week 10 sem 2

Question 1

Metabolism

Answer 1

the sum of all biochemical reactions that occur in the body.

Question 2

Catabolic reations

Answer 2

break down larger substances into smaller one
release energy that can be used to synthesis ATP
E.g., used in glycolysis, Krebs cycle, electron transport chain and digestion of food

Question 3

Anabolic reactions

Answer 3

make simple molecules into bigger ones (build up)
Consumes energy i.e., use more energy than they produce
Cells synthesis new organic components for:
Structural maintenance or repairs
Support growth
Produce secretions
Store nutrient reserves e.g. glycogen and triglycerides

Question 4

BMR

Answer 4

the minimum resting energy expenditure of an awake, alert person.

Question 5

Physiology of energy balance
equation

Answer 5

Energy intake = BMR (60%) + Physical activity (30%) + Thermogenesis (10%)

Question 6

influences on BMR

Answer 6

Total lean mass
Sex
Age
Body temperature
Diet/food intake
Exercise
Hormones

Question 7

influences on physical activity

Answer 7

Amount of physical activity
Type of physical activity ( anaerobic, aerobic)

Question 8

influences on Thermogenesis

Answer 8

Dietary-induced thermogenesis - increased body temperature required during digestion
Adaptive thermogenesis - increased thermogenesis to cope with temperature changes

Question 9

ATP

Answer 9

ATP is the energy currency of cells
Structurally, ATP molecules consist of an adenine, a ribose, and three phosphate groups. The chemical bond between the second and third phosphate groups represents the greatest source of energy in a cell.

Question 10

Dephosphorylated

Answer 10

(i.e. ATP → ADP + Pi)

Releases energy
Cells use this energy to carry out anabolic reactions including, building new tissue and repairing damaged tissue

Question 11

Phosphorylated

Answer 11

(i.e. ADP + Pi → ATP)

Energy is stored in the ATP molecule
Cells can use this energy for future cellular functions

Question 12

Carbohydrate metabolism

Answer 12

first broken down into glucose
carbohydrates are broken down to monosaccharides (glucose, fructose and galactose) that can be transported across the intestinal wall into the circulatory system to be transported to the liver. The liver then converts fructose and galactose into glucose.

Question 13

Glycolysis

Answer 13

breakdown of glucose

Occurs in the cytosol
Does not require oxygen (anaerobic)
This catabolic process uses two ATP and produces four ATP (net gain of two ATP)
Glucose becomes two pyruvic acids

o2 not present it will turn into lactic acid (in the liver lactic acid is stored then converted back to pyruvic acid once oxygen is available)
If oxygen is available, pyruvic acid enters mitochondria and is converted to acetyl coenzyme A (aerobic respiration). Acetyl coenzyme A enters the Kreb’s cycle.

Question 14

kreb cycle

Answer 14

Requires oxygen (aerobic)
Acetyl CoA enters the Krebs cycle in the matrix of mitochondria
Kreb’s cycle releases carbon dioxide
Energy (electrons) transferred to two energy carrying coenzymes, NAD+ and FAD
For each turn of the cycle (citric acid to oxaloacetic acid): 3 NADH, 3 H+, 1 FADH and 1 ATP are generated
Two turns of the cycle per glucose (two pyruvic acid → two acetyl CoA)
Therefore from 1 glucose → 2 ATP + 4 CO2 + 6 NADH + 6 H+ + 2 FADH2 are generated → and electrons enter electron transport chain

Question 15

electron transport chain

Answer 15

Requires oxygen (aerobic)
On inner mitochondrial membrane, cristae increase surface area
Integral membrane proteins that are electron carriers form a chain in the membrane
Electrons passed along the chain generating ATP by pumping of hydrogen ions (H+); known as chemiosmosis
Final electron acceptor is oxygen
Water and 26-28 ATP are generated

Question 16

Cellular respiration summary

Answer 16

Cellular respiration summary:

Glycolysis: 2 ATP (net gain)
Kreb’s cycle: 2 ATP
Electron transfer: 26-28 ATP
Total yield: 30-32 ATP
Provides 16 kJ per gram
Can be summed up with the following equation: C6H12O6 + 6 O2 → 6 CO2 + 6 H2O + 32 ATP + heat

Question 17

Glycogenolysis (breakdown of glycogen)

Answer 17

When blood glucose levels drop, stored glycogen in hepatocytes release glucose into blood
Note: skeletal muscle cells do not release glucose from glycogenolysis into blood, it is kept for their own use
Triggered by glucagon and adrenaline

Question 18

Glycogenesis (synthesis of glycogen)

Answer 18

Glycogen: glucose molecules joined together
Allows for storage of glucose in the liver and skeletal muscle cells
Formed when not needed to produce ATP inside cells or when blood glucose levels are high
Triggered by insulin

Question 19

Gluconeogenesis (synthesis of glucose from new (non-carbohydrate) sources)

Answer 19

Production of glucose when blood glucose level is low
Generation of ATP from non-carbohydrate sources e.g., amino acids, lactic acid, glycerol
60% of the body’s amino acids can be used for gluconeogenesis
Triggered by cortisol and glucagon
Also catabolic

Question 20

Lipolysis (lipid breakdown)

Answer 20

Lipids are important energy reserves (37 kJ per gram) because they can provide large amounts of ATP

During lipolysis, triglycerides are broken down to:
1 Glycerol – enzymes in the cytosol convert glycerol to pyruvate, which then enters the Kreb’s cycle
3 Fatty acids – converted to acetyl-CoA and enters Kreb’s cycle

Question 21

Lipogenesis (lipid synthesis)

Answer 21

Occurs in the liver
Glucose or amino acids can be converted into glycerol and fatty acids and assembled into triglycerides
Stimulated by insulin
Some fatty acids cannot be synthesised in the body (essential fatty acids)

Question 22

Proteolysis (protein breakdown)

Answer 22

Proteins only broken down for energy (17 kJ per gram) under special circumstances.

Worn out cells are broken down to release amino acids which are recycled into new proteins
Liver cells can convert amino acids into fatty acids or glucose
During starvation the body can break down protein

Question 23

Proteogenesis (protein synthesis)

Answer 23

Formation of peptide bonds between amino acids to produce proteins
Occurs in the ribosomes
Requires energy
Under direction of DNA and RNA
Adequate protein is essential for growth

Question 24

What is obesity

Answer 24

Overweight – increase body weight above a standard defined in relation to height
Obesity – abnormally high % of body fat generalised or localised
Obesity is a disease
Risk factor for chronic diseases

Question 25

Why does obesity occur

Answer 25

Long term positive energy balance (energy input > output)