Unit 2- Section 3 Variation In Biochemistry And Cell Structure Flashcards
What is haemoglobin?
It’s a large protein with a quaternary structure, it’s made up of four polypeptide chains. Each chain has a haem group which contains iron and gives haemoglobin the red colours. Each molecule of human haemoglobin can carry four oxygen molecules
What is the role in haemoglobin?
Human haemoglobin is found in red blood cells, it’s role is to carry oxygen around the body. There are many chemically similar types of haemoglobin found in many different organisms, all of which carry out the same function. As well as being found in all vertebrates, haemoglobin is found in earthworms, starfish and some insects, some plants and in some bacteria
How does haemoglobin turn into oxyhemoglobin?
In the lungs oxygen joins to haemoglobin in red blood cells to form oxyhemoglobin. This is a reversible reaction. Near the body cells, oxygen leave oxyhaemoglobin and it turns back into haemoglobin. When an oxygen molecule joins to haemoglobin it’s referred to as an association or loading. When oxygen leave oxyhaemoglobin it’s referred to as dissociation or unloading.
What does affinity for oxygen mean? And partial pressure
It’s the tendency a molecule has to bind with oxygen. Haemoglobin affinity for oxygen varies depending on the conditions it’s in. One of the conditions that affects it is the partial pressure of oxygen.
Partial pressure is a measure of oxygen concentration. The greater the concentration of dissolved oxygen in cells, the higher the partial pressure. As the partial pressure increases, haemoglobins affinity for oxygen also increases
When oxygen loads onto haemoglobin to form what? When there is a what partial pressure?
Forms oxyhaemoglobin where there is a higher partial pressure
Oxyhaemoglobin unloads it’s what in a what partial pressure?
Unloads it’s oxygen where there is a lower partial pressure
Where does oxygen enter the blood?
Enters the blood via the capillaries at the alveoli in the lungs. Alveoli have a high partial pressure, so oxygen loads onto haemoglobin to form oxyhaemoglobin. When cells respire, they use up oxygen- this lowers the partial pressure. Red blood cells deliver oxyhaemoglobin to respiring tissues, where it unloads it’s oxygen. The haemoglobin then returns to the lungs to pick up more oxygen.
What are the characteristics of the alveoli considering partial pressure.
High oxygen concentration
High partial pressure
High affinity
Oxygen loads
Characteristics of respiring tissue when considering partial pressure etc
Low oxygen concentration
Low partial pressure
Low affinity
Oxygen unloads
What does a oxygen dissociation curve show?
How saturated the haemoglobin is with oxygen at any given partial pressure, the affinity of haemoglobin for oxygen affects how saturated the haemoglobin is
What happens on a oxygen association graph when the partial pressure is high?
Haemoglobin has a high affinity (eg lungs) for oxygen, so it has a high saturation of oxygen when the partial pressure is h
What happened on a oxygen dissociation curve when the partial pressure is low?
In respiring tissues the partial pressure is low. Haemoglobin has a low affinity for oxygen, so it has a low saturation of oxygen
Why is the oxygen dissociation graph S shaped and not straight?
The saturation of haemoglobin can also affect the affinity. When haemoglobin combines with the first oxygen molecule, it’s shape alters in a way that makes it easier for other molecules to join too.
What happens when the haemoglobin gets saturated?
It gets harder for more oxygen molecules to join. As a result, the curve has a steep bit in the middle where it is really easy for oxygen molecules to join, and shallow bits at each end where it is harder
What happens when the curve is steep?
A small change in partial pressure causes a big change in the amount of oxygen carried by the haemoglobin
What does 100% saturation mean?
Every haemoglobin molecule is carrying the maximum of 4 molecules of oxygen
What does 0 saturation mean?
None of the haemoglobin molecules are containing any oxygen
What is the partial pressure of carbon dioxide a measure of?
The concentration of carbon dioxide in a cell,
What does the partial pressure of carbon dioxide affect?
Oxygen unloading. Haemoglobin gives up oxygen more readily at a higher partial pressure of carbon dioxide. It’s a cunning way of getting more oxygen to cells during activity
What do cells produce when they respire?
They produce carbon dioxide, which raises the partial pressure of carbon dioxide. This increases the rate of oxygen unloading, the dissociation curve ‘shifts’ right. The saturation of blood with oxygen is lower for a given partial pressure of carbon dioxide meaning that more oxygen is being released. This is called the Bohr effect
How can low oxygen environments have different types of haemoglobin?
Organisms that live in environments with a low concentration of oxygen have haemoglobin with a higher affinity for oxygen than human haemoglobin. This is because there isn’t much oxygen available,so the haemoglobin has to be very good at loading any available oxygen. The dissociation curve of their haemoglobin is to the LEFT of ours
What happens it the haemoglobin of an organism with high activity levels?
Organisms that are very active and have a high oxygen demand have haemoglobin with a lower affinity for oxygen than human haemoglobin. This is because they need their haemoglobin to easily unload oxygen, so that it’s available for them to use. The dissociation curve of their haemoglobin is to the RIGHT of the human one.
How can the size of an animal affect haemoglobin?
Small mammals tend to have a higher surface area to volume ratio than larger mammals. This means they lose heat quickly, so they have a high metabolic rate to help them keep warm which means they have a high oxygen demand. Mammals that are smaller than humans have haemoglobin with a lower affinity for oxygen than human haemoglobin, because they need their haemoglobin to easily unload oxygen to meet their high oxygen demand. The dissociation curve of their haemoglobin is to the RIGHT of the human one
What is the structure of an animal cell?
Plasma membrane- holds the cell wall together and controls entry and exit of cell
Cytoplasm- gel like substance where most of the chemical reactions occur
Mitochondria- where most of the reactions for respiration take place. Respiration releases energy that the cell needs to work
Robosomes- protein synthesis
Nucleus- contains genetic information and controls activities within the cell
