Chapter 10
Mutation
Any change in the nucleotide sequence of a cells DNA, involving large regions of a chromosome or just a single nucleotide pair, as in Sickle-Cell Disease.
R Plasmids
Carry genes for enzymes that destroys antibiotics.
Prions
Causes a number of degenerative brain diseases in various animal species.
Nonsense Mutations
Change an amino acid codon into a stop codon.
Missense Mutation
Changes one amino acid to another one.
Which of the following correctly ranks the structures in order of size, from largest to smallest?
Chromosome-gene-codon-nucleotide.
Messenger RNA (mRNA)
Conveys genetic messages from DNA to the translation machinery of the cell.
Silent Mutation
If a mutation causes an mRNA codon to change from GAA to GAG, no change in the protein product would result because GAA and GAG both code for the same amino acid.
Triplet Code
The flow of information from gene to protein.
Codons
The genetic instructions for the amino acid sequence of a polypeptide chain are written in DNA and RNA as a series of nonoverlapping three base "words".
Explain how some viruses replicate without having DNA.
The genetic material of these viruses is RNA, which is replicated inside the host cell by special enzymes encoded by the virus. The viral genome (or its complement) serves as mRNA for the synthesis of viral proteins.
P Site
Holds the growing polypeptide.
RIBOSOMES use amino-acid bearing molecules called?
tRNA.
A Phage Replication Cycle
1.) A Phage attaches itself to a bacterial cell. 2.) The phage injects its DNA into the bacterium. 3.) The Phage DNA directs the host cell to make more phage DNA and proteins; new phages assemble. 4.) The cell lyses and releases the new phages.
What is the minimum number of nucleotides necessary to code for 100 amino acids?
300.
Polynucleotide
A nucleotide polymer chain.
Ribosomal RNA (rRNA)
A ribosome consists of two subunits, a large subunit and a small subunit, each made up of proteins and a kind of RNA.
How does a ribosome facilitate protein synthesis?
A ribosome holds mRNA and tRNA's together and connects amino acids from the tRNA's to the growing polypeptide chain.
Anticodon
A single stranded loop at one end of the folded molecule contains a special triplet of bases.
Plasmid
A small circular DNA molecule separate from the bacterial chromosome.
How could a single nucleotide substitution result in a shortened protein product?
A substitution that changed an amino acid codon into a stop codon would produce a prematurely terminated polypeptide.
What is T2?
A virus that infects the bacterium E. Coli.
PROTEIN are one or more polymers made from monomers called?
Amino Acids.
What is the function of DNA polymerase in DNA replication?
As free nucleotides base-pair to a parental DNA strand, the enzyme covalently bonds them to the 3 end of a growing daughter strand.
Compare and contrast DNA and RNA polynucleotides.
Both are polymers of nucleotides consisting of a sugar, a nitrogenous base, and a phosphate. In RNA, the sugar is ribose; in DNA, it is deoxyribose. Both RNA and DNA have the bases A, G, and C, but DNA has a T and RNA has a U.
Nucleotides
DNA and RNA are nucleic acids, consisting of long chains (polymers) of chemical units (monomers).
DNA (Deoxyribonucleic Acid)
DNA's location in the nuclei of eukaryotic cells.
Which of the following molecules or structures does not participate directly in translation: ribosomes, transfer RNA, messenger RNA, DNA?
DNA.
Adenine(A) and Guanine(G)
Double ring structures called purines.
The nucleotide sequence of a DNA codon is GTA. A messenger RNA molecule with a complementary codon is transcribed from the DNA. In the process of protein synthesis, a transfer RNA pairs with the mRNA codon. What is the nucleotide sequence of the tRNA anticodon?
GUA.
Semiconseruative Model
Half of the parental molecule is maintained in each daughter molecule.
Virus
Infectious particle.
Why dosent a flu shot one year give us immunity to the flu in subsequent years?
Influenza viruses evolve rapidly by frequent mutation; thus, the strains that infect us later will most likely be different from the ones to which we've been vaccinated.
What is a anticodon, and what is its function?
It is the base triplet of a tRNA molecule that couples the tRNA to a complementary codon in the mRNA. THis is a key step in translating mRNA to polypeptide.
DNA Ligase
Links the pieces together into a single DNA strand.
Lytic Cycle
Lysis (breaking open) of the host cell and the release of the viruses that were produced within the cell.
Introns
Most genes of plants and animals include internal noncoding regions (intervening sequences).
Mutagens
Mutations caused by physical or chemical agents like high energy radiation.
Frameshift Mutations
Mutations involving the insertion or deletion of one or more nucleotides in a gene.
Capsid
Nucleic acid wrapped in a protein coat.
Promoter
Nucleotide sequence acts as a binding site for RNA Polymerase and determines where transcription starts and on which strand.
DNA is a polymer made from monomers called?
Nucleotides
What makes prions different form all other known infectious agents?
Prions are proteins and have no nucleic acid.
TRANSCRIPTION is performed by an enzyme called?
