exam 3

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1

What is a gene?

segment o DNA that encodes a functional product, usually a protein

2

What is genome?

entire DNA sequence of an organism

3

What is chromosome?

structure containing DNA that physically carries hereditary information, chromosomes contain genes

4

What is genetics?

study of what genes are, how they carry information, how information is expressed and how genes are replicated

5

What is phenotype?

manifestation of genotype (what you can see and test for, what proteins are made and expressed)

6

What is genotype?

actual genes present, information that codes for characteristics

7

What is structure of DNA?

Sugar-phosphate backbone, nucleotides held together by weak hydrogen bonds

8

What does anti-parallel mean?

sugar-phosphate backbone of one strand is upside down relative to the backbone of the other stand

9

What nucleotides are in DNA, and which ones pair?

Adenosine, Thymine, Guanine, Cytosine
Adenosine pairs with Thymine
Guanine and Cytosine pair

10

What is function of DNA polymerase?

synthesizes DNA, proofreads and repairs DNA

11

What is function of ligase?

makes covalent bonds to join DNA strands, joins Okazaki fragments and new segments in excision repair

12

What is function o RNA polymerase?

copies RNA from a DNA template

13

What is function of helicase?

unwinds double-stranded DNA

14

Where does DNA synthesis take place in Eukaryotes and Prokaryotes?

In eukaryotes takes place in nucleus in prokaryote in the cytoplasm.

15

What is the replication fork?

where DNA unwinds

16

What is role of primer?

RNA primer initiates DNA synthesis

17

What does semiconservative mean?

One parent strand is constantly transferred on to daughter helix of DNA

18

What are the leading strand and the lagging strand in DNA replication?

Leading strand is synthesized continuously by DNA polymerase, lagging strand is synthesized discontinuously

19

What are Okazaki fragments and where does energy come from to join them?

segments of DNA synthesized discontinuously, ligase joins fragments, energy comes from hydrolysis of phosphate bonds

20

What is transcription?

DNA is transcribed to make mRNA. Begins when RNA polymerase binds to promoter sequence, proceeds in 5-3" direction, stops when it reaches terminator sequence

21

What is difference between DNA and RNA?

DNA is genetic material, directs protein synthesis, replicates itself before cell division, sugar is deoxyribose, double strand coiled into a double helix. RNA carries out genetic instructions for protein synthesis, sugar is ribose, single strand straight or folded

22

What is genetic code?

nucleotide triplets of DNA and RNA molecules that carry genetic information in living cells

23

What does degenerate mean?

more than one codon for one amino acid

24

How many nucleotides are needed for amino acid?

three

25

What is a start codon?

either of two codons, AUG or GUG, that signal initiation of translation and the fist amino acid in polypeptide chain

26

What is a stop codon?

any of three codons in a molecule of mRNA that don't code for an amino acid and signal termination of the synthesis of protein

27

What is most common amino acid start codon?

AUG, methionine

28

What are codons?

sequence of three nucleotides that together form a unit of genetic code in DNA or RNA molecule

29

What are anticodons?

sequence of three nucleotides forming a unit of genetic code in a transfer RNA molecule, corresponding to complimentary codon in mRNA

30

Where are codons found?

mRNA strands

31

Where are anticodons found?

found on tRNA

32

what is translation?

whole process by which the base sequence of a mRNA is used to order and to join amino acids in a protein

33

Where does translation take place Eukaryotes?

in ribosomes in nucleus

34

where does translation take place in prokaryote?

in cytoplasm

35

What does structure of prokaryote cell allow it to do regarding transcription and translation?

allows to occur at same time, lacks introns

36

Describe prokaryote ribosome

Large subunit with tRNA binding sites, and small subunits. first binding sit is P, second is A, they form polypeptide bond, move to E site

37

What is constitutive gene?

expressed at a fixed rate, needed all the time, used for major processes like glycolysis

38

what are operons?

linear sequences of DNA composed of a promoter sequence, followed by an operator gene, followed by one or more structural genes that act as blueprints for proteins, can be inducible (turned-on by substrate) or repressible (turned-off by a product)

39

What is promoter and operator?

where RNA polymerase binds, on/off switch

40

what is trp operon?

operon that promotes production of tryptophan when tryptophan isn't present in environment, represses gene trancription

41

what is lac operon?

lactose binds to repressor protein, allowing gene transcription

42

What does cAMP have to do with lac operon?

