Respiration Part 1 - (Week 2) Flashcards
(54 cards)
1
Q
What is Respiration?
A
- chemical reactions in cells that sustains life
- metabolic reaction - creating energy from food
- metabolic reaction using created energy for biological process e.g. growth, division
- removal of waste products
2
Q
What is metabolism?
A
- chemical reactions in cells required to sustain life
3
Q
What is catabolism?
A
- breaking down of molecules
4
Q
What is anabolism?
A
- building of molecules
5
Q
Within Metabolism, what processes occur?
A
- carbohydrates to Glucose (vice versa)
- proteins to amino acids (vice versa)
- fats to glycerols/ fatty acids (vice versa)
6
Q
ATP is only required for anabolic reactions. True or False?
A
False - also chemical synthesis
7
Q
Give an example of what cellular work metabolism is known for.
A
Active transport of molecules.
8
Q
What is active transport?
A
- movement of molecules where they don’t want to go
- required for some nerve transmission + some steps of respiration
- required for intracellular signalling (calcium pumps)
9
Q
An average heart weighs 300g so how much ATP does it need in a day?
A
5kg - 5000g (16x it’s weight)
10
Q
What is ATP?
A
- adenosine 5’ - triphosphate
- energy carrying molecule
- used for different processes e.g anabolism, active transport
- a chemical bond in “carrier molecules” that can diffuse rapidly throughout the cell
11
Q
Which other molecules are important for carrying energy in respiration?
A
NADH
FADH2
12
Q
What is ADP able to bind to?
A
- phosphate - bond between between the 2nd & 3rd bond gives high energy.
13
Q
What is NAD+?
A
- nicotinamide adenine dinucleotide
- picks up energy in the form of 2 electrons and a proton (H+)
- can be regarded as electron donors/acceptors
14
Q
What FAD+?
A
- flavin adenine dinucleotide
- picks up energy in the form of 2 electrons & 2 protons (H+)
- can be regarded as electron donors/ acceptors
15
Q
Where does respiration take place?
A
- inside the body
- inside cells
- in the cytoplasm (glycolysis)
- in the mitochondria (matrix) - (link reaction, TCA cycle, oxidative phosphorylation)
16
Q
What are key points of mitochondria? - timeline
A
- ‘mito’= thread, ‘chondrion’ = granule, grain like
- vary in number, size, and shape
- endosymbiotic theory
17
Q
What are some aspects of the outer membrane?
A
- smooth
- composed of equal amounts of phospholipids & proteins
- contains porins
- porins render the members freely permeable to nutrient molecules ions e.g. ATP, & ADP
18
Q
What are porins?
A
- integral membrane proteins that allow the passage of small molecules
19
Q
What are some aspects of the inner membrane?
A
- multiple folded cristae - varying in number
- cristae/proteins - sites of various chemical reactions e.g. production of ATP
- only permeable to oxygen & ATP
20
Q
Why is the cristae folded?
A
- increased SA
- gives a 5 -fold increase in SA - therefore more reactions at once
21
Q
What is the inter membrane space?
A
- space between the outer & inner membrane
- largely same composition as the cytoplasm but a difference in protein content
22
Q
What is the matrix?
A
- cytoplasm like region
- complex mixture of proteins & enzymes
- important in the synthesis of ATP molecules
- not encoded by the genomic DNA (gDNA) in the nucleus
23
Q
What is glycolysis?
A
- splitting apart with glucose
- yields a small amount of DNA
- occurs in the cytoplasm
- does not require oxygen, (anaerobic & aerobic)
- generates pyruvate, then converted to lactate (causing pain in muscles)
- costs ATP (phosphates are added to glucose)
24
Q
What are the 3 key steps of glycolysis?
A
- Phosphorylation of hexose (glucose) to hexose bisphosphate (fructose biphosphate)
- Splitting of hexose biophosphate (fructose biophosphate) into two triose phosphate molecules (glyceraldehyde phosphate)
- Oxidation to pyruvate, producing a small yield of ATP & reduced to NAD
25
What happens in phosphorylation?
Addition of phosphate groups
26
What happens within phosphorylation? - Step 1
- phosphate group = attached to glucose (hexose) from ATP
- trapped inside the group - cannot be transported back out
- isomerised to fructose (hexose)
- raises energy level - more reactive
- another phosphate group attaches to fructose
27
What is fructose biphosphate?
- carbon on the 6th phosphate
28
What happens in Step 2? - (splitting of hexose)
- fructose biphosphate (hexose) is split into 2 glyceraldehyde phosphate (triose) molecules
29
What happens in Step 3? - (oxidation to pyruvate)
- glyceraldehyde phosphate (triose) molecules oxidised
- H+ atoms removed - (anaerobically)
- NAD+ reduced as they accept the hydrogen atoms
- oxidation adds a second phosphate (not from ATP)
- Biphosphoglycerate (triose) no longer a sugar
30
What is substrate level phosphorylation?
