Lec 13 and 14: Cellular Respiration I and II Flashcards
explain the diffference between metabolism, catabolism and anabolism
metabolism: all the chemical reactions in the body
catabolism: beaking down complex molecules
Anabolism: (endergonic) building of complex molecules
metabolism is the balance between the energy inputs and outputs of anabolism and catabolism
in what type of reactions is ATP used and made?
ATP is used in anabolic reactions
can be made in catabolic reactions
how is catabolism and anabolism coupled by ATP?
- catabolic reactions transfer energy from moleciles to ATP (releasing heat)
- these are simple molecules such as glucose, amino acids, glycerol and fatty acids.
- anabolic reactions transfer energy from ATP to complex molecules (releasing heat)
- these are molecules such as starch, proteins and lipids
cycle starts again
In starvation catabolism drops, explain what happens to the rate of anabolic processes
drop in catabolism means a drop in the break down of complex molecules
that provide energy for the production of ATP
therefore resulting in less amount of energy from ATP being provided
for the building of complex molecules (anabolic reactions)
rate of anabolic processes lowers
In liver cells (metabolises poisons) does anabolism or catabolism predominate?
catabolism
In a pancreatic cell producing digestive enzymes does anabolism or catabolism predominate
anabolism
What are the bodies main ways of storing energy
stores energy in nutrients
molecules such as glycogen (in liver) and triglycerides (in adipose tissue) store energy
why is ATP a good energy source for cells?
- contains high energy phospahte bond
- which can be released easily and quickly
what is oxidation
removal of electrons or hydrogen
/
addition of oxygen
decreasing potential energy
does oxidation or reduction take place in dehydrogenation reactions?
oxidation
what is NAD?
give the eqaution for the reduction of NAD
nicotinamide adenine dinucleotide
a derivative of the B vitamin niacin
what is FAD?
give the eqaution for the reduction of FAD
flavin adenine dinucleotide
derivative of the B vitamin riboflavin
how does phosphorylation (addition of P group) affect potential energy?
increases a molecules potential energy
what is subtrate level phosphorylation?
where does it occur
Transferring high-energy phosphate group from an intermediate directly to ADP
(occurs in the cytosol)
what is oxidative phosphorlyation?
where does it occur?
Remove electrons and pass them through electron transport chain to oxygen
occurs in the inner mitochondrial membrane
where is the only place Photophosphorylation takes place?
Only in chlorophyll-containing plant cells
what type of cell converts fructose to glucose
intestinal epithelial cells
what type of cells convert fructose and galactose to glucose?
hepatocytes
how does glucose move into the cells of the Gi tract?
by co transport
what is insulin and what is its function?
Insulin is a hormone
made by the pancreas
that allows your body to use glucose from carbohydrates in the food
for energy or to store glucose for future use.
Insulin helps keeps your blood sugar level from getting too high (hyperglycemia) or too low (hypoglycemia).
what happens in glycolysis?
steps 1-5
- Splits 6-carbon glucose into two 3-carbon molecules of pyruvic acid
- Consumes 2 ATP but generates 4
- Glucose –> Glucose 6-phosphate
(hexokinase, uses ATP and produces ADP + H+)
- Gluocse 6-phosphate –> Fructose 6-phosphate
(isomerase)
- Fructose 6-phosphate –> Fructose 1,6-biphosphate
(phosphofructase, uses ATP ad produces ADP + H+)
4a. Fructose 1,6-biphosphate –> Glyceraldehyde 3-phosphate
(aldolase)
4b. Fructose 1,6-biphosphate –> dihydroxyacetone phosphate
(aldolase)
- Glyceraldehyde 3-phosphate –> dihydroxy acetone phosphate
(triosephosphate isomerase)
what is the key regulator of glycolysis?
Phosphofructokinase
PFK
when are phosofructokinase levels high?
when ADP levels are high
how do ADP levels affect glycolysis
high ADP levels
indicate high phoshofructokinase acitivity
so high rate of glycolysis
/
low ADP levels
glucose is shunted away from glycolysis
to the glycogen storage pathway
what is Tarui disease?
where there is a lack of PFK
results in exercise intolerance, with pain, cramps and, occasionally, myoglobinuria (acute muscle breakdown leading to rust-colored urine).
A partial deficiency of phosphofructokinase in the red blood cells results in the breakdown of those cells and an increase in blood levels of bilirubin (a chemical found in red blood cells)
what happens in glycolysis?
steps 6-10
- Glyceraldehyde 3-phosphate –> 1,3-biophosphoglycerate
(glyceraldehyde phosphate dehydrogenase uses NAD and HPO42- to make NADH + H+)
- 1,3-biphoshpoglycerate –> 3-phosphoglycerate
(phosphoglycerate kinase, uses ADP to make ATP)
- 3-phosphoglycerate –> 2-phosphoglycerate
(phosphoglycerate muatase)
- 2-phosphoglycerate –> phosphoenolpyruvate
(enolase)
- phosphoenlpyruvate –> pyruvate
(pyruvate kinase, uses ADP + H+ to make ATP)
In glycolysis;
how many NADH + H+ molecules are made
how many ATP molecules are used and generated
6 NADH + H+ molecules
use 2 ATP molecules and generate 4
what are the NADH + H+ molecules used to make? and in which cells?
