2.2 Metabolism

Question 1

______ is the sum of all chemical reactions required to support cellular fxn

Answer 1

metabolism

Question 2

catabolism

Answer 2

breaking things down (releases energy)

Question 3

anabolism

Answer 3

building things (uses energy)

Question 4

Metabolism is highly regulated to permit organisms to respond to changing conditions, and regulation ensures _______ of materials in a pathway

Answer 4

unidirectional flow

Question 5

Having pathways that are irreversible prevents what?

Answer 5

a futile cycle (no overall effect)

Question 6

flow of material through a metabolic pathway depends on what 3 things?

Answer 6

1. supply of substrate
2. removal of products
3. properties of enzymes

Question 7

It is really hard to turn an enzyme completely off, but you can _____

Answer 7

turn down their activity

Question 8

covalent regulation is at the _____ level, and allosteric regulation is at the _____ level

Answer 8

hormonal, cellular

Question 9

there must be control over enzyme activity so right lvls of products are produced, these controls include what?

Answer 9

• enzyme production
• covalent modification
• allosteric modification
• sequesteration
• turnover
• protein-protein interactions

Question 10

ATP is the universal energy carrier and is generated by ______

Answer 10

the oxidation of metabolic fuels

Question 11

the energy released by the oxidation of food is stored in carrier molecules like these 3:

Answer 11

FADH2, NADH, NADPH

Question 12

ATP can be generated by what 2 processes

Answer 12

substrate phosphorylation, oxidative phosphorylation

Question 13

substrate-lvl phosphorylation

Answer 13

formation of ATP from ADP and a phosphorylated intermediate

- anaerobic

Question 14

oxidative phosphorylation

Answer 14

• molecule is oxidized and energy is captured by NADH/FADH2
• energy is transferred by a series of e- to create a chemical gradient
• this gradient powers ATP synthase
• aerobic

Question 15

way to remember oxi/reduction reaction?

Answer 15

OIL RIG
Oxidation is Loss, Reductio is GAIN
(in respect to electrons)

Question 16

______ are small organic molecules that cycle between being oxidized and reduced and are used to transport e- during metabolic rxns

Answer 16

Electron carriers
Oxidized form: NAD+, FAD, NADP+
Reduced form: NADH, FADH, NADPH

Question 17

NAD+ and FAD accept electrons and carry them to the ETC to make ATP, which one can you get more energy out of?

Answer 17

NADH (floats freely in membrane, FAD can only donate to ETC)

Question 18

NADH cant cross the membrane and must use the ______ to translocate electrons

Answer 18

malate- aspartate shuttle

Question 19

malate aspartate shuttle

Answer 19

• MDH reduces Oxaloacetate (OAA) –> malate while oxidizing NADH–> NAD+
• malate enters the mitochondrion
• reverse reaction is performed by mitochondrial malate dehydrogenase
• H+ is now in the mitochondrial matrix

Question 20

Overview of glucose catabolism

Answer 20

GLYCOLYSIS (glucose –> pyruvate –> acetyl CoA) (release ATP, NADH)
TCA (Acetyl CoA circle)(release CO2, NADH, QH2)
ETC

Question 21

fatty acids can be converted to _____ and enter glycolysis, and amino acids can enter the cycle as what 3 things?

Answer 21

• Acetyl CoA

1. pyruvate
2. Acetyl CoA
3. part of TCA

Question 22

where does glycolysis take place?

Answer 22

cytosol

Question 23

where does TCA take place?

Answer 23

Mitochondrial matrix

Question 24

what is the energy yield from glycolysis?

Answer 24

2 pyruvate, 2 ATP, 2 NADH, 2H+, 2H2O

Question 25

_______ is the aerobic catabolism of nutrients to CO2, H2O, energy and involves an Electron transport system where O2 is the final e- acceptor

Answer 25

aerobic respiration

Question 26

you need ______ to get electrons from NADH/FADH2

Answer 26

O2

Question 27

Under anaerobic conditions, _____ is obligatory end product to re-make NAD+

Answer 27

lactate

Question 28

under anaerobic conditions, lactate can be released to the blood stream it can ______

Answer 28

lower the pH and cause acidosis

Question 29

under aerobic conditions, lactate can be sent to _____

Answer 29

TCA and produce NADH/FADH2

Question 30

which organs use glucose as their primary form of energy?

