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Genetics > Lecture 6 > Flashcards

Lecture 6 Flashcards

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Biology 101 flashcards
1
Q

In triploid organisms, how do they become triploid (sterile)?

A

Polar bodies in meiosis II aren’t extruded

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2
Q

Most common non-LTR retrotransposons (retroelements)

A

LINE-1 and Alu

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3
Q

Eukaryotic cells were broken open at low or moderate salt concentrations
and the DNA was seen in this form, allowing what to be seen?

A

Nucleosomes

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4
Q

In real life, there is more ___ than protein

A

DNA

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5
Q

In regular chromatin, what percent is DNA?

A

50%

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6
Q

The most common nucleosome width is?

A

30 nm

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7
Q

At ___ salt concentrations, the
nucleosomes display a classic
beads-on-a-string morphology

A

low

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8
Q

Two proteins responsible for loops of the 30 nm fibers

A

SMC and CTCF

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9
Q

Where is heterochromatin located?

A

Half of it at the nuclear periphery and half of it internal

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10
Q

What happens is euchromatin is overexpressed?

A

Heterochromatin is lost quickly

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11
Q

A temporary copy of a gene that contains information to make a polypeptide

A

mRNA

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12
Q

Produces a polypeptide using the information in mRNA

A

translation

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13
Q

becomes part of a functional protein that contributes to an organism’s traits

A

polypeptide

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14
Q

What is the central dogma?

A

DNA replication (using chromosomal DNA)–> transcription (using mRNA)–> translation into polypeptide

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15
Q

Rosalind Franklin revealed what? Using what?

A

DNA as a helix shape using X ray diffraction

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16
Q

Watson and crick realized Rosalind Franklins discovery as DNA as a helix, was….

A

too wide to be single stranded

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17
Q

Who discovered the three ways DNA may replicate

A

Mathew Meselson and Frank Stahl

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18
Q

Both parental strands stay together after DNA replication

A

Conservative model

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19
Q

The double-stranded DNA contains one parental and
one daughter strand following replication

A

Semi-conservative model

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20
Q

Parental and daughter DNA are interspersed in both strands
following replication

A

Dispersive model

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21
Q

Watson and crick confirmed which way to replicate?

A

Semi-conservative

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22
Q

What experiment was done to distinguish between the three
models of DNA replication?

A
  1. Grew e. coli in the presence of 15N (heavy isotope of Nitrogen) for many generations.
  2. Switch to e coli medium containing only 14N
  3. Collect sample of cells
  4. Analyze the DNA density by centrifugation using a CsCl gradient
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23
Q

When analyzing the DNA from distinguishing the models of DNA replication, what DNA disappeared and was replaced with something ___. This proved what type of DNA replication.

A

heavier, lighter, semi-conservative

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24
Q

During the DNA analysis of distinguishing the DNA models of replication–After ~ two generations, DNA is of two types: ____. After one generation DNA is ____

A

light and half heavy (semi-conservative). half heavy (consistent with dispersive and semi-conservative)

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25
Q

In DNA replication, the two dna strands separate and each serves as a ___

A

template strand for the synthesis of new strands

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26
Q

In DNA replication, The two newly made strands =

A

daughter strands

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27
Q

When a DNA strand is synthesized, nucleotides are only added onto the ___ end of the strand

A

3 prime

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28
Q

Bacterial DNA Replication
as seen by the

A

electron microscope

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29
Q

In bacterial DNA, there is one origin or replication and the polymerases meet where?

A

At opposite ends

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30
Q

The origin of replication in E. coli is termed

A

oriC (origin of Chromosomal replication)

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31
Q

Synthesis of DNA proceeds ___ around the bacterial chromosome

A

bidirectionally

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32
Q

The replication forks eventually meet at the ____ side of the bacterial chromosome

A

opposite

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33
Q

E. Coli OriC and the replication origins of other bacteria have ___ DNA sequences

A

highly conserved

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34
Q

DNA replication is initiated by the binding of ___ to the DnaA box sequences

A

DnaA proteins, DNaA box sequences

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35
Q

The binding of DnaA proteins to the DnaA box sequences, stimulates what?

