Chapter 3, Section B Key Terms - Genetics

Question 1

Gene

Answer 1

A sequence of DNA nucleotides containing the information that specifies the amino acid sequence of a single polypeptide chain.

Question 2

Genome

Answer 2

The total genetic information coded in the DNA of a typical cell in an organism. The human genome contains roughly 30,000 to 40,000 genes.

Question 3

Histones

Answer 3

A class of proteins that participate in the packaging of DNA within the nucleus; strands of DNA form coils around the histones.

Question 4

Nucleosomes

Answer 4

Nuclear complexes of several histones and their associated coils of DNA.

Question 5

Transcription

Answer 5

The process of transferring genetic information from DNA to RNA in the nucleus.

Question 6

Translation

Answer 6

The process that uses the coded information in RNA to assemble a protein in the cytoplasm.

Question 7

Stop Signals

Answer 7

Three-nucleotide sequence in mRNA that signifies the end of protein coding sequence.

Question 8

Messenger RNA (mRNA)

Answer 8

The class of RNA molecules that specifies the amino acid sequence of a protein and carries this message from DNA to the site of protein synthesis in the cytoplasm.

Question 9

RNA polymerase

Answer 9

Enzyme that forms RNA by joining together appropriate nucleotides after they have base-paired to DNA.

Question 10

Template strand

Answer 10

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Question 11

Promoter

Answer 11

Specific nucleotide sequence at beginning of gene that controls the initiation of gene transcription; determines which of the paired strands of DNA is transcribed into RNA.

Question 12

Codon

Answer 12

A three based sequence in RNA that specifies one amino acid.

Question 13

Exons

Answer 13

DNA gene region containing code words for a part of the amino acid sequence of a protein.

Question 14

Intron

Answer 14

Regions of noncoding nucleotides in a gene.

Question 15

Spliceosome

Answer 15

Protein and nuclear RNA complex that removes introns and links exons together during gene transcription.

Question 16

Ribosomal RNA (rRNA)

Answer 16

Type of RNA used in ribosome assembly; becomes part of ribosome.

Question 17

Transfer RNA (tRNA)

Answer 17

Type of RNA; different tRNAs combine with different amino acids and with codon on mRNA specific for that amino acid, thus arranging amino acids in sequence to form specific protein.

Question 18

Anticodon

Answer 18

Three nucleotide sequence of tRNA able to base pair with complementary codon in mRNA during protein synthesis.

Question 19

Initiation factors

Answer 19

A protein required for ribosomal assembly and the establishment of an initiation complex that allows new protein synthesis to begin.

Question 20

Transcription factors

Answer 20

Proteins that act as gene switches, interacting in a variety of ways to activate or repress the initiation process that takes place at the promoter region of a particular gene.

Question 21

Preinitiation complex

Answer 21

A group of transcription factors and accessory proteins that associate with promoter regions of specific genes; the complex is required for gene transcription to commence.

Question 22

Mutation

Answer 22

Any alteration in the nucleotide sequence that spells out a genetic message in DNA.

Question 23

Mutagens

Answer 23

Environmental factors that increase the rate of mutation

Question 24

Natural selection

Answer 24

Organisms that function less effectively are less likely to produce and pass on their genes.

Question 25

Ubiquitin

Answer 25

Small intracellular peptide that attaches to proteins and directs them to proteasomes.

Question 26

Proteasome

Answer 26

A complex of proteins capable of denaturing (unfolding) other proteins and assisting in protein degradation.

Question 27

Signal sequence

Answer 27

Initial portion of newly synthesized protein (if protein is destined for secretion).

Question 28

Primary RNA transcript

Answer 28

An RNA molecule transcribed from a gene before intron removal and splicing.