Quiz: Mutations

There are multiple types of mutations in DNA. mutations occur when a single base is changed to a different base pair. mutations remove one or more bases from a segment of DNA, resulting in a frameshift mutation. mutations are also considered frameshift mutations, and occur when one or more extra bases are added to a segment of DNA.

substitution, deletion, isertion

he diagram shows the effect of a point mutation on a section of a gene. The nitrogenous base adenine ("A") is inserted into the sequence. (Note: The diagram shows the base sequence of DNA in the top row, and the transcribed mRNA in the bottom row.)What best describes this mutation and its effect on the protein that the gene produces?

It is a frameshift mutation that changes many amino acids.

Compare the two DNA sequences and polypeptide chains they produce. What type of mutation has occurred to the bottom sequence?

Deletion

Manny is using a computer model to investigate the effects of substitution mutations. The model presents Manny with a long base sequence for a gene. Manny then selects one base for a mutation, such as by substituting cytosine, "C", for adenine, "A".Manny completes many trials of mutations. In most trials, the result of the substitution mutation is either no effect, or a polypeptide in which one amino acid is altered. In one trial, however, the result is a truncated polypeptide. Many of its terminal amino acids are missing.What is the most likely explanation for the truncated polypeptide.

The mutation introduced a stop codon in the middle of the gene.

Frieda is developing a computer model of mutations in human DNA. She plans for the model to incorporate one point mutation for every 10 million base pairs of DNA, which is a rate that is supported by her research. However, her advisor argues that mutations could occur 100 times more frequently under certain circumstances.Which could most likely cause the increase in mutation rate that the advisor describes?

mutagens in the environment, such as tobacco smoke and certain pesticides

One or more extra whole sets of chromosomes is called Choose... mutagen traffic transcription error frameshift mutation polyploidy , which often is beneficial in plants.

polyploidy