5.9.23 Keystone Review

A mutation present in a parent’s genetic code impacts offspring. Which statement most likely describes the mutation?

• The mutation can be recognized and repaired by enzymes.

• The mutation is observed in the somatic cells of the parent.

• The mutation changes a base without changing an amino acid.

• The mutation alters the function of the protein made by the gene.

Answer explanation

The mutation changes the sequence of bases and prevents the protein from working properly.

Which mutation would most likely affect the organism’s phenotype?

• A

• B

• C

• D

Answer explanation

The original sequence codes for Cys, while the mutated

sequence codes for a stop. This could result in a change in the organism’s phenotype.

During a cell division cycle, chromosome segments from two homologous chromosomes exchange places. Which result is most likely to occur following this cycle?

• Genetic material will be lost.

• The number of chromosomes will increase.

• The total number of genes in the cell will decrease.

• A change in gene location will occur on both chromosomes.

Answer explanation

Translocation is an exchange of pieces of homologous

chromosomes.

An inversion occurs along part of a chromosome. How does the inversion most likely affect the region in which it occurs?

• Recessive alleles in the region become dominant alleles.

• The information in the region is read differently during transcription.

• The coding sequence in the region disappears entirely from the cell.

• Multiple frame-shift errors in the region are triggered after translation.

Answer explanation

An inversion occurs when a chromosomal segment is rotated and reinserted in the same location, which causes the region to be read

differently.

New technologies can extract certain oils from plants to make renewable biodiesel fuel.

Scientists have altered the genome of a species of plant to increase the amount of this oil that each plant produces. To do this, scientists activated a gene that directs cells to store plant oils. To further increase the amount of plant oil produced, scientists are planning to duplicate the gene that codes for oil production.

Describe how the altering of the plant’s genome by the scientists is similar to naturally occurring genetic mutations.

Answer explanation

The naturally occurring mutation could cause a similar effect as the scientific duplicating of a gene.

The scientists’ plan to alter the plant’s gene uses a naturally occurring type of mutation.

A section of DNA in a cell is altered. Which mutation is being illustrated in the DNA section in the image?

• deletion

• insertion

• duplication

• nondisjunction

Answer explanation

The altered strand of DNA is shorter than the original

strand; this suggests that one or more bases were deleted.

A mutation occurred that caused a change in an mRNA sequence. The mRNA codon UAC was replaced by the codon UAA. Which statement describes the most likely outcome of the mutation?

• It will produce the same protein using a different set of codons.

• It will result in an incomplete protein that does not function properly.

• It will cause mRNA to attach a new amino acid chain during transcription.

• It will change the bonding pattern between the amino acids joining together.

Answer explanation

The codon UAA codes for a stop, which will result in the

formation of an incomplete protein.