- Most cells use these to generate 4 ATPs in the electron transport chain
- Hepatocytes and cardiac muscle fibres generate 6 ATPs from them
where is the location of glycolysis?
cystosol
what is the fate of pyruvic acid depending on whether anaerobic or aerobic respiration takes place?
anaerobic: reduced to 2 lactic acid molecules
2 molecules are reduced by 2 H atoms from NADH
lactic acid enters the blood and is converted back to pyruvate by hepatocytes
aerobic: converted to acetylcoenzyme A
why is the reduction of pyruvate in anaerobic respiration important to glycolysis?
when 2 pyruvates are reduced by 2 NADH
it regenerates 2NAD+
which are required in step 6:
- Glyceraldehyde 3-phosphate –> 1,3-biophosphoglycerate
(glyceraldehyde phosphate dehydrogenase uses NAD and HPO42- to make NADH + H+
without the NAD glycolysis can not continue
what is the importance of converting pyruvate to acetyl coenzyme A in aeoribic respiration
- molecule links glycolysis (cytoplasm) to Krebs (matrix of mitochondria)
- RBC’s lack mitochondria so can only perform glycolysis
what enzyme converts pyruvate to acetyl coenzyme A?
pyruvate dehydrogenase
what is the net gain of ATP, NADH and Acetyl coenzyme A molecules in glycolysis and krebs cycle?
Net gain from glycolysis and link reaction
- 2 ATP molecules
- 4 NADH molecules
- 2 Acetyl coenzyme A molecules
what is Pyruvate dehydrogenase deficiency?
a sex linked disease
Pyruvate dehydrogenase deficiency
where does the krebs reaction take place?
in the matrix of the mitochondria
*NOTE* Krebs cycle overview
start of with:
3 NADH
1 FADH2
Contain the energy originally stored in glucose
Later each NADH makes 3 ATP molecules
FADH2 makes 2 ATP molecules
1 ATP made by substrate level phosphorylation
how many ATP molecules are made in total in the krebs cycle?
12 ATP (24 per glucose molecule)
what are the steps in the krebs cycle?
- Entry of acetly group to create citrate & regeneration of CoA
- Isomerisation to isocitric acid
- Oxidative decarboxylation. Remove CO2 & formation of NADH & alpha ketoglutarate
- Oxidative decarboxylation and addition of CoA to form succinyl-CoA & NADH
- Substrate level phosporylation. CoA is displaced for a phosphate group, which is transferred to GDP and donated to ATP. Forms succinate
- Dehydration. Succiante is oxidised furmarate by FADH2 formation
- Hydration. Furmarate is converted to malate by addition of water
- Dehydrogenation to oxaloacetate & formation of NADH
how many CO2 molecules does krebs produce from each glucose molecule?
4
1Which enzyme in Krebs allows for substrate level phosphorylation?
succinyle co-A synthetase
why do you breathe out more CO2 after excersise?
more turns of krebs
which three enzymes in krebs reduce NAD?
- isocitrate
- ketogluterate
- malate dehydrogenase
what is the electron transport chain?
a series of electron carries in the inner mitochondrial membrane
what is the final electron acceptor?
oxygen
what happens in the electron transport chain?
- Energy from NADH + H+ passes along the electron transport chain (via REDOX) & is used to pump the proton pump
- A high concentration of H+ accumulates between the membranes
- ATP synthesis occurs as the H+ ions flow back into the matrix through the H+ channels
how many molecules of ATP are produced in the electron transport chain?
32 or 34 per glucose molecule
how many molecules of ATP are made from NADH + H+ and FADH2
10 molecules of NADH + H+ produce 28 or 30 mols of ATP
2 molecules of FADH2 produce 2 mols of ATP
*NOTE* for NADH in krebs cycle
- NADH made in glycolysis cannot enter the mitochondria.
- They donate electrons to malate or glycerol phosphate shuttle
which organs use the malate shuttle and how many ATP molecules are produced as a result?
•Liver, kidneys & the heart= 3ATP molecules result
how many ATP molecules are made as a result of the glycerol phosphate shuttle?
2 ATPs
how many molecules of ATP are made in substrate level phosphorlyation in glycolysis and krebs cycle?
substrate level phosphorylation in glycolysis = 2 ATP
substrate level phosphorylation in the Krebs cycle = 2ATP
*NOTE* ATP yield per glucose molecule
what is the role of NAD dehydrogenase in the krebs cycle?
reduces NAD/FAD by oxidising a substrate
what is chemiosmosis?
the use of energy in a chemical gradien to generate ATP by the flow of hydrogen ions through ATP synthase
how is a H+ gradient built up in the mitochondria? that is the purpose of this?
H+ ions from the matris are pumped into the intermembrane space
the inner mitcohondrial membrane is impermeable to H+ ions
so a gradient forms
H+ ions move down their concentration gradient, into the matrix using protein channels that are associated with the enzyme ATP synthase
ATP synthase phosphorylates 1 ADP for each H+ ion
therefore protons are a direct energy source for producing ATP
why can a liver cell make more ATP per glucose molecule than a lung cell?
liver cells use the malate shuttle to recieve electrons from NAD
this results in the production of 3 ATP molecules
where as a lung cell would use the glycerol phosphate shuttle
resulting in the production of 2 ATP molecules
what stimulates glycogenesis?
insulin in hepatocytes and muscle cells
what is the role of phosphoglucomutase?
interconverts Glucose 6-phosphate to Glucose 1-phosphate
under what metabolic conditions will glycogensis occur?
in high levels of ATP and glucose
what hormone stimulates glycogenesis?
insulin
how can the hormone glucagon help keep blood sugars up?
- pancreas releases glucagon when blood glucose levels are too low
- glucagon stimulates glycogenolysis
which produces glucose from glycogen with the use of phosporylation
which two hormones activate glycogen phosphorylase?
glucagon and adrenaline
