AP Bio Midterm Key Terms Ch. 19

Question 1

activator

Answer 1

A protein that binds to DNA and stimulates transcription of a specific gene.

Question 2

alternative RNA splicing

Answer 2

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

Question 3

cell differentiation

Answer 3

The structural and functional divergence of cells as they become specialized during a multicellular organism’s development; dependent on the control of gene expression.

Question 4

chromatin

Answer 4

The complex of DNA and proteins that makes up a eukaryotic chromosome. When the cell is not dividing, chromatin exists as a mass of very long, thin fibers that are not visible with a light microscope.

Question 5

control element

Answer 5

A segment of noncoding DNA that helps regulate transcription of a gene by binding proteins called transcription factors.

Question 6

differential gene expression

Answer 6

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

Question 7

enhancer

Answer 7

A DNA segment containing multiple control elements that may be located far away from the gene it regulates.

Question 8

epigenetic inheritance

Answer 8

Inheritance of traits transmitted by mechanisms not directly involving the nucleotide sequence.

Question 9

euchromatin

Answer 9

The more open, unraveled form of eukaryotic chromatin that is available for transcription.

Question 10

genomic imprinting

Answer 10

Phenomenon in which expression of an allele in offspring depends on whether the allele is inherited from the male or female parent.

Question 11

heterochromatin

Answer 11

Nontranscribed eukaryotic chromatin that is so highly compacted that it is visible with a light microscope during interphase.

Question 12

histone

Answer 12

A small protein with a high proportion of positively charged amino acids that binds to the negatively charged DNA and plays a key role in its chromatin structure.

Question 13

histone acetylation

Answer 13

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

Question 14

micro-RNA (miRNA)

Answer 14

A small, single-stranded RNA molecule that binds to a complementary sequence in mRNA molecules and directs associated proteins to degrade or prevent translation of the target mRNA.

Question 15

multigene family

Answer 15

A collection of genes with similar or identical sequences, presumably of common origin.

Question 16

nucleosome

Answer 16

The basic, bead-like unit of DNA packaging in eukaryotes, consisting of a segment of DNA wound around a protein core composed of two copies of each of four types of histone.

Question 17

oncogene

Answer 17

A gene found in viruses or as part of the normal genome that is involved in triggering cancerous characteristics.

Question 18

p53 gene

Answer 18

The guardian angel of the genome, a gene that is expressed when a cell’s DNA is damaged. Its product, p53 protein, functions as a transcription factor for several genes.

Question 19

proteasome

Answer 19

A giant protein complex that recognizes and destroys proteins tagged for elimination by the small protein ubiquitin.

Question 20

proto-oncogene

Answer 20

A normal cellular gene corresponding to an oncogene; a gene with a potential to cause cancer but that requires some alteration to become an oncogene.

Question 21

pseudogene

Answer 21

A DNA segment very similar to a real gene but which does not yield a functional product; a gene that has become inactivated in a particular species because of mutation.

Question 22

Ras gene

Answer 22

A gene that codes for Ras protein, a G protein that relays a growth signal from a growth factor receptor on the plasma membrane to a cascade of protein kinases that ultimately results in the stimulation of the cell cycle. Many ras oncogenes have a point mutation that leads to a hyperactive version of the Ras protein that can lead to excessive cell division.

Question 23

repetitive DNA

Answer 23

Nucleotide sequences, usually noncoding, that are present in many copies in a eukaryotic genome. The repeated units may be short and arranged tandemly (in series) or long and dispersed in the genome.

Question 24

repressor

Answer 24

A protein that suppresses the transcription of a gene.

Question 25

retrotransposon

Answer 25

A transposable element that moves within a genome by means of an RNA intermediate, a transcript of the retrotransposon DNA.

Question 26

RNA interference (RNAi)

Answer 26

A technique to silence the expression of selected genes in nonmammalian organisms. The method uses synthetic double-stranded RNA molecules matching the sequence of a particular gene to trigger the breakdown of the gene’s messenger RNA.

Question 27

transcription factor

Answer 27

A regulatory protein that binds to DNA and stimulates transcription of specific genes.

Question 28

transposon

Answer 28

A transposable genetic element that moves within a genome by means of a DNA intermediate.

Question 29

tumor-suppressor gene

Answer 29

A gene whose protein products inhibit cell division, thereby preventing uncontrolled cell growth (cancer).