Lecture 11 - Respiration Flashcards
what are the 3 fates of nutrients from the diet?
supply energy, serve as building blocks and stored for future use
how many enzyme controlled steps are in the breakdown of glucose?
19
what is cellular respiration?
a set of metabolic reactions and processes that take place in the cells of organisms to convert biochemical energy from nutrients int ATP and then release waste products
what is cell metabolism?
the sum total of all chemical reactions that occur inside the cell
what is catabolism?
the breakdown of larger molecules into smaller ones for the purpose of energy production
what is anabolism?
production of larger molecules to make chemical building blocks for the body
Describe the relationship between ATP in catabolic and anabolic reactions
ATP is used in anabolic and produced in catabolic
what percent of energy from catabolism is used for cellular function?
40%
what is oxidation?
removal of electrons or hydrogen or addition of oxygen which decreases potential energy
after oxidation what are the hydrogen atoms transferred to other compounds by?
coenzymes
what is NAD+?
an oxidising agent
what is NADH?
a reducing agent
what is NAD?
a derivative of the B vitamin niacin
what is FAD?
a derivative of the b vitamin riboflavin
what is the role of an erythrocyte?
to carry oxygen to other tissues, contains no mitochondria or nucleus and is metabolically inactive
Describe the first 5 steps in glycolysis
energy in the form of ATP is invested.
the 6 carbon glucose splits into two 3 carbon of glyceraldehyde 3 phosphate
what is the role of phosphofructokinase ?
its the key regulator of glycolysis, its activity is high when ADP levels are elevated
what occurs when ADP levels are low?
glucose is shunted away from glycolysis to the glycogen storage pathway
Describe the second 5 steps of glycolysis
two glyceraldehyde m molecules are converted into two pyretic acid molecules
ATP is generated, as are NADH + H+
what is the net gain of ATP in glycolysis?
+ 2 ATP
what protein transports pyruvate into the mitochondria?
pyruvate translocase
what occurs during pyruvate decarboxylation?
each pyretic acid is converted into 2-carbon acetyl group which is attached to coenzyme A to form acetyl co enzyme A
what is the net gain from glycolysis and the link reaction (pyruvate decarboxylation)?
2 ATP
4NADH
2 acetyl coenzyme A
Describe the first 4 steps of the Krebs cycle
- entry of acetyl coA to create citrate and regeneration of coA
- isomerisations to isometric acid
- oxidative decarboxylation to remove CO2 and form NADH and alpha ketoglutarate
- oxidative decarboxylation and addition of CoA to form succinylcholine CoA and NADH
Describe steps 5-8 of the Krebs cycle
- substrate level phosphorylation, CoA is displaced for a phosphate group which is transferred to GDP and donated to ATP to form succinate
- dehydration, succinate is oxidised to fumigate by FADH2 formation
- Hydration, fumigate is converted to malate by addition of water
- dehydrogenation to oxaloacetate and formation of NADH
what maximises the area for ETC?
Cristae
Describe complex 1 (NADH dehydrogenase) of the electron transport chain
NADH produced in there Krebs cycle is oxidised which produces H+, NAD+, 2e- which bind to the complex
4H+ are translocated into the inter membrane space
Describe complex 2 (succinate dehydrogenase) of the electron transport chain
electrons are delivered into the quinine pool from succinate via FAD
this electron pathway is parallel to complex 1
it does not transport any H+ into the inter membrane space therefore has a lower energy production than complex 1
Describe complex 3 (CoQH2 cytochrome C reductase) of the electron transport chain
- receives 2 electrons from the coenzyme Q that are passed to cytochrome C
- 2 other electrons are also passed to reduce the quinolone section of the cytochrome c to quinol
- quinol is the oxidised producing 4H+ that are transferred to the inter membrane space
Describe complex 4 (cytochrome c oxidase ) of the electron transport chain
- 4 electrons are removed from 4 molecules of cytochrome c
- these are transferred to oxygen which binds with H+ ions in the matrix to form two molecules of water
- 4H+ ions are translocated into the inter membrane space
How is ATP formed in the electron transport chain ?
H+ ions move down their concentration gradient via complex V (ATP synthase) and for every H+ one ADP molecule is phosphorylated
what is the use of a chemical gradient to produce ATP via ATP synthase called?
chemiosmosis
How many ATP’s are formed in total over respiration?
36/38 for each molecule of glucose
what do high insulin levels increase?
expression of GluT4
what his glycogenesis stimulated by?
by insulin in hepatocytes and muscle cells
what is glycogen phosphorylase activated by?
the hormones glucagon and adrenaline
what is a hepatocyte?
main cell in the liver
what us the function of glycogen phosphorylase?
to catalyse the rate limiting step in glycogenolysis
what is the function of a hepatocyte?
to convert most of the fructose and galactose to glucose
where is GLUT1 present in?
most cells
where is GLUT2 present in?
liver, beta cells, hypothalamus
where is GLUT3 present in?
neurones, placenta, testes
where is GLUT4 present in?
skeletal and cardiac muscle, fat
where is GLUT5 present in?
small intestine
what are GLUT1,2,3,4,5?
glucose transporters
