the mitochondrion and energy

Question 1

main parts of the mitochondrion

Answer 1

matrix: internal space
inner membrane highly folded into cristae, outer membrane, enclosing inter membrane space

Question 2

what is chemiosmotic coupling?

Answer 2

the process which links the electron transport chain to ATP synthesis

(2nd part of oxidative phosphorylation)

Question 3

how does the e- transport chain work?

Answer 3

e- from the oxidation of food transferred down carriers in inner membrane (e-transp chain), releasing energy which pumps protons across the membrane, generating an electrochemical gradient

Question 4

name the e- donor and e- acceptor in the e-transport chain

Answer 4

e- donor = NADH (as hydride ion => H+ and 2e-)
e- acceptor = oxygen (form water)

Question 5

how does the electrochemical gradient generate ATP?

Answer 5

via catalyst ATP synthase, a mechanical rotary pump, driven by the proton motive force (memb potential + proton grad) across the inner membrane

Question 6

define oxidative phosphorylation

Answer 6

e- transport chain + chemiosmosis

Question 7

ratio of ATP:ADP in cells

Answer 7

10:!
high ratio maintained by mitochondria as ATP is moved out, ADP flows into the matrix

Question 8

define catabolic / anabolic pathways

Answer 8

catabolic = break down foodstuffs into smaller molecules, generating energy and building blocks for the cell

anabolic = uses energy harnessed by catabolism to drive synthesis of molecules

Question 9

How is NADH generated?

Answer 9

a product of the citric acid cycle

Question 10

where does the citric acid cycle occur

Answer 10

in the matrix of the mitochondria

Question 11

what does the mitochondria use for fuel ?

Answer 11

pyruvate (from glucose)
fatty acids (from fats)

both transported from the cytosol into the matrix for use in the CitA cycle

Question 12

what type of reactions are central to metabolism?

Answer 12

redox

Question 13

Gibbs energy equation

Answer 13

G = H - TS
H is enthalpy
T is temperature
S is entropy

Question 14

how to interpret a Gibbs energy value

Answer 14

∆G < 0, energetically favourable, spontaneous
∆G>0, can only occur when coupled to a second energetically favourable reaction
at equilibrium, ∆G = 0

Question 15

name some activated carrier molecules and their features

Answer 15

ATP, NADH, NADPH
energy rich covalent bonds
store energy in an easily exchangeable form
hydrolysed to release
(links energy from catabolism to energy provided for anabolism)

Question 16

In ATP, which bond is broken in hydrolysis?

Answer 16

the high energy phosphate bond to produce ATP and Pi

Question 17

define glycolysis and where it occurs

Answer 17

the process by which glucose is broken down to produce energy (pyruvate, ATP, NADH, H2O)
ANAEROBIC - no O2 involved
occurs in the cytosol of the cell

Question 18

how is pyruvate from glycolysis converted to acetyl CoA?

Answer 18

pyruvate produced in cytosol transported to mitochondria
decarboxylated by pyruvate dehydrogenase complex
produces CO2, NADH, acetyl CoA

Question 19

in aerobic organisms / conditions, how is ATP mostly generated?

Answer 19

by glycolysis (not O2 requiring)
pyruvate and NADH e- stay in cytosol.

also true in skeletal muscle when O2 is limited

Question 20

fermentation energy definition

Answer 20

the extraction of energy from carbohydrates in the absence of O2

Question 21

two ways energy storage in animals

Answer 21

store fatty acids as fat droplets of triacylglycerols
short term: sugar as glucose subunits stored in large branched polysaccharide glycogen

Question 22

how is acetyl CoA produced

Answer 22

by the breakdown of glucose (glycolysis, converted from pyruvate) and the oxidation of fatty acids

Question 23

oxidation of fatty acids in the mitochondria produces

Answer 23

acetyl CoA
NADH
FADH2

Question 24

major products of the citric acid cycle

Answer 24

CO2 and high energy e- in the form of NADH

Question 25

in starvation conditions, what happens to metabolism

Answer 25

amino acids are used to fuel ATP production

Question 26

in excess conditions, what happens to metabolism

Answer 26

mitochondrion supply cytosol w excess citrate used for fatty acid synthesis and storage