A

binding of an additional 20 to 40 DnaA proteins to form a large complex

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36
Q

What other proteins bind the DnaA protein to initiate bacterial DNA replication

A

HU and IHF also bind

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37
Q

This causes the region to wrap around the DnaA proteins and separates the AT-rich region

A

HU and IHF

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38
Q

Composed of six subunits, first to come in into initiation of bacterial DNA replication

A

Helicase

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39
Q

Helicase travels along the DNA in the ___ direction, ___of polymerase

A

5’ to 3’, opposite

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40
Q

Helicase uses what to break the hydrogen bonds between the DNA strands

A

ATP

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41
Q

Separates the DNA in both directions, creating 2 replication forks

A

DNA helicase

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42
Q

The synthesis of leading and lagging strands from a…

A

single origin of replication

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43
Q

Polymerases connected in what strands

A

Leading and lagging

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44
Q

Topoisomerase is located where on the helicase

A

Head of helicase

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45
Q

Role of the single stranded binding proteins?

A

Keep the parental strands apart, slows down the re-annealing of DNA strands

46
Q

Synthesizes an RNA primer

A

Primase

47
Q

Synthesizes a daughter strand of DNA

A

DNA poly 3

48
Q

Excises the RNA primers and fills in with DNA

A

DNA polymerase I

49
Q

Covalently links the Okazaki fragments together

A

DNA ligase

50
Q

The unwinding of DNA by ___ generates positive supercoiling ahead of each replication fork but ___ (a.k.a. topoisomerase II) travels ahead of the helicase and alleviates these supercoils

A

DNA helicase, DNA gyrase

51
Q

bind to the separated DNA strands to keep them apart

A

Single-strand binding proteins

52
Q

Short RNA primers are synthesized by…

A

DNA primase

53
Q

Keeps genetic material from accumulating mutations at a high rate

A

RNA primers

54
Q

The leading strand has how many primers, the lagging strand has how many primers?

A

Leading strand- single primer
Lagging strand- mutiple primers

55
Q

Extends from 1 RNA primer and when it reaches the next primer—comes off and gets placed by DNA polymerase I

A

DNA poly 3

56
Q

RNA primer on leading strand is replaced by ___

A

DNA poly 3 after 11 bases

57
Q

attaches nucleotides in a 5’ to 3’ direction as it slides
toward the opening of the replication in ___

A

dna poly 3

58
Q

in what strand: the direction is away from the replication fork

A

lagging

59
Q

What polyermase uses the RNA primers to synthesize small
DNA fragments (1000 to 2000 nucleotides each)? These are termed?

A

3, okazaki fragments

60
Q

DNA poly is in __ direction in lagging strand

A

opposite

61
Q

Helicase is ___ of polyermase direction

A

opposite

62
Q

If wrong nucleotide gets base paired and ligated into DNA, this will remove it

A

3’ exonuclease site

63
Q

What DNA polys cannot initiate DNA synthesis? What does this instead?

A

DNA 1 AND 3, RNA PRIMASE

64
Q

What DNA poly: Responsible for subsequent
DNA replication until it meets RNA

A

3

65
Q

Takes over and removes the
RNA primers using its 5’ to 3’ exonuclease
activity and replaces them with DNA

A

DNA poly 1

66
Q

Note that both Pol III and Pol I can only
attach nucleotides only in the ___
direction

A

5’ to 3’

67
Q

links two adjacent single DNA
strands together

A

DNA ligase

68
Q

The two copies of DNA Poly ___
are attached to each other

A

3

69
Q

unlinks the circular daughter
chromosomes at the termination of Bacterial Replication

A

topoisomerase

70
Q

Proofreading function
by DNA polymerases
involve

A

‘exonuclease
sites’

71
Q

At what rate can bacterial cells divide into 2 daughter cells?

A

Very fast (faster than eukaryotes)

72
Q

E.coli division rate

A

20-30 mins

73
Q

Why is DNA replication in eukaryotes is more
complex?

A

large linear chromosomes, tight packaging with nucleosomes, more complicated regulation

74
Q

How many origins of replication in eukaryotes

A

mutiple to ensure that DNA can be replicated in time

75
Q

provided evidence for the multiple origins of
replication

A

Huberman and Riggs

76
Q

How did Huberman and Riggs provide evidence for the multiple origins of
replication

A

They fed growing eukaryotic cells radioactive deoxythymidine that got
incorporated into DNA and then exposed DNA to film

77
Q

Huberman and Arthur Riggs used a clever ____
experiment to show that mammalian cells are replicated by numerous
bidirectional origins

A

thymidine labeling

78
Q

Huberman and riggs found

A

more than 2 replication forks (s phase)

79
Q

what has a strong influence when origins get replicated?

