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biology 1305 > chapter 16 > Flashcards

chapter 16 Flashcards

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1
Q

What did T.H Morgan’s group show

A

That genes exist as parts of chromosomes

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2
Q

What are the two chemical components of chromosomes

A

dna and proteins

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3
Q

who was frederick griffith

A

british officer who tried to develop a vaccine against pneumonia

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4
Q

what bacteria did griffith study

A

streptococcus pneumonia

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5
Q

what is streptococcus pneumonia

A

bacteria that causes pneumonia in mammals

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6
Q

what strains did griffith have

A

two strains (varieties of bacterium) one pathogenic and one nonpathogenic

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7
Q

what does pathogenic mean

A

disease causing

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8
Q

what does nonpathogenic mean

A

harmless

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9
Q

why was the frederick griffith experiment important

A

it first experiment suggesting that bacteria are capable of transferring genetic information through a process known as transformation.

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10
Q

what two strains does streptococcus have

A

smooth and rough strain

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11
Q

what are some characteristics of the smooth strain

A

capsule that protects it from the immune system

highly pathogenic

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12
Q

what are some characteristics of the rough strain

A

lacks capsule and easily killed

nonpathogenic or harmless

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13
Q

what happens when the smooth strain is injected into the mice

A

it dies

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14
Q

what happens when the rough strain is injected into the mice

A

it survives

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15
Q

what happened when the smooth strain was heated and injected into the mice

A

the mice survived

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16
Q

what happened when the heat killed smooth strain and the rough stain were injected to the mice and what did it indicate

A

the mouse died; transformation

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17
Q

what is transformation

A

rocesses by which genetic material in the form of “naked” deoxyribonucleic acid (DNA) is transferred between microbial cells

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18
Q

Who later identified the transforming change as DNA

A

□ Oswald avery, Maclyn McCarty, Colin MacLeod

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19
Q

why are avery, mccarty and macleod important

A

showed that DNA (not proteins) can transform the properties of cells

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20
Q

what was the avery,mccarty, macleod experiment

A

took lysate of heat killed s strain and treated it with different enzymes and dnase did not convert the s train to r strain

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21
Q

what are bacteria phages

A

virus that infects bacteria

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22
Q

what is a virus

A

small collection of genetic code, either DNA or RNA, surrounded by a protein coat. A virus cannot replicate alone.

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23
Q

How can a virus produce more viruses

A

□ Must infect a cell and take over the cell’s metabolic machinery

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24
Q

what did scientists believe in the early 20th century

A

that proteins was the genetic material

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25
what are the order of the experiments
griffith, avery macleod mccarty, hershey and chase
26
in the Hershey chase experiment what were the two bacteriophages labeled with
bacteriophage coat was labeled with (Protein) S35 and the bacteriophage dna was labeled with P32 (DNA)
27
what organism was used in the hershey chase experiment
bacteriophage
28
what were hershey and chase trying to prove
if dna is the genetic material or protein
29
what two things do viruses contain
dna core with a protein coat
30
what did they use to label the dna
radioactive tags
31
where is phosphate found
in dna and not in proteins
32
where is sulfur found
in proteins
33
what did they figure out with the sulfur labeled tag
most of the radioactivity remained with the virus and did not enter the bacteria
34
what bacteriophage did hershey and chase use
e.coli
35
what is the polymer of nucleotides
dna
36
what are the components of dna
nitrogenous base, deoxyribose pentose sugar, phosphate group
37
what are the dna bases
adenine, guanine, thymine, cytosine
38
a =?
t
39
g =?
c
40
what were chargaffs rules
dna base composition varies between species | the percentages of a and t bases are roughly equal and the percentages of g and c bases are roughly equal
41
what is rosalind franklin famous for
x ray crystallography which provided clues to the structure of dna
42
what does a double helix mean
the dna has two strands
43
what was franklins arrangement of the dna
sugar phosphate backbones were outside of the dna molecule | negatively charged phosphate groups facing aqeuous solutions
44
who were watson and crick and what did they do
scientists that discovered the shape of dna was a helix
45
what did watson construct
□ An antiparallel structure
46
what does antiparallel mean
Subunits run in opposite directions
47
what type of bond links the nucleotides together
covalent sugar phosphate bonds
48
the phosphate group is attatched to what ed
5 end of sugar
49
the bases are attatched to what end
1 end of the sugar
50
what is the bond that keeps the bases together
hydrogen bond
51
what interaction happens between stacked base pairs
van der waals
52
what is dna replication
the copying of dna
53
what is the semiconservative model
after one round of replication, every new DNA double helix would be a hybrid that consisted of one strand of old DNA bound to one strand of newly synthesized DNA
54
what is the conservative model
the entire original DNA double helix serves as a template for a new double helix
55
what is the dispersive model
each strand of both daughter molecules contains a mixture of old and newly synthesized dna
56
what was the importance of the meselson and stahl experiment
supported the semiconservative model of dna replication
57
what is the origins of replication
where replication of chromosomal dna begins and they are short stretches of dna that have specific nucleotides
58
what are some characteristics of the e coli chromosome
circulur and has a single origin
59
what is the replication fork
y shaped region where the parental strands are being unwound
60
what is helicase
enzyme that untwist the double helix at the replication forks and make them available as template strands
61
what are single-strand binding proteins
bind to the unpairaed dna strands and keep them from re-pairing
62
what is topoisomerase
breaks and rejoins dna strands and it relives the dna
63
what direction is dna read
5 to 3
64
what end is dna added
3 end
65
what can the enzymes not do in dna replication
initiate synthesis of dna they can only add nucleotides to an already existing chain
66
what is a primer
pre existing chain of rna that is produced during dna synthesis
67
what is primase
starts a complementary rna chain with a single rna nucleotide ands rna nucleotides one at a time
68
what does dna polymerase do
catalyze the syntehsis of new dna by adding nucleotides to the 3 end proof read the dna
69
what does dna poly 3 do in ecoli
adds dna nucleotide to the rna primer
70
what do most polymerases require
a primer and a dna template strand
71
what is the leading strand
a single DNA strand that, during DNA replication, is replicated in the 3' – 5' direction
72
what is the lagging strand
a single DNA strand that, during DNA replication, is replicated in the 5' - 3' direction synthesized disontinuously
73
what are okazaki fragments
segments of the lagging strand
74
what happens in a mismatch pair
other enzymes remove and replace incorrectly paired nucleotides
75
what is a nuclease
dna cutting enzyme
76
what is a nucleotide excision repair
dna repair system
77
what is a telomere
the repetitive DNA repeat sequences at the end of linear eukaryotic chromosomes protecting chromosome ends from degradation and illegitimate recombination
78
what are the functions of telomeres
1. ) prevent the stagered ends of the daughter molecule from activating the cells systems 2. ) buffer zone that protects against organisms genes shortening
79
what is a nucleosome
the basic unit of dna packing
80
what are histones
proteins that help pack the dna in interphase
81
what is euchromatin
less compacted and more dispersed dna
82
what is heterochromatin
more compact and denser chromatin

biology 1305 (6 decks)

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