As concentration of glucose increases amount of cAMP decreases, as cAMP decreases amount complex decreases. Decrease in complex inactivates promoter, lac operon is turned off. positive control over the expression of lac operon

43

What is difference between DNA of eukaryotic and prokaryotic cells?

Prokaryotic DNA is circular and there is only one replication origin when replication starts. Eukaryotic DNA is linear, when replicated theres as many as 1000 replication origins

44

What is an intron?

segment of DNA or RNA molecule that doesn't code for proteins and interrupts the sequence of genes, not in prokaryotic DNA

45

What is exon?

segment of DNA or RNA molecule containing information coding for a protein or peptide sequence

46

what are snRNPs?

small nuclear ribonucleic particles are RNA-complexes that combine with unmodified pre-mRNA and various other proteins to form a spiceosomal

47

what is conjugation?

transfer of genetic material between bacterial cells by direct cell-to-cell contact or by a bridge-like connection between two cells

48

What is sex pili?

filament projector on surface of bacterium that are important in conjugation

49

What is recombinant DNA?

DNA that has been formed artificially by combining constituents from different organisms

50

What is mutation?

changing of structure of a gene resulting in variant form that may be transmitted to subsequent generations

51

What are two main kinds of mutations?

frame-shift and base substitution

52

what is missense mutation substitution?

creates codon for a different amino acid, may or may not affect function of protein

53

What is silent mutation?

base substitution may not change amino acid, common if substitution is in third nucleotide of codon

54

what is frame-shift mutation?

shifts reading frame for each amino acid, changes every amino acid after change

55

what is mutagen?

agent that causes mutations

56

what is carcinogen?

substance capable of causing cancer in living tissue

57

what are nucleoside analogs?

molecules that act like nucleosides in DNA synthesis, include antiviral products used to prevent viral replication in infected cells

58

what is thymine dimer?

pair of abnormally chemically bonded adjacent thymine bases in DNA, resulting from damage by UV irradiation

59

what does exonuclease do?

proofreads DNA

60

How does ionizing radiation affect DNA?

can cause mispairing and physical breaks in chromosomes

61

`What does auxotrophic mean?

auxotrophic mutant is mutant with differential nutrient requirements from parent strain

62

what is replica plating?

Sterile velvet is pressed on grown colonies on master plate, cells from each colony transferred from velvet to new plate, plates incubated, growth on plate compared

63

What is vertical and horizontal gene transfer?

Vertical-occurs during reproduction between generations of cells, horizontal-transfer of genes between cells of same generation

64

What is Ames test?

reversion test, allows knowledge of what gene is being mutated and know exactly what type of mutation is being reverted. begin with histidine-dependent bacteria, look for revertant ability to grow on histodine negative media

65

what is Griffiths experiment?

demonstrated genetic transformation using encapsulated an nonencapsulated bacteria, proved recombination of bacteria DNA

66

what are transposons?

sequences of DNA that can move around to different positions within a genome of a single cell, process called transposition

67

what is a plasmid?

genetic structure in a cell that can replicate independently of chromosomes

68

What is DNA transfer between f+ and f- cell?

when an F factor (plasmid) is transferred from a donor (f+) to a recipient (f-), the f- cell converts to f+ cell.

69

what is transduction?

process of transferring genetic material from one cell to another by plasmid or bacteriophage

70

what is R factor?

name for plasmid that codes for antibiotic resistance

71

what is transformation?

process by which the genetic makeup of a organism is altered by insertion of new gene into its genome

72

what are competent cells?

take up foreign DNA wanted to be included in cell