Energy Reactions in Cells

Question 1

Define metabolism

Answer 1

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

Question 2

What is a catabolic pathway?

Answer 2

A metabolic pathway that breaks down larger molecules into smaller more manageable chemical entities that can be converted

Question 3

State 2 characteristics of catabolic pathways

Answer 3

1) releases large amounts of free energy

2) oxidative

Question 4

What is an anabolic pathway?

Answer 4

Biosynthetic pathways that synthesise larger cellular components from intermediate metabolites

Question 5

State 2 characteristics of anabolic pathways

Answer 5

1) Uses energy (ATP) released from catabolism

2) Reductive (uses H+ released in catabolism)

Question 6

What is the energy from catabolic metabolism used for?

Answer 6

• building block materials
• organic precursors
• biosynthetic reducing power
• energy for cell function

Question 7

Define energy

Answer 7

The capacity to do work

Question 8

What are the 3 types of work?

Answer 8

1) Biosynthetic work
2) Transport work
3) Specialised functions

Question 9

What is biosynthetic work?

Answer 9

The synthesis of cellular components (e.g. proteins, storage molecules, etc)

Question 10

What is transport work?

Answer 10

Work involving the membrane; maintenance of the ion gradient & nutrient uptake

Question 11

What is the basal metabolic rate?

Answer 11

The energy required by an wake individual during physical, digestive and emotional rest at 18 degrees celcius (includes all body tissues)

Question 12

What effects the amount of energy needed for activity?

Answer 12

The type, intensity and duration of activity (only includes heart and skeletal muscle)

Question 13

What is the specific dynamic action of food?

Answer 13

The energy cost of ingestion, digestion and absorption of food

Question 14

Why do we need energy?

Answer 14

• to carry out basic metabolic reactions
• during activity
• muscular activity
• energy lost as heat

Question 15

What happens to energy when energy intake > energy required?

Answer 15

Excess energy is stored:

• for growth and synthesis of new tissue
• production of adipose tissue

Question 16

What happens when energy intake < energy required?

Answer 16

Tissue is lost

Question 17

What is the average dietary intake?

Answer 17

Carbohydrates - 15%
Proteins - 5%
Lipids - 8%

Question 18

What is primary lactase deficiency?

Answer 18

Absence of the lactase persistence allele

Question 19

In what people does primary lactase deficiency occur in?

Answer 19

Adults

Question 20

What is secondary lactase deficiency?

Answer 20

Lactase deficiency caused by injury to the samll intestine

Question 21

In what people can secondary lactase deficiency occur in?

Answer 21

Adults and children

Question 22

Is primary lactase deficiency reversible?

Answer 22

No

Question 23

Is secodary lactase deficiency reversible?

Answer 23

Yes, fix primry issue

Question 24

What is congenital lactase deficiency?

Answer 24

Autosomal recessive defect in lactase gene

Question 25

What are symptoms of lactase deficiency?

Answer 25

Diarrhoea Vomiting Rumbling stomach

Question 26

Where are GLUT2 transport proteins used?

Answer 26

Kidney Liver Small intestine Pancreatic Beta cells

Question 27

Where are GLUT4 transport proteins used?

Answer 27

Insulin regulation Striated muscle Adipose tissue

Question 28

When is pyruvate converted into lactate?

Answer 28

low 02 conditions | NAD+ deficiency

Question 29

When does lactic acidosis occur?

Answer 29

Plasma lactate concentration > 5mM

Question 30

When does hyperlactaemia occur?

Answer 30

Plasma lactate concentraion between 2-5mM

Question 31

How does fructose intolerance occur?

Answer 31

Aldolase B missing

Question 32

What are the effects of fructose intolerance?

Answer 32

Fructose-1-phosphate accumulates in the liver, causing liver damage

Question 33

What is galactosaemia?

Answer 33

The bodies inability to use galactose, casusing a build up of galactose and/or galactose-1-phosphate

Question 34

What is a symptom of galactosaemia and how is it caused?

Answer 34

Clouding of the eye lens: Galactose undergoes a different pathway to form galactitol which uses NADH NADH needed to keep disulfide bridges in their reduced form, not occuring so loss of structural and functional integrity

Question 35

What occurs if galactose-1-phosphate builds up?

Answer 35

Liver damage

Question 36

What is covalent modification?

Answer 36

phosphorylation/dephosphorylation, altering protein structure, altering activity

Question 37

What is product inhibition?

Answer 37

When there is enough product so the product feeds back up the pathway and binds to a regulatory site on the first step to inhibit it

Question 38

What is feedback inhibition?

Answer 38

A build up in ATP or NADH feeds back and inhibits the pathway

Question 39

What is the committing step?

Answer 39

The step at which a substrate must go all the way down its pathway

Question 40

What is the hormones/products regulates glycolysis?

Answer 40

Phosphofructokinase | NADH

Question 41

How is phosphofructokinase regulated?

Answer 41

``` Allosteric regulation: Stimulated by AMP Inhibited by ATP Phosphoenolpyruvate Citrate H+ ``` Hormonal regulation: Stimulated by insulin, dephosphorylates PFK Inhibited by glucagon, phosphorylated by glucagon

Question 42

What hormones regulate pyruvate kinase?

Answer 42

Insulin | Glucagon

Question 43

What metabolite regulates hexokinase?

Answer 43

Glucose-6-phosphate

Question 44

What is the committing step in glycolysis?

Answer 44

3 - PFK

Question 45

What factors inhibit Pyruvate Dehydrogenase?

Answer 45

Acetyle CoA NADH ATP Citrate

Question 46

What 2 enzymes regulate the TCA Cycle?

Answer 46

alpha-ketogluterate dehydrogenase | Isocitrate dehydrogenase