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BIO110 > Chapter 10 > Flashcards

Chapter 10 Flashcards

Genetic Material

1
Q

bacteriophages

A

(phages) viruses that exclusively infect bacteria

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2
Q

bacteriophage replication steps:

A

1) phage attaches to a bacterial cell wall
2) phage injects own DNA into bacterial cell
3) phage DNA directs bacterial cell to make more phage DNA / protein; assemble new phages
4) cell lyses and new phages are released

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3
Q

monomer of DNA / RNA

A

nucleotides

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4
Q

polymer of nucleotides ?

A

DNA / RNA

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5
Q

polynucleotide

A

polymer of many nucleotide monomers covalently bonded together

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6
Q

DNA

A

double-stranded helical nucleic acid molecule

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7
Q

what makes up DNA ?

A
  • nitrogenous base (A / T & G / C)
  • phosphate group
  • deoxyribose sugar
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8
Q

what makes up RNA ?

A
  • nitrogenous base (A / U & G / C)
  • phosphate group
  • ribose sugar
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9
Q

pyrimidines

A

1 ring nitrogenous base
- T / C / U

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10
Q

purines

A

2 ring nitrogenous base
- A / G

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11
Q

nucleotide

A

building block of nucleic acids
- 1 phosphate group, 1 5C sugar, nitrogenous base

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12
Q

sugar-phosphate backbone

A

alternating chain of 5C sugar and phosphate group where nitrogenous base attaches to

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13
Q

how does the nitrogenous base connect to the phosphate-sugar backbone ?

A

bonding w/ the 5C sugar

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14
Q

double helix

A

DNA structure;
- two DNA strands interwound together in helical shape

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15
Q

how many hydrogen bonds hold together G / C ?

A

functional groups form 3 hydrogen bonds

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16
Q

how many hydrogen bonds hold together A / T ?

A

functional groups form 2 hydrogen bonds

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17
Q

orientation of the 2 DNA strands ?

A

antiparallel; one runs one way while other runs opposite way
5’ ——— 3’
3’ ——— 5’

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18
Q

5’ end of single DNA strand holds what ?

A

phosphate group

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19
Q

3’ end of single DNA strand holds what ?

A

OH

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20
Q

what model showed the helical structure of DNA ?

A

watson-crick model
- rosalind franklin contributed a lot

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21
Q

what main point does watson-crick model suggest ?

A

molecular explanation for genetic inheritance

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22
Q

complimentary DNA sequence of GGCATAGGT ?

A

CCGTATCCA

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23
Q

primary function of DNA ?

A

encode / store genetic info
- molecular basis of heredity

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24
Q

how does DNA strands replicate ?

A

original helix strands unravel and 2 new strands are made to wind with 2 original template strands
- new strands lay down coinciding base pairs to original template strands
- 1 helix becomes 2 helixes

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25
Q

semiconservative model

A

type of DNA replication in where new replicated helix consists of new strand one original template strand from original helix

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26
Q

how does complimentary base pairing make DNA replication possible ?

A

free nucleotides can form a new strand by bonding w/ their base pair along the original template strand
- synthesizes a new DNA strand

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27
Q

where does DNA replication start on the original DNA strand ?

A

sites called origins of replication
- short strands of specific nucleotide sequences

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28
Q

what direction does DNA replication go ?

A

goes out from either side of origin of replication
- forms replication bubble

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29
Q

why is there many origins of replication and in-turn, many replication bubbles in eukaryotic chromosomes ?

A

lessens time to fully replicate DNA strand

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30
Q

DNA polymerase

A

assembles DNA nucleotides using template DNA strand to form new DNA strand
- proofreads all nucleotides placed down; removes any base-paired incorrectly

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31
Q

what direction will DNA polymerase lay down nucleotides ?

A

5’ —> 3’
- can only lay down nucleotides on the 3’ end

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32
Q

how does DNA polymerase lay down nucleotides on DNA strand 3’ —> 5’ ?

A

lays down nucleotides in 5’ —> 3’ direction in sections
- okazaki fragments

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33
Q

strand that is synthesized by DNA polymerase leading in 5’ —> 3’ direction ?

A

leading strand
- continuous synthesize
- synthesize toward forking point

34
Q

strand that is synthesized by DNA polymerase leading in 3’ —> 5’ direction ?

A

lagging strand
- fragment synthesis
- synthesize out from forking point

35
Q

DNA ligase

A

enzyme that joins together okazaki fragments on lagging strand to make one continuous DNA strand

36
Q

how can DNA strands be harmed ?

A
  • ultraviolet light
  • x-rays
  • toxic chemicals (tobacco)
37
Q

how are DNA strands repaired ?

A

by DNA polymerase / ligase

38
Q

transcription

A

synthesis of DNA —> RNA
- in nucleus

39
Q

hows does transcription work ?

A

essentially just DNA replication using A/U
& G/C nucleotide pairs
- uses a single DNA strand from unraveled helix and makes 1 RNA strand

40
Q

initiation of transcription

A

RNA polymerase attaches to promoter and starts RNA synthesis

41
Q

elongation of transcription

A

RNA polymerase continues to elongate RNA strand using DNA template

42
Q

termination of transcription

A

RNA reaches terminator DNA
- RNA polymerase detaches from RNA strand

43
Q

translation

A

synthesis of RNA —> proteins
- in cytoplasm

44
Q

how does translation work?

