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Biology > Chapters 16-18 > Flashcards

Chapters 16-18 Flashcards

0
Q

purine

A

nitrogenous base with two rings, includes adenine and guanine

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1
Q

phosphodiester bonds

A

bonds formed between the phosphate on the 5’ carbon of one nucleotide and the 3’ carbon of the next nucleotide

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2
Q

pyrimidine

A

nitrogenous base with single ring structure, includes thymine, cytosine and uracil

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3
Q

nucleotide

A

3 phosphate groups + pentose sugar + nitrogenous base

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4
Q

nucleoside

A

pentose sugar + nitrogenous sugar

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5
Q

nucleotide residue

A

1 phosphate, pentose sugar, and nitrogenous base

the bond holding phosphates breaks to make energy for building process

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6
Q

first scientists credited with DNA structure

A

James Watson and Francis Crick

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7
Q

polarity of nucleotide chain

A

one end contains the roof of the pentose sugar (5’ carbon) and the other end is the left base of the pentose sugar (3’ carbon)

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8
Q

how many nucleotides chains are in RNA?

A

1

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9
Q

how many nucleotide chains are in DNA?

A

DNA is a double helix formed by combining two chains

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10
Q

how are two nucleotide chains linked?

A

hydrogen bonds between their bases (A,G,T,C)

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11
Q

antiparallel

A

run in opposite directions. 5’ end and 3’ end of opposite nucleotide chains are side-by-side

DNA is antiparallel

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12
Q

how does the sugar-phosphate backbone remain straight?

A

A purine always bonds with pyrimidine. always 3 rings in any pair, providing consistent width

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13
Q

What complementary base pair has 2 hydrogen bonds?

A

Adenine and Thymine

NOT URACIL because only DNA does this

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14
Q

What complementary base pair has 3 hydrogen bonds?

A

Guanine and Cytosine

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15
Q

angstrom

A

equal to 0.1 nanometers. used to measure wavelengths of EM radiation

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16
Q

distance between base pairs (steps of ladder)

A

3.4 angstroms

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17
Q

distance between sugar-phosphate backbones

A

20 angstroms

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18
Q

distance between every complete twist of helix

A

34 angstroms

3.4 angstroms between pairs, so 10 pairs per twist

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19
Q

Chargaff’s Rule

A 
#purines = #pyrimidines
#adenines = #thymines
#cytosines = #guanines

ratio is very unlikely to be 1:1:1:1

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20
Q

Scientists used to think genetic material was ______

A

proteins

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21
Q

First proof that nucleic acid was genetic material and not protein

A

Bacterial transformation studies ny Frederick Griffith - 1928

Involved bacteria with glyco protein coats and without

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22
Q

Denaturation study by Oswald Avery, Colin Macleod, and Maclyn McCarty - 1944

A

Protein was destroyed with enzyme but bacteria transformation occurred

RNA was destroyed but bacteria transformation occurred

DNA was destroyed and transformation didn’t occur

Genetic material must be DNA

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23
Q

bacteriophage labeling by Hershey and Chase - 1952

A

radioactive sulfur was put into bacteriophage making protein coat radioactive

radioactive phosphorous was put into virus making nucleic acid radioactive

phosphorus was found in new phages, so DNA is genetic material

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24
Q

Tobacco Mosaic Virus Study by Fraenkel-Conrat and Singer - 1957

A

TMV protein coat put onto HRV RNA to make hybrid.

When virus replicates it is HRV RNA and protein coat. Therefore RNA was genetic material.

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25
Q

replication

A

when DNA makes copies of itself during synthesis stage of the cell cycle

semiconservative

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26
Q

Conservative

A

Two strands of DNA reassociate, therefore parental double helix is always together.

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27
Q

semiconservative

A

two strands of parental DNA molecule separate and act as a template for new complementary strand.

therefore each DNA strand is half parental and half new material

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28
Q

dispersive

A

each strand of DNA contains both old and newly synthesized DNA

old is dispersed throughout the strand

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29
Q

Matthew Meselson and Franklin Stahl - 1958

A

Grew E. coli in heavy isotope of nitrogen N (15) for several generations to make DNA heavy

Allow heavy DNA to replicate one time in normal nitrogen (14). Take sample and let it replicate one more time in normal nitrogen and take another sample.

