Bioenergetics Flashcards
Why do living organisms need energy?
- Muscle contraction
- Growth
- Biosynthesis
- Transport
- Reproduction
Define bioenergetics
Transformation and utilisation of energy in cells and biological systems
(Usually in form of ATP)
What is the main source of ATP?
Oxidation of dietary carbohydrates, lipids and proteins
What occurs when dietary carbohydrates, fats etc. are oxidised?
- 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
Define cellular respiration
Oxidation of fuels to generate ATP
How des ATP carry so much energy?
- 3 phosphate groups - negative and takes lot of energy to hold together
- When ATP converted to ADP, some energy released
Outline the process of metabolism and where each stage occurs
- Glycolysis - cytoplasm
- Citric acid cycle - mitochondrial matrix
- Oxidative phosphorylation - cristae
Define metabolism.
- Set of chemical reactions in organisms to maintain life.
What is the purpose of metabolism?
- Removal of metabolic waste
- Conversion of food to building blocks for proteins/lipids/nucleic acids or conversion of food to energy
What are the two types of metabolic reactions?
CATABOLIC
ANABOLIC
Describe catabolic reactons
- Breakdown of large complex molecules into smaller molecules e.g hydrolysis
- Degradative, oxidative, exergonic
Define anabolic
- Large complex molecules synthesised from smaller molecules e.g condensation
- Synthesise molecules for cellular function
- Biosynthetic, reductive and endergonic
What is the first law of thermodynamics?
- Law of conservation of energy
- Food - oxidised to be produce heat and energy
- Respiration - produce ATP for cellular processes
What is the second law of thermodynamics?
- Natural processes cannot occur unless accompanied with an increase in entropy
- ΔG = ΔH - TΔS
- Above equation determines if a reaction occurs spontaneously
What does it mean if ΔG is positive and negative?
- POSITIVE - spontaneous and exergonic (CATABOLIC)
- NEGATIVE - nonspontaenous and endergonic (ANABOLIC)
RECAP: Compare and contrast exergonic and endergonic reactions.
- EXERGONIC - catabolic, needs O2 e.g cellular respiration, oxidation reactions
- ENDERGONIC - opposite of exergonic
Outline the catabolic and anabolic pathways in respiration.
- CATABOLIC - degradation of respiratory substrates e.g lipids, carbohydrates and TCA cycle (molecules oxidised to CO2)
- Anabolic - Reduction of NAD and FAD, ATP synthesis
What are the functions of water?
- Cellular transport
- Lubricant
- Thermoregulation
- Blood pressure/volume maintenance
- Acid-base balance
Water forms hydrogen bonds. What allows it to do this?
Water is dipolar.
How does water interact with the following:
- Polar organic molecules
- Inorganic salts
- Cations/anions
- 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
What is the difference between hydrophilic and hydrophobic with examples?
- 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
What are amphiphatic molecules? Give an example.
- Contain nonpolar, hydrophobic and polar, hydrophilic regions
- EXAMPLE: Phospholipids - polar head groups and nonpolar hydrocarbon tails
How do lipid molecules aggregate in water?
- Hydrophobic tails buried in interior
- Hydrophilic heads exposed to water
Define the hydrophobic effect.
Tendency of nonpolar molecules to aggregate to minimise surface area and exclude water molecules
What structures can lipids form in water?
- Micelles
- Bilayer sheets
- Liposomes
Outline the composition of plasma.
- 55% of total blood volume
- 92% water and 8% plasma proteins
- Composed of proteins, nutrients and electrolytes
Outline the purpose of plasma in the blood
- Transport of nutrients and waste products throughout the body
- Involved in immune response
Give examples of electrolytes and where they’re found, and what they may be used for.
- ECF - sodium and chloride ions
- ICF - potassium and phosphates
- Maintains fluid and electrolyte balance
How are electrolytes such as Na+ involved in fluid balance?
OSMOLALITY
- Amount of fluid depends on electrolyte concentration
Where will water have a tendency to move away from?
- Will move away from a region of low electrolyte concentration
Describe electrolyte balance in the kidneys.
- Actively moved in/out of cells to maintain correct concentrations
- Kidneys can filter from blood and return some to blood
What can cause raised increased serum osmolality?
- Decreased water in blood or increased solutes
What are the consequences of raised serum osmolality?
- Water will move out of cells
- Can cause dehydration
What is the standard level of saline in RBCs?
- 0.9%
-Lower than concentration of pure water
