Genetics and Mutations Practice Flashcards

Flashcards covering the fundamentals of genetics including genotypes, phenotypes, alleles, inheritance patterns, and various types of genetic mutations.

What is the difference between a genotype and a phenotype?

Genotype is the genetic makeup of a cell or organism, whereas phenotype is the physical expression of genes into observable traits.

What are the different forms of a gene called?

Alleles.

Distinguish between homozygous and heterozygous genotypes.

Homozygous genotypes have two identical alleles (e.g., $BB$ or $bb$), while heterozygous genotypes have different alleles (e.g., $Bb$).

How are mutations defined in a genetic context?

Any heritable change in the genetic material that can affect protein structure and function.

What is the consequence of a harmful mutation in the $HTT$ gene?

It increases glutamines in the final protein product and results in Huntington's disease.

Which gene encodes a taste receptor on the tongue that may be tested with $PTC$ (Phenylthiourea-Phenylthiocarbamide) paper?

$TAS2R38$.

What is an example of a beneficial mutation mentioned in the notes?

A mutation in the gene that encodes lactase, the enzyme that breaks down lactose, which improves survival and reproduction.

What characterizes mutation rates in humans compared to other species?

Humans have the lowest number of mutations per nucleotide per replication but the highest number of mutations per genome per generation.

In humans, which sex typically has a higher mutation rate?

Males.

Distinguish between somatic and germ-line cells.

Somatic cells are body cells, while germ-line cells are sex cells (gametes).

What is the difference in the inheritance of somatic vs. germ-line mutations?

Somatic mutations occur in nonreproductive cells and stay within the individual; germ-line mutations occur in reproductive cells and are passed to offspring.

What is the primary cause of malignancy in most cancers, such as colon cancer?

The accumulation of multiple mutations in somatic cells.

Do antibiotic-resistant mutations arise because of exposure to antibiotics?

No, they arise before exposure to antibiotics, not as a result of it.

What results from a point mutation where a single nucleotide substitution does not change the amino acid?

A silent (synonymous) mutation.

What results from a point mutation where a single nucleotide substitution changes the amino acid?

A missense (nonsynonymous) mutation.

What is a nonsense mutation?

A nucleotide substitution that creates a stop codon.

What occurs when 1 or 2 base pairs are inserted or deleted in a sequence?

A frameshift mutation, which changes the reading frame and significantly alters the amino acid sequence.

What mutation causes the most common form of Cystic Fibrosis?

A deletion of 3 nucleotides in the $CFTR$ gene, resulting in a missing amino acid (PHE) at position 508 and a misfolded protein.

What are transposable elements (transposons)?

DNA sequences that can jump out of a gene and re-insert elsewhere in the genome, potentially disrupting gene function.

Who hypothesized and discovered transposable elements through the study of corn kernels?

McClintock.