meds2003

Question 1

when you lose weight, where does the fat go?

Answer 1

mostly, energy/heat

Question 2

What is the point of the Krebs cycle

Answer 2

ripping out hydrogens and complete oxidation of carbon atoms to carbon dioxide.
No oxygen is involved. It just rips out hydrogens.

Question 3

What does NAD like to oxidise

Answer 3

CH2CHOH

becomes NADH

Question 4

What does FAD like to oxidise

Answer 4

CH2CH2 to CHCH

Question 5

Some massive concepts for how fuel is used to make ATP

Answer 5

The hydrogen and electron carriers are in short supply
ADP is in short supply and ATP is really stable

The inner mitochondrial membrane is impermeable to protons
Protons only flow into the matrix if the ATP is being made

The proton pumps don’t work if the proton gradient is very high

No proton pumping would result in no electron movement down the ET chain

Question 6

Beta oxidation

Answer 6

Fatty acids trapped in cytoplasm as fatty AcylCoA

fatty Acyl CoA is transported into matrix by carnitine.
Acetyl CoA somehow released by beta oxidation.

Question 7

How is fatty acid transported in the blood

Answer 7

They are transported as being bound by albumin.

They could passively diffuse from the blood into the cytoplasm

Question 8

How is fatty acyl CoA moved into the matrix

Answer 8

So carnitine acyl transferases turn FA-CoA to just FA

FA basically combines with carnitine and this helps move it into the cytoplasm

Question 9

Outline beta oxidation

Answer 9

basically there are 2 main phases,
first the FAD hydrogen stripping phase

Then the second NAD hydrogen stripping phase

Question 10

Outline the first hydrogen stripping phase

Answer 10

1) with acyl CoA dehydrogenase, and FAD,
a double bond is formed between the alpha and beta carbons
This forms trans enoyl CoA

trans enoyl CoA is hydrated along with enoyl CoA hydratase.
The double bond is hydrated

Question 11

Outline the second hydrogen stripping phase

Answer 11

The hydroxy group is turned into a ketone group by beta hydroxyacyl CoA dehydrogenase

Then acylCoA transferase reacts with beta ketoacyl CoA, and this is what forms acetyl CoA

Question 12

What are 2 sources of G6P in glycolysis?

Answer 12

Glycogen and glucose

Question 13

How is glucose moved into the cytoplasm

Answer 13

Glucose is taken into the cytoplasm from blood using GLUT proteins. Hexokinase transforms glucose into glucose 6 phosphate preventing glucose from exiting the cell

Question 14

What is the point of glucose preparation

Answer 14

to basically produce 2 symmetrical items and
glucose 6 phosphate goes to fructose 6 phosphate
Then it goes to fructose 1,6 bisphosphate
Then fructose 1,6 bisphosphate gets split into 2

Question 15

outline how G3p goes to pyruvate (the return phase)

Answer 15

g3p
gets phosphorylated by inorganic phosphates and NAD to form 1-3 bisphosphoglycerate

Then 1,3-Bisphosphoglycerate gets forms atp this is called substrate level phosphorylation

you eventually get to pyruvate

a second substrate level phosphorylation happens along here

Question 16

What is the overall point of the kreb cycle

Answer 16

completely oxidise acetate carbons to CO2
produce lots of NADH and FADH2
performs the reactions on a carrier molecule and regenerate the carrier

Question 17

How do we measure the rate at which ATP is used?

Answer 17

We measure the rate of oxygen and or carbon dioxide, as the rate of fuel oxidation is matched to the rate at which the ATP is used.

Question 18

What happens when there is no proton gradient

Answer 18

There is no driving force for ATP synthesis:

1) No back-pressure to stop H+ pumping
2) No restriction on H/e- movement down the transport chain

Instant regeneration of NAD from NADH
massive fuel oxidation rate
massive oxygen consumption

No ATP synthesis

Question 19

DNP

Answer 19

hydrophobic when protonated
can move freely across membrane

weak acid

When hydrogen comes off negative charge can be delocalised
still hydrophobic

Question 20

How does uncoupling protein mechanism work?

Answer 20

Noradrenaline binds to beta 3 receptors on cell surface, stimulates fatty acid release then opens proton channel so targeted and controllable

Question 21

NAD structure

Answer 21

basically a dinucleotide with a nicotanamide group (niacin)

changes absorption spectrum

Question 22

fad structure

Answer 22

adenine recerptor with a ring structure called fmn

Question 23

Glycerol 3 phosphate shuttle

Answer 23

essentially bypasses complex 1

NADH from the cytoplasm basically just reacts with cytoplasmic glycerol 3 phosphate dehydrogenase to produce glycerol 3 phosphate, and glycerol 3 phosphate donates hydrogen to FAD on a mitochondrial glycerol 3 phosphate dehydrogenase

Question 24

Malate aspartate shuttle

Answer 24

reacting cytoplasmic NADH with oxaloacetate to give malate,
and malate delivers hydrogen into the mitochondria
move cytoplasmic NADH into the cytoplasm

With no loss of proton pumping potential

Question 25

What are the 4 routes to Q

Answer 25

from complex 1
from complex 2 (which is really succinate dehydrogenase in the krebs cycle

from the first step of beta oxidation

from the glycerol 3 P shuttle

Question 26

what are other ways of uncoupling other than thermogenin

Answer 26

apparently you could send the hydrogen from NADH directly to oxygen via alternative oxidase

Question 27

where does free radicals come from?

Answer 27

oxygen can react with the complexes prematurely or hydrogens could sneak out of the chain

You get oxygen free radicals that could mutate DNA