Questions of the Weeks Round Up

1) For the photolysis of water, we talked about the highly oxidising nature of p680+. But isn't there a Mn complex involved?

Yes it is true. The Mn Complex will interact directly with water to extract the e- to be passed to p680+. But it is not required of you to know. =)

2) SER: tubular and RER: flattened?

A pic speaks a thousand words and better than the one I drew in class


3) How polypeptides can get into the lumen of RER?



The diagram shows that a partially formed polypeptide chain is directed to the RER by the peptide signal sequence where the rest of the polypeptide chain will then continue to be formed and entered the lumen.

4)
Cell Membrane

1 D 6 C 11 D
2 C 7 B 12 D
3 B 8 A 13 B
4 A 9 D 14 B
5 A 10 A 15 C

Common Mistakes/Correction to note:

4) the width is within 10nanometers!
7) you should know the nature of the core of bilayer; having a fluid mosaic is a consequence not a reason.
9) aerobic = there is production of large amounts of ATP; from the table we can deduce that the first two rows undergo passive diffusion and active transport but active transport is halted under anerobic conditions.
11) if you choice include any of the proteins, you are not listening in class when I mentioned that the presence of proteins to affect fluidity is only a minor point and definitely not their main purposes.
14) same above in 11.
15) similar to 9 whereby air bubbled implied oxygen introduced into culture → aerobic respiration.


Cell Structure


1 D 6 C 11 B 16 D
2 E 7 A 12 C 17 B
3 D 8 E 13 D 18 D
4 C 9 C 14 A 19 A
5 C 10 D 15 B 20 C


Common Mistakes/Corrections to note:

2) sucrose: used to maintain osmotic difference of the mitochondria with its external environment so that one can view it in its native shape under microscope.
5) at the slowest speed, the most dense organelles will be spun down and that will be the nuclei/dna.
6) you should know this!
7) B is wrong. It is pointing to the RER/ribosomes where rRNA/mRNA and maybe even tRNA are present.
9) hydrolytic enzymes are found in lysosomes!
10) expected to know. It is also the site for carbohydrate synthesis and detoxification
11) B is correct; bacteria do have cell wall.
13) D: NADP is found in chloroplasts; NAD is found in mitochondria; membrane- bound enzymes refers to enzymes that are bound to the membrane e.g. ETC which is made up of a series of enzymes (although we did not go into the details) like oxidase, reductase. Try Wiki.
17) refer to 9
19) (In metabolism some substances are broken down to yield energy for vital processes while other substances, necessary for life, are synthesized) so all we need to recognise is that products can be exported out of cell via exocytosis or budded off to another site within cell where the products are needed.
20) another major featuer of prokaryotic cell; remember your essay comparing chloroplast and mitochorion?