HUMANBIOLOGY_CHAPTERSEVEN

DNA (deoxyribonucleic acid)

genetic material consisting of a double helix of nucleotides, each containing the sugar deoxyribose

transcription

production of RNA using DNA as a template

translation

assembly of an amino acid chain according to the sequence of nucleotides in mRNA

RNA (ribonucleic acid)

nucleic acid typically consisting of a single strand of nucleotides, each containing the sugar ribose

promoter

a control sequence at the start of a gene; attracts RNA polymerase and (in eukaryotes) transcription factors

RNA polymerase

enzyme that uses a DNA template to produce a molecule of RNA

intron

portion of an mRNA molecule that is removed before translation

exon

portion of an mRNA that is translated after introns are removed

operon

group of related bacterial genes plus a promoter and operator that control the transcription of the entire group at once

transcription factor

in a eukaryotic cell, a protein that binds a gene’s promoter and regulates transcription

mutation

a change in a DNA sequence

substitution mutation

replacement of one nucleotide in a gene with another

mutagen

any external agent that causes a mutation

allele

one of two or more alternative forms of a gene

virus

infectious agent that consists of genetic information enclosed in a protein coat

protein coat

structural component that surrounds the genetic material of a virus

What role does DNA play in the cell?

store instructions for making proteins

In the "central dogma," information flows from DNA to RNA to ______.

proteins

The ______ is a sequence of DNA that signals the start of a gene and also which of the two strands of DNA is the template for transcription.

promoter

As RNA is synthesized in transcription, it can curl into a three-dimensional shape that is dictated by ______ within the molecule.

complementary base pairing

The instructions in ______ encode the information that a cell needs to produce proteins, which perform a variety of functions in living things, such as speeding up chemical reactions.

DNA

In archaea and eukaryotes, a part of an mRNA molecule that is removed before translation is called a(n)

intron

In the "central dogma," describing the flow of genetic information from DNA to protein, DNA is copied to RNA in a process called ______, and the information in RNA is used to direct the synthesis of a protein in a process called ______.

transcription; translation

At the beginning of transcription, RNA polymerase binds to the ______ on the DNA.

promoter

Transcription, translation, nucleotide synthesis, and modification of mRNA are all processes that require

energy.

In transcription, the genetic information in DNA is copied into a(n) ______ molecule, and in translation, the "message" in an mRNA molecule is translated into a(n) ______ sequence.

mRNA; amino acid

In bacteria, a(n) ______ is a group of genes under control of a single promoter.

operon

Tryptophan

Cysteine

STOP

Threonine

Encoded by 6 mRNA codons

Arginine

In eukaryotic cells, proteins called ______ factors bind at specific DNA sequences and form a pocket that allows RNA polymerase to initiate transcription.

transcription

During translation, the ribosome moves down the ______ one codon at a time, and ______ molecules bring amino acids to the ribosome in the order specified by the codons.

mRNA; tRNA

After translation is complete, the newly synthesized protein must ______, as determined by some regions of the amino acid chain.

fold into its functional shape

Only producing proteins that are needed allows a cell to

save energy.

The replacement of one DNA base with another is called a(n) _____.

substitution mutation

UV rays, X-rays, some chemicals found in tobacco, and radioactive fallout are all examples of ______, agents that can damage DNA and cause mutations.

mutagens

In eukaryotes, RNA polymerase cannot bind to the promoter and initiate transcription without the presence of regulatory proteins called

transcription factors.

A variant of a gene is referred to as a(n)

allele

A(n) _____ is a noncellular, small, infectious agent that is simply genetic information enclosed in a protein coat.

virus

All viruses contain genetic material, which is either RNA or ______, and a ______ coat that surrounds the genetic material.

DNA; protein

What describes a substitution mutation?

One DNA base is replaced with another.

A(n) _____ is any external agent, such as X-rays or chemicals, that induces mutations.

mutagen

Mutation provides the raw material for evolution because it can create new alleles, which are alternative forms of the same ______.

gene

Attachment, penetration, synthesis, assembly, and release are the stages of ______.

viral replication