Centrifuge spins DNA in Cesium Chloride

results: There was a single band midway in the tube after first replication. There were two bands, one midway and one higher up, in the tube after second replication

First replication was half and half heavy and nonheavy, second replication was one half and half and one all normal. Therefore semiconservative.

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30
Q

Replication is bidirectional

A

DNA strands unzip in opposite directions from the origin (where the DNA first opens)

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31
Q

replication forks/Y-junctions

A

opposite areas of unzipping

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32
Q

Number of origins in small molecules

A

only one origin for small chromosomes, such as E. coli

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33
Q

number of origins in larger chromosomes

A

there are multiple origins in larger chromosomes

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34
Q

replicon

A

area under control of 1 origin

there are multiple replicons in replicating eukaryotic DNA

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35
Q

Rates of replication

A

~25,000 bp/min in E. coli

~2,000 bp/min in eukaryotes (slower due to histones that get in the way)

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36
Q

Replication is semidiscontinuous

A

one strand replicates continuously, the other replicates in fragments (discontinuously)

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37
Q

leading strand

A

replicates in one piece

38
Q

lagging strand

A

replicates in fragments

39
Q

Okakazi fragments

A

new DNA fragments on the lagging strand

40
Q

DNA ligase

A

later stitches together Okakazi fragments

41
Q

Why is replication semidiscontinuous?

A

DNA can only build in the 5’ –> 3’ direction, with the phosphate on the 5’ carbon of the newly arriving nucleotide bonding to the 3’ carbon of the last nucleotide in the chain. Because the DNA molecule is antiparallel, the two new strands cannot be former in the same direction.

42
Q

DNA proofreading

A

DNA Polymerase III proofreads while it builds the new DNA strand. If it has put it in an incorrect nucleotide, it has an exonuclease region that will remove the incorrect nucleic acid and replace it with the correct one.

43
Q

error rates of replication

A

~1 incorrect nucleotide per 100,000 basepairs

post-proofreading ~1 incorrect nucleotide per 10 billion base pairs

44
Q

In a nucleotide, the nitrogenous base is attached to the sugar’s _____ carbon and the phosphate group is attached to the sugar’s _____ carbon.

A

The nitrogenous base is attached to the sugar’s 1’ carbon and the phosphate group is attached to the sugar’s 5’ carbon.

45
Q

The first step in the replication of DNA is catalyzed by

A

helicase. The first step of the DNA replication is unwinding the DNA double helix.

46
Q

The action of helicase creates

A

Replication forks and replication bubbles

47
Q

replication fork

A

transition region between paired and unpaired DNA strands

48
Q

origin

A

area in middle of DNA where replication occurs bidirectionally

49
Q

theta structure

A

structure when half of bacteria circular chromosome is replicated and the chromosome looks like the letter theta

50
Q

histone

A

protein balls that DNA wraps around to keep DNA from getting tangled

its difficult for enzymes to build DNA around histones

51
Q

core DNA

A

DNA that wraps around histones

52
Q

linker DNA

A

DNA between histones

53
Q

nucleosome

A

half linker DNA and histone and core DNA

54
Q

Flow of genetic information (replication, transcription, translation) is called

A

central dogma

55
Q

transcription is controlled by which enzyme?

A

RNA polymerase

56
Q

Steps of Transcription

A

Initiation, Elongation, Termination

57
Q

initiation

A
  1. RNA polymerase searches for and binds to the promoter site on the DNA.
  2. RNA polymerase melts the DNA strand open.
58
Q

where is the region of the promoter located in eukaryotic cells?

A

approximately 25 base pairs up stream from where transcription of RNA from the DNA template will begin.

59
Q

wht is the TATA box

A

region of promoter site containing several thymine-adenine bonds

60
Q

Elongation

A

Transcription continues as nucleotides are added to the growing RNA strand by RNA polymerase in the 5’ -> 3’ direction according to the rules of complementarity until a terminator sequence is reached

61
Q

Termination

A
  1. RNA polymerase detects a termination signal AAUAAA on the pre-mRNA strand
  2. The pre-mRNA drops free from the DNA template.
  3. Both ends of the pre-mRNA are capped to protect RNA from being destroyed by hydrolytic enzymes. A 5’ cap protects the leading edge of the mRNA and also helps the ribosome know where to attach to the mRNA. The 3’ end is protected by a poly-A tail (50-250 adenine)
62
Q

Prokaryotic vs Eukaryotic transcription

A

prokaryotic cells do not have a nuclear envelope, transcription and translation can occur simultaneously

in eukaryotes transcription occurs in nucleus and translation occurs in the cytoplasm

63
Q

introns

A

parts of pre-mRNA cleaved out of mRNA before leaving nucleus

64
Q

exons

A

pieces of eukaryotic RNA that leave nucleus and travel to ribosomes for translation

65
Q

spliceosomes

A

nuclear organelles that remove the introns and splice the exons together

66
Q

how do spliceosomes work?