A

3 RNA nucleotides make up a codon
- specific codon translates into specific amino acid

45
Q

codon

A

3 nucleotides sequence in mRNA
- basic unit of genetic code

46
Q

what is the minimum # of nucleotides to code for polypeptide 100 amino acids long ?

A

300 nucleotides

47
Q

genetic code

A

set of rules that dictate amino acid translation of each mRNA nucleotide triplet

48
Q

RNA polymerase

A

transcription enzyme;
- links together RNA nucleotides during transcription
- opens DNA helix and uses 1 strand as template

49
Q

promoter

A

binding site of RNA polymerase;
- where transcription begins
- specific nucleotide sequence in DNA

50
Q

terminator

A

signals RNA polymerase to release formed RNA strand and depart from gene
- special DNA sequence showing end of gene

51
Q

messenger RNA (mRNA)

A

type of RNA that encodes genetic info and conveys it to the ribosomes
- ribosomes translate info into amino acid sequence

52
Q

how is mRNA modified before leaving the nucleus in eukaryotic organisms ?

A
  • small cap of modified G nucleotides at 5’ end
  • large cap of (50-250) A nucleotides at 3’ end
    caps are NOT translated into proteins
53
Q

what is the point of modifying mRNA w/ caps at both 5’ / 3’ end before leaving the nucleus ?

A
  • facilitate export
  • protect from degradation
  • help ribosomes bind to mRNA strand
54
Q

introns

A

noncoding region of RNA from DNA that will not be translated into proteins
- removed from mRNA strand before leaving nucleus

55
Q

exons

A

part of a gene that will be expressed and translated into proteins
- exons will join together before leaving nucleus to form continuous mRNA strand

56
Q

RNA splicing

A

removal of introns and joining of exons before mRNA leaves nucleus
- forms continuous mRNA strand

57
Q

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

A

because of RNA splicing, intron portions are removed from strand while exons are kept

58
Q

transfer RNA (tRNA)

A

type of RNA
- pick up specific amino acid
- lay amino acid to specific codon on mRNA

59
Q

anticodon

A

on tRNA, 3 nucleotide sequence complimentary to codon tiplet on mRNA
- how amino acid knows where to lay amino acid
- opposite side of amino acid attachment side

60
Q

how are amino acids attached to tRNA ?

A

by a enzyme for each specific amino acid

61
Q

where does the formation for the amino acid polypeptide chain by tRNA in accordance to mRNA strand occur ?

A

in the ribosome

62
Q

ribosomes

A

cell structure of RNA and proteins
- site of protein synthesis
- 1 large subunit / 1 small subunit

63
Q

ribosomal RNA (rRNA)

A

type of RNA w/ proteins that make up ribosomes
- most abundant RNA in most cells

64
Q

where does mRNA bind on a ribosome ?

A

the small subunit

65
Q

where does tRNA bind on a ribosome

A

the large subunit
- P / A site

66
Q

how does a ribosome facilitate protein synthesis ?

A

ribosome holds together mRNA / tRNA together
- connects amino acids from tRNA to growing polypeptide chain according to mRNA

67
Q

three phases of transcription / translation:

A

1) initiation
2) elongation
3) termination

68
Q

initiation of translation

A

1) mRNA binds to small subunit of ribosome via start codon
2) large subunit of ribosome binds to small making functioning ribosome
- initiator tRNA fits into tRNA binding site (P site) on ribosome

69
Q

start codon

A

on mRNA, 3 nucleotide sequence (AUG) where initiator tRNA binds
- starting translation

70
Q

P site

A

ribosome binding site where initiator tRNA binds
- holds tRNA carrying polypeptide chain

71
Q

A site

A

(aminoacyl tRNA) one of ribosome’s binding site
- holds the tRNA that carries the next amino acid of polypeptide chain

72
Q

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

A

mRNA transcribed from mutated gene would not work because ribosomes cannot start translation correctly

73
Q

elongation of transcription

A

1) anticodon of incoming tRNA carrying amino acids in A site of ribosome
2) polypeptide chain separates from tRNA in P site and attaches to amino acid of tRNA in A site
3) P site tRNA leaves site, ribosome moves A site tRNA w/ polypeptide chain to now empty P site
repeats

74
Q

termination of transcription

A

stop codon stops protein synthesis;
- one of 3, 3 nucleotide codons that signal gene to stop
- polypeptide is released from last tRNA and ribosome subunits separate

75
Q

the 3 stop codons

A
  • UAA
  • UAG
  • UGA
76
Q

what would happen if a mutation caused a codon in the middle of the mRNA to be a stop codon ?

A

translation will end prematurely

77
Q

which type of nucleic acid does not directly participate in translation ?

A

DNA

78
Q

mutation

A

change in genetic information of cell

79
Q

mutagen

A

chemical / physical agent that interacts w/ DNA and causes mutation

80
Q

how could a single nucleotide substitution result in a shortened polypeptide ?

A

substitution that changes a codon to now code for a stop codon
- ending polypeptide chain prematurely

81
Q

one gene one enzyme hypothesis

A

each gene produces a specific polypeptide
- polypeptide may function as an enzyme / subunit of an enzyme

BIO110 (12 decks)

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