A

chromatin

80
Q

In contrast to bacteria, the leading and lagging strands (in regards to polymerases) are replicated by ___ in eukaryotes

A

different polymerases

81
Q

In bacteria, the ___ is involved in both the leading and lagging strands and
___ helps out out on the lagging strands

A

dna poly 3, dna poly 1

82
Q

In eukaryotes, pol ___ does the the leading strand while pol ___ and pol ___ do the lagging strand

A

poly epsilon, poly alpha, poly delta

83
Q

Bacteria or eukaryotes: the polymerase taking over from primase (pol III) synthesizes most of the lagging strands before being replaced (by pol I)

A

Bacteria

84
Q

In eukaryotes: the polymerase taking over from primase (pol ___) is in a complex with primase and synthesizes only a little bit before being replaced by pol ___.

A

alpha, delta (s shape)

85
Q

How do the ends of linear eukaryotic
chromosomes get replicated?

A

have repepitive sequences at their ends (most telomeres have these) TTAGGC

86
Q

In eukaryotes, DNA polymerase ___ link two nucleotides togethers ___ a primer

A

cannot, without

87
Q

Ends of eukaryotic linear
chromosomes are
replicated by an enzyme
called

A

telomerase

88
Q

Adds on DNA repeats using an RNA template to ends. RNA template has 1.5 copied of telomere

A

ribozyme

89
Q

The telomeric repeat in eukaryotic chromosomes have how many bases

A

6

90
Q

site for RNA polymerase
binding; signals the beginning of
transcription.

A

Promoter

91
Q

site for the binding of
regulatory proteins; the role of regulatory
proteins is to influence the rate of transcription.
In eukaryotes, regulatory sequences can be
found in a variety of locations.

A

Regulatory sequences

92
Q

Parts of DNA sequence for transcription

A

promotor, regulatory sequence, terminator

93
Q

translation begins near this site in the mRNA. In
eukaryotes, a ribosome scans the mRNA for a
start codon

A

ribosomal binding site

94
Q

specifies the first amino acid in a
protein sequence, usually a formylmethionine
(in bacteria) or a methionine (in eukaryotes)

A

start codon

95
Q

Link AA together from start codon to stop codon

A

ribosomal binding site

96
Q

a 3-nucleotide sequence within the mRNA
that specifies a particular amino acid.

A

codons

97
Q

The sequence of ___ within mRNA determines the
sequence of amino acids within a polypeptide

A

codons

98
Q

Bacterial mRNA may be ___, which
means it encodes two or more polypeptides.

A

polycistronic

99
Q

What is a closed complex

A

when polymerase is bound to promotor and strands haven’t separated yet

100
Q

The ___ functions as a recognition site for transcription factors

A

promoter

101
Q

The transcription factor(s) enables ___ to
bind to the promoter. Following binding, the DNA is denatured into a
bubble known as the ___.

A

RNA polymerase, open complex

102
Q

RNA polymerase slides along the DNA in an ___ to synthesize RNA

A

open
complex

103
Q

causes RNA
polymerase and the RNA transcript
to dissociate from the DNA

A

termination signal

104
Q

Prokaryotes have ____ RNA polymease, eukaryotes have ___

A

1, 3

105
Q

A large proportion of bacterial promotors are organized like this, with….

A

-10 and -35 sequences conserved and 1st base pair with rna nucleotide layed down

106
Q

In bacterial promoters, what is relationship with consensus sequences and promoters

A

the closer to the Consensus Sequence, the stronger the promoter

107
Q

In bacterial promoters, when there is a weak conformity to consensus sequence what happens to transcription

A

less

108
Q

In bacterial promoters, -10 sequence is known as a

A

pribnow box

109
Q

In the initiation of bacterial transcription, Binding of RNA polymerase holoenzyme forms a…

A

closed complex

110
Q

Describe bacterial transcription

A
  1. RNA poly core enzyme moves along DNA until they reach a promotor.
  2. Sigma factor then binds -10 and -35, stopping RNA polymerase from moving on DNA
  3. When is stops, RNA polymerase separates 2 DNA strands, initiating RNA synthesis and creating an open complex.
  4. As RNA initiates synthesis, a conformational change in RNA poly occurs and lets go of sigma factor
  5. When RNA poly releases sigma factor, theres a shape change in sigma factor and it lets go of -10 and -35 sequences
111
Q

Many bacterial transcripts are terminated using the protein called…

A

rho

Genetics (11 decks)

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