produced by pancreas, mouth and stomach, breaks down fats into food for absorption in intestines

Question 47

6 Enzyme Activity Factors

Answer 47

- temperature - pH - substrate concentration - enzyme concentration - inhibitors - cofactors

Question 48

Temperature on Enzyme Activity

Answer 48

Increases rate of reaction, too high can denature (reaction rate to zero)

Question 49

pH on Enzyme Activity

Answer 49

each enzyme has an optimum pH, pH outside of this range can slow enzyme activity, extreme values can denature enzymes

Question 50

Substrate Concentration on Enzyme Activity

Answer 50

increasing concentration increases reaction rate to a certain point, at some point, all enzymes will be saturated

Question 51

Enzyme Concentration on Enzyme Activity

Answer 51

increasing concentration will increase reaction, as long as there is substrate available to bind to

Question 52

Inhibitors

Answer 52

chemicals that bind to an enzyme and reduce its activity

Question 53

Competitve Inhibitors

Answer 53

similar shape to substrate to bind to the active site, competes will substrate, increasing substrate will make substrate more likely to win

Question 54

Non-Competitive Inhibitors

Answer 54

binds to allosteric site, inducing a conformational change so that substrate can no longer bind, increasing substrate concentration can not increase maximum rate of reaction

Question 55

reversible inhibitors

Answer 55

binds to enzyme with weak bonds like hydrogen bonds

Question 56

irreversible inhibitors

Answer 56

binds to enzyme with strong, covalent bonds

Question 57

feedback inhibition

Answer 57

end products produced in a series of reactions suppress the activities of enzymes earlier in the reaction as a non-competitive inhibitor

Question 58

Cofactors (examples)

Answer 58

Some enzymes require cofactors to bind to them in order to function. Cofactors include metal ions or organic molecules called coenzymes.

Question 59

Apoenzyme

Answer 59

inactive enzyme without the cofactor

Question 60

Holoenzyme

Answer 60

complete enzyme with the cofactor

Question 61

negative feedback

Answer 61

counteract changes from target values (set points)

Question 62

positive feedback

Answer 62

amplify initiating stimuli, moving system away from starting state

Question 63

positive feedback

Answer 63

amplify initiating stimuli, moving system away from starting state