BIO130H1 Final: Final Lab Review All you need to know for lab MC in final exam!

In order to isolate the protein, seeds were ground and extracted with water. The proteins in the extract were precipitated with hydrochloric acid and the pellet isolated by centrifugation was discarded. The supernatant was heated to 70°C to remove heat-labile proteins, then lyophilized (freeze-dried). The lyophilized powder was dissolved in a small amount of ammonium acetate buffer at pH = 5 and the sample was loaded onto a Sephadex G-251 gel filtration column. The elution profile showed four peaks. Most of the BN protein eluted in the first peak. a. On what basis is separation achieved on the Sephadex gel filtration column? b. Compare the BN protein to other proteins found in the B. nigra seeds.

1. Polypeptide strands is the active form of a digestive enzyme in the stomach that breaks polypeptide chains into smaller polypeptides.

2. Cleavage of proteins by pepsin in the stomach results in formation of pepsinogen which get broken down further in the small intestine.

3. An amino acid chain made up of three amino acids joined together is called a tripeptide.

4. Dipeptide describes an amino acid chain made up of two amino acids joined together.

5. The 20 different amino acids are the building blocks used for protein synthesis.

6. Amino acid pools are stockpiles found in the blood and other cells of the body that can be used to build new proteins.

7. The continual process of degrading and synthesizing protein is called protein turnover.

8. The stomach produces pepsin, which denatures protein.

9. Denaturation occurs when a protein is exposed to heat, acid, bases, or mechanical agitation resulting in unfolding of the protein, though the peptide bonds remain intact.

10. The part of an amino acid that contains nitrogen is called the amine group.

11. The acid group is also known as the carboxyl group.

12. Single amino acids that are absorbed in the small intestine travel to the liver via the portal vein.

Please correct these sentences AS SOON AS POSSIBLE.. Some of them are not correct and I didn't figure out what are they!

1. The histones that form the core of the nucleosome get into the nucleus by which of the following?

a) Passive diffusion through nuclear pores

b) Selective and facilitated active transport through nuclear pores

c) Ribosomes located in the nucleus synthetize histones in the nucleus

d) Histones are made at the ER membrane and then diffuse to the nucleus

2. Membrane proteins that belong to the golgi, lysosome, or plasma membrane first pass through which organelle before reaching their final subcellular destination?

a) The golgi apparatus

b) The smooth ER

c) The nucleus

d) The ER membrane

e) The ER lumen

3. Where in the cell would a ribosomal protein be located if it has had its nuclear export signal inactivated (non-functional or non-existent).

a) The protein would be found in the ER lumen

b) The protein would remain in the nucleus

c) The protein would be secreted

d) The protein would remain in the cytoplasm

e) The protein would be in the ER membrane

4. Where would be the final destination of a protein if it contained a NLS anywhere in the protein sequence (and which is exposed to the cytoplasm after protein folding) but also contained an ER signal sequence at the carboxy terminus?

a) The ER lumen

b) The nucleus

c) The cytoplasm

d) The inner nuclear membrane

e) The ER membrane

5. The sequence K-D-E-L serves as a retention/retrieval signal for ER proteins.

a) True

b) False

6. The following are true for both cell membrane proteins and secretory proteins EXCEPT?

a) Precursors of the mature proteins contain signal sequence.

b) Both types of proteins contain stop-transfer sequences

c) Both types of proteins enter the ER while being synthetized

d) Both types of proteins pas through the golgi apparatus

e) Both are carried by clatherin-coated vesicles

7. If you isolate a regulated secreted protein from a secretory/storage vesicle and inject it into the cytosol, is will?

a) Be secreted through channels in the plasma membrane

b) Be taken up into secretory vesicle and secreted

c) Remain in the cytosol until it is degraded

d) Be taken up into the rough ER and follow the secretory pathway