Metabolism- Glycolysis Flashcards
What is the function of metabolism?
Cells need a source of energy
Where is the energy provided from?
Electrons with negative redox potential (high energy electrons
What do cells need in order to build cellular components?
Carbon
What equation makes up metabolism?
Catabolism + anabolism
Give the components of catabolism
- Large complex organic molecules are decomposed into small molecules
- Degradative
- Oxidative
- Energy is liberated
- Converging
Give the components of anabolism
- Large complex organic molecules are constructed from small molecules
- Biosynthetic
- Reductive
- Energy is required
- Diverging
What is oxidation and reduction in terms of loss and gain of electrons?
Oxidation is loss
Reduction is gain
As one molecule is oxidised, another one is reduced. What is the term used for this?
Redox pair
In order of functional groups what groups are in most reduced state and highest free energy. Highest to lowest
Alkane -> alcohol -> aldehyde -> carboxylic acid -> carbon dioxide
What does glucose oxidation release?
Energy
What are oxidised to release high energy electrons?
Organic compounds
- carbohydrates, amino acids, lipids
What do organic cofactors act as?
Electron carriers
What happens to a terminal electron acceptor?
Its reduced
Definition of enzyme
Proteins that catalyse the conversion of a substrate into a product
Name the different classes of enzymes
Oxidoreductases Transferases Hydrolases Lyases Isomerases Ligases
More than half of all organic carbon is in what two polysaccharides?
Starch
Cellulose
What is glucose oxidised to?
CO2 and H20
What cell types require glucose as energy source?
Erythrocytes
Retina
Renal medulla
Brain
What is the formula of glucose?
C6H1206
What is the three carbon sugar called?
Glyceraldehyde
What are the pentoses called?
Ribose
Deoxyribose
What are the hexoses called?
Mannose
Galactose
Fructose
What does an alpha-1,2 glycosidic linkage result in?
Sucrose
What does an alpha-1,4 glycosidic linkage result in?
Maltose
What does a beta-1,4 glycosidic linkage result in?
Cellobiose
Name the polysaccharides
Cellulose
Starch and glycogen
Name the three intracellular stages of metabolism
- Acetyl-CoA production
- Acetyl-CoA oxidation
- Electron transfer and oxidative phosphorylation
How does glucose transport into the cell?
Via Na+/glucose symporters
Where is GLUT1,2,3,4 and 5 (glucose transporters) located in the body?
1- Brain 2- Liver, pancreatic B cells 3- Brain 4- Muscle, adipose tissue 5- Gut
What happens to GLUT1 when glucose binds to it?
Triggers a conformational change so that the binding site faces inwards
Give the overall reaction pathway for the conversion of glucose to pyruvate
glucose + 2ADP + 2Pi + NAD+ -> 2pyruvate + 2ATP + 2H20 + 2H20 + 2NADH + 2H+
Describe stage 1 of glycolysis
Glucose is trapped and destabilised
Describe stage 2 of glycolysis
Two interconvertible three-carbon molecules are formed
Describe stage 3 of glycolysis
Generation of ATP
What are the two major cellular needs in glycolysis?
Production of ATP
Provision of building blocks for synthetic reactions
What is a potential control point in glycolysis?
Enzymes catalyzing essentially irreversible reactions
What are the three irreversible/controlled reactions in glycolysis?
Hexokinase
Phosphofructokinase
Pyruvate kinase
What is the key enzyme in the control of glycolysis?
Phosphofructokinase
Show the reaction for phosphofructokinase
fructose 6-phosphate + ATP -> fructose 1,6-biphosphate + ADP + H+
What are the negative modulators in glycolysis?
- ATP
- Citrate (early intermediate in KREBS, biosynthetic precursors are abundant)
- H+ (prevents excessive formation of lactic acid)
What are the positive modulators in glycolysis?
- AMP
- fructose 2,6-biphosphate
What does it mean if all adenylate nucleotides are in the shape of ATP?
the cell is fully charged
What does it mean when the cell only contains AMP and PI?
The cells is discharged
Why is AMP and not ADP the postive regulator?
Adenylate kinase can salvage some of the energy in ADP
2ADP -> ATP + AMP
