Biochemistry overview Flashcards
1
Q
what does catabolic mean
A
- a catabolic pathway is when you break things down to produce ATP, carbon dioxide and water
2
Q
what is an anabolic pathway
A
- this is when you build things such as ATP carbon dioxide and water into proteins, lipids, carbohydrates and nucleic acids
3
Q
describe how catabolic pathways work
A
- Start with the small molecules such as fats, proteins and carbohydrates, these are then converted into acetyl coenzyme A
- This goes through the TCA cycle
- This produces coenzymes which can go through the electron transport chain and produce carbon dioxide water and ATP
4
Q
why are metabolic pathways so complex
A
- Efficient energy capture
- Efficient control
- Branches enable links to related pathways
- Different outputs depending on the conditions
- Allows them to adapt to the different conditions that the body finds it in
5
Q
what is metabolism mediated by
A
enzymes
- the reaction is usually reversible
6
Q
How do we control which direction the pathway of the reaction goes in
A
- Energetics
- Push/pull
- Compartments – control what goes in and out of the compartments allow you to drive the pathway in a particular direction
- Regulation of enzymes
7
Q
describe how compartments control the direction that the pathway reaction goes in
A
- Metabolic pathways may be sited at different levels and work differently
1. Organs and tissues
2. Cells and organelles
8
Q
describe the cori cycle as an example of compartmentalisation
A
- Muscle is taking glucose and breaking it down to produce energy
- High intensity which means that there is insufficient oxygen so therefore you are carrying out anaerobic exercise and producing lactate
- Lactic acid is acidic
- Glycogenesis – lactic acid is converted back to glucose
9
Q
describe the rate limiting enzyme characteristics
A
- Near start of the pathway
- Relatively low activity
- Reaction often can only go one direction due to thermodynamics
- Multiple subunits
10
Q
how do you control regulatory enzymes by turning them on and off
A
- Allostery – modifier binds to enzyme and changes 3D conformation of enzyme to make active site more/less active – short term
- Covalent modification – addition (or removal) of phosphate group to enzyme by another enzyme makes it more/less active – short term
- Protein synthesis – hormones control gene expression of enzyme protein – long term
11
Q
give an example of why you use enzymes to control body processes
A
- maintain blood glucose level
12
Q
what does insulin do
A
- Increase storage
- Increase utilisation
- Increased uptake
13
Q
what does glucagon do
A
- Release from storage
- Reduce utilisation – alternative fuels
- Decreased uptake
