Chapter 14 Practice
The following sequence of DNA is part of the normal, wild-type gene. 5' ATG CGG 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 G will cause a frameshift, resulting in a premature stop codon and a truncated protein
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
What has a strong effect? (3)
1.CGA---> TGA near beginning of gene 2.GAG-->GTG change in important part of coding region 3.Insertion of one base (+1) shortly after start codon
What has weak effect?(1)
1.Change of a codon for one acidic amino acid into another acidic amino acid
Following steps in the development of cancer in an individual with xeroderma pigmentosum:
1.Mutation in DNA repair enzyme gene 2.Exposure to UV light 3.Mutation of a tumor-suppresor gene -initiates abnormal cell growth 4.Benign growth- the earliest cell growth 5.Malignant growth- later stage of cell growth 6.Metastasis- last step of cancer, usually fatal
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
After a tautomeric shift in adenine....
Adenine binds with cytosine
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
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
A ____________ can cause fusion of two genes together, resulting in formation of chimeric oncogene
Chromosomal translocation
What characteristic of DNA makes nucleotide excision repair (NER) mechanisms possible?
DNA is a double helix so once damaged region is recognized, it can be removed and synthesized based on the healthy opposite strand
When a tautomeric shift occurs______
In the new DNA strand, a purine is always replaced by a purine, and a pyrimidine is always replaced by a pyrimidine
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 CGG 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 deletion of G will cause a frameshift, resulting in a premature stop codon and a truncated protein
The insertion of a _______ into the promoter of a gene could result in increased expression of the gene, resulting in cancer
Virus
A change in the number of _____ of a gene can cause too much protein to be made
Copies
In a tautomeric shift ______
Hydrogen atoms move to form a nucleotide base with altered bonding properties
The nucleic acid sequence in mRNA is determined by____
Nucleotide sequence in DNA
If a cell accumulates DNA damage during mitosis, the cell cycle can pause at a __________
checkpoint
What has no effect? (3)
1.AAG-->AAA in middle of gene 2.TGA-->TAA at end of coding region 3.Change of a C to a G before the ATG
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
