Lecture 4

Question 1

What does the endomembrane system use transport vesicles for?

Answer 1

Moves membrane components and soluble proteins - Eat, drink, secrete - Requires phases of budding, docking and fusion

Question 2

What do transport vesicles do?

Answer 2

carry soluble proteins and membrane between compartments

Question 3

What is vesicle budding driven by?

Answer 3

the assembly of a protein coat

Question 4

What does vesicle docking depend on?

Answer 4

Tethers and SNAREs

Question 5

what is dynamin?

Answer 5

GTP binding protein - pinches off membrane to separate

Question 6

what are adaptins?

Answer 6

provide cargo specificity

Question 7

Describe general steps of tethering & docking

Answer 7

Tethering protein brings these closer to dock, snares bring closer to initiate fusion - combinations of Rab (GTPase) create that specificity

Question 8

General steps of fusion

Answer 8

Vesicle and target SNAREs interact to fuse lipid bilayers

Question 9

List three roles of the ER in protein regulation

Answer 9

Extracellular proteins are enriched in disulfide bonds and often glycosylates (rare in cytosolic proteins), ER releases only properly folded proteins, ER accumulates misfolded proteins

Question 10

What does the Golgi do for protein regulation?

Answer 10

Once folded in the ER, the Golgi further modifies and sorts protein cargo

Question 11

Compare constitutive and regulated pathways in exocytosis

Answer 11

No cargo aggregation, Carried by transport vesicles vs. Cargo aggregates - facilitates high concentration,
Packaged into secretory vesicles

Question 12

What are the sub types of endocytosis

Answer 12

Specialized phagocytic cells ingest external large particles, Fluid and macromolecules are taken up by pinocytosis

Question 13

What is receptor-mediate endocytosis

Answer 13

Provides a specific route into animal cells

Question 14

What are endosomes - compare early, late, and phagosome

Answer 14

Membrane enclosed compartment; usually shuttles endocytosed cargo to the lysosome - surface, nucleus, brought in by phagocytosis

Question 15

What are lysosomes?

Answer 15

principal sites of intracellular digestion, contains enzymes active only at low pH (high acidity)

Question 16

What happens in autophagy

Answer 16

An autophagosome will eventually fuse with the lysosome - cargo is from the cell itself

Question 17

What can energy released through hydrolysis be used for

Answer 17

to fuel cellular processes

Question 18

what are the two ways ATP can be generated

Answer 18

Substrate level phosphorylation, oxidative phosphorylation

Question 19

What happens during substrate level phosphorylation

Answer 19

Food molecules oxidized to form ATP directly - Begins in the cytosol; generates carriers for oxidative phosphorylation, and some other subunits are further modified in the mitochondria

Question 20

what happens during oxidative phosphorylation

Answer 20

Requires an electron carrier (ex. NADH or FADH2), Takes place in the inner mitochondrial membrane

Question 21

Describe the first stage of food break down

Answer 21

outside of cell, Food broken down into simple subunits

Question 22

Describe the second stage of food break down

Answer 22

mostly in cytosol - Simple subunits converted to acetyl CoA, Limited amounts of ATP and NADH produced

Question 23

Describe the third stage of food break down

Answer 23

mitochondria - Acetyl CoA converted to water and CO2, Large amounts of ATP produced

Question 24

Units in glycolysis (sugar splitting)

Answer 24

1 molecule of glucose = 2 molecules of pyruvate

Question 25

what happens to pyruvate in stage 2

Answer 25

moves to mitochondria, converted to acetyl CoA

Question 26

what is stage 3 made up of (2)

Answer 26

Citric acid cycle, oxidative phosphorylation / electron transport chain

Question 27

What happens in citric acid cycle

Answer 27

Acetyl CoA converted to water and CO2, Large amounts of NADH produced

Question 28

Where does main source of ATP come from

Answer 28

Oxidative phosphorylation / electron transport chain

Question 29

What must be put in for stage 2, glycolysis

Answer 29

Energy must be invested (ATP), NAD must be available - for chemical reactions to take place, Limited amount of energy produced, 2 ATP & 2 nicotinamide adenine dinucleotide (NADH) per molecule glucose, NADH is utilized later in oxidative phosphorylation

Question 30

what are some sugar products of glycolysis

Answer 30

Fructose 1,6, bisphosphate, Glyceraldehyde 3-phosphate (x2; actual splitting occurs in step 4 -5), Pyruvate (x2)

Question 31

What is gluconeogenesis

Answer 31

Process to store and increase available glucose; Glucose "shipped" to tissues that need it - Builds glucose molecules from pyruvate, Requires energy input (4 ATP & 2 GTP) - costly

Question 32

where is glucose stored?

Answer 32

Stored as glycogen in animal cells and starch in plants

Question 33

How does glycogen get to glucose

Answer 33

Glycogen is synthesized by glycogen synthase and broken down into glucose by glycogen phosphorylase

Question 34

Difference in what pyruvate does in aerobic cells vs anaerobic cells

Answer 34

pyruvate moves to mitochondria; pyruvate can be broken down into the cytosol by fermentation

Question 35

what is fermentation

Answer 35

break down sugar in absence of oxygen

Question 36

Explain pyruvate in acetyl coenzyme A

Answer 36

pumped into the mitochondrial matrix, Rapidly decarboxylated into CO2, NADH (e-carrier), and acetyl CoA (for CAC)

Question 37

What does the citric acid cycle do

Answer 37

Catalyzes the oxidation of carbon atoms of the acetyl group in acetyl CoA, converting them to CO2.

Question 38

What are the 3 types of energy carriers the Krebs cycle generates

Answer 38

NADH, FADH2, GTP

Question 39

Formula of glycolysis

Answer 39

glucose -> 2 pyruvate + 2ATP + 2NADH

Question 40

Formula of citric acid cycle

Answer 40

per 1 glucose = 2 pyruvate = 6 NADH, 2 GTP, 2 FADH, 4 CO2