11.1 and 11.2

Question 1

Gene regulation

Answer 1

The turning on and off of genes within a cell in response to environmental stimuli or other factors (such as developmental stage)

Question 2

Gene expression

Answer 2

The process whereby genetic information flows from genes to proteins; the flow of genetic information from the genotype to the phenotype

Question 3

Promoter

Answer 3

A specific nucleotide sequence in DNA located near the start of a gene that is the binding site for RNA polymerase and the place where transcription begins

Question 4

Operator

Answer 4

In prokaryotic DNA, a sequence of nucleotides near the start of an operan to which and active repressor protein can attach. The binding of repressor presents the RNA polymerase from attaching to the promoter and transcribing the genes of the operon. The operator sequence thereby acts as a genetic switch that can find all the genes in an operon on or off as a single functional unit

Question 5

Operon

Answer 5

A unit of genetic regulation common in prokaryotes; a cluster of genes with related functions, along with the promoter and operator that control their transcription

Question 6

Repressor

Answer 6

A protein that blocks the transcription of gene or operon

Question 7

Regulatory gene

Answer 7

A gene that codes for a protein, such as a repressor, that controls the transcription of another gene or group of genes

Question 8

Activators

Answer 8

A protein that switches on a gene or group of genes

Question 9

Differentiation

Answer 9

The specialization in the structure and function of cells that occurs during the development of an organism; results from selective activation and deactivation of the cells genes

Question 10

Histone

Answer 10

A small protein molecule important in DNA packing in the eukaryotic chromosome. Eukaryotic chromatin consists of roughly equal parts of DNA and histone protein

Question 11

Nucleosome

Answer 11

The bead like unit of DNA packing in a eukaryotic cell; consists of DNA wound twice around a protein core made up of eight histone molecules

Question 12

Epigenetic inheritance

Answer 12

The inheritance of traits transmitted by mechanisms not directly involving the nucleotide sequence of a genome, such as the chemical modification of histone proteins or DNA bases

Question 13

X chromosome inactivation

Answer 13

In female mammals, the inactivation of one X chromosome in each somatic cell

Question 14

Barr body

Answer 14

A dense body formed from a deactivated X chromosome found in the nuclei of female mammalian cells