Chapter 10 (Molecular Biology Of The Gene)

Front 1

What is molecular biology?

Back 1

- study of the molecular basis of genes and gene expression
- molecular genetics

Front 2

What is bacteriphages?

Back 2

- virus that infects bacteria
- aka phage

Front 3

radioactively labeled phage DNA, but not labeled protein, entered the host cell during infection and directed the synthesis of new proteins.

Back 3

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

Front 4

What are nucleotides?

Back 4

building bloack of nucleic acids, consisting of a 5-carbon sugar covalently bonded to a nitragenous base and 1 or more phosphate groups

Front 5

What is polynucleotide?

Back 5

polymer made up of many nucleotide monomers covalently bonded together

Front 6

What is a sugar phosphate group?

Back 6

in a polynucleotide (DNA/RNA strand), alternating chain of sugar and phosphate to which nitragenous bases are attached.

Front 7

What is deoxyribonucleic acid?

Back 7

double-standed helical nucleic acid molecule consisting of nucleotide monomers with deoxyribose sugar and the nitrogenous bases adenine, cytosine, guanine, and thymine.

Front 8

What is thymine?

Back 8

- single ring nitrogenous base found in DNA
- aka pyrimidines

Front 9

What is cytosine?

Back 9

single-ring nitrogenous base found in DNA and RNA

Front 10

What is adenine?

Back 10

- double ring nitrogenous base found in DNA and RNA
- aka purine

Front 11

What is guanine?

Back 11

double ring nitrogenous base found in DNA & RNA

Front 12

What is uracil?

Back 12

single ring nitrogenous base found in RNA.

Front 13

- both are polymers of nucleotides consisting of a sugar, 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.

Back 13

What is the difference between DNA and RNA polynucleotides?

Front 14

What is double helix?

Back 14

form of native DNA, referring to its 2 adjacent polynucleotide strands interwound into a spiral shape

Front 15

What is a semiconservative model?

Back 15

type of DNA replication in which the replicated double helix consists of 1 old strand, derived from the old molecule, and 1 newly made strand

Front 16

when 2 strands of the double helix separate, free nucleotides can base-pair along each strand, leading to the synthesis of new complimentary strands.

Back 16

How does complimentary base pairing make possible the replication?

Front 17

What is DNA polymerase?

Back 17

lare molecular complex that assembles DNA nucleotides into polynucleotides using a preexisting strand of DNA as a template.

Front 18

What is DNA ligase?

Back 18

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

Front 19

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

Back 19

What is the function of DNA polymerase in DNA replication?

Front 20

What is transcription?

Back 20

synthesis of RNA on a DNA template

Front 21

What is translation?

Back 21

- synthesis of a polypeptide using the genetic info encoded in an mRNA molecule
- change of language from nucleotides to amino acids

Front 22

- transcription is the transfer of info from DNA to RNA
- translation is the use of the info in RNA to make a polypeptide

Back 22

What are the functions of transcription and translation?

Front 23

What is a triplet code?

Back 23

set of 3 nucleotide-long words that specify the amino acids for polypeptide chains

Front 24

What is a codon?

Back 24

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

Front 25

What is RNA polymerase?

Back 25

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

Front 26

What is a promoter?

Back 26

specific nucleotide sequence in DNA located near the start of a gene that is the binding site for RNA polymerase and the place where transcription begins

Front 27

What is a terminator?

Back 27

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

Front 28

What are introns?

Back 28

internal noncoding regions

Front 29

What are messenger RNA?

Back 29

type of RNA that encodes genetic info from DNA and conveys it to ribosomes, where the info is translated into amino acid sequences

Front 30

What are exons?

Back 30

parts of a gene that are expressed

Front 31

What is RNA splicing?

Back 31

- removal of introns and joining of exons in eukaryotic RNA, forming an mRNA molecule with a continuous coding sequence
- occurs before mRNA leaves the nucleus

Front 32

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

Back 32

Why are most Eukaryotic genes longer than mRNA that leaves the nucleus?

Front 33

What is transfer RNA?

Back 33

- type of ribonucleic acid that functions as an interpreter in translation
- each tRNA molecule has a specific anticodon, picks up a specific amino acid, and conveys the amino acid to the appropriate codon on mRNA.

Front 34

What is anticodon?

Back 34

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

Front 35

- base triplet of a tRNA molecule that couples the tRNA to a complementary codon in the mRNA
- key step in translating mRNA to polypeptide

Back 35

What is an anticodon, and what is their function?

Front 36

What are ribosomes?

Back 36

- cell structure consisting of RNA and protein organized into 2 subunits and functioned as the site of protein synthesis in the cytoplasm
- in eukaryotic cells, the ribosomal subunits are constructed in the nucleus

Front 37

What is ribosomal RNA?

Back 37

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

Front 38

ribosomes holds mRNA and tRNA together and connects amino acids from the tRNAs to the growing polypeptide chain

Back 38

How does a ribosome facilitate protein synthesis?

Front 39

What is start codon?

Back 39

on mRNA, specific 3 nucleotide sequence (AUG) to which an initiateor tRNA molecule binds starting translation of genetic information.

