Week 2 Flashcards
Define metabolism
Combination of all the reactions happening in a cell providing energy for viral processes and synthesising new organic materials
What are the two types of metabolism?
- Catabolism - breaking down organic matter which produces energy
- Anabolism - using energy to make macromolecules
Why do animals need energy?
Maintain body temperature, active transport, DNA replication, cell division
Why do plants need energy?
Similar processes to animals including photosynthesis
Describe respiration and the effect
Cells release energy from glucose to power cellular processes. It may be aerobic and anaerobic.
How does the process of respiration conserve energy?
It is a controlled stepwise oxidation of sugar to preserve the useful energy
What does the stepwise nature of respiration help with?
Reducing heat losses
How do active carrier molecules work?
They transport the energy to the energetically unfavourable reaction (anabolism requiring energy), they then go to the energetically favourable reaction (catabolism) to receive the energy then it repeats.
How is the energy from respiration used?
Used to make ATP (adenosine triphosphate)
Describe ATP
It is a nucleotide whose reactivity resides in its terminal phosphate groups
How does ATP release energy?
The phosphate groups are negative and held together by energy in the form of chemical energy and when the terminal inorganic phosphate group is released to turn it into ADP it releases energy. This is catalysed by ATPase
How does an ADP and inorganic phosphate group join together?
It is catalysed by ATP synthase
Describe Acetyl Coenzyme A (CoA)
Carries carbon atoms to the citric acid cycle
The -thioester bond is strong!
Describe NADPH
Important carrier of electrons
Reduces power for biosynthetic reactions or anabolic reactions
Why is glucose catabolism an oxidation/reduction reaction?
- The covalent electrons in C-H bonds are shared approximately equally due to similar levels of electronegativity
- But in C-O bonds the electrons are shifted towards the O as it is more electronegative so carbon is oxidised and oxygen is reduced
Why is energy released in the respiration? (to do with redox)
When carbon is oxidised as electrons are relocated closer to the oxygen
How do organisms extract energy from foods?
- Food is digested - C,H,O to sugars, proteins and amino acids, fats to fatty acids
- Simpler compounds undergo catabolism - energy stored in the chemical bonds used to power ATP production
What are the three stages of respiration
- Glycolysis
- Citric acid cycle
- Oxidative phosphorylation
What is the first stage in glycolysis?
Phosphorylation of glucose:
- Invest 2 ATP
- Using the two inorganic phosphates released to make 2 molecules of triose phosphate
What is the second stage of glycolysis?
Oxidation of triose phosphate making:
- 2 pyruvate molecules
- NAD collects H+ ions
- 4 ATPs
Summarise the inputs and outputs of the first stage of glycolysis
Inputs: glucose, 2 ATP
Outputs: 2 triose phosphate
Summarise the inputs and outputs of the second stage of glycolysis
Inputs: 2 triose phosphate
Outputs: Each triose phosphate creates a parallel pathway creating half of the total products.
The products are 2 NADH 4 ATP and 2 pyruvate
Describe the link reaction
Input: Pyruvate
Reaction: produces CO2, NAD+ collects hydrogen to be NADH
Further input: coenzyme A
Output: Acetyl CoA
Describe the citric acid cycle
Catalysing the complete oxidation of the carbon atoms in acetyl CoA
What are the inputs and outputs of the citric acid cycle?
Input: acetyl CoA
Outputs: 3 NAD and H+, CO2, GTP, FADH2 and 2 ATP (this process is substrate level phosphorylation)
What is the first stage of oxidative phosphorylation?
Electron transport:
- Hydrogen from NAD and FAD split into protons and electrons
- Electrons pass through the carriers losing energy
- Energy is used to pump protons across the inner mitochondria/cell membrane
What is the second stage of oxidative phoshphorylation?
- Concentration of protons is higher on one side which is an electrochemical gradient
- Protons move back via the ATP synthase. As they do this ATP is made
- The movement of protons is called chemiosmosis
Approx. how much energy is released per glucose molecule?
720 kcal
What are 3 examples of direct products of metabolism?
Beer
Antibiotics
Biobutanol
Define metabolic engineering
Improving the product formation or cellular properties by modifying specific biochemical reactions or the introduction of new reactions with the use of recombinant DNA technology. Also, the redirection of one or more enzymatic reactions to produce new compounds in an organism which improves the production of existing compounds or mediate the degradation of compounds.
What are the goals of biomanufacturing?
Improve:
- product quantity
- quality
- consistency
Define metabolic flux?
Rate of turnover of molecules through a metabolic pathway
What 4 factors is the rate of metabolic reaction dependent on?
Concentrations of:
- Enzyme
- Substrate
- Product
- Regulatory molecules
What factors affect flux at the local level?
Concentrations of:
- enzymes, substrates and products
What factors affect flux at the global level?
Concentrations of:
- enzymes and regulatory molecules
What is a non-metabolic factor that flux can depend on?
Processes can work much better in vitro than in vivo due to the cell being a large network of reactions
What two ways can you regulate metabolism?
- Changing the activity of enzymes
- Changing the concentration of enzymes
How can you modulate the activity of enzymes?
- Inhibition (stopping substrate from going to the enzyme)
- Feedback inhibition and activation (neg/pos feedback)
- Phosphorylation or other post-translations modifications (adding phosphates can change the structure)
How can you alter the concentrations of enzymes?
Synthesis rate - alter how fast they are being produced
Protein degradation - alter how fast they are being broken down
What is the equation for the reaction rate?
