Krebs Cycle

Question 1

can pyruvate enter the mitochondria?

Answer 1

Yes

Question 2

what molecule is pyruvate converted to in the first step of the TCA cycle?

Answer 2

Acetyl CoA

Question 3

function of pyruvate dehydrogenase

Answer 3

removes hydrogen from pyruvate and gives it to NAD+ to convert it to NADH
- makes carbon weak and falls off
- allows CoA to bind
- gives off co2

Question 4

Can pyruvate enter the TCA cycle as it is?

Answer 4

no, must be converted to acetyl coa

Question 5

krebs cycle happens in the

Answer 5

mitochondria

Question 6

what happens to acetyl coa and oxaloacetate

Answer 6

they fuse together to make citrate
- 2 carbons fuse with 4 carbons coa falls off

Question 7

citrate has how many carbons

Answer 7

6

Question 8

function of citrate synthase

Answer 8

fuses oxaloacetate and acetyl coa

Question 9

what deactivates citrate synthase

Answer 9

lots of ATP NADH succinyl coa

Question 10

what activates citrate synthase

Answer 10

adp

Question 11

citrate is converted to

Answer 11

isocitrate

Question 12

is the conversion of citrate to isocitrate reversible or irreversible?

Answer 12

reversible

Question 13

what enzyme converts citrate to isocitrate

Answer 13

aconitase

Question 14

what is fluoroacetate?

Answer 14

it inhibits aconitase - stops production of ATP - rat poison

Question 15

what is isocitrate converted to?

Answer 15

alpha ketoglutarate

Question 16

how many carbons are in isocitrate? alpha ketoglutarate?

Answer 16

6 in isocitrate, 5 in alpha keto glutarate

Question 17

what is the role of isotrate dehydrogenase?

Answer 17

• converts isocitrate to alpha ketoglutarate
• takes a hydrogen and gives it to nad+ to form nadh
• carbon of isocitrate gets weak and falls off
• gives off co2

Question 18

what deactivates isotrate dehydrogenase?

Answer 18

atp
explanation - high amount of atp mean that we do not need any more in the system so the krebs cycle is not needed to keep going

Question 19

what activates isotrate dehydrogenase?

Answer 19

ca2+ and adp
explanation - ca2+ works with atp, if ca is signaling it needs atp then the krebs cycle need to work, high amounts of adp mean that we need energy as well

Question 20

what two molecules work together for muscle contraction

Answer 20

atp and ca2+

Question 21

where does glycolysis occur

Answer 21

in the cytoplasm

Question 22

what is alpha ketoglutarate converted to

Answer 22

succinyl coa

Question 23

how many carbons are in a ketoglutarate? succinyl coa?

Answer 23

5 and 4

Question 24

function of a ketoglutarate dehydrogenase

Answer 24

• converts a ketoglutarate to succinyl coa
• gives hydrogen to nad+ to form nadh
• carbon fall off to give off co2
• coa binds to carbon

Question 25

succinyl coenzyme a inhibits what two enzymes via feedback mechanism

Answer 25

citrate synthase and alpha ketoglutarate dehydrogenase

Question 26

what activates alpha ketoglutarate dehydrogenase?

Answer 26

calcium

Question 27

what deactivates alpha ketoglutarate dehydrogenase?

Answer 27

NADH and succinyl coa - accumulation of these means that we have enough energy and do not need to go on with the krebs cycle

Question 28

what is succinyl coa converted to

Answer 28

succinate (4c)

Question 29

why does the coa fall off of succinyl coa

Answer 29

- inorganic phosphate attaches to gdp to make gtp - creates energy to remove coa

Question 30

two ways to get rid of coa

Answer 30

- fusing with a molecule that doesnt have coa will force it to fall off - inorganic phosphate fusing with gdp to make gtp forms energy to take off coa

Question 31

gtp has affinity for... and what happens

Answer 31

adp - gives phosphate to adp to form atp

Question 32

what enzyme converts succinyl coa to succinate

Answer 32

succinyl coa synthetase

Question 33

what is succinate converted to

Answer 33

fumarate

Question 34

what enzyme converts succinate to fumarate

Answer 34

succinyl dehydrogenase

Question 35

what is the function of succinyl dehydrogenase

Answer 35

- converts succinate to fumarate - gives two hydrogens at the SAME time to fad to form fadh2 - cannot use nad here because we need a molecule that can take two hydrogens at the same time

Question 36

fumarate fuses with... to be converted to

Answer 36

water to be converted to malate

Question 37

oxaloacetate and malate can

Answer 37

talk to each other

Question 38

can oxaloacetate leave the mitochondria?

Answer 38

no

Question 39

can malate leave the mitochondria

Answer 39

yes

Question 40

what enzyme converts malate to oxaloacetate

Answer 40

malate dehydrogenase

Question 41

function of malate dehydrogenase

Answer 41

- convertse malate to oxaloacetate - gives hydrogen to nad to form nadh BUT not from the first carbon

Question 42

what is the transition step

Answer 42

conversion of pyruvate to acetyl coa connects cytosol to mitochondria

Question 43

how many molecules of CO2 are made in the kerbs cycle

Answer 43

2

Question 44

how many molecules of nadh are made in the tca cycle

Answer 44

3

Question 45

how many molecules of atp are made - tca

Answer 45

1

Question 46

how many molecules of fadh2 - tca

Answer 46

1

Question 47

what are the steps of oxidative decarboxylation

Answer 47

- conversion of isocitrate to alpha ketoglutarate using isocitrate dehydrogenase - conversion of alpha ketoglutarate to succinyl coa using alpha ketoglutarate dehydrogenase

Question 48

how many molecules of nadh are produced in oxidative decarboxylation

Answer 48

2

Question 49

how many molecules of co2 are produced in oxidative decarboxylation

Answer 49

2

Question 50

what other role does alpha ketoglutarate have?

Answer 50

amino acid synthesis (neurotransmitters)

Question 51

what other role does oxaloacetate have?

Answer 51

amino acid synthesis

Question 52

what other role does succinyl coa have?

Answer 52

heme synthesis

Question 53

what other role does malate have?

Answer 53

gluconeogenesis

Question 54

what two enzymes need vitamin B1 in order to work properly

Answer 54

pyruvate dehydrogenase and alpha ketoglutarate dehydrogenase

Question 55

what part of the body is involved with Dry beriberi

Answer 55

CNS

Question 56

what part of the body is involved with wet beriberi

Answer 56

cardiovascular system

Question 57

what is beriberi

Answer 57

deficiency in vitamin B1 (thiamin) - vitamin that allows tca enzymes to work at full capcity

Question 58

what two enzymes does arsenic inhibit completely

Answer 58

pyruvate dehydrogenase and alpha ketoglutarate dehydrogenase

Question 59

symptoms of arsenic poisoning

Answer 59

- memory loss and other neurological conditions such as parkinsons - brain damage - apoptosis of cerebral neurons - brain dna damage leading to brain cell death