3.1 Flashcards
importance of ATP
Why is ATP important in cells
Provides energy for most reactions in all cells of all cellular organisms. For example, provides energy for nerve transmission and muscle contraction
What is ATP
A nucleotide which is a major energy currency of the cell
ATP’s real name?
Adenine triphosphate
How does ATP release energy?
The bond between the middle and terminal phosphate is broken which removes the terminal phosphate and releases energy
Equation for ATP to ADP
ATP + water = ADP + Pi + 30.6 KJmol-1
Where does the 30.6 KJmol-1 come from
From the oxidation / breaking down of glucose during respiration
How can you reform ATP after the hydrolysis reaction
Phosphorylation.
Energy can be used to add inorganic phosphate to ADP to reform ATP
Phosphorylation equation for ADP to ATP
ADP + Pi + 30.6 KJmol-1 = ATP + water
Where does ATP transfer energy to and from?
Transfers free energy from energy rich compounds like glucose to cellular reactions which don’t need it.
Is making ATP endergonic or exergonic?
Endergonic because it requires energy
Is ATP releasing energy endergonic or exergonic?
Exergonic, because it releases energy.
Where is ATP produced
Cytoplasm, mitochondria, chloroplasts
Uses of ATP
Active transport.
Muscle contraction.
Nerve transmission.
Endo and Exocytosis.
Advantages of ATP
- only needs one reaction (hydrolysis).
- soluble in water so easily transported.
- releases energy in small amounts when and where needed.
- common source of energy.
- only 1 enzyme (ADPase) needed for hydrolysis.
How have cells with high ATP demands adapted?
Most ATP is produced in mitochondria so cells with high demands like muscle fibres have many mitochondria
What are the 3 kinds of phosphorylation?
- Substrate level phosphorylation.
- Photophosphorylation.
- Oxidative phosphorylation.
What is Substrate level phosphorylation (in cytoplasm and mitochondria matrix)
ATP produced during conversion of organic molecules from one to another. Simplest way because metabolic pathways are short, and no electron proton gradient or oxygen is needed.
What is Photophosphorylation (in thylakoid membrane of chloroplasts)
Occurs during light dependent stage of photosynthesis by generation of a proton gradient. ATP produced is used to provide energy needed to fix CO2 into carbohydrate.
What is Oxidative phosphorylation (in inner membranes of mitochondria)
Most ATP molecules produced this way.
Protons, electrons and oxygen required and ATP is produced by the generation of a proton gradient during chemiosmosis.
What is respiration?
A process controlled by enzymes where energy is transferred from 1 molecule to another along metabolic pathways.
4 stages of aerobic respiration
glycolysis, link reaction, krebs cycle, electron transport chain
3 products of glycolysis
2 Pyruvate molecules, 2 ATP, 2 reduced NAD molecules
What does glycolysis involve
Splitting one molecule of glucose (6C) into 2 smaller molecules of pyruvate (3C)
What happens to reduced NAD if oxygen is present
It transports the hydrogen atoms to the electron transport chain which takes place across inner membranes of mitochondria.
How do the pyruvate molecules from glycolysis take place in the link reaction
The 2 molecules of pyruvate diffuse from the cytoplasm into the mitochondrial matrix and take part in the link reaction
How is pyruvate converted to Acetyl
Loses a hydrogen by dehydrogenation and loses Co2 by decarboxylation
How is reduced NAD or FAD formed
By carrying hydrogen atoms
Why does acetyl become Acetyl CoA
The coenzyme A combines with Acetyl to carry it to the Krebs cycle
Products of the Krebs cycle and what they’re used for
- 2 CoA reused in link reaction.
- 2 4C molecules reused in krebs cycle
-4 CO2 as waste - 2 ATP as energy
- 6 reduced NAD and 2 reduced FAD to transport H to electron transport chain
Number of ATP (net), NAD reduced and FAD reduced formed per molecule of glucose in glycolysis
2 ATP, 2 NADred, 0 FADred
Number of ATP (net), NAD reduced and FAD reduced formed per molecule of glucose in link reaction
0 ATP, 2 NADred, 0 FADred
Number of ATP (net), NAD reduced and FAD reduced formed per molecule of glucose in Krebs cycle
2 ATP, 6 NADred, 2 FADred
What are NAD and FAD
Nucleotides which are coenzymes that carry H atoms to the electron transport chain
Why are the protons in hydrogen essential
Needed to create a proton or electrochemical gradient
What happens when FAD / NAD let go of H?
FAD/NAD are oxidised and return to collect more H. H splits into its subatomic particles (e- and H+)
What happens when electrons jump from electron carrier to carrier?
The high energy electrons’ energy level drops and is absorbed by the pumps to pump H+ and the concentration gradient causes flow of charge so H+ can flow down channel protein and electrochemical gradient formed.
