BIO 102 CHAPTER 7 - OLE MISSS
Messenger RNA carries information that specifies the amino acid sequence of a
protein.
A substitution mutation is said to be ______ if the mutated gene encodes the same protein as the original gene version.
silent
what agents or processes can cause mutations?
some forms of radiation errors in DNA replication chemical mutagens
How does a fever help fight a viral infection?
speeds immune responses
Sometimes a substitution mutation changes a base triplet into a ______ codon, such as UAA or UGA, which shortens the protein product.
stop
When the ribosome reaches a UGA, UAG, or UAA codon on the mRNA, it halts because none of these codons has a corresponding tRNA. These three sequences are called _____ codons.
stop
What role does DNA play in the cell?
store instructions for making proteins
Sickle cell disease results from a(n) ______ mutation in which a single codon is changed and specifies a different amino acid.
substitution
The replacement of one DNA base with another is called a(n)...
substitution mutation.
The first virus ever discovered was ______, a virus that infects over 120 plant species.
tobacco mosaic virus
In a process called ______, an RNA copy of a gene sequence on the DNA molecule is made.
transcription
The DNA strand that is "read" during transcription is called the _________ strand.
template
Vaccines work by causing
the immune system to recognize molecular components of the virus without the person having the disease.
A latent viral infection is one in which
the viral genetic information remains inside the cell but does not cause disease symptoms.
The instructions in ______ encode the information that a cell needs to produce proteins, which are vital to living things.
DNA
______ in DNA may arise spontaneously as errors in replication, or they can be induced by chemicals called mutagens.
Mutations
what is true regarding mutations?
Mutations are alterations in DNA sequences. Mutations can occur in a promoter region.
what of the following are true with respect to mutations?
Mutations provide the raw material for evolution. Some mutations can increase an organism's reproductive success. Some mutations produce detrimental alleles. Mutations can cause drug resistance in bacteria.
what are bases that can be present in DNA nucleotides?
adenine guanine cytosine thymine
At the beginning of a viral infection, a viruses attaches to a host cell by
adhering to a receptor molecule on the cell's surface.
Stabilization of a protein or the alteration of its structure are examples of controlling gene expression
after translation
Mutations are important to evolutionary change because they create new ______, which are alternate versions of genes.
alleles
Gene expression is the production of
an RNA molecule or protein.
During transcription, a gene's DNA sequence is transcribed into a
complementary RNA molecule.
what are true about chromosomes?
contain DNA and proteins can be tightly coiled contain DNA with no known function
What symptom of influenza infection is due to dead and damaged host cells in the airway?
cough and sore throat
A_________is any external agent, such as X-rays or chemicals, that induces mutations.
mutagen
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
A change in a gene sequence or a regulatory DNA sequence is called a(n) ______.
mutation
A___________ is a change in a cell's DNA sequence.
mutation
The high ______ rate of flu viruses makes it difficult to produce influenza vaccines that are effective against all strains.
mutation
The DNA double helix is made up of two strands of ______ monomers oriented in opposite directions
nucleotide
Subunits called ______ are the building blocks of DNA.
nucleotides
what are following that are present in a bacterial operon?
promoter operator group of genes
The start codon AUG of translation corresponds to ______.
methionine
What disease results when HIV causes such an immense loss of T cells that the body's immune system is defenseless against infections and cancer?
AIDS
During translation initiation, the first codon to specify a particular amino acid is usually ______, which encodes the amino acid ______.
AUG; methionine
During transcription, the template strand of ______ contains the nucleotide sequence that is transcribed into RNA.
DNA
What type of mutation is most likely to alter many amino acids in a protein?
Frameshift mutation
What virus is responsible for the disease AIDS?
HIV
what are the reasons that gene regulation is advantageous in multicellular eukaryotic organisms?
It saves energy. Not all cells need all proteins encoded in the genome.
During transcription, what reads the template strand within a gene and adds complementary bases?
RNA polymerase
The modern definition of gene is any sequence of DNA that is transcribed into
RNA.
What structure is the site of protein synthesis (translation)?
Ribosome
What contains about 6.4 billion base pairs and about 20,000 genes?
The human genome
Cancer can be caused by a latent virus because
The latent virus is signaling the host cell to continue to divide
what are true about the termination stage of translation?
The polypeptide is released. The large and small ribosomal subunits separate. A release factor protein prompts the release of the last tRNA from the ribosome.
what is true about viral infection of a host cell?
