Week 5 - energy and replication] Flashcards Preview

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Flashcards in Week 5 - energy and replication] Deck (15)
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1
Q

redox

A
  • energy is generated by OXIDATION of organelle compounds
  • the transfer of electrons during chemical reactions releases energy stored in organic molecules
  • DURING RESPIRATION the released energy is ultimately used to synthesise ATP
2
Q

electron carriers

A
  • Types: SOLUBLE, membrane-bound, move within membrane → ALL CARRIERS CAN BE EASILY OXIDISED AND REDUCED
  • some just carry electrons, some electrons & protons
  • the electron carriers help to ‘carry’ electrons betw. cellular processes in a safe * controlled manner
  • NAD+ acquires 2 electrons & a proton to be NADH
3
Q

aerobic respiration

A
  • oxygen used to oxidise glucose
  • glucose is oxidised to form carbon dioxide
  • oxygen is reduced to form water
4
Q

aerobic respiration - oxidation of glucose

A
  • C-H & O-H bonds will be broken
  • electrons will be transferred to carriers NAD & FAD → glycosis & krebs cycle
  • the electrons will be passed through a transport chain
    → the energy from the electrons used to pump protons
    → energy from diffusion of protons to make ATP
5
Q

cellular respiration - stages

A
  1. GLYCOSIS - breaks down glucose into 2 molecules of pyruvate
  2. CITRIC ACID CYCLE/ KREBS CYCLE- completes breakdown of glucose
  3. OXIDATIVE PHOSPHORYLATION- (accounds for most of ATP synthesis) further subdivided into electron transport & then chemiosmosis (atp synthesis)
6
Q

glucosis

A
  • breakdown of glucose to pyruvic acid →occurs in cyto plasm & anaerobic
  • two ATP molecules are used to energise glucose
  • as glucose is metabolised, enough energy is released: :
    make 4 ATP molecules
    → 4 ATP make - 2 ATP used= net production of 2 ATP reduce 2 NAD+ to mak e NADH
7
Q

chemical energy ATP

A

cells able to make ATP via:

  1. SUBSTRATE-LEVEL PHOSPHORYLATION
    - transferring a phosphate directly to ADP from another molecule
    - this occurs in one step of glucolysis
  2. OXIDATIVE PHOSPHORYLATION
    - use of ATP synthase and energy derived from a proton (H+) gradient to make ATP
8
Q

PYRUVATE

A

WITH OXYGEN PRESENT:

  • pyruvate is oxidised to acetyl-CoA which enters the Krebs cycle ( TCA cycle)
  • aerobic respiration

WITHOUT OXYGEN PRESENT:

  • pyruvate is reduced to oxidise NADH back to NAD+
  • fermentation
9
Q

kreb’s cycle

A

AKA citric acid cycle/ tricarboxylic acid → BREAKDOWN of pyruvic acid, released as CO2
enough enrgy is released as one pyrivic acid molecule is metabolised to :
- make 1 ATP
- reduce 4 NAD+ to form 4 NAHD
- reduce 1 FAD to form 1 FADH2
- regenerates oxaloacetate

occurs in the MITOCHONDRIAL MATRIX

10
Q

KREB’S CYCLE - SEGMENTS

A

oxidises the acetyl group from pyruvate
biochemical pathway of 9 steps in 3 segments
1. acetyl - CoA+oxaloacetate → citrate
2. citrate rearrangement and decarboxylation
3. regeneration of oxaloacetate

11
Q

electron transport chain

A
  • ECT is a series of membrane-bound electron carriers
  • embedded in the inter mitochondrial membrane
  • electrons from NADH & FADH2 are transferred to complexes of the ETC
    →protein pump that helps to create a protoon gradient across the inner mitochondrial membrane
    →trnasfers electron to next carrier
12
Q

chemiosmosis

A
  • ACCUMULATION of protons in the intramembrane space drives protons via diffusion
  • membrane relatively impermeable to ions
  • most protons can ony re-enter matrix through ATP synthase →uses energy of gradient to make ATP to form ADP + P
13
Q

recycling NADH

A

for glycolysis to continue, NADH must be recycled to NAD+ by either

  1. AEROBIC RESPIRATIONL oxygen is available as the final electron acceptor - produces significant amount of ATP
  2. FERMENTATION- occurs when oxygen is not available
14
Q

fermentation - lactic acid

A
  • starts w/ glycolysis
  • during lactic acid fermentation: pyruvic acid is reduced to form lactic acid while NADH is oxidised to NAD+
  • Muscle cells have the enzumes to perform fermentation, but brain cells dont
    → muscle cells can survive brief period of oxygen deprivation but braincells cant
    →lactic acid ‘burns are offten described as a feeling one gets in muscle upon rigorous exercise
15
Q

interconversion - fats, carbs, protein

A
  • all can be used for energy → glycolysis & krebs cicle allow these types of molecules to be interchanged
  • if more calories are consumed than used → excess food is stored
    → once organism has all protein needed & carb stores are full : remainder is convered to and stored as fat