~AS Bio doubts Here !!~

[arsimme]

was that clear for u or i shud write again ?

 

[arsimme]

3. Relationship between structure and function of Haemoglobin and Collagen.

Haemoglobin

An example of a globular protein that you must know about is haemoglobin. It is a pigment that carries oxygen and is found in red blood cells. It has four poly peptide chains, two α chains, two β chains, and is almost spherical. Each polypeptide chain contains a haem group, and is important and permanent part of a protein molecule that is not made of amino acids and is known as the prosthetic group. Each of these haem group contains an iron ion, Fe2+, and one oxygen molecule can bind with each iron ion. A complete haemoglobin molecule has four haem groups, and thus can carry four oxygen molecules at a time. The haem group is also responsible for the colour of haemoglobin - if haemoglobin is combined with oxygen (oxyhaemoglobin), it is bright red, else it is purple.
As with all globular proteins, the hydrophilic R groups pointing out maintain it's solubility in water - however this can be affect by a disease known as sickle cell anaemia. In this case, one amino acid of one of the β polypeptide chains, in a hydrophilic section is replaced which a different amino acid, the original being a polar amino acid, the replacement being non-polar. As you will see in the water section, this will cause problems. It makes haemoglobin much less soluble, and is unpleasant and dangerous in anyone whose haemoglobin is all of this faulty type.

Collagen

As previously mentioned, collagen is a fibrous protein that is found in skin, tendons, bones, teeth, cartilage and importantly in the walls of blood vessels and it is a generally important structural protein in many animals. The reason collagen is so strong is that it consists of three polypeptide chain, each in the shape of a helix, wound together to form a three stranded 'rope'. Nearly every amino acid in the chain is glycine, which is small, and allows the three strands to lie close together and form a tight coil, and hydrogen bonds bond the strands.
The cross-links between the collagen(the complete 3 stranded collagen molecule) form fibres, providing it with tremendous tensile strength (withstanding large pulling forces).

 

[filza94]

it was now jux keep on riting m prinitng itt

 

[arsimme]

1. What are the main types of lipids?
The main types of lipids are triglycerides (fats and oils), phospholipids, waxes and steroids.

2. What is the structural formula of glycerol? To which organic function do these molecules belong?
Glycerol is a linear chain of three carbons; the central carbon is bound to one hydroxyl radical and to one hydrogen and the two other carbons in the extremities are bound to a hydroxyl radical and to two hydrogens. Spatial sides of the hydroxyls are the same.

3. How are triglycerides made?
Triglycerides, fats or oils, are made of three molecules of fatty acids bound to one molecule of glycerol. Hydroxyls of each one of the three fatty acids and each hydrogen of the hydroxyls of the glycerol bind to form three molecules of water that are liberated.

4. What are phospholipids?
Phospholipids are molecules made of glycerol bound to two long molecules of fatty acids and to one phosphate group. Therefore, phospholipids are amphipathic molecules, i.e., they have a non-polar portion, due to the long fatty acid chains, and a polar portion, due to the group phosphate.

Phospholipids are the main component of cell membranes. Sphingomyelin, the substance that forms the myelin sheath of axons in the nervous system, is a phospholipid too.

 

[filza94]

hmm okay then more answers gimem fastt!!!!

 

[arsimme]

THE STRUCTURE OF AN ANTIBODY IS RELATED
TO ITS FUNCTION
The function of an antibody is to bind foreign or nonself molecules. The host can produce a vast array of
antibodies that are structurally similar (all are Yshaped molecules) yet unique. This variability was a
startling finding because all other protein molecules
made by an individual are identical; they all have the
same amino acid sequence. However, antibodies come
in millions of different amino acid sequences and are
the most diverse proteins known.
The chemical structure of antibodies explains three
functions of antibodies: (1) binding versatility, (2)
binding specificity, and
(3) biological activity.

 

[filza94]

OKAY NOW LEAVE DIX ALL TELMEE EXPLAIN THE DIFFERENCES BETWEEN BLOOD TISSUE FLUID AND LYMPH!!!!

 

[arsimme]

ops dont know this one...sorry

 

[filza94]

hmm dix all plzz itx urgent
(r) describe the external and internal structure of the mammalian heart;
(s) explain the differences in the thickness of the walls of the different chambers in terms of their functions;
(t) describe the mammalian circulatory system as a closed double circulation;
(u) describe the cardiac cycle;
(v) explain how heart action is initiated and controlled (reference should be made to the sinoatrial node, the
atrioventricular node and the Purkyne tissue)

 

[Xthegreat]

tissue fluid
- form from blood plasma that leaks out from pores between endothelium cells
- for the exchange of material between cells and blood
- found between spaces of cells
- contains WBC, water, glucose, ions, very little protein, waste products
- does not contain RBC

Lymph
- form from 10% of the tissue fluid that did not flow back into the blood capillaries
- to return excess water and protein molecules back to the blood
- found in the lymphatic veins
- contains WBC, antibodies, very little protein, fats
- does not contain RBC

 

[filza94]

wat abt blood???

 

[adsterr007]

i have a couple of questions and would really appreciate it if someone cud clear them up
1. what is the function of constant region in an antibody molecule?
2. whats the significance of self and non-self antigen?
3. function of smooth muscle?
4. definition of mass flow
5. what are the importance of base pairing and hydrogen bonding?
6. definiton of endocytosis and excocytosis

 

[naelmizan1994]

1. constant region binds to receptors on phagocytes and helps phagocytosis.
2. Sorry! I have never heard of these terms
3. smooth muscle controls the diameter of a particular tube ( blood vessel or trachea or whatever)
4. continuous flow of a solution with no breaks in their stream.
5. Base pairing and hydrogen bonding provides stability to a molecule. base pairing also ensures tht there are no errors made during Dna replication or during transcription and translation.
6. Endocytosis is an energy consuming process resulting in the bulk intake of large substances by a cell.
Exocytosis is an enrgy consuming process leading to the expulson of large substances by a cell. u ccan also mention the fact that membrane fluidity enables these processes to occur.

 

[adsterr007]

are u sure exocytosis and endocytosis consume energy???

 

[naelmizan1994]

Yes. 100% sure . it was written in the mark scheme. i was a bit surprised myself.

 

[filza94]

lsn explain why it is important that an extract copy of DNA IS MADE DURING REPLICATION?

 

[naelmizan1994]

an exact copy of dna is essential as errors may cause the cell to loose its function and become unsuited for its job. the cell may also get mutated. mutated cells are rejected by the immune system.
these are the points given in the mark scheme.

 

[adsterr007]

an exact copy of dna is essential as errors may cause the cell to loose its function and become unsuited for its job. the cell may also get mutated. mutated cells are rejected by the immune system.
these are the points given in the mark scheme.

=___="
either ur mark schemes are magical OR m blind!!! y cant i get such cool answers frm the mark schemes??? :Search:

 

[filza94]

explain the differences between blood , tissue fluid and lymph?

 

[adsterr007]

blood has large plasma proteins, red blood cells
lymph and tissue fluid are almost the same. lymph has a higher concentration of lipids (most probably) and lower water potential than tissue fluid.