Week 2 Flashcards
(40 cards)
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
