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BSCI170 > Exam 3 > Flashcards

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
Q

DNA polymerase I

A

Fill gaps

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26
Q

Primase

and what it looks like

A

5-10 nucleotides long; needed to intitiate new DNA strands and comes from RNA

attached to template and daughter strand in replicaiton bubble

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27
Q

Which way does DNA unzip?

A

away from replication bubble

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28
Q

lagging strand

template and daughter strand directions

A

5’->3’ template strand, 3’->5’ daughter strand
daughter strand synthesized away from replication fork and towards orgin

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29
Q

leading strand

template and daughter strand directions

A

3’->5’ template strand, 5’->3’ daughter strand
daughter strand synthesized towards replication fork and away from orgin

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30
Q

telomerase

A

An enzyme in cells that helps keep them alive by adding DNA to telomeres (the ends of chromosomes).

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31
Q

What does telomerase prevent?

A

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.

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32
Q

What happens to cancerous cells?

A

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

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33
Q

How is telomeres extended?

A

Telomeres carries an RNA template that base pairs with single-strand 3’ overhang left after DNA replication of the lagging strand.

34
Q

Where is telomerase active in multicellular organisms?

A

only in germ cells
and certain stem cells

35
Q

What does adenine (A) pair with?

in DNA

A

thymine (T)

36
Q

What does cytosine (C) pair with?

in DNA

A

guanine (G)

37
Q

What does RNA replace thymine (T) with?

A

uracil (U)

38
Q

What is most of DNA seen as?

A

junk

39
Q

Promoter

A

Specific DNA sequence at 5’
end of gene where RNA polymerase binds

start site for transcription

40
Q

Transcription unit

A

DNA sequence
that is transcribed

41
Q

primer

A

Short piece of RNA added in 5’-3’
direction to start DNA synthesis

42
Q

ligase

A

Glue DNA fragments together

43
Q

Okazaki fragments

A

short sections of DNA formed at the time of discontinuous synthesis

44
Q

coding strand

A

5’ -> 3’
Complementary to template

45
Q

template strand

A

3’ -> 5’
DNA strand that is copied

46
Q

direction of synthesizing RNA

A

5’->3’

47
Q

Start Codon

A

Methionine
AUG

48
Q

Stop Codon

A

UAA
UAG
UGA

49
Q

RNA Polymerase

A

Catalyzes the addition of complementary ribonucleotides to growing RNA chain
-works off a single-stranded DNA template
-unzips, unwinds DNA

50
Q

number of RNA Polymerase in prokaryotes

A

1

51
Q

number of RNA Polymerase in eukaryotes

A

3

52
Q

What does RNA polymerase I synthesize?

A

rRNA

53
Q

What does RNA polymerase II synthesize?

A

mRNA, iRNA, snRNA, and snoRNA
genes

54
Q

What does RNA polymerase III synthesize?

A

tRNA

55
Q

promoter

A

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
Q

transcription unit

A

the DNA sequence
that is transcribed

57
Q

transcription factors

A

Proteins that stabilize RNA polymerase
binding
* Regulate transcription initiation (they could also prevent RNA polymerase binding to promoter)

58
Q

Transcription Initiation Complex

A

Formed when RNA polymerase and
associated transcription factors bind to
the promoter

59
Q

Why are transcription errors more common than replication
errors?

A
  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
Q

downstream

A

direction towards transcription unit

61
Q

upstream

A

direction towards promoter

62
Q

RNA Splicing
Mechanism

in eukaryotes pre-RNA

A

Internal noncoding RNA sequences (introns) are removed and expressed sequences (exons) are spliced together.

important source of protein
diversity

63
Q

How does RNA Splicing
Mechanism work?

A

Small nuclear riboprotein particles (snRNPs) bind to sequences within an intron

64
Q

5’cap

in eukaryotes RNA

A

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
Q

poly-A tail (AAAAAA)

A

– 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
Q

synonymous

A

Single base change that doesn’t
change the protein

67
Q

missense

A

Single base change that changes
the protein

68
Q

nonsense

A

Base change that creates a stop codon where it’s not supposed to be

69
Q

loss-of-stop

A

Base change so there is no longer
a stop codon

70
Q

frame-shift mutations

A

Consists of insertions and
deletions

71
Q

amino acid binding site on tRNA

A

active site, a little circle shape at top

72
Q

mRNA binding site on tRNA

A

anticodon, flat side at bottom

73
Q

functions of rRNA (3)

be able to write this!

A
  • 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
Q

Translation Initiation Steps (3)

A
  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
Q

intitiation complex

A

charged tRNA binds to start codon

76
Q

sites in tRNA

left to right

A

E site, P site, A site

77
Q

Translation Elongation

A
  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
Q

Translation Termination

A
  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
Q

Phosphorylation

A

occurs during cell signaling (enzyme activation)
adds phosphate groups, alters shape of proteins

80
Q

Glycosylation

A

occurs in ER & Golgi apparatus
adding sugars is important for targeting and recognition

81
Q

proteolysis

A

cleaving the polypeptide allows fragments to fold into different shapes

82
Q

common post translational modifications (80% of proteins)

A

removal of signal sequence and methionine

BSCI170 (3 decks)

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