LT2: Cancer genetics

Question 1

Mutation definition

Answer 1

Permanent alteration in a parental SNA sequence (eg A turns in to C)

Question 2

Types of mutations

Answer 2

Chromosome mutations (effect expression of many genes)
Gene mutations (effect few genes)

Question 3

Types of chromosome mutations

Answer 3

Translocations
Multi-locus deletions
chromosoms losses/gains

Question 4

Types of gene mutations

Answer 4

Deletions/insertions
Base pair substitions
Frameshift mutations

Question 5

Gene mutations occur in….?

+ effect of the gene mutation?

Answer 5

• Intron –> often no effect
• Promoter –> may decrease transcription effiency
• Splice site –> may effect splicing
• Exon –> may effect protein composition

Question 6

With what exons starts the sequence always?

Answer 6

GT

Question 7

With what exons ends the sequence always?

Answer 7

AG

Question 8

Missense mutation definition

Answer 8

Point mutation in which a single nucleotide change results in a codon that codes for a different amino acid

Question 9

What happens when evolutionary conserved regions ondergo mutations?

Answer 9

Will lead to function loss

Question 10

How many mutations do you need to transfer a cell into a malignant tumor?

Answer 10

6/7

Question 11

The chance that you get cancer is really low, why do people still get cancer?

Answer 11

• Some mutations lead to genomic instability –> incresing mutation rate
• Mutation rate is much higher in some people
• Epigenetic silencing of genes can impair gene function
• You can carry prpedisponing mutations

Question 12

Which 2 classes of genes are there? + difference

Answer 12

• Oncogenes –> you only need mutation in one allele for activation (gain of function)
• Tumor supressor genes –> you only need mutation in both alleles for activation (loss of function)

Question 13

Which mechanisms can turn a proto-oncogene in a oncogene?

Answer 13

• Coding mutation –> leads to a abnormal protein
• Regulatory mutation –> excessive amount of protein
• Translocation –> novel protein
• Gene amplification –> excessive amount of protein

Question 14

In cancer, Ras can’t get active. Describe the mechanism

Answer 14

Ras is bound to GDP –> growth signal –> GEF turns GDP in GTP –> active Ras –> GAP binds to Ras –> inactive Ras

Question 15

Translocation in Burklitt lymphoma’s

Answer 15

translocation between chromosome 8 & 14 –> production os MYC (=growth protein)

Question 16

Translocation in chronic myloid leukemia

Answer 16

translocation between chromosome 9 & 22

Question 17

Which mutations do mostly happen in oncogenes?

Answer 17

Missence mutations & mutation hotspots

Question 18

Which mutations do mostly happen in tumor suppressor genes?

Answer 18

truncating mutations