Energy Reactions In Cells

Question 1

Catabolic Pathways

activate when ADP or AMP levels increase

Answer 1

• break down large molecules into intermediary metabolites
• release large amounts of free energy
• oxidative - release H atoms ‘reducing power’

Question 2

Anabolic Pathways

activated when ATP concentrations increase

Answer 2

• synthesise larger important cellular components from intermediary metabolites
• use energy released from catabolism (ATP)
• reductive (use H ions released in catabolism)

Question 3

Products of catabolic metabolism

Answer 3

• building block material (sugars, amino acids, fatty acids)
• organic precursors (acetyl CoA)
• Biosynthetic reducing power (NADH, NADPH)
• energy for cell function (adenosine triphosphate - ATP)

Question 4

Energy usage

mainly chemical bond energy

Answer 4

Biosynthetic work - anabolism 
Transport work 
- maintenance of ion gradients 
- nutrient uptake 
Specialised functions 
- mechanical work - muscle contraction 
- electrical - nervous impulse conduction 
- osmotic work - transfer and retention of water in the kidneys

Question 5

Energy content

Answer 5

Fat - 37kJ.g - 9Kcal.g
Carbohydrates - 17kJ.g - 4Kcal.g
Protein - 16kJ.g - 4Kcal.g
Alcohol - 29kJ.g - 7Kcal.g

Question 6

Metabolism

Answer 6

• a set of processes which derive energy and raw materials from food stuffs and use them to support repair, growth and activity of the tissues in the body to sustain life

Question 7

Energy requirements

Answer 7

kg X 4.2 for kJ.24hrs
Basal metabolic rate - energy required when awake during physical, digestive and emotional rest at 18C
Activity - depends on type, intensity and duration of activity
Specific dynamic action of food - energy cost of ingestion, digestion and absorption of food
Energy lost as heat
CAN SURVIVE APPROXIMATELY 20-70 WITHOUT FOOD IF GIVEN WATER

Question 8

Chemical bond energy

Answer 8

Exergonic

• releases energy CATABOLIC
• reaction is spontaneous
• delta G 0

Question 9

Redox Reactions

Answer 9

Oxidation - removal of electrons or removal H atoms

OIL RIG = oxidation is loss of e-, reduction is gain

Question 10

Carrier molecules

Answer 10

Oxidised (low energy signals)
- NAD+, NADP+, FAD
Reduced (high energy signals)
NADH + H+, NADPH + H+, FADH2

Question 11

ATP

Answer 11

stable in the absence of specific catalysts

Only an energy carrier - not a store

Question 12

Creatine Phosphate

immediate store of energy in skeletal muscle

Answer 12

Creatine + ATP to phosphocreatine + ADP via creatine kinase enzymes

Question 13

Creatine Kinase

a marketer of myocardial infarction

Answer 13

CK is released from cardiac myocytes when damaged

appears in blood after a few hours

Question 14

Creatinine

used as a measure of muscle mass

Answer 14

24h is proportional to muscle mass of the individual

creatinine concentration in urine is a marker of urine dilution