Variation In Biochemistry And Cell Strucutre UNIT 2 Flashcards
(34 cards)
Red blood cells contain…
Haemoglobin
Oxygen is carried round the body by
Haemoglobin
What is haemoglobin
Large protein with a quaternary structure, so made up of four polypeptide chains. Each chain has a haem group which contains iron and gives haemoglobin its red colour. Haemoglobin has a high affinity for oxygen, each molecule can carry four oxygen molecules. In the lungs oxygen join to haemoglobin in red blood cells to form oxyhemoglobin. Is a reversible reaction, when oxygen leaves oxyhemoglobin near the body cells it turns back into haemoglobin
What does affinity for oxygen mean
Tendency to combine with oxygen
Aswell as being found in all vertebrates haemoglobin is found in….
Earthworms, starfish, some insects and plants
Haemoglobin saturation depends on…..
The partial pressure of oxygen
What is the partial pressure of oxygen
A measure of oxygen concentration
The greater the conc of dissolved oxygen in cells, the higher the partial pressure
What is the partial pressure of carbon dioxide
Measure of conc of carbon dioxide in a cell
Oxygen combines with haemoglobin to form oxyhaemoglobin where there’s a high …..
Partial pressure of oxygen
When does oxyhaemogblon lose its oxygen
When there’s a lower partial pressure of oxygen
Why does oxygen enter blood capillaries at the alveoli in the lungs
Alveoli have a high partial pressure of oxygen, so oxygen combines with haemoglobin to form oxyhaemoglobin
When cells respire they use up oxygen which …..
Lowers the partial pressure of oxygen. Red blood cells deliver oxyhaemoglobin to respiring tissues , where it unloads oxygen
Haemoglobin returns to lungs to pick up more oxygen
What does a dissociation curve show
How saturated the haemoglobin is with oxygen at any given partial pressure
Haemoglobin gives up its oxygen more readily at ….
Higher partial pressures of carbon dioxide. Gets more oxygen to cells during activity
What is the Bohr effect
When cells respire they produce carbon dioxide which raises the partial pressure of carbon dioxide. This increases rate of oxygen unloading , the dissociation curve shifts down, curves more to the right. The saturation of blood is lower for a given partial pressure of oxygen, meaning more oxygen is being released to tissues for high respiration
Haemoglobin is different in different…
Organisms.
Organisms that live in environments with a low conc of oxygen have haemoglobin with a higher affinity for oxygen than human haemoglobin, the dissociation curve is to the left of ours.
Organisms that are very active and have a high oxygen demand have haemoglobin with a lower affinity for oxygen than human haemoglobin, the curve is to the right of the human one
What is starch
The main energy storage material in plants. Plants store excess glucose as starch. Starch is a mixture of 2 polysaccharides- amylose and amylopectin
Amylose- long, unbranched alpha glucose, coiled so good for storage. Compact
Amylopectin- long, branched alpha glucose, it’s side branches allow the enzyme that breaks it down to get to the glycosidic bonds easily so glucose can be released quickly.
Insoluble in water so doesn’t cause water to enter cells by osmosis
What is glycogen
The main energy store in animals
Animals get energy from glucose, store excess glucose as glycogen. It’s structure is similar to amylopectin, except it has many more side branches coming off it. Means glucose can be released quickly which is important for energy release in animals. Very compact so good for storage
What is cellulose
The major component of cell walls in plants
Long, unbranched chains of beta glucose. The bonds between between the sugars are straight so cellulose chains are straight. He chains are linked by hydrogen bonds, form strong fibres called microfibrils= support
Insoluble in water
People living at high altitudes have more red blood cells than people living at sea level. What is the advantage of this?
They have more haem so can pick up more oxygen
2 examples of cells that are adapted to their function
Squamous epithelium cell
Palisade mesophyll cell
What is a squamous epithelium cell
Adapted for its function. Thin, not much cytoplasm. Found in lungs, where they line the alveoli and are thin to allow gases to pass through them easily
What is a palisade mesophyll cell
Adapted for its function. Found in leaves, contains many chloroplasts which means it can absorb as much sunlight as possible for photosynthesis. Walls of cells are thin so CO2 can pass through them easily
Examples of tissues
Squamous epithelium
Phloem
Xylem
