BIO-1200 Chapter 14: Mutation and Cancer
The following sequence of DNA is part of the normal, wild-type gene. 5' ATG C(G)G GTA GTT AGC CGA TAG 3' A deletion occurs during DNA replication, causing the guanine shown in red to be removed from the nucleotide strand. What effect is this most likely to have on the final protein?
The deletion of the G will cause a frame shift, resulting in a premature stop codon and a truncated protein.
The nucleic acid sequence in mRNA is determined by
nucleotide sequence in DNA.
If a frameshift mutation causes a stop codon to be inserted into the DNA sequence
the resulting protein will be too short and non-functional.
The insertion of a ____________ into the promoter of a gene could result in increased expression of the gene, resulting in cancer.
virus
After a tautomeric shift in adenine
adenine bonds with cytosine
In a tautomeric shift
hydrogen atoms move to form a nucleotide base with altered bonding properties.
A ____________ can alter the structure of a protein (but not the total number of amino acids) so that it now has abnormally high activity.
missense mutation
When a tautomeric shift occurs, the resulting nulceotide is a(n) __________ of the nucleotide prior to the shift.
structural isomer
A young girl was born with a patch of soft fur that ran from the base of her neck to her tailbone. She did not display any other symptoms of disease, and results of her karyology seemed normal. No one on either her mother or father's side of the family had ever been born with this oddity. Her concerned mother asked a doctor if her daughter would have children that were similarly furry. The doctor told her that while he couldn't be 100% certain, he suspected that this characteristic was the result of
A somatic mutation that occurred in the developing embryo, but probably wouldn't affect the daughter's egg cells
What characteristic of DNA makes nucleotide excision repair (NER) mechanisms possible?
DNA is a double helix so once a damaged region is recognized, it can be removed and synthesized based on the healthy opposite strand.
CCR5 is a cell surface receptor protein of white blood cells that attracts them to specific tissue and organs to elicit an immune response. It is also the receptor to which R5 strains of HIV bind to and enter T cells. Between 5-14% of people from Northern European descent possess an allele known as CCR5-Δ32. In this allele, a 32 base pair section of the gene has been deleted. What phenotype would you predict for people carrying the CCR5-Δ32 allele?
People with CCR5-Δ32 will likely have impaired immune function, but will have resistance to HIV infection.
The following sequence of DNA is the normal, wild-type gene. 5' ATG C(G)G GTA GTT AGC CGA TAG 3' An insertion occurs during DNA replication, causing an additional GUANINE to be inserted into the nucleotide strand after the GUANINE shown in red. What effect will this have on the final protein?
The addition of the G will cause a frame shift, resulting in a premature stop codon and a truncated protein.
Why are people afflicted with xeroderma pigmentosa likely to develop skin cancer?
Because they are born with a mutation in their DNA repair system and they cannot repair DNA that is mutated by UV radiation
When a tautomeric shift occurs, what happens?
In the new DNA strand, a purine is always replaced by a purine, and a pyrimidine is always replaced by a pyrimidine.
A ____________ can cause fusion of two genes together, resulting in formation of a chimeric oncogene.
chromosomal translocation
A change in the number of ____________ of a gene can cause too much protein to be made.
copies
A nucleotide deletion in DNA replication
causes the amino acids inserted after the deletion to be incorrect
Many cells that have accumulated mutations are eliminated by ____________
cell death
A mutation that causes a change in a single nucleotide in DNA
changes the corresponding nucleotide in mRNA, resulting in a different codon.
If a cell accumulates DNA damage during mitosis, the cell cycle can pause at a ____________
checkpoint
