Respiration and carbohydrates Flashcards
Respiration definition
Cells break down food molecules and release the energy they contain
Glycolysis
Occurs in cytoplasm where glucose is broken down into pyruvate
Pyruvate fermentation
Under anaerobic conditions pyruvate is fermented and NADH is recycled
What is the mitochondrial matrix?
- Pyruvate enters under aerobic conditions
- Pyruvate is decarboxylated to produce acetyl CoA for TCA cycle
What is the TCA cycle?
The second stage of cellular respiration
What is produced in the TCA cycle?
- 3 NADH
- 1 FADH2
- 1 ATP
- Release of 2 CO2 molecules
The electron transport chain
- Located in the inner mitochondrial membrane
- NADH and FADH2 are oxidised back to HAD and FAD
- Electrons from NADH pass down a series of electron carriers and are donated to oxygen
- Protons are pumped out of the mitochondria to produce ATP
How many protons are needed for ATP production?
4
How is the TCA cycle controlled?
- Pyruvate dehydrogenase is inhibited by ATP, acetyl CoA and NADH
- Isocitrate dehydrogenase is inhibited by NADH and ATP but activated by ADP
- Ketoglutarate dehydrogenase is inhibited by NADH, ATP and succinyl CoA
How is glycolysis controlled?
Feedback regulation allows cells to switch from glucose breakdown to synthesis
What is glycogenesis?
Generation of glucose from non-carbohydrate sources
Function of glucogenesis
Maintain blood glucose levels in liver and kidney
Lactase
Made from glucose and galactose
Maltose
Made from 2 glucose molecules
Trehalose
Made from 2 units of glucose but with a different glycosidic bond
Uses of polysaccharides
Storage or structure
What is cellulose?
Polymer of glucose which provides structure in cell walls
How are cellulose fibres made?
Glucose polymers cross link into cellulose microfibrils which align into cellulose macrofibrils and hence cellulose fibres
What are cell walls made from?
Cellulose cross linked by hemicellulose, pectin and proteins
How is cellulose made into the cell wall?
Cellulose synthase enzyme complex
What do cellulase enzymes do?
Break down cellulose into glucose
What carbohydrates are used in plants and animals?
Starch and glycogen
What is inulin?
Polymer of fructose
What is glycogen?
Polymer of glucose joined by 1-4 linkages and 1-6 linkages
What is glycogenin?
A protein at the centre of glycogen which initiates glycogen biosynthesis and adds glucose molecules
Where is glycogen found in humans?
Skeletal muscles and liver
Why is glycogen important?
Can be degraded by phosphorylase to maintain sugar levels
Digestion of cellulose
Cows and termites are effective at digestion as they have long digestion times but human digestion is poor
What is chitin?
Polymer of glucose with 1 acetyl amine group
What is chitosan?
Chitin waste treated with alkali for positive use