Front 40

What is a P site?

Back 40

- one of 2 of a ribosome's binding sites for tRNA during translation
- it holds the tRNA carrying the growing polypeptide chain

Front 41

What is an A site?

Back 41

- 1 of 2 of a ribosome's binding sites for tRNA during translation
- it holds the tRNA that carries the next amino acid in the polypeptide chain

Front 42

messegner RNA transcribed from the mutated gene would be nonfunctioning because ribosomes could not initiate translation correctly

Back 42

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

Front 43

What is the elongation process?

Back 43

1. Codon recgonition
2. peptide bond formation
3. translocation

Front 44

What is stop codon?

Back 44

- in mRNA, 1/3 tripltets ( UAG, UAA, UGA) that signal gene translation to stop.

Front 45

- in the A site, its mino acids receives the growing polypeptide from the tRNA that precedes it
- in the P site, it gives up the polypeptide to the tRNA that follows it.

Back 45

What happens as a tRNA passes throught he A&P binding sites on the ribosome?

Front 46

What is a mutation?

Back 46

- change in the nucleotide sequences of an organism's DNA
- ultimate source of genetic diversity
- can occur in the DNA or RNA of a virus

Front 47

What is a silent mutation?

Back 47

- mutation in a gene that changes a codon to one that encodes for the same amino acid as the original codon
- amino acid sequence of the resulting polypeptide is thus unchanged

Front 48

What is a missense mutation?

Back 48

- change in the nucleotide sequence of a gene that alters the amino acid sequence of the resulting polypeptide
- in this , a codon is change from encoding 1 amino acid to encoding a different amino acid

Front 49

What is nonsense mutation?

Back 49

- changein the nucleotide sequence of a gene that converts an amino acid encoding codon to a stop codon
- it results in shortened polypeptide

Front 50

What is a reading frame?

Back 50

way a cell's mRNA-translating machinery groups the mRNA nucleotides into codons

Front 51

What is a mutagenesis?

Back 51

creation of a change in the nucleotide sequence of an organism's DNA

Front 52

What is a mutagen?

Back 52

chemical or physical agent that interacts with DNA and or a mutation

Front 53

substitution that changes an amino acids codon into a stop codon would produce a prematurely terminated polypeptide

Back 53

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

Front 54

What is a virus?

Back 54

- microscopic particle capable of infecting cells of living organisms and inserting its genetic material
- generally not considered to be alive because they don't display all the characteristics of life

Front 55

What is a capsid?

Back 55

protein shell that encloses a viral genome

Front 56

What is lytic cycle?

Back 56

- type of viral replication cycle resulting in the release of new viruses by lysis (breaking open) of the host cell

Front 57

What is the lysogenic cycle?

Back 57

- type of bacteriophage replication cycle in which the viral genome is incorporatedinto the bacterial host chromosome as a prophage
- new phages aren't produced, and the host cell isn't killed or lysed unless the viral genome leaves the host chromosome

Front 58

What is prophage?

Back 58

phage DNA that has inserted by genetic recombination into the DNA of a bacterial chormosme

Front 59

- genetic material of these viruses is RNA, which is replicated inside the hsot cell by special enzymes encoded by the virus
- viral genome (or its compliment) serves as mRNA for the synthesis of viral proteins

Back 59

How do viruses replicate without having DNA?

Front 60

What are emerging viruses?

Back 60

viruses that has appeared suddenly or recently come to the attention of medical scientists

Front 61

What is AIDS?

Back 61

late stages of HIV infection, characterized by a decreasing number of T cells and the appearance of characteristic opportunistic infections

Front 62

What is HIV?

Back 62

retrovirus that attacks the human immune system and cause AIDS

Front 63

What is reverse transcriptase?

Back 63

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

Front 64

What is a retrovirus?

Back 64

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

Front 65

- it synthesizes DNA from its RNA genome
- reverse of the usual DNA to RNA into flow

Back 65

Why is HIV classified as a retrovirus?

Front 66

What are viroids?

Back 66

plant pahtogens composed of molecules of naked, circular DNA several hundred nucleotides long

Front 67

What are prions?

Back 67

- infecions form of protein that may multiply by converting related proteins to more of these
- they cause several related diseases in difference animals, including scrapie in sheep and mad cow disease

Front 68

prions are proteins and have no nucleic acid

Back 68

What makes prions different from all other known infections agents?

Front 69

What is transformation?

Back 69

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

Front 70

What is transduction?

Back 70

transfer of bacterial genes from 1 bacterial cell to another by a phage

Front 71

What is conjugation?

Back 71

union of 2 bacterial cells or protist cells and the transfer of DNA between the 2 cells

Front 72

What is a F factor?

Back 72

- piece of DNA that can exist as a bacterial plasmid
- it carries genes for making a sex pili and other structures needed for conjugation, as well as site where DNA replication can start
- fertility

Front 73

What are plasmids?

Back 73

- small ring of independtly replicating DNA separate from the main chromosomes
- found in prokaryotes and yeasts

Front 74

What are R plasmids?

Back 74

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

Front 75

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

Back 75

What would plasmids be useful tools for genetic engineering?