Biology Chapter 11 Vocab

Question 1

Activator

Answer 1

A protein that switches on a gene or group of genes.

Question 2

Adult Stem Cell

Answer 2

A cell present in adult tissues that generates replacements
for nondividing differentiated cells. Adult stem cells are
capable of differentiating into multiple cell types, but they are not as
developmentally flexible as embryonic stem cells.

Question 3

Alternative RNA Splicing

Answer 3

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

Question 4

Barr Body

Answer 4

A dense body formed from a deactivated X chromosome

found in the nuclei of female mammalian cells.

Question 5

Differentiation

Answer 5

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 6

Embryonic Stem Cell

Answer 6

Cell in the early animal embryo that
differentiates during development to give rise to all the different
kinds of specialized cells in the body.

Question 7

Enhancer

Answer 7

A eukaryotic DNA sequence that helps stimulate the transcription
of a gene at some distance from it. An enhancer functions
by means of a transcription factor called an activator, which binds to
it and then to the rest of the transcription apparatus.

Question 8

Epigenetic Inheritance

Answer 8

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 9

Gene Expression

Answer 9

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

Question 10

Gene regulation

Answer 10

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

Question 11

Histone

Answer 11

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 12

Homeotic Gene

Answer 12

A master control gene that determines
the identity of a body structure of a developing organism, presumably
by controlling the developmental fate of groups of cells.

Question 13

Nucleosome

Answer 13

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 14

Operator

Answer 14

In prokaryotic DNA, a sequence of nucleotides near the start
of an operon to which an active repressor protein can attach. The
binding of a repressor prevents 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 turn all the genes
in an operon on or off as a single functional unit.

Question 15

Operon

Answer 15

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 16

Regulatory Gene

Answer 16

A gene that codes for a protein, such as a repressor,

that controls the transcription of another gene or group of genes.

Question 17

Repressor

Answer 17

A protein that blocks the transcription of a gene or operon.

Question 18

Reproductive Cloning

Answer 18

Using a somatic cell from a multicellular organism

to make one or more genetically identical individuals.

Question 19

Signal Transduction Pathway

Answer 19

In cell biology, a series of molecular
changes that converts a signal on a target cell’s surface to a specific
response inside the cell.

Question 20

Therapeutic Cloning

Answer 20

The cloning of human cells by nuclear transplantation
for therapeutic purposes, such as the generation of embryonic stem
cells. See also nuclear transplantation; reproductive cloning.

Question 21

Totipotent

Answer 21

Describing a cell that can give rise to all of

the different types of cells within an organism.

Question 22

Transcription Factor

Answer 22

In the eukaryotic cell, a protein that functions
in initiating or regulating transcription. Transcription factors bind to
DNA or to other proteins that bind to DNA.

Question 23

Tumor-Suppressor Gene

Answer 23

A gene whose product inhibits cell division,
thereby preventing uncontrolled cell growth. A mutation that deactivates
a tumor-suppressor gene may lead to cancer.