A

complementary base pairs of RNA inside spliceosomes connect to pre-mRNA and pull the pieces together

67
Q

messenger RNA

A

carries genetic message from the DNA template in the nucleus to ribosomes in the cytoplasm where proteins are made

68
Q

transfer RNA

A

brings amino acids (monomers of polypeptides) to the ribosomes where they will be linked together into a polypeptide

69
Q

anticodon

A

area of transfer RNA where it connects to codon on mRNA

70
Q

ribosomal RNA

A

forms a structural component of ribosomes

71
Q

small nuclear RNA (snRNA)

A

tiny pieces of RNA combined with protein that are found in the nucleus of eukaryotic cells. they form a structural component of the spliceosome

72
Q

Translation

A

using the genetic message transcribed in a strand of mRNA to code for the arrangement of amino acids into a polypeptide

73
Q

Enzyme that attaches amino acid onto appropriate tRNA

A

aminoacyl-tRNA synthetase

74
Q

Aminoacyl tRNA

A

a “charged amino acid”. amino acid attached to RNA

75
Q

codon

A

sequence of 3 nucleotides on the mRNA strand. Each codon codes for the placement of one amino acid in the growing peptide strand.

there are 4 nucleotides and 3 nucleotides per codon so there are 64 (4 x 4 x 4) possible codons

76
Q

regions of ribosome (3 letters)

A

EPA

77
Q

A site of ribosome

A

aminoacyl-tRNA binding site; receives the newly arriving tRNA

78
Q

P-site of ribosome

A

peptidyl-tRNA binding site; holds the tRNA with the growing peptide chain

79
Q

e-site of ribosome

A

exit site; releases the empty tRNA

80
Q

steps of translation

A

initiation, elongation, termination

81
Q

Initiation of translation

A
  1. mRNA is threaded into the small ribosomal subunit (initiation factors aid this step)
  2. The first tRNA carrying methionine (Met) attaches to the start codon (AUG) of the mRNA strand
  3. The large ribosomal subunit combines with the small subunit. GTP is the energy source that combines the ribosomal subunit.
82
Q

Elongation of translation

A
  1. Next tRNA arrives at a-site
  2. amino acid chain is added to new tRNA with peptidyl transferase
  3. translocase moves the ribosome down 3 nucleotides, putting old tRNA in e-site and exiting it
83
Q

peptidyl transferase

A

enzyme used to form peptied bond between amino acid chain and new tRNA

84
Q

translocase

A

enzyme that moves ribosome down three nucleotides

85
Q

termination of translation

A
  1. a stop codon (UAG, UAA, or UGA) hits A-site
  2. further peptide elongation is blocked
  3. The last tRNA is released from ribosome
  4. Polypeptide chain is releases from ribosome
  5. mRNA is releases from ribosome
  6. Ribosomal units dissociate and are available to start process again

Release factors aid the release of tRNA, polypeptides and mRNA from ribosome

86
Q

evolution

A

changes in the frequences of alleles in a population from one generation to the next

87
Q

population

A

members of a species that occur together in a localized region; have a good probability of interbreeding

88
Q

species

A

organisms potentially capable of interbreeding and producing viable, fertile offspring; often spatially separated

89
Q

gene pool

A

sum of all alleles in a population

90
Q

hardy-weinberg equilibrium

A

allelic frequences stay the same across generation

91
Q

conditions of H-W equilibrium

A 
P - Large population size
R - Random Mating
I - Isolation (no immigration or emigration)
S - No selection (survival)
M - no mutations
92
Q

genetic drift

A

random shifts in alleles due to small population sizes

93
Q

two equations of HW values

A

p + q = 1.0
p2 + 2pq + q2 = 1.0

p is dominant (power)
q is recessive (quiver)

Biology (9 decks)

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