S5 - Unit Two Flashcards
What does the term metabolism mean?
All chemical reactions that occur within a living cell
What are metabolic pathways?
Pathways that are integrated and controlled by enzyme-catalysed reactions within a cell
What names can be given to reactions within metabolic pathways?
Catabolic or Anabolic reactions
What is the definition of a catabolic reaction?
The break down of large molecules into smaller molecules which releases energy
What is an example of a learned about catabolic reaction?
Respiration
What is the definition for an anabolic reaction?
The build up of large molecules from smaller molecules which requires energy
What is an example of a learned about anabolic reaction?
Protein synthesis
What type of steps can occur in a metabolic pathway?
- Reversible
- Irreversible
- Alternative routes
Why do metabolic pathways have different types of steps?
To allow them to be kept under precise control
What does a cell membrane consist of?
Protein pores, pumps and enzymes
What is the use of the following in a cell membrane?
- Pores
- Pumps
- Enzymes
- Used in diffusion
- Used for active transport
- Used to speed up the rate of a chemical reaction
What are metabolic pathways controlled by?
The presence of absence of particular enzymes and the regulation rate of reaction of key enzymes
What is the activation energy?
The energy required to break the bonds between reactant molecules
What do enzymes do to the activation energy?
Lower it
What is induced fit?
When the active site of an enzyme changes shape to better fit a substrate after it binds
What does affinity mean?
The chemical attraction molecules have for each other
What factors affect the rate of reaction?
The substrate concentration, temp. and concentration
What happens at a low substrate conc. to the rate of reaction and why?
It decreases as not enough substrate molecules are present to fill the active site
What happens at a high substrate conc. to the rate of reaction and why?
It increases as more active sites are filled
When does the rate of reaction when substrates bind to enzymes stop increasing?
When all the active sites have been filled
Why do we have inhibitors?
To regulate the action of a metabolic pathways enzymes
What is an inhibitor?
A substrate which decreases the rate of an enzyme controlled reaction
What types of inhibitors are there?
Non-competitive and competitive
How do competitive inhibitors affect an enzyme and its rate?
By binding to the enzymes active site due to it having a similar shape to the substrate, preventing the substrate from binding
How can competitive inhibitors be reversed and why is this?
By increasing the substrate conc.
Because the substrate molecules outnumber the inhibitors
How do non-competitive inhibitors affect an enzyme and its rate?
By binding away from the active site but changing the shape of the active site preventing a substrate from binding
When does feedback inhibition occur?
When the end product in the metabolic pathway reaches a critical conc.
How does feedback inhibition work and what does it do?
An end product inhibits an earlier enzyme, blocking the pathway and therefore preventing further synthesis of the end product
What is ATP used for?
To transfer energy to cellular processes that require energy
What is phosphorylation and what is a common example in Higher?
An enzyme controlled process by which a phosphate group is added to a molecule
ADP + Pi = ATP
What happens if ATP is used to phosphorylate another molecule?
The molecules becomes more reactive
What are the stages in aerobic respiration?
- Glycolysis
- Citric Acid Cycle
- Electron Transport Chain
Where do each of the stages in aerobic respiration take place?
- Cytoplasm
- The matrix of the mitochondria
- The inner membrane of the mitochondria
Name the stage of aerobic respiration and the missing words.
What is glycolysis?
The breakdown of glucose to pyruvate in the cytoplasm
Why is ATP needed in the first phase of glycolysis?
To phosphorylate glucose and intermediates
What does the phosphorylation of glucose and intermediates in phase one of glycolysis lead to?
The generation of more ATP in the second phase, resulting in a net gain of ATP
What do dehydrogenase enzymes do in glycolysis?
Remove hydrogen ions and electrons, passing them to the enzyme NAD which then forms NADH
Name the stage of aerobic respiration and the missing words
What does the enzyme NAD do in the second stage of aerobic respiration?
Becomes NADH and passes the hydrogen ions and electrons to the third and final stage
Name the stage of aerobic respiration and the missing words
What happens in aerobic respiration when no oxygen is present?
Fermentation takes place
Name the cell the fermentation is occurring in and the missing words
Where does fermentation take place?
The cytoplasm
What is metabolic rate?
The quantity of energy consumed by an organism per unit time
What are the different ways metabolic rate can be measure as?
- Oxygen consumption (per unit time)
- Carbon dioxide production ‘’
- Heat production ‘’