RNA Polymerase
Terminator
RNA Polymerase adds RNA nucleotides until it reaches a sequence of DNA bases, which signals the end of the gene.
Uracil(U)
RNA has a nitrogenous base.
Viroids
Small circular RNA molecules that infect plants.
Retrovirus
RNA virus that reproduces by means of a DNA molecule.
Stop Codon
Reaches the ribosomes A Site.
Why is HIV reverse transcriptase a good target for anti-AIDS drug therapy?
Reverse transcriptase is unique to HIV; we do not normally copy genetic information from RNA to DNA, so disabling reverse transcriptase would not affect a human.
TRANSLATION is performed by structures called?
Ribosomes.
rRNA molecules are components of?
Ribosomes.
Plasmids are useful tools for genetic engineering. Can you guess why?
Scientists can take advantage of the ability of plasmids to carry foreign genes, to replicate, and to be inherited by progeny cells.
Thymine(T) and Cytosine(C)
Single ring structures called pyrimidines.
Describe one way a virus can perpetuate its genes without destroying its host cell. What is this type of replication cycle called?
Some viruses can insert their DNA into a chromosome of the host cell, which replicates the viral genes when it replicates its own DNA prior to cell division. This is called they lysogenic cycle.
How does RNA polymerase recognize the start and end of the gene?
Special DNA sequences make the start (promoter) and end (terminator) of a gene.
Mutagenesis
Spontaneous mutations result from errors during DNA replication or recombination.
Ribosomes
Structures in the cytoplasm that coordinate the functioning of mRNA and tRNA and catalyze the synthesis of polypeptides.
A geneticist found that a particular mutation had no effect on the polypeptide encoded by a gene. This mutation probably involved?
Substitution of one nucleotide.
Emerging Viruses
Sudden viruses in a community.
AIDS (Acquired Immunodeficiency Syndrome)
The "aftermath" of HIV.
F Factor
The ability of a donor E Coli cell to carry out conjugation is usually due to a specific piece of DNA.
Genetic Code
The amino acid translations of each of the nucleotide triplets.
Exons
The coding regions, parts of the gene that are expressed.
RNA Splicing
The cutting and pasting process of DNA sequence.
RNA Polymerase
The enzyme moves along the gene, forming a new RNA strand by following the base pairing rules.
DNA Polymerases
The enzymes that link DNA nucleotides to a growing daughter strand.
What would happen if a genetic mutation in a gene changed a start codon to some other codon?
The messenger RNA transcribed from the mutated gene would be nonfunctional because ribosomes could not initiate translation correctly.
Sugar Phosphate Backbone
The nucleotides are joined to one another by covalent bonds between the sugar of one nucleotide and the phosphate of the next, which forms a repeating pattern of Sugar-Phosphate-Sugar-Phosphate.
Prophage
The phage DNA, most of its genes are inactive.
Conjugation
The physical union of two bacterial cells and the DNA transfer between them.
Scientists have discovered how to put together a bacteriophage with the protein coat of phage T2 and the DNA of phage lambda. If this composite phage were allowed to infect a bacterium, the phages produced in the host cell would have ________.
The protein and DNA of lambda.
Molecular Biology
The study of heredity at the molecular level.
Reverse Transcriptase
The synthesis of DNA on an RNA template.
Transcription
The synthesis of RNA under the direction of DNA.
Translation
The synthesis of protein under the direction of RNA.
Transduction
The transfer of bacterial genes by a phage.
Transformation
The uptake of foreign DNA from the surrounding environment.
HIV (Human Immunodeficiency Virus)
The virus that becomes AIDS.
Explain why most eukaryotic genes are longer than the mRNA that leaves the nucleus.
These genes have introns, noncoding sequences of nucleotides that are spliced out of the initial RNA transcript to produce mRNA.
The Nitrogenous bases of DNA
Thymine(T), Cytosine(C), Adenine(A), and Guanine(G).
Transfer RNA (tRNA)
To convert the three letter "words" of nucleic acids (Codons) to the amino acid "words" of proteins, a cell uses a molecular interpreter.
What are the functions of transcription and translation?
Transcription is the transfer of information from DNA to RNA. Translation is the use of the information in RNA to make a polypeptide.
The three modes of gene transfer between bacteria are _______, which is transfer via a virus;_______, which is the uptake of DNA from the surrounding environment; and _________, which is bacterial "mating".
Transduction, Transformation, Conjugation.
What would happen if a codon I the middle of an mRNA mutated form UUA to UAA?
Translation would stop permanently, because a stop codon was introduced.
Double Helix
Two polynucleotide strand.
Lysogenic Cycle
Viral DNA replication occurs without destroying the host cell.
Bacteriophages (or Phages)
Viruses that exclusively infect bacteria.
How does complementary base pairing make possible the replication of DNA?
When the two strands of the double helix separate, free nucleotides can base-pair along each strand, leading to the synthesis of new complementary strands.
Start Codon
Where translation is to begin on the mRNA molecule.
RNA comes in three kinds called?
mRNA, rRNA, and tRNA.
A Site
tRNA binding site.