Answer 30

brain (ketone in starvation) and RBC

Question 31

how can RBC and brain be sure they get glucose?

Answer 31

glucose transport into cells is regulated

Question 32

Insulin

Answer 32

- released after meal - tells body to take up glucose and start glycolysis - goal: lower glucose levels in bloodstream and store it

Question 33

Glucagon

Answer 33

- induced by low blood glucose - tells body to stop glycolysis and release glucose - raises blood sugar

Question 34

______ is the glucose transporter for Liver/Pancreas B- cells and can only uptake glucose when it is in high concentrations

Answer 34

GLUT2

Question 35

which glucose transporters have a high affinity for glucose?

Answer 35

``` GLUT 1 (RBC), GLUT 3 (neural) KM = 1mM ```

Question 36

Muscle and fat cells have regulated exocytosis, meaning what?

Answer 36

they have to be told to bring glucose into the membrane

Question 37

in the presence of Insulin or exercise, _____ undergoes exocytosis to the plasma membrane

Answer 37

GLUT4

Question 38

All intermediates in glycolysis are _____ so they cant leave the cell

Answer 38

phoshorylated

Question 39

glucose is phosphorylated to G6P by ____ or_____

Answer 39

hexokinase/glucokinase

Question 40

glucokinase vs hexokinase

Answer 40

Glucokinase: in liver, kidney, beta cells of pancreas. lower affinity (higher KM) for glucose Hexokinase: found in most tissues and has a high affinity for glucose (lower KM)

Question 41

Glycolysis steps

Answer 41

1. glucose --> G6P 2. G6P ---> F6P 3. F6P --> F1,6BP 4. F1,6BP --> DHAP + GAP 5. GAP --> 1,3BPG 6. 1,3BPG --> 3PGL (lose 1 P, make ATP) 7. 3PGL --> 2 PGL 8. 2PGL --> PEP (-H2O) 9. PEP --> pyruvate (makes ATP)

Question 42

Glycolysis regulation occurs at what 3 reversible rxns?

Answer 42

1. hexokinase/glucokinase (g-->g6P) 2. phosphofructokinase (F6P--> F16BP) 3. pyruvate kinase (PEP--> pyruvate)

Question 43

3 mechanisms of regulation

Answer 43

1. allosteric 2. covalent 3. modulating lvl of transcription/expression of enzymes

Question 44

____ up-regulates transcription of glucokinase, PFK, and pyruvate kinase because it wants the glucose to be used

Answer 44

insulin

Question 45

high G6P concentrations feedback inhibit _____ but not _____

Answer 45

hexokinase, gluokinase

Question 46

G6P is the pivotal intermediate of glucose metabolism and can go what 3 pathways?

Answer 46

1. store energy as glycogen 2. pyruvate 3. pentose phosphate pathway

Question 47

primary target for regulation of glycolysis is ____

Answer 47

PFK-1

Question 48

____ catalyzes the rate limiting reaction in the pathway

Answer 48

PFK-1

Question 49

high energy indicators (ATP/citrate) _______ PFK-1, while low energy indicators (AMP/ADP) _____ PFK-1

Answer 49

inhibit, activate

Question 50

PFK-1 is ______ regulated by insulin

Answer 50

positively

Question 51

Pyruvate kinase is allosterically inhibited by ______ and is allosterically activated by _____

Answer 51

1. signs of abundant energy | 2. F-1,6-biphosphate (to increase flow through glycolysis)

Question 52

galactose can enter pathway through _____

Answer 52

g-6-p

Question 53

fructose in the liver can bypass regulation and enter the cycle as _____

Answer 53

DHAP

Question 54

fructose in adipose tissue can enter the cycle as ____

Answer 54

F-6-P

Question 55

Functions of pentose phosphate pathway

Answer 55

1. generate NADPH for reductive biosynthesis rxns 2. provide cell with Ribose-5-phosphate 3. can rearrange carbon skeletons of dietary carbs into glycolytic/gluconeogenesis intermediates

Question 56

_____ is the unique provider to maintain/regenerate the cellular detoxifying and antioxidative defense systems

Answer 56

NADPH