Energy Transfers In and Between Organisms Flashcards
how many stages are there in respiration?
4
list the steps of respiration in order
- glycolysis
- link reaction
- krebs cycle
- oxidative phosphorylation
describe the process of glycolysis
- glucose phosphorylated by 2 ATP to form glucose phosphate
- glucose phosphate breaks down into 2 molecules of triose phosphate
- triose phosphate oxidised to produce pyruvate
- NAD coenzyme gains the hydrogen to form reduced NAD
what are the products of glycolysis?
2 x reduced NAD
2 x pyruvate molecules
2 x ATP (net gain)
where does glycolysis take place?
cytoplasm
where does the link reaction take place?
mitochondrial matrix
describe the process of the link reaction
- pyruvate from glycolysis actively transported from cytoplasm into mitochondrial matrix + is decarboxylated in form of CO2 + oxidised to form acetate
- NAD reduced to form NADH
- acetate combines with coA to produce acetyl coA
how many times does the link reaction occur for every glucose molecule?
2
what are the products of the link reaction per glucose molecule?
2 x acetyl coenzyme A
2 x CO2
2 x reduced NAD
where does the krebs cycle take place?
mitochondrial matrix
describe the process of the krebs cycle
- acetyl CoA (2c) reacts with oxaloacetate (4c) to form citrate (6c). CoA returns to link reaction to be reused
- citrate decarboxylated so converted to a 5 carbon compound. dehydrogenation occurs - hydrogen used to produce NADH
- 5c molecule is converted to oxalacetate due to decarboxylation and dehydrogenation. this also caused 1 molecule of FADH and 2 molecules of NADH to be produced
- ATP produced by direct transfer of a phosphate group from an intermediate to ADP (substrate-level phosphorylation)
how many times does the krebs cycle occur for every glucose molecule?
2
what are the products of the krebs cycle per glucose molecule?
2 x CoA
2 x Oxaloacetate
4 x CO2
2 x ATP
6 x NADH
2 x FADH
where does oxidative phosphorylation take place?
mitochondrial inner membrane
describe the process of oxidative phosphorylation
- NADH + FADH oxidised - release H atoms. H atoms split into H+ + e-
- e move along etc, lose energy at each carrier
- e carriers pump H+ from matrix into intermembrane space
- conc of H+ now higher in intermebrane space than in matrix - forms echem gradient
- H+ move down echem gradient back across inner membrane + into matrix - happens via ATP synthase
- movement of H+ through ATP synthase drives synthesis of ATP from ADP + Pi
- in matrix, at end of etc, H+, e- + oxygen combine to form water
what is an electrochemical gradient?
a concentration gradient of ions
what is the final electron acceptor in respiration?
oxygen
where does anaerobic respiration occur?
cytoplasm only
describe the process of anaerobic respiration in animals
- pyruvate from glycolysis reduced using H from NADH to form lactate
- this reoxidises NAD so can be used in glycolysis + ensures even more ATP is continued to be produced
give an equation for anaerobic respiration in animals
pyruvate + NADH –> lactate + NAD
describe the process of anaerobic respiration in plants and microbes
- pyruvate produced in glycolysis is reduced to form ethanol and carbon dioxide by gaining the hydrogen from NADH
- this reoxidises NAD so that it can be used in glycolysis + ensures even more ATP is continued to be produced
why can anaerobic respiration only occur for a short period of time?
ethanol is toxic and lactic acid is an acid so both would denature enzymes if anaerobic repiration occured for a long period of time
how many ATP molecules can be produced from one NADH? how does this compare to the ATP produced from one FADH?
- one NADH can result in a yield of 3 ATP molecules
- one FADH can result in a yield of 2 ATP molecules
what is the total yield of ATP molecules from aerobic respiration?
38
why is aerobic respiration only approximately 32% efficient?
- some protons leak across the mitochondrial membrane during oxidative phosphorylation
- some ATP used to actively transport pyruvate and NADH into the matrix
- some energy is lost as heat
what is the total yield of ATP molecules for anaerobic respiration?
2
what happens when oxygen is used up quicker that it is supplied?
an oxygen debt occurs
what is the effect of lactate on muscle tissue? how is this reversed?
- causes cramp and fatigue
- can be oxidised back to pyruvate or taken to liver and converted to glycogen
why is oxygen important?
so H atoms produced in glycolysis + krebs cycle can be converted to water + drive production of ATP
what happens in the absence of oxygen?
- link reaction, krebs cycle and oxidative phosphorylation can’t take place so glycolysis is the only source of ATP molecules
- pyruvate builds up in the cell
list 8 key structures of a chloroplast
- outer and inner membranes
- intermembrane space
- stroma
- thylakoids
- lumen (inside of thylakoid)
- lamella (links grana)
- granum ( a stack of thylakoids)
describe the structure and adaptations of the thylakoid membranes
- folded membranes (large sa = more proteins) that contain photosynthetic proteins (chlorophyll)
- electron carrier proteins are embedded on the membranes
- both proteins involved in LDR
describe the structure of the stroma
fluid centre which contains enzymes involved in the LIR
describe the function of the inner and outer membranes of the chloroplast
control what can enter and leave the cytoplasm
how many key pigments make up chlorophyll?
5
what is the most abundant pigment in chlorophyll?
chloropyhyll a
list the 5 key pigments that make up chlorophyll in all plants
- chlorophyll a
- chlorophyll b
- carotene
- xanthophyll
- phaeophytin
what colour is chlorphyll a?
blue/green
what colour is chlorophyll b?
yellow/green
what colour is carotene?
orange
what colour is xanthophyll?
yellow
what colour is phaeophytin?
grey
at what wavelength is light poorly absorbed by all pigments?
500-550nm
what is the advantage of chlorophyll being made up of multiple different pigments?
- wider range of wavelengths of light is absorbed
- therefore more light energy is absorbed for the LDR (more photoionisation of chlorophyll)
what are the 2 stages of photosynthesis?
- light dependent reaction (LDR)
- light independent reaction (LIR)
where does the LDR occur?
thylakoid membranes