Question

Question 1

What post-translational modification will cause the biggest increase in the size of a protein, immediately when added?

Select one:

a. Phosphorylation

b. Ubiquitination

c. Acetylation

d. Methylation

Question 2

What does HMT do?

Select one:

a. It acts as an epigenator

b. It modifies nitrogenous bases

c. It produces euchromatin

d. It modifies histones

Question 3

Where can an epigenetic maintainer act?

Select one:

a. On the sequence of nucleotides

b. On the sequence of nucleotides and on the nucleotides directly

c. On certain nucleotides and amino acids

d. On certain amino acids

e. On certain nucleotides

Question 4

Which of the following types of protein could be coded by a tumour-suppressor gene?

Select one:

a. A protein that stimulate progression through the cell cycle.

b. A protein that forms part of a growth factor signaling pathway.

c. A protein that codes for a DNA repair enzyme.

d. A protein that helps prevent apoptosis.

e. A protein that repairs lost telomeres

Question 5

Which is NOT a typical mechanism by which a proto-oncogene is converted to an oncogene?

Select one:

a. A point mutation in the proto-oncogene

b. A chromosomal translocation resulting in the up-regulation of the proto-oncogene

c. Duplication of a chromosome region containing a proto-oncogene

d. Complete deletion of the proto-oncogene

e. Amplification of the proto-oncogene

Question 6

Why do you think familial retinoblastoma and Li-Fraumeni are considered to be inherited as autosomal dominant traits when the responsible genes are recessive?

Select one:

a. They are expressed in a dominant fashion in males, but recessive in females.       

b. People with this mutation are always homozygous for this allele.

c. If you are born with one allele mutated in every cell, the chance that the other allele will be mutated in one of the retinal cells is extremely high.

d. This recessive gene needs only one copy to express this phenotype.

e. Retinoblastoma was mischaracterized originally when it was called an autosomal dominant trait.

Question 7

Question text

In a normal cell, pRB binds to __________, which inhibits cell division. In the presence of __________ pRB becomes __________, which leads to cell division.

Select one:

a. cyclin+Cdk; oncogenes; dephosphorylated

b. transcription factors; cyclin+Cdk; phosphorylated

c. tumor suppressor; p53; phosphorylated

d. p21; p53; dephosphorylated

e. tumor suppressor; p21; hyperactive

Question 8

The following information relates to the next three questions:

A few decades ago, Knudsen and colleagues proposed a theory that, for a normal cell to become a cancer cell, a minimum of two genetic changes had to occur in that cell. Knudsen was studying retinoblastoma, a childhood cancer of the eye.

Two children are born from the same parents. Child one inherits a predisposition to retinoblastoma (one of the mutations) and child two does not. However, both children develop the retinoblastoma. Which of the following would you expect?

Select one:

a. a history of exposure to mutagens in child one but not in child two

b. increased levels of apoptosis in both children

c. an earlier age of onset in child one

d. decreased levels of DNA repair in child one

e. a more severe cancer in child one

Question 9

In colorectal cancer, several genes must be mutated in order to make a cell a cancer cell, supporting Knudsen’s hypothesis. Which of the following kinds of genes would you expect to be mutated?

Select one:

a. genes that are especially susceptible to mutation

b. the same genes that Knudsen identified as associated with retinoblastoma

c. genes coding for enzymes that act in the colon

d. the genes of the bacteria that are abundant in the colon

e. genes encoding transcription factors that regulate cyclin production

Question 10

Knudsen and colleagues also noted that persons with hereditary retinoblastoma that had been treated successfully lived on but then had a higher frequency of developing osteosarcomas (bone cancers) later in life. This provided further evidence of their theory because:

Select one:

a. osteosarcoma cells express the same genes as retinal cells.

b. one of the mutations involved in retinoblastoma is also one of the changes involved in osteosarcoma.

c. p53 gene mutations are common to both tumours.

d. retinoblastoma is a prerequisite for the formation of osteosarcoma later in life.

e. both kinds of cancer involve uncontrolled proliferation of cells.

Answer 1

1.- b) Ubiquitination. That is ebcause this is the largest molecule that can be attached to the peptide, it is whole other protein that is attached

2.- d) It modifies histones. HMT is the Histone MethylTransferase, its action goes over the histones

3.- e) On certain nucleotides

4.- c) A protein that codes for a DNA repair enzyme. You have to choose a function that prevents loss of control in the cell cycle, and this is the only one, all the others produce such lack of control

5.- d) Complete deletion of the proto-oncogene. Such conversion can occur by either point mutation, amplification or translocation of the proto oncogene, while deleting it won't

6.- c) If you are born with one allele mutated in every cell, the chance that the other allele will be mutated in one of the retinal cells is extremely high.

7.- b) transcription factors; cyclin+Cdk; phosphorylated

8.- c) an earlier age of onset in child one

9.- c) genes coding for enzymes that act in the colon

10.- b) one of the mutations involved in retinoblastoma is also one of the changes involved in osteosarcoma.