N: CARB: metabolism

Question 0

define catabolism:

Answer 0

breakdown of larger molecules into smaller

eg. glycogen -> glucose ***yields energy

Question 1

where do metabolic reactions take place?

Answer 1

inside cells

eg. liver, muscle cells

Question 2

define anabolism:

Answer 2

build up of smaller molecules into larger

eg. amino acids -> protein ***needs energy

Question 3

understand the role of ATP energy provision

learning objective

Answer 3

ADP + P => ATP => ADP + P
(APP+P) (APPP)
- energy is stored in high energy phosphate bonds
- energy in the last 2 bonds most important

Question 4

how many ATP does glucose make?

Answer 4

1 glucose yields 32 ATPs

Question 5

what are coenzymes?

Answer 5

protein catalysts specific to metabolic reactions

Question 6

stages involved in converting glucose energy into ATP?

Answer 6

1) glycolysis (sugar splitting)
pyruvate -> acetyle-CoA (aerobic) no oxygen? pyruvate -> lactic acid
2) Tricarboxylic Acid Cycle (high energy intermediates NADH&FADH2)
3) Electron Transport Chain - uses NADH & FADH2 transfer into ATP

Question 7

describe glycolysis:

Answer 7

glucose -> 2 pyruvate
co-enzyme needed to gain H+
2NAD+ -> 2NADH(substituted into electron transport chain)

2 ATP used but 4 ATP created so net gain of 2ATP during glycolysis

Question 8

what is the electron transport chain? where does it occur?

Answer 8

it is a series of proteins that use the H+ gradient to produce ATP

inner membrane of mitochondrion

Question 9

what happens to the 2 pyruvates produced by glycolysis?

Answer 9

2 pyruvate + CoA -> 2CO2 + 2 Acetyl-CoA

these 2 acetyl-CoA’s go into TCA cycle
make either fats when energy is plentiful OR
generate ATP when cell is low in energy via. TCA cycle

Question 10

what co-enzymes does conversion of pyruvate -> acetyl-CoA need?

Answer 10

1) CoA - co-enzyme A
2) TPP - thiamine pyrophosphate -> vit B1 thiamine
3) NAD+ -> vit B3 niacin

Question 11

what is pyruvate converted to?

Answer 11

either

a) acetyl-CoA - oxygen available - CO2 produced
b) lactic acid - no oxygen - fermentation

this depends on oxygen availability

Question 12

if plenty of energy is available what can acetyl-CoA be converted into?

Answer 12

fatty acids

Question 13

why can acetyl-CoA not be produced if no oxygen is available?

Answer 13

no oxygen means NAD+ depleted therefore conversion to acetyl-CoA prevented
pyruvate will accumulate(in muscle) and converted to lactic acid which will produce NAD+ => which will allow glycolysis to continue

Question 14

where is lactic acid converted back to glucose?

Answer 14

after build up in muscle goes to liver to be converted back to glucose

Question 15

what is termed the most vital substance in the TCA cycle and where does it come from?

Answer 15

oxaloacetate

comes from adequate carb intake

Question 16

describe the TCA cycle:

Answer 16

• this is what acetyl-CoA feeds into, it combines with oxaloacetate to make H+
• H+ created will then combine with cofactors: NAD+ & FAD
• this makes high energy intermediates NADH & FADH2
• NADH & FADH2 feed into electron transport chain

Question 17

understand importance of oxaloacetate in primary the TCA cycle

***** like always an exam question

Answer 17

• oxaloacetate is the first and last step in the TCA cycle
• it combines with acetyl-CoA to produce citrate
• its made from CARBOHYDRATE (glucose -> pyruvate)
• oxaloacetate cannot be made from fat
• therefore adequate carb intake vital to efficiently metabolise fat

Question 18

what does the electron transport chain utilise to make energy?

Answer 18

the H+ pH gradient

Question 19

what reaction happens in the ETC?

Answer 19

high energy intermediates are combined with oxygen to make water and energy-ATP
2NADH & FADH2 + O2 -> H2O
=> 4H + O2 -> 2H2O **energy madeeee

Question 20

where does glycolysis occur?

Answer 20

outside cell!

the only part of the metabolism process to occur not within mitochondrion

Question 21

in the ETC high energy intermediates made in the TCA cycle need to pass through multiple membrane proteins where they “give” H+
what are these proteins in order?

Answer 21

1) flavoprotein
2) co-enzyme Q
3) cytochrome b
4) cytochrome c
5) cytochrome a

Question 22

where does NADH give up its H in the ETC?

Answer 22

at the first protein on the inner membrane of the mitochondiron
FLAVOPROTEIN

Question 23

where does FADH2 give up its H on the ETC?

Answer 23

on the second protein/co-enzyme

CO-ENZYME Q

Question 24

why do NADH and FADH2 give their H atoms at different points in the chain?

Answer 24

as they have different energies

FADH2 has less energy than NADH as it comes later in the chain

Question 25

general steps in carb metabolism:

Answer 25

carb

• > glucose
• > pyruvate
• > acetyl-CoA
• > TCA cycle
• > ETC => ATP!!! oh and water haha