- Enzymatic addition of phosphate to ADP
| - 2 ATP produced when the phosphates are removed
31
What are the products of glycolysis? - for a single molecule of glucose
- 2 ATP
- 2 NADH (reduced NAD+)
- 2 pyruvate (~triose) - no longer a sugar
32
What happens to pyruvate after glycolysis?
- actively transported into the mitochondria (aerobic)
| - remains in the cytoplasm ( under anaerobic conditions)
33
What happens in pyruvate transport?
- transport into the mitochondria
- with a proton, down the proton conc. gradient
- gradient = maintained by proton pumping costing energy (active transport)
34
What happens in link reaction?
- pyruvate cannot directly enter the TCA Cycle
- converted to acetate
- linked to coenzyme A (CoA)
- required for enzyme reactions
- acetyl CoA can enter the TCA cycle
35
What happens in decarboxylation?
- removal of a carboxyl group (lost as CO2)
| - catalysed by pyruvate decarboxylase
36
Fact about enzymes:
Enzymes usually do what they say e.g. pyruvate decarboxylase, removes a carbon from a pyruvate molecule
37
What happens in dehydration? (Link reaction)
- removal of protons, accepted by NAD+
| - catalysed by pyruvate dehydrogenase
38
What happens in CoA Addition? (Link reaction)
- Coenzyme A joined to acetate forming acetyl coenzyme A
| - allows acetate to enter the TCA cycle
39
In a link reaction, for each glucose entering glycolysis 2 pyruvate molecules are made. True or False?
True - 2 link reactions occur
- the molecules bind to NAD+ and CoA (3 carbons)
- producing acetyl CoA and NADH, making H+ ions and carbon dioxide (2 carbons)
40
Who was the Krebs Cycle first sequenced by?
Hans Krebs
41
What happens in Step 1 of the TCA cycle?
- acetyl CoA (2c) from the link reaction combines with oxaloacetate (4c) to make citrate (6c)
42
What happens in Step 2 of the TCA cycle?
- citrate (6c) is decarboxylated & dehydrogenated
| - forms alpha-ketoglutarate (5c), CO2 and NADH
43
What happens in Step 3 of the TCA cycle?
- alpha-ketoglutarate (5c) = decarboxylated & dehydrogenated
- forms oxaloacetate (4c), CO2, NADH, FADH2, ATP
- ATP from substrate level phosphorylation process from the enzyme
- oxaloacetate (4c) can start the cycle again
44
What are the products of link reaction and TCA cycle?
For a single molecule of pyruvate (triose):
- 1 ATP (substrate level phosphorylation)
- 4 NADH (reduced NAD+)
- 1 FADH2 (reduced FAD+)
- 3 CO2
* values double for a glucose (hexose) molecule
45
In a link reaction and TCA cycle, the equivalent of a glucose molecule is lost as carbon dioxide. True or False?
True - 6C in , 6C out + energy
46
What happens in oxidative phosphorylation?
- in 2 parts
electron transport chain (ETC):
- electrons = passed from one member of the transport chain to another in a series of redox reactions
- produces a proton gradient
Chemiosmosis:
- proton gradient used to produce ATP - uses energy stored here
47
What happens in Step 1 of Electron Transport Chain?
- NADH and FADH2, reduced in previous steps & carry electrons
- transfer their electrons to the beginning of the transport chain
- become oxidised again e.g. back to FAD+
- to be reused in other steps of respiration, cycle of redox reactions
48
What happens in Step 2 of Electron Transport Chain?
- electrons = passed down the chain of proteins (cytochromes & redox enzymes)
- electrons move to a lower energy level releasing their energy
- some of the energy pumps protons (H+ ions) from the matrix into the inter membrane space
- pumping establishes an electrochemical gradient, same principle as a concentration gradient
49
What happens in Step 3 of Electron Transport Chain?
- at the end of the electron transport chain, electrons = transferred to molecular oxygen (O2)
- oxygen splits in half + reacts with 2H+ to make H2O
50
What happens in chemiosmosis?
- gradient-driven synthesis of ATP - using the proton gradient
- ETC established a proton electrochemical gradient
- protons (H+ ions) flow back to this gradient into the matrix
- pass through the enzyme ATP synthase
- drives the enzyme to synthesise ATP ( part of ATP production by photosynthesis)
- also used in bacteria rather than aerobic respiration - maintains an electrochemical gradient between the cytoplasm & their environment
51
How many molecules of ATP can be produced by oxidative phosphorylation by each NADH?
2.6 molecules
52
What is the overall production of ATP?
- 30 ATP Yield per glucose molecule by oxidative phosphorylation
- 4 ATP per glucose molecule by substrate level phosphorylation
- 34 Total ATP - per glucose molecule
53
Is oxidative phosphorylation possible in anaerobic conditions?
No, as there is significantly less energy produced.
54
What is ATP yield reduced by?
- energy required for active transport into mitochondria e.g ADP
- energy required for active transport out of mitochondria
- dissipation of the proton gradient (leaky membrane) - protons leaking out of the mitochondria = wasted instead of driving ATP production
