Topic 8 - How Genes Work

Question 1

Allele

Answer 1

A particular version of a gene.

Question 2

Ambiguous

Answer 2

The genetic code is not _______ because a given codon only specifies one type of amino acid.

Question 3

Chromatin

Answer 3

The complex of DNA and proteins, mainly histones that compose eukaryotic chromosomes. Can be highly compact (heterochromatin) or loosely coiled (euchromatin).

Question 4

Codon

Answer 4

A sequence of three nucleotides in DNA or RNA that codes for an amino acid or a start or stop signal for protein synthesis.

Question 5

Gene

Answer 5

(1) In a molecular context, a section of DNA (or RNA, for some viruses) that contains the regulatory sequences and coding information for the transcription of one or more related functional RNA molecules, some of which encode polypeptides. (2) In Mendelian genetics, the hereditary determinant of a trait, such as flower colour or seed shape in pea plants.

Question 6

Genotype

Answer 6

All the alleles of a gene or genes present in a given individual.

Question 7

Heterozygous

Answer 7

Having two different alleles of a gene.

Question 8

Homologous chromosomes

Answer 8

In diploid organisms, a member of a pair of chromosomes that are similar in size, shape, and gene content. Also called a homologous pair.

Question 9

Homozygous

Answer 9

Having two identical alleles of a gene.

Question 10

Phenotype

Answer 10

The detectable traits of an individual. E.g.: presence/absence of an enzyme, blood type, hair colour.

Question 11

Redundant

Answer 11

The genetic code is _________ because multiple codons could result in the addition of the same amino acid to a protein.

Question 12

Reverse transcriptase

Answer 12

An enzyme that can synthesize DNA from an RNA template.

Question 13

Sister chromatids

Answer 13

The paired, double-stranded DNA copies of a recently replicated chromosome. They are connected most tightly at the centromere and eventually separate during anaphase of mitosis or meiosis II.

Question 14

Transcription

Answer 14

The process by which RNA is synthesized from a DNA template. It is catalyzed by then enzyme RNA polymerase and it happens in the nucleus of the cell.

Question 15

Translation

Answer 15

The process by which proteins and peptides are synthesized from a messenger RNA template. It happens in the cytoplasm and it is catalyzed by ribosomes that could be free or attached to the rough endoplasmic reticulum.