Chapter 18 Part II

Question 1

Gene expression can be fine-tuned

Answer 1

• after transcription that enables the cell to rapidly respond to specific cellular needs
• 2 post-transcription ways and 1 post-translation
  1) Alternative RNA splicing
  2) mRNA degradation or destruction
  3) Translation initiation and post-translation

Question 2

1) Alternative RNA splicing

Answer 2

• different mRNA molecules are produced from the same primary transcript
• create RNA variation or different lengths

Question 3

2) mRNA degradation or destruction

Answer 3

in the cytoplasm is an important factor in determining the protein synthesis in a cell
- degrade

Question 4

3) Translation initiation and post-translation

Answer 4

of various types of protein processing are also subject to control

Question 5

Protein processing after translation

Answer 5

including cleavage and the addition of chemical groups, are subject to control

Question 6

Ubiquitin

Answer 6

will tag proteins and target them for destruction

Question 7

Proteasomes

Answer 7

giant protein complexes that bind protein molecules and degrade them

Question 8

Cancer

Answer 8

may result from genetic changes that affect normal genes for cell cycle control and gene regulation systems

i.e. Ras, ERK, ELK-1, p53

Question 9

Oncogene

Answer 9

cancer-causing genes

Question 10

Proto-oncogenes

Answer 10

normal cellular genes that code for proteins that stimulate normal growth and division

i.e. RAS, ERK, ELK-1

Question 11

Tumor-suppressor genes

Answer 11

encode proteins that inhibit abnormal cell division

i.e. p53

Question 12

DNA change of a proto-oncogene

Answer 12

that makes a proto-oncogene excessively active converts it to an oncogene, which may promote excessive cell division and cancer

Question 13

Conversion of photo-oncogene to an oncogene

Answer 13

can lead to abnormal stimulation of the cell cycle by

1) movement of DNA
2) Amplification
3) Point mutations

Question 14

1) Movement of DNA within the genome

Answer 14

if it ends up near an active promoter, transcription may increase

Question 15

2) Amplification of a proto-oncogene

Answer 15

increases the number of copies of the gene

Question 16

3) Point mutations in the proto-oncogene or its control elements:

Answer 16

causes an increase in gene expression

Question 17

Mutations

Answer 17

in the res photo-oncogene and p53 tumor-suppressor gene are common in human cancers

Question 18

Mutations in the RAS gene

Answer 18

can lead to production of a hyperactive RAS protein and increased cell division