Chapter 3

Question 0

Variation

Answer 0

In alleles of genes, it occurs both within and among populations. Genetic variation is important because it provides the genetic material for natural selection.

Question 1

Mutation

Answer 1

A change in the nucleotide sequence of the genome of an organism, virus, or extrachromosomal genetic element. Mutations result from unprepared damage to DNA or to RNA genomes (typically caused by radiation or chemical mutagens), errors in the process of replication, or from the insertion or deflection of segments of DNA by mobile genetic elements.

Question 2

Single Nucleotide Polymorphism (SNP)

Answer 2

A DNA sequence variation occurring when a single nucleotide in the genome differs between members of a biological species or paired chromosomes.

Question 3

Transversion

Answer 3

The substitution of a purine for a pyrimidine, or vice versa.

Question 4

DNA polymerase

Answer 4

A cellular or viral enzyme that synthesizes DNA molecules from their nucleotide building blocks, distinguishing from RNA polymerase or other polymerase.

Question 5

INDELs

Answer 5

The insertion or deletion of bases in the DNA of an organism.

Question 6

Hydrolysis

Answer 6

The cleavage of chemical bonds by the addition of water.

Question 7

Heteroduplex

Answer 7

A double-stranded (duplex) molecule of nucleic acid originated through the genetic recombination of single complementary strands derived from different sources, such as from different homologous chromosomes, or even from different organisms.

Question 8

Lesion

Answer 8

Any abnormality in the tissue of an organism, usually caused by disease or trauma.

Question 9

CpG (sites)

Answer 9

Regions of DNA where a cytosine nucleotide occurs next to a guanine nucleotide in the linear sequence of bases along its length. “CpG” is shorthand for “—C—phosphate—G—”, that is, cytosine and guanine separated by only one phosphate.

Question 10

Dinucleotide

Answer 10

A nucleotide consisting of two units each composed of a phosphate, a pentose, and a purine or pyrimidine base.

Question 11

Methylation

Answer 11

The addition of a methyl group to a substrate or the substitution of an atom or group by a methyl group. It is a form of alkylation with a methyl group, rather than a larger carbon chain, replacing a hydrogen atom. In biological systems, methylation is catalyzed by enzymes; such methylation can be involved in modification of heavy metals, regulation of gene expression, regulation of protein function, and RNA processing.

Question 12

Open Reading Frame (ORF)

Answer 12

The part of a reading frame that contains no stop codons. The transcription termination pause site is located after the ORF, beyond the translation stop codon, because if transcription were to cease before the stop codon, an incomplete protein would be made during translation.

Question 13

Promoter

Answer 13

A region of DNA that initiates transcription of a particular gene. Tey are located near the transcription start sites of genes, on the same strand and upstream on the DNA.

Question 14

Enhancer

Answer 14

A short (50-1500 bp) region of DNA that can be bound with proteins to activate transcription of a gene or genes.

Question 15

Polydenylation

Answer 15

The addition of a poly(A) tail to a primary transcript RNA. The poly(A) tail consists of multiple adenosine monophosphates; in other words, it is a stretch of RNA that has only adenine bases. In eukaryotes, it is part of the process that produces mature messenger RNA for translation, making it important for gene expression.

Question 16

MicroRNA (miRNA)

Answer 16

A small, non-coding RNA molecule found in plants, animals, and some viruses, which functions in transcriptional and post-transcriptional regulate of gene expression.

Question 17

Gene Conversion

Answer 17

The process by which one DNA sequence replaces a homologous sequence such at the sequences become identical after the conversion event.

Question 18

Gene Duplication

Answer 18

A major mechanism through which new genetic material is generated during molecular evolution. It can be defined as any duplication of a region of DNA that contains a gene. They can arise as products of several types of errors in DNA replication and repair machinery as well as through fortuitous capture by selfish genetic elements.

Question 19

Variable Number Tandem Repeat (VNTR)

Answer 19

A location in a genome where a short nucleotide sequence is organized as a tandem repeat. These can be found on many chromosomes, and often show variations in length between individuals. Each variant acts as an inherited allele, allowing them to be used for personal or parental identification.