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Exam 3 Flashcards

1
Q

What would happen to Fredrick Griffith’s mice injected with living S cells?

Streptococcus pneumoniae R strain is
benign (detected by host’s immune system), S stain virulent (undetected by host’s immune system)

A

Mouse dies

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2
Q

What would happen to Fredrick Griffith’s mice injected with living R cells?

Streptococcus pneumoniae R strain is
benign (detected by host’s immune system), S stain virulent (undetected by host’s immune system

A

Mouse healthy

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3
Q

What would happen to Fredrick Griffith’s mice injected with heat-killed S cells?

Streptococcus pneumoniae R strain is
benign (detected by host’s immune system), S stain virulent (undetected by host’s immune system

A

mouse healthy

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4
Q

What would happen to Fredrick Griffith’s mice injected with a mixture of heat-killed S cells and living R cells?

Streptococcus pneumoniae R strain is
benign (detected by host’s immune system), S stain virulent (undetected by host’s immune system

A

mouse dies

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5
Q

What does Fredrick Griffith’s experiment conclude?

Griffith injected mice with R and S cells.

A

Genetic material was passed from S cells to R cells, transforming R cells into S
cells.

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6
Q

What happened in Oswald Avery’s experiment when he added living R cells to a treatment with heat-killed S cells and no protein?

A

S cells appear

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7
Q

What happened in Oswald Avery’s experiment when he added living R cells to a treatment with heat-killed S cells and no RNA?

A

S cells appear

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8
Q

What happened in Oswald Avery’s experiment when he added living R cells to a treatment with heat-killed S cells and no DNA?

A

no S cells appear

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9
Q

What did Oswald Avery’s experiment conclude?

Avery continued Griffith’s work by removing the DNA, RNA, or protein of treatments of heat-killed S cells and then adding living R cells.

A

Transformation cannot occur unless DNA is present. Therefore,
DNA must be the hereditary/genetic material

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10
Q

In the supernatant of the centrifuged media, did Hershey and Chase find P-32 or S-35?

Alfred Hershey and Martha Chase employed bacteriophages that were radiolabeled either with
Phosphorous-32 or Sulfur-35 to determine if the genetic material was DNA or protein. These
radiolabeled bacteriophages were allowed to infect bacteria. The bacteria-bacteriophage media
was then blended and centrifuged.

A

S-35

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11
Q

In the pellet of the centrifuged media, did Hershey and Chase find P-32 or S-35?

Alfred Hershey and Martha Chase employed bacteriophages that were radiolabeled either with
Phosphorous-32 or Sulfur-35 to determine if the genetic material was DNA or protein. These
radiolabeled bacteriophages were allowed to infect bacteria. The bacteria-bacteriophage media
was then blended and centrifuged.

A

P-32

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12
Q

What could Hershey and Chase conclude from their experiment?

A

Bacteriophage transferred DNA and not proteins to bacteria. Therefore,
DNA is the genetic material.

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13
Q

Maurice Wilkins role in determining the structure of DNA

A

produced DNA samples that contained very uniformly oriented DNA samples that helped with x-ray diffraction data

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14
Q

Rosalind Franklin role in determining the structure of DNA

A

realized sugar-phosphate
backbone had to be on the outside bc had a good picture of B form of DNA

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15
Q

James Watson and Francis
Crick role in determining the structure of DNA

A

Looked at the B form diffraction pattern
and understood the following:
1. DNA is a helix.
2. Width & density of diffraction lines in the crystal suggested two strands not three.

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16
Q

replication bubble

A

expands outwards from replication orgin

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17
Q

replication fork

A

points on both sides of replication bubble

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18
Q

Helicase

and what it looks like

A

– Unzips the helix at the replication fork
– Necessary to generate the template
strands

circle at replication fork

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19
Q

Single-Strand Binding Proteins

and what it looks like

A

– Binds to and stabilizes the single-stranded
templates
– Prevents the helix from rewinding

attached to template strand in DNA replication bubble

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20
Q

Topoisomerase

and what it looks like

A

– Causes single-strand breaks that allows the
DNA to unwind and relieve the supercoil
strain.
– It also reseals the breaks before replication

purple blob on next to replication fork

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21
Q

DNA Polymerase

A

Covalently binds the nucleotide to the end of
the daughter strand (joins DNA nucleotides)

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22
Q

3 functional restrictions of DNA Polymerase

A
  1. Can only copy single-stranded
  2. Cannot initiate a new polymer from
    scratch
  3. Can only add nucleotides onto –OH of a free 3ʹ end; never onto the 5ʹ end
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23
Q

DNA polymerase III

A

regular synthesis

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24
Q

DNA
polymerase II

A

Proofreading, repair/editing synthesizes

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25
DNA polymerase I
Fill gaps
26
Primase | and what it looks like
5-10 nucleotides long; needed to intitiate new DNA strands and comes from RNA attached to template and daughter strand in replicaiton bubble
27
Which way does DNA unzip?
away from replication bubble
28
lagging strand | template and daughter strand directions
5'->3' template strand, 3'->5' daughter strand daughter strand synthesized away from replication fork and towards orgin
29
leading strand | template and daughter strand directions
3'->5' template strand, 5'->3' daughter strand daughter strand synthesized towards replication fork and away from orgin
30
telomerase
An enzyme in cells that helps keep them alive by adding DNA to telomeres (the ends of chromosomes).
31
What does telomerase prevent?
Each time a cell divides, the telomeres lose a small amount of DNA and become shorter. Over time, the chromosomes become damaged and the cells die.
32
What happens to cancerous cells?
Divides more often, and its telomeres become very short (could cause cell death). cells escape death by making more telomerase enzyme, which prevents telomerase from getting shorter, causing cancer
33
How is telomeres extended?
Telomeres carries an RNA template that base pairs with single-strand 3' overhang left after DNA replication of the lagging strand.
34
Where is telomerase active in multicellular organisms?
only in germ cells and certain stem cells
35
What does adenine (A) pair with? | in DNA
thymine (T)
36
What does cytosine (C) pair with? | in DNA
guanine (G)
37
What does RNA replace thymine (T) with?
uracil (U)
38
What is most of DNA seen as?
junk
39
Promoter
Specific DNA sequence at 5' end of gene where RNA polymerase binds | start site for transcription
40
Transcription unit
DNA sequence that is transcribed
41
primer
Short piece of RNA added in 5’-3’ direction to start DNA synthesis
42
ligase
Glue DNA fragments together
43
Okazaki fragments
short sections of DNA formed at the time of discontinuous synthesis
44
coding strand
5' -> 3' Complementary to template
45
template strand
3' -> 5' DNA strand that is copied
46
direction of synthesizing RNA
5'->3'
47
Start Codon
Methionine AUG
48
Stop Codon
UAA UAG UGA
49
RNA Polymerase
Catalyzes the addition of complementary ribonucleotides to growing RNA chain -works off a single-stranded DNA template -unzips, unwinds DNA
50
number of RNA Polymerase in prokaryotes
1
51
number of RNA Polymerase in eukaryotes
3
52
What does RNA polymerase I synthesize?
rRNA
53
What does RNA polymerase II synthesize?
mRNA, iRNA, snRNA, and snoRNA genes
54
What does RNA polymerase III synthesize?
tRNA
55
promoter
Specific DNA sequence at 5' end of gene where RNA polymerase binds – Includes the start site for transcription - determines which DNA strand is transcribed
56
transcription unit
the DNA sequence that is transcribed
57
transcription factors
Proteins that stabilize RNA polymerase binding * Regulate transcription initiation (they could also prevent RNA polymerase binding to promoter)
58
Transcription Initiation Complex
Formed when RNA polymerase and associated transcription factors bind to the promoter
59
Why are transcription errors more common than replication errors?
1. DNA more important than RNA 2. RNA is not designed to live long and only code so much for each protein. 3. DNA is designed to live long and continue to pass on genetic info for each generation. 4. DNA contains every gene needed to code for proteins we need to survive. 5. replication errors in DNA cause problems for as long as cell is alive 6. DNA is much longer in comparison to RNA which is only a few thousand bps long
60
downstream
direction towards transcription unit
61
upstream
direction towards promoter
62
RNA Splicing Mechanism | in eukaryotes pre-RNA
Internal noncoding RNA sequences (introns) are removed and expressed sequences (exons) are spliced together. **important source of protein diversity**
63
How does RNA Splicing Mechanism work?
Small nuclear riboprotein particles (snRNPs) bind to sequences within an intron
64
5'cap | in eukaryotes RNA
Addition of a protective cap (modified G residue) at the 5’ end **– Protects RNA from being broken down in cytoplasm – Helps ribosome attach to mRNA to make proteins**
65
poly-A tail (AAAAAA)
– Addition of 50–250 adenines at the 3' end, when encountering a polyadenylation signal sequence (AAUAAA) **– Makes RNA more stable and helps it get exported from nucleus to cytoplasm **
66
synonymous
Single base change that doesn’t change the protein
67
missense
Single base change that changes the protein
68
nonsense
Base change that creates a stop codon where it’s not supposed to be
69
loss-of-stop
Base change so there is no longer a stop codon
70
frame-shift mutations
Consists of insertions and deletions
71
amino acid binding site on tRNA
active site, a little circle shape at top
72
mRNA binding site on tRNA
anticodon, flat side at bottom
73
functions of rRNA (3) | be able to write this!
* ensures** proper alignment** of mRNA codon and tRNA anticodon * breaks bond between AA and tRNA * catalyzes the formation of peptide bond between two adjacent AA: **peptidyl transferase activity** (ribozyme) | ribosome RNA!
74
Translation Initiation Steps (3)
1. small ribosome subunit binds to mRNA at 5' end and finds start codon 2. tRNA binds to start codon 3. large subunit joins, tRNA in P site
75
intitiation complex
charged tRNA binds to start codon
76
sites in tRNA | left to right
E site, P site, A site
77
Translation Elongation
1. incoming tRNA binds to A site 2. AA on P site binds to AA on A site 3. ribosome shifts towards 3' 4. new tRNA binds to A sitfe
78
Translation Termination
1. release factor binds to complex when stop codon enters A site 2. release factor releases polypeptide from tRNA in p site 3. remaining component seperate
79
Phosphorylation
occurs during cell signaling (enzyme activation) adds phosphate groups, alters shape of proteins
80
Glycosylation
occurs in ER & Golgi apparatus adding sugars is important for targeting and recognition
81
proteolysis
cleaving the polypeptide allows fragments to fold into different shapes
82
common post translational modifications (80% of proteins)
removal of signal sequence and methionine

BSCI170 (3 decks)

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