Chapter 18

Front 1

operator

Back 1

In bacterial and phage DNA, a sequence of nucleotides near the start of an operon to which an active repressor can attach.

Front 2

operon

Back 2

A unit of genetic function found in bacteria and phages, consisting of a promoter, an operator, and a coordinately regulated cluster of genes whose products function in a common pathway.

Front 3

repressor

Back 3

A protein that inhibits gene transcription.

Front 4

regulatory gene

Back 4

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

Front 5

corepressor

Back 5

A small molecule that binds to a protein's shape, allowing it to bind to the operator and switch an operon off.

Front 6

inducer

Back 6

A specific small molecule that binds to a bacterial repressor protein and changes the repressor's shape so that it cannot bind to an operator, thus switching an operon on.

Front 7

cyclic AMP (cAMP)

Back 7

Cyclic adenosine monophosphate, a ring-shaped molecule made from ATP that is a common intracellular signaling molecule in eukaryotic cells.

Front 8

activator

Back 8

A protein that binds to DNA and stimulates gene transcription.

Front 9

differential gene expression

Back 9

The expression of different sets of genes by cells with the same genome.

Front 10

histone acetylation

Back 10

The attachment of acetyl groups to certain amino acids of histone proteins.

Front 11

DNA methylation

Back 11

The presence of methyl groups on the DNA bases (usually cytosine) of plants, animals, and fungi.

Front 12

epigenetic inheritance

Back 12

Inheritance of traits transmitted by mechanisms that do not involve the nucleotide sequence.

Front 13

control elements

Back 13

A segment of noncoding DNA that helps regulate transcription of a gene by serving as a binding site for a transcription factor.

Front 14

enhancers

Back 14

A segment of eukaryotic DNA containing multiple control elements, usually located far from the gene whose transcription it regulates.

Front 15

alternative RNA splicing

Back 15

A type of eukaryotic gene regulation at the RNA-processing level in which mRNA molecules are produced from the same primary transcript, depending on which RNA segments are treated as exons and which as introns.

Front 16

microRNAs (miRNAs)

Back 16

A small, single-stranded RNA molecule, generated from a double-stranded RNA precursor.

Front 17

small interfering RNAs (siRNAs)

Back 17

One of the multiple small, single-stranded RNA molecules generated by cellular machinery from a long, linear, double-stranded RNA molecule.

Front 18

RNA interference (RNAi)

Back 18

A mechanism for silencing the expression of specific genes.

Front 19

differentiation

Back 19

The process by which a cell or group of cells becomes specialized in structure and function.

Front 20

morphogenesis

Back 20

The development of the form of an organism and its structures.

Front 21

cytoplasmic determinants

Back 21

A maternal substance, such as a protein or RNA, that when placed into an egg influences the course of early development by regulating the expression of genes that affect the developmental fate of cells.

Front 22

induction

Back 22

A process in which a group of cells or group through close-range interactions.

Front 23

determination

Back 23

The progressive restriction of developmental potential in which the possible fate of each cell becomes more limited as an embryo develops.

Front 24

pattern formation

Back 24

The development of a multicellular organism's spatial organization, the arrangement of organs and tissues in their characteristic places in three-dimensional space.

Front 25

positional information

Back 25

Molecular cues that control pattern formation in an animal or plant embryonic structure by indicating a cell's location relative to the organism's body axes.

Front 26

homeotic genes

Back 26

Any of the master regulatory genes that control placement and spatial organization of body parts in animals, plants, and fungi by controlling the developmental fate of groups of cells.

Front 27

embryonic lethals

Back 27

A mutation with a phenotype leading to death of an embryo or larva.

Front 28

maternal effect gene

Back 28

A gene that, when mutant in the mother, results in a mutant phenotype in the offspring, regardless of the offspring's genotype.

Front 29

egg-polarity genes

Back 29

A gene that helps control the orientation of the egg.

Front 30

bicoid

Back 30

A maternal effect gene that codes for a protein responsible for specifying the anterior end in Drosophila melanogaster.

Front 31

morphogens

Back 31

A substance, such as Bicoid protein in Drosophila, that provides positional information in the form of a concentration gradient along an embryonic axis.

Front 32

oncogenes

Back 32

A gene found in viral or cellular genomes that is involved in triggering molecular events that can lead to cancer.

Front 33

proto-oncogenes

Back 33

A normal cellular gene that has the potential to become an oncogene.

Front 34

tumor-suppressor genes

Back 34

A gene whose protein product inhibits cell division, thereby preventing the uncontrolled cell growth that contributes to cancer.

Front 35

p53 gene

Back 35

A tumor-suppressor gene that codes for a specific transcription factor that promotes the synthesis of proteins that inhibit the cell cycle.