Biology topic 4 Flashcards
What is endocytosis
Cell extensions called pilli engulf material to form vesicles and enter the cytoplasm
What is exocytosis?
The vesicle fuses with cell membrane and release contents from the cell.
Role of exo/endocytosis
To move large molecules across the cell membrane
Role of ATP in active transport
Binds to carrier protein to provide it with energy for protein to change shape and carry substances in and out of the cell
How is ATP energy released
When ADP is phosphorylated to ATP, energy is generated. When ATP is hydrolysed the energy is released
What happens to haemoglobin affinity for oxygen and saturation when partial pressure increases
Haemoglobins affinity for oxygen increases, saturation increases
What happens to haemoglobin affinity for oxygen and saturation when partial pressure decreases
Haemoglobins affinity for oxygen decreases, saturation decreases
What factors affect haemoglobins affinity for oxygen?
Partial pressure of oxygen and carbon dioxide
What effect does increased partial pressure of CO2 have on haemogobins affinity for O2
Presence of CO2 causes haemo’s affinity for O2 to decrease
Oxygen released, dissociates from haemo to be used in repairing tissues (Bohr effect)
How many polypeptide chains does haemoglobin contain?
4 polypeptide chains
How many polypeptide chains does myoglobin contain?
1 polypeptide chain
Function of haemoglobin
Transport oxygen
Function of myoglobin
Store oxygen
Dissociation curves S shape
Due to cooperative binding of O2
After one O2 molecule binds, the shape of haemoglobin changes making it easier for other oxygen molecules to bind (steep part)
As haemo becomes highly saturated, harder for oxygen to bind (graph plateaus)
Bohr effect
Curve shifts to the right due to increased CO2
Lowers pH causing haemo to change shape
Reduces affinity for O2
Increased O2 unloading in respiring tissues used for respiration.