Proteins & Enzymes

Question 1

Membrane Proteins function

Answer 1

interspersed within the lipid bilayer
-serve as pumps, gates, receptors, transporters of ions & molecules, energy transducers, enzymes, cellular signaling

Question 2

Carbohydrate Composition of Membranes

Answer 2

Greater carbohydrate content exposed to the outside of the cell (glycocalyx)
(ex. glycolipids, glycoprotein, oligosaccharide side chain)

Question 3

Oligosaccharide side chain function

Answer 3

Serve as distinctive identification tags as a receptor for hormones, some nutrients

Question 4

What do Transporters, channels, gates, and pumps transport through the body?

Answer 4

-nutrients (ex. maltoporin)
-ions (ex. k-channel)
-neurotransmitters (ex. serotonin reuptake protein)

Question 5

What is received on receptors?: detecting signals from outside

Answer 5

-Light (ex. opsin)
-hormones (ex. insulin receptor)
-neurotransmitters (ex. acetylcholine receptor)
-pheromones (ex. taste/smell receptors)

Question 6

Function of Enzymes

Answer 6

protein w catalytic properties due to its power of specific activation

-lipid biosynthesis (some acyltransferases)
-ATP synthesis (ATPase)
-increase rate of rxn w/o increasing temp

Question 7

Transport proteins are responsible for what kinds of transport? (membrane proteins)

Answer 7

-passive Transport (diffusion & facilitated diffusion)
-active transport

Question 8

Receptor proteins function

Answer 8

-act as attachment sites for specific external stimuli
(ligands: hormones, growth factor, nutrients)
-proteins that modify the cell’s response to its environment
-triggers a cascade rxn

Question 9

Hormones that act via cAMP mechanisms?

Answer 9

Epinephrine and Glucagon

Question 10

3 types of receptor proteins?

Answer 10

1. convert the ligand stimulus into an internal chemical signal (ex. cAMP triggers a cascade towards kinase which phosphorylates or dephosphorylates a molecule)
2. act as ion channels: regulate total charge of cells
3. internalize stimuli (ex. insulin touchdown on insulin receptor to open GLUT4 gate so glucose can enter the cell for protein synthesis, etc. )

Question 11

the smaller the Km…

Answer 11

the higher the affinity of specific enzyme w a transport

Question 12

What effects do temperature changes have?

Answer 12

-Increasing the temp makes molecules move faster
-biological systems are very sensitive to temp changes

Question 13

Factors affecting enzymes

Answer 13

-substrate concentration
-pH (affect relative activity)
-Temp
-coenzymes/cofactors (nonprotein molecs like vitamins, metal ions)
-inhibitors (natural, drugs)

Question 14

Enzyme classes: Hydrolases

Answer 14

catalyze the hydrolysis of a chemical bond (ex. proteases)

Question 14

Enzyme classes: oxidoreductates

Answer 14

catalyze the transfer of electrons from one molecule to another

Question 14

Enzyme classes: Transferases

Answer 14

catalyze the transfer of functional group from one molecule to another

Question 15

Kinases (phosphotransferases)

Answer 15

enzymes that transfer phosphate groups from high energy donor molecules (like ADP to ATP) to specific substrates

Question 16

Glucagon & epinephrine

Answer 16

-trigger cAMP synthesis–> shutting down of glycogen synthesis–> stimulate glycogen degradation (glycogen phosphorylase)

Question 17

Enzyme classes: isomerases

Answer 17

catalyze the structural rearrangement of isomers

Question 18

Enzyme classes: lyases

Answer 18

catalyze the breaking of bonds forming double bonds or ring structures

Question 19

Enzyme classes: ligases

Answer 19

catalyze the joining of 2 large molecules by forming a new chemical bond

Question 20

Cytoskeleton provides…

Answer 20

-structural support (cell shape)
-framework for positioning organelles
-intermediate filaments

Question 21

Cytoskeleton is a protein filament complex made up of…

Answer 21

-microtubules (made of tubulin)
-microfilaments (made of actin)
-intermediate filaments (provide mechanical strength-made of microtubules and actin)

Question 22

What does the Michaelis-Menten constant (Km) represent?

Answer 22

the concentration of a substrate that is found in an occurring rxn when the rxn is at 1/2 its maximum velocity (Vmax)

Question 23

What is Km?

Answer 23

an inverse measure of the strength of binding between the enzyme & its substrate