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BIO EXAM #5 > 1. DNA and its role in heredity > Flashcards

1. DNA and its role in heredity Flashcards

1
Q

what is a polymer?

A

made up of monomers

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2
Q

we already know that DNA is a _____ made up of ______

A

polymer
nucleotides

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3
Q

we also know that there are #___ ______ bases called? _____ & _____

A

4 nitrogenous
purines & pyrimidines

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4
Q

purines are …..

A

adenine & guanine

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5
Q

pyrimidines are …

A

cytosine & thymine

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6
Q

_______ in 1950 found?

A

Chargaff
that all DNA/life has the same ratio of purines and prymidines

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7
Q

BUT NOT ALL DNA has the same # of A + T & G + C because they differ in?

A

species and individuals

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8
Q

purines always equal ______ because?

A

pyrimidines
purines WILL ALWAYS pair with pyrimidines

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9
Q

so for every purine there is a ……

A

pyrimidines

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10
Q

therefore purines will never pair with?
& pyrimidines never pair with?

A

purines
pyrimidines

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11
Q

what is a x-ray diffraction?

A

its creating a substance that you will then purify and eventually turning it into a crystal

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12
Q

who was Rosalind Franklin?

A

she was an expert in x-ray crystallography

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13
Q

** Rosalind Franklin took pictures that indicated?

A
  1. the bases (A,G,C,T) pointed inward so inside the sugar phosphate backbones
  2. SO the sugar phosphate groups are on the outside of each strand
  3. the strands run antiparallel
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14
Q

** what is the orientation of the 2 strands in DNA?

A

1 strand is a 5’ prime end (phosphate group on the end) and on the other strand it is a 3’ prime end (lose hydroxyl group at the end [OH-])

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15
Q

which end has a phosphate group?

A

5’ prime end

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16
Q

what does the 3’ prime end have?

A

a hydroxyl group … OH-

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17
Q

Rosalind Franklin data was?
BUT her contributions were?

A

stolen and seen without her permission but was INSTRUMENTAL to the discovery of DNA Structure
NOT RECOGNIZED in her lifetime

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18
Q

Rosalind Franklin’s data was shared without her permission to?

A

Watson & Crick

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19
Q

who build a model of DNA using evidence from Chargaff’s rule and evidence from x-ray crytaollography?

A

James Watson & Francis Crick

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20
