Bioenergetics

Question 1

Why do living organisms need energy?

Answer 1

• Muscle contraction
• Growth
• Biosynthesis
• Transport
• Reproduction

Question 2

Define bioenergetics

Answer 2

Transformation and utilisation of energy in cells and biological systems

(Usually in form of ATP)

Question 3

What is the main source of ATP?

Answer 3

Oxidation of dietary carbohydrates, lipids and proteins

Question 4

What occurs when dietary carbohydrates, fats etc. are oxidised?

Answer 4

• Generates heat and ATP, CO2 and H2O released as by-products
• CO2 expired from lungs
• H2O secereted as sweat/urine
• ATP utilised and converted to ADP

Question 5

Define cellular respiration

Answer 5

Oxidation of fuels to generate ATP

Question 6

How des ATP carry so much energy?

Answer 6

• 3 phosphate groups - negative and takes lot of energy to hold together
• When ATP converted to ADP, some energy released

Question 7

Outline the process of metabolism and where each stage occurs

Answer 7

• Glycolysis - cytoplasm
• Citric acid cycle - mitochondrial matrix
• Oxidative phosphorylation - cristae

Question 8

Define metabolism.

Answer 8

• Set of chemical reactions in organisms to maintain life.

Question 9

What is the purpose of metabolism?

Answer 9

• Removal of metabolic waste
• Conversion of food to building blocks for proteins/lipids/nucleic acids or conversion of food to energy

Question 10

What are the two types of metabolic reactions?

Answer 10

CATABOLIC
ANABOLIC

Question 11

Describe catabolic reactons

Answer 11

• Breakdown of large complex molecules into smaller molecules e.g hydrolysis
• Degradative, oxidative, exergonic

Question 12

Define anabolic

Answer 12

• Large complex molecules synthesised from smaller molecules e.g condensation
• Synthesise molecules for cellular function
• Biosynthetic, reductive and endergonic

Question 13

What is the first law of thermodynamics?

Answer 13

• Law of conservation of energy
• Food - oxidised to be produce heat and energy
• Respiration - produce ATP for cellular processes

Question 14

What is the second law of thermodynamics?

Answer 14

• Natural processes cannot occur unless accompanied with an increase in entropy
• ΔG = ΔH - TΔS
• Above equation determines if a reaction occurs spontaneously

Question 15

What does it mean if ΔG is positive and negative?

Answer 15

• POSITIVE - spontaneous and exergonic (CATABOLIC)
• NEGATIVE - nonspontaenous and endergonic (ANABOLIC)

Question 16

RECAP: Compare and contrast exergonic and endergonic reactions.

Answer 16

• EXERGONIC - catabolic, needs O2 e.g cellular respiration, oxidation reactions
• ENDERGONIC - opposite of exergonic

Question 16

Outline the catabolic and anabolic pathways in respiration.

Answer 16

• CATABOLIC - degradation of respiratory substrates e.g lipids, carbohydrates and TCA cycle (molecules oxidised to CO2)
• Anabolic - Reduction of NAD and FAD, ATP synthesis

Question 16

What are the functions of water?

Answer 16

• Cellular transport
• Lubricant
• Thermoregulation
• Blood pressure/volume maintenance
• Acid-base balance

Question 16

Water forms hydrogen bonds. What allows it to do this?

Answer 16

Water is dipolar.

Question 16

How does water interact with the following:
- Polar organic molecules
- Inorganic salts
- Cations/anions

Answer 16

• Polar organic molecules readily dissolve - form hydrogen bonds
• Inorganic salts readily dissolve - form electrostatic interactions
• Cations/anions surrounded by hydration shell of water molecules. Cations bind with negative charge on oxygen/ anions - positive charge on hydrogen

Question 17

What is the difference between hydrophilic and hydrophobic with examples?

Answer 17

• HYDROPHILIC - molecules that mix well with water e.g charged substances like ions and partially charged sugars
• HYDROPHOBIC - molecules that don’t mix well with water e.g lipids, uncharged hydrocarbons

Question 18

What are amphiphatic molecules? Give an example.

Answer 18

• Contain nonpolar, hydrophobic and polar, hydrophilic regions
• EXAMPLE: Phospholipids - polar head groups and nonpolar hydrocarbon tails

Question 19

How do lipid molecules aggregate in water?

Answer 19

• Hydrophobic tails buried in interior
• Hydrophilic heads exposed to water

Question 20

Define the hydrophobic effect.

Answer 20

Tendency of nonpolar molecules to aggregate to minimise surface area and exclude water molecules

Question 21

What structures can lipids form in water?

Answer 21

• Micelles
• Bilayer sheets
• Liposomes

Question 22

Outline the composition of plasma.

Answer 22

• 55% of total blood volume
• 92% water and 8% plasma proteins
• Composed of proteins, nutrients and electrolytes

Question 23

Outline the purpose of plasma in the blood

Answer 23

• Transport of nutrients and waste products throughout the body
• Involved in immune response

Question 24

Give examples of electrolytes and where they’re found, and what they may be used for.

Answer 24

• ECF - sodium and chloride ions
• ICF - potassium and phosphates
• Maintains fluid and electrolyte balance

Question 25

How are electrolytes such as Na+ involved in fluid balance?

Answer 25

OSMOLALITY
- Amount of fluid depends on electrolyte concentration

Question 26

Where will water have a tendency to move away from?

Answer 26

• Will move away from a region of low electrolyte concentration

Question 27

Describe electrolyte balance in the kidneys.

Answer 27

• Actively moved in/out of cells to maintain correct concentrations
• Kidneys can filter from blood and return some to blood

Question 28

What can cause raised increased serum osmolality?

Answer 28

• Decreased water in blood or increased solutes

Question 29

What are the consequences of raised serum osmolality?

Answer 29

• Water will move out of cells
• Can cause dehydration

Question 30

What is the standard level of saline in RBCs?

Answer 30

• 0.9%
  -Lower than concentration of pure water