MODULE 1.4 RESPIRATION Flashcards
Outline reasons why living organisms need to respire
-protein synthesis, synthesis of cellulose from beta glucose
-exocytosis and endocytosis
-active transport across plasma membranes against conc gradient
-movement I.e bacterial flagella, muscle contraction
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What is respiration.
Process where energy that I stored in complex organic molecules is broken down to make ATP
What is the structure of an ATP molecule
Made of adenosine (adenine and ribose) and 3 phosphate molecules
What is an anabolic reaction
Synthesis of larger molecules from smaller ones in biochemical reactions
What are catabolic reactions
Hydrolysis of larger molecules into smaller ones
Why are coenzymes needed
Normal enzymes good at catalysing metabolic reactions but not at reactions involving oxidation and reduction
What is NAD
Organic non protein molecule that helps dehydrogenase enzymes do oxidation reactions
Made of TWO linked nucleotides
One containing nicotinamide ring, phosphate and ribose and the other containing adenine, phosphate and ribose
What does the nicotinamide ring on one of the NAD molecules do
Accepts hydrogen atoms that are later split into hydrogen ion and electron
How does NAD work
Accepts hydrogen atoms with electrons and becomes reduced and when it loses it becomes oxidised
Define glycolysis
The breakdown of a hexose(glucose) sugar into 2 pyruvate molecules and occurs in the cytoplasm of all cells
Common in aerobic and anaerobic respiration
What is the structure of coenzyme a and how does it work
Made of adenosine, 3phosphate groups, cysteine and pantothenic acid
Carries acetate groups made during link reaction onto krebs cycle and acetate groups made from some fatty or amino acids
What are mitochondria?
They are organelles found in eukaryote cells– site for link reaction Krebs cycle and oxidative phosphorylation
What is the ultrastructure of mitochondria
– It has an outer and inner membrane which make up the envelope
- outer membrane smooth and inner folded into cristae for large surface area
- inner membrane has matrix which is semi rigid and gel like
What happens in the matrix and How does the structure of the matrix allow it to carry out its functions
Links reaction and krebs cycle
- contains enzymes that catalyse these reactions
- NAD
- oxaloacetate
- mitochondrial DNA which may code for proteins and mito enzymes
- mito ribosomes
How does glycolysis happen
-phosphorylation whereby ATP is hydrolysed and phosphate produced added onto glucose and carbon 6 causing fructose 6 phosphate
Another ATP hydrolysed added at first carbon making fructose 1,6 biphosphate, molecule now unstable
-this split into 2 molecules of trios phosphate
-trios p oxidised: 2 h atoms removed aided by dehydrogenase enzymes and NAD : 2 mol of NAD reduced and 2 mol of ATP formed
-triose phosphate converted to pyruvate and 2 mol of ATP formed
define mitochondria
organelles found in eukaryote cells
describe the structure of mitochondria
- inner and outer phospholipid membrane e.g envelope
- outer smooth and inner folded into cristae with ATP synthase and electron carriers
- matrix enclosed by inner membrane
what happens in the link reaction
- decarboxylation and dehydrogenation of pyruvate to acetate
- NAD accepts hydrogen and co enzyme a accepts acetate to carry to krebs reaction
- takes place in mitochondrial matrix
how does lactate fermentation occur
reduced NAD is reoxidised by lactate dehydrogenase and pyruvate accepts the H+ ions
NAD+ can then go on to accept more h+ ions so enough ATP is produced by substrate level phosphorylation in glycolysis
what happens to lactate once lactate fermentation has occured
is carried in the blood to liver cells where it can be reoxidised to pyruvate once enough oxygen is available so can enter link and krebs
or can be recyles to glucose and glycogen
what happens in alcoholic fermentation
pyruvate decarboxylated to ethanal (pyruvate decarboxylase)
ethanal accepts h+ ions from RNAD which becomes ethanol (ethanol dehydrogenase)
reoxidised NAD can now accept more h+ from glucose