Viral penetration into a host cell may not cause immediate death of the host cell.
what are methods of gene regulation found in eukaryotes but not prokaryotes?
blocking mRNA exit from the nucleus adding methyl groups to silence genes splicing exons in alternative ways
what describes RNA?
can catalyze chemical reactions nucleotides contain the sugar ribose can be single-stranded the nitrogenous base uracil is used instead of thymine
what is true about the human immunodeficiency virus (HIV)?
can cause latent infections has an RNA genome contains the enzyme reverse transcriptase
Latent viruses, such as human papillomavirus and Epstein-Barr virus, can induce a cell division disorder called ______ because they are signaling the host cell to continue to divide.
cancer
After transcription in eukaryotes, a modified nucleotide called the ______ is added to one end of the mRNA molecule, and a string of 100 to 200 adenines called the ______ is added to the opposite end of the mRNA molecule.
cap; poly A tail
After a virus attaches to and penetrates a host cell, a virus can enter a phase where symptoms of the infection are delayed or it can...
cause immediate cell death.
DNA is coiled around proteins to form discrete packages called
chromosomes.
In an RNA molecule, a(n) ______ is a genetic "code word" that corresponds to one amino acid.
codon
A DNA molecule consists of two intertwining strands of nucleotides that form a
double helix
Transcription, translation, nucleotide synthesis, and modification of mRNA are all processes that require
energy
Some viruses have an outer lipid-rich ______ that surrounds the protein coat.
envelope
What are coding regions of eukaryotic mRNA that are translated?
exons
_____ are portions of mRNA that get spliced together to form mature mRNA before translation occurs in eukaryotes.
exons
True or false: Complementary base pairing rules state that in DNA, A pairs with G and T pairs with C.
false
In ______ mutations, nucleotides are added or deleted by a number other than a multiple of three, such that the reading frame of the gene is disrupted.
frameshift
A(n) ______ is a sequence of DNA nucleotides that codes for a specific protein or RNA molecule.
gene
The development of antiviral drugs is difficult due to the ______ of many viruses.
genetic variability
What human body system responds to viral infection by triggering fever and inflammation?
immune system
what of the following are diseases caused by viruses?
influenza chickenpox AIDS
A(n) ______is a portion of mRNA that is about 1,000 nucleotides long and that is removed before translation.
intron
What process describes the removal of portions of mRNA after transcription to produce mRNA consisting of regions to be translated?
intron removal and splicing together of exons
In archaea and eukaryotes, a part of an mRNA molecule that is removed before translation is called a(n)
intron.
In archaea and eukaryotes, a part of an mRNA molecule that is removed before translation is called a(na)
intron.
In eukaryotic cells, the mRNA is altered before it leaves the nucleus. After transcription, the ______ are removed from mRNA, and ______ are spliced together to form the mature mRNA.
introns; exons
what types of protein modification that can occur after translation to produce a functional protein.
joining with other polypeptides cutting of the protein by enzymes
An animal virus can cause a(n) ______ viral infection, in which disease symptoms are not produced immediately, but the viral information remains inside the cell.
latent
what are features that viruses have?
lipid-rich envelope enzymes
The outer envelope present in some viruses, such as the influenza virus and the human immunodeficiency virus (HIV), is composed of ______, which may be derived from the host cell's membrane.
lipids and proteins
A codon consists of three ______ that correspond to one ______.
mRNA bases; amino acid
During the elongation stage of translation, the ribosome exposes codons on the ______ one at a time; each codon determines what ______ will bring its attached amino acid to the ribosome to be added to the polypeptide chain.
mRNA; tRNA
What describes a substitution mutation?
one DNA base is replaced with another
In bacteria, a(n) ______ is a group of genes under control of a single promoter.
operon
Tobacco mosaic virus (TMV) infects many species of
plants
RNA ______ is the enzyme that builds the RNA chain during transcription.
polymerase
Some proteins are composed of multiple ______ that join together after translation.
polypeptides
what are the following that are ways to control gene expression after translation?
preventing a protein from reaching its correct destination block modifications or alterations to proteins degrading proteins
In the "central dogma," information flows from DNA to RNA to ____
proteins
What is produced during translation?
proteins
What type of RNA combines with proteins to form a ribosome?
rRNA
what can be components of RNA nucleotides?
ribose adenine guanine uracil
A(n) is composed of rRNA and proteins and is the site of protein synthesis.
ribosome
In eukaryotes, the cap and poly A tail on the mature mRNA protect the mRNA and ensure that ______.
ribosomes attach to the correct end of the mRNA for translation
Only producing proteins that are needed allows a cell to
save energy
A mutation that causes an mRNA nucleotide to change from GGC to GGA is a ______ mutation.
silent
In a process called ______, an RNA molecule is used to produce a protein.
translation
True or false: Although mutations often cause changes that are harmful, they are also the source of genetic variation for evolution.
true
True or false: Gene regulation allows cells to produce only the proteins that they need.
true
Attachment, penetration, synthesis, assembly, and release are the stages of
viral replication
A small, infectious agent that is composed of genetic information inside of a protein coat is a called a
virus
A(n)________ is a noncellular, small, infectious agent that is simply genetic information enclosed in a protein coat.
virus
Although they do not have cell components such as cytoplasm or ribosomes, some ________ have enzymes and lipid-rich envelopes.
viruses
The common cold, rabies, warts, and many illnesses are caused by infectious, noncellular particles called ______.
viruses