Biology - Unit 2- The Variety of Life

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  • Created by: FireDwarf
  • Created on: 22-03-14 15:04
What is a haemoglobin molecule made up of?
It is a protien and therefore a primary, secondary, tertiary structure. It ais made up of 4 polypeptide chains therefore a quarternary structure is also present. also one due to prosphetic (haem) groups.
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What does each haem group have? How many haem groups in one hameoglobin structure? Because? How much O2 carried?
a Fe2+ ion which can combine with a single O2 molecule. 4 haem groups, 1 to each polypeptide. Therefore 4 O2 molecules (or 8 O atoms). can be carried.
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What are the two roles of hameoglobin?
Readily assosiate with O2 molecules at the surface where gas exchange takes place & to readily disossociate from O2 at tissues requiring it.
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Whats the issue with this?
They are essentially opposite functions that the same molecule needs to carry out, how can it be adapted to it?
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So how does it achieve this?
It changes its affinity towards Oxygen under diffrent conditions. Its shape changes in the presence of certian substances (eg: Co2).
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So what happens in the Tissues? What happens in the lungs?
When they come towards tissues, high level of Co2 due to their resperation. Changes hameoglobin structure to that it dissosiates with oxygen more easilly due to lower affinity. Lungs, low conc, so it has a high affinity towards oxygen.
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Do organisims have the same hameoglobin? Why not?
No. Because diffrent organisims have diffrent metabolic rates and therefore diffrent assosiate/dissosiate rates of O2. Also diffrence is O2 abundance leads to diffrence in shape.
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What causes the hameoglobin shape to be diffrent?
The sequence of amino acids in the polypeptide chains (primary structure).
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What are the two highest ranges for hameoglobin diffrences?
Hameoglobin with a high affinity towards oxygen, where it takes it easilly but loses it less rapidly. Second,, low affinity, harder to take up O2 but easier to lose it.
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Expalin diffrences in hameoglobin structure for organisms in a area with low oxygen abundance.
Low o2 therefore the hameoglobin must be able to assosiate with O2 more easilly to absorb enough. Provided that its metabolic rate is low, it would not need to dissosiate with O2 are readily.
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High abundance?
A high metabolic rate will cause a high amount of O2 needed for respiration. Therefore, must be able to dissosiate with O2 more easilly. Providing there is a high abundance, the need to assosiate with O2 is lower.
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What is partial pressure? Why is it better then concentration?
The pressure which that specific gas (in this case oxygen) contributes towards the total pressure of the gas mixture. Gives you the amount of O2 present out of the total.
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What is the equation for the assosiation of O2?
Hb + 4O2 Hb(O2)4
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Step by step? (4 binding steps)
Hb Hbo2 Hb(o2)2 Hb(o2)3 Hb(o2)4
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Is there a diffrence in how hard it is to assosiate with O2?
It is harder for the 1st o2 molecule to bind to a haemoglobin because the 4 hameoglobin are united and therefore closley packed. As they absorb the first molecule, the 3 other polypeptides load more easilly.
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What does the graph show about the relationship between partial pressure and saturation?
At low pressures, as the pressure changes we see a dramatic diffrence in saturation of hameoglobin. At higher values, the diffrence in saturation is far less significant.
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What is important to remember regarding the posistion of the curve, left or right?
More left, the higher the affinity towards O2. The graph shows this because it becomes fully saturated at a lower pressure and needs higher pressure to remove the O2). To the right, lower affinity.
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Where is Co2 low in conc? What effect does this have on the curve? Co2 High? Effect?
In the gas exchange (co2 moves into exchange system via diffusion and ventilation keeps it low) cauing it to shift to the left. Higher at respiring tissues, so shifts to the right.
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What effect does Co2 have on the affinity of O2 of the hameoglobin? (high)
The Co2 dissolves in the blood plasma forming carbonic acid. decreases the ph which changes shape of haemoglobin molecule to have a low affinity. Causes O2 to be more easilly dissociated which increases O2 supplied to tissues.
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Link this with partial pressure?
If Co2 is high in conc, then the partial pressure of O2 will be lower. This will cause pressure changes to cause lots of O2 to be dissosiated from the hameoglobin.
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Less Co2 causes less to be dissolved to form carbonic acid. Therefore, higher Ph. A higher ph causes the hameoglobin molecule to change its shape to have a high affinity for O2. Therefore loses O2 less easilly and assosiates more readily.
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Are all O2 molecules released from the hameoglobin?
No, when at a low respiring rate only one of the O2 molecules is normally released. But if tissue is more active, then 3 are released. Some are kept in reserve in case they are needed.
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What makes starch very compact?
Tightly coiled
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How is starch adapated to its job?
Insouble, doesnt draw water in via osmosis, doesnt diffuse out of cells easilly, compact, lots can be stpred. hydrolsed into alpha glucose.
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Celluose, how are the beta glucose arranged in each linear chain?
Beta glucose are joined together in linear strips, with each glucose momomer being 180 to the other. Ch2Oh group alternates being above and below.
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Between chains ? whats it called?
Hydrogen bonding between linear chains to form microfibrils which then get arranged into parrelell groups called fibres.
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How does this adapt it?
The numerous hydrogen bonds give it strengh which herefore provides rigidity.
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Other way a cell wall is important?
Creates an inward pressure to prevent the cell from taking too much water and bursting (osmotic lysis).
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What type of cells are plant cells?
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What does a leaf palisade cell contain?
Nucleus, vaccuole, cytoplasm, chloroplasts, cell surface membrane, mitochondira, cellulose cell wall.
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How is it suited to its function? (2)
Long thin cells (contineous layer) to absorb sunlight. Have numerous chloroplasts that are arranged in best posistions to collect max light.
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what about the vaccuole?
Is large and pushes the cytoplasm and chloroplasts to the edge of the cell.
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What are chloroplasts?
Organelle which carry out photosythesis.
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Features of the chloroplast? (5)
Envolope, grana, thylaoids, chlorophyll, stroma.
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What is the envolope?
double plasma membrane which surrounds the organelle. Hiighly selective on what it allows to move into/out of the organelle.
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The grana?
Stacks of thylakoids.
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Disc like structure that have chlorophyll in them.
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photosythetic pgiment.
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The matrix where the second stage of photosythesis takes place. Contains starch granuelles, enzymes.
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How is it adapted? (the chloroplasts)
Granal membranes provide a large surface area for the 1st part of photosythesis. electron carries, chlorphyll and enzymes attatch.
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2nd adaption? 3rd?
fluid contains the enzymes it needs for the second part. Chloroplasts have both DNA and ribosomes so can manufacture protiens needed for photosythesis.
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Card 2


What does each haem group have? How many haem groups in one hameoglobin structure? Because? How much O2 carried?


a Fe2+ ion which can combine with a single O2 molecule. 4 haem groups, 1 to each polypeptide. Therefore 4 O2 molecules (or 8 O atoms). can be carried.

Card 3


What are the two roles of hameoglobin?


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Card 4


Whats the issue with this?


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Card 5


So how does it achieve this?


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