Biol1400 - Chapter 10

Front 1

What convinced Hershey and Chase that DNA, rather than protein, is the genetic material of phage T2

Back 1

Radioactively labeled phage DNA, but not labeled protein, entered the host cell during infection and directed the synthesis of new viruses

Front 2

Compare and contrast DNA and RNA polynucleotides

Back 2

Both are polymers of nucleotides consisting of a sugar, a nitrogenous base, and a phosphate. In RNA, the sugar is ribose, in DNA, its deoxyribose. Both RNA and DNA have the bases A,G, and C, but DNA has a T and RNA has a U.

Front 3

Along one strand of a double helix is the nucleotide sequence GGCATAGGT. What is the complementary sequence for the other DNA strand?

Back 3

CCGTATCCA

Front 4

How does complementary base pairing make possible the replication of DNA?

Back 4

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.

Front 5

What is the function of DNA polymerase in DNA replication?

Back 5

As free nucleotides base-pair to a parental DNA strand, the enzyme covalently bonds them to the 3' end of a growing daughter strand.

Front 6

What are the functions of transcription and translation?

Back 6

Transcription is the transfer of information from DNA to RNA. Translation is the use of the information in RNA to make a polypeptide.

Front 7

What is the minimum number of nucleotides necessary to code for 100 amino acids?

Back 7

300. (triplets so 100 x 3)

Front 8

Translate the RNA sequence CCAUUUACG into the corresponding amino acid sequence

Back 8

Pro - Phe - Thr

Front 9

How does RNA polymerase recognize the start and end of the gene?

Back 9

Special DNA sequences mark the start (promoter) and end (terminator) of a gene.

Front 10

Explain why most eukaryotic genes are longer than the mRNA that leaves the nucleus

Back 10

These genes have introns, noncoding sequences of nucleotides that are spliced out of the initial RNA transcript to produce mRNA.

Front 11

What is an anticodon, and what is its function

Back 11

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.

Front 12

How does a ribosome facilitate protein synthesis?

Back 12

A ribosome holds mRNA and tRNA together and connects amino acids from the tRNAs to the growing polypeptide chain.

Front 13

What would happen if a genetic mutation in a gene changed a start codon to some other codon?

Back 13

The messenger RNA transcribed from the mutated gene would be nonfunctional because ribosomes could not initiate translation correctly.

Front 14

What would happen if a codon in the middle of an mRNA mutated from UUA to UAA?

Back 14

Translation would stop prematurely, because a stop codon was introduced.

Front 15

Which of the following molecules or structures does not participate directly in translation: ribosomes, transfer RNA, messenger RNA, DNA?

Back 15

DNA (its really mRNA that is getting the info from DNA)

Front 16

How could a single nucleotide substitution result in a shortened protein product?

Back 16

A substitution that changed an amino acid codon into a stop codon would produce a prematurely terminated polypeptide.

Front 17

Describe one way a virus can perpetuate its genes without destroying the host cell. What is this type of replication cycle called?

Back 17

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 the lysogenic cycle.

Front 18

Explain how some viruses replicate without having DNA

Back 18

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.

Front 19

Why doesn't a flu shot one year gives us immunity to flu in subsequent years?

Back 19

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.

Front 20

Why is HIV reverse transcriptase a good target for anti-AIDs drug therapy?

Back 20

Reverse transcriptase is unique to HIV; we do not normally copy genetic information from RNA to DNA, so disabling reverse transcription would not affect a human.

Front 21

What makes prions different from all other known infectious agents?

Back 21

Prions are proteins and have no nucleic acid.

Front 22

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"

Back 22

transduction, transformation, conjugation

Front 23

Plasmids are useful tools for genetic engineering. Can you guess why?

Back 23

Scientists can take advantage of the ability of plasmids to carry foreign genes to replicate, and to be inherited by progeny cells.

Front 24

Define nucleotide

Back 24

A building block of nucleic acids, consisting of a five carbon sugar covalently bonded to a nitrogenous base and one ore more phophate groups.

Front 25

Define molecular biology

Back 25

The study of biological structures functions and heredity at the molecular level.

Front 26

Define messenger RNA (mRNA)

Back 26

The type of ribonucleic acid that encodes genetic information from DNA and conveys it to ribosomes, where the information is translated into amino acid sequences.

Front 27

Define P site and A site on ribosomes

Back 27

P Site - One of two of a ribosomes binding sites for tRNA during translation. The P site holds the tRNA carrying the growing polypeptide chain (P stands for peptidyl tRNA)

A site - one of two of ribosomes binding sites for tRNA during translation. The A site holds the tRNA that carries the next amino acid in the polypetid chain (A stands for aminoactyl tRNA)

Front 28

Define anticodon

Back 28

On a tRNA molecule, a specific sequence of three nucleotides that is complementary to a codon triplet on mRNA

Front 29

Define frameshift mutation

Back 29

A change in the genetic material that involves the insertion or deletion of one ore more nucleotides in a gene, resulting in a change in the triplet grouping of nucleotides.

Front 30

Define silent mutation

Back 30

A mutation in a gene that changes a codon to one that codes for the same amino acid as the original codon.

Front 31

Define polynucleotide

Back 31

A polymer made up of many nucleotide monomers covalently bonded together

Front 32

Define transfer RNA (tRNA)

Back 32

A type of ribonucleic acid that functions as teh interpreter in translation. Each tRNA molecule has a specific anticodon, picks up a specific amino acid, and conveys the amino acid to the appropraite codon on mRNA

Front 33

Contrast lytic cycle vs lysogenic cycle

Back 33

Lytic cycle - A type of viral replication cycle resulting in the release of new viruses by lysis of the host cell

lysogenic cycle - a type of bacteriophage replication cycle in which the viral genome is incorporate into the bacterial host chromosome as a prophage. New phages are not produced, and the host cell is not killed or lysed unless the viral genome leaves the host chromosome.

Front 34

Define f factor

Back 34

A piece of DNA that can exist as a bacterial plasmid. The F factor carries genes for making sex pili and other structures needed for conjugation, as well as a site where DNA replication can start. F stands for fertility.

Front 35

Define ribosomal RNA (rRNA)

Back 35

The type of ribonucleic acid that together with proteins, makes up ribosomes, the most abundant type of RNA in most cells.

Front 36

Define transformation

Back 36

The incorporation of new genes into a cell from DNA that the cell takes up from the surrounding environment.

Front 37

Define reverse transcription

Back 37

An enzyme encoded and used by retroviruses that catalyzes the synthesis of DNA on an RNA template

Front 38

Define transduction

Back 38

1. The transfer of bacterial genes from one bacterial cell to another phage.

Front 39

Define transcription

Back 39

The synthesis of RNA on a DNA tempalte

Front 40

Define viroid

Back 40

A plant pathogen composed of molecules of naked, circulur RNA several hundred nucleotides long

Front 41

Define capsid

Back 41

The protein shell that encloses a viral genome

Front 42

Define conjugation

Back 42

The union (mating) of two bacterial cells or protist cells and the transfer of DNA between teh two cells.

Front 43

Define prion

Back 43

An infectious form of protein that may multiply by converting related proteins to more prions. Prions cause several related diseases in different animals, including scrapie in sheep and mad cow disease

Front 44

Define bacteriophage or phage

Back 44

A virus that infects bacteria

Front 45

Define plasmid

Back 45

A small ring of independently replicating DNA separate from the main chromosomes. Plasmids are found in prokaryotes and yeasts

Front 46

What are the 3 stop codons?

Back 46

UAG, UAA, UGA

Front 47

What is the start codon

Back 47

AUG

Front 48

Define translation

Back 48

The synthesis of a polypeptide using the genetic information encoded in an mRNA molecule. There is a change of language from nucleotides to amino acids

Front 49

Define sugar phosphate backbone

Back 49

IN a polynucleotide (DNA or RNA) the altnerating chain of sugar and phosphate to which nitrogenous bases are attached.

Front 50

Define retrovirus

Back 50

An RNA virus that reproduces by means of a DNA molecule. IT reverse-transcribes its RNA into DNA, inserts the DNA into a cellular chromosome, and then transcribes more copies of the RNA from the viral DNA. HIV and a number of cancer-causing viruses are retroviruses

Front 51

Define prophage

Back 51

Phage DNA that has inserted by genetic recombination into the DNA of a bacterial chromosome

Front 52

Define terminator

Back 52

A special sequence of nucleotides in DNA that marks the end of a gene. It signals RNA polymerase to release the newly made RNA molecule and then to depart from the gene.

Front 53

Define DNA polymerase

Back 53

A large molecular complex that assembles DNA nucleotides into polynucleotides using a preexisting strand of DNA as a tempalte

Front 54

Define DNA ligase

Back 54

An enzyme, essential for DNA replication, that catalyzes the covalent bonding of adjacent DNA polynucleotide strands. DNA ligase is used in genetic engineering to paste a specific piece of DNA containing a gene of interest into a bacterial plasmid or other vector

Front 55

Define RNA polymerase

Back 55

A large molecular complex that links together the growing chain of RNA nucleotides during transcription, using a DNA strand as a tempalte

Front 56

Define R plasmid

Back 56

A bacterial plasmid that carries genes for enzymes that destroy particular antibiotics, thus making the bacterium resistant to the antibiotics

Front 57

Define the semiconservative model

Back 57

Type of DNA replication in which the replicated double helix consists of one old strand, derived from the old molecule and one newly made strand

Front 58

Define virus

Back 58

A microscopic particle capable of infecting cells of living organisms and inserting its genetic material. Viruses are generally not considered to be alive because they do not display all the characteristics associated with life.

Front 59

Define nonsense mutation

Back 59

A change in the nucleotide sequence of a gene that converts an amino-acid encoding codon to a STOP codon. A nonsense mutation results in a shorted polypeptide

Front 60

Define missense mutation

Back 60

A change in the nucleotide sequence of a gene that alters the amino acid sequence of the resulting poplypetid. In a missesnse mutation, a codon is changed from encoding one amino acid to encoding a different amino acid.

Front 61

Define codon

Back 61

A 3 nucleotide sequence in mRNA that specifies a particular amino acid or polypeptide termination signal; the basic unit of the genetic code.

Front 62

Define genetic code

Back 62

The set of rules that dictates the amino acid translation of each mRNA nucleotide triplet

Front 63

Define mutation

Back 63

A change in the genetic information of a cell; the ultimate source of genetic diversity. A mutation also can occur in the DNA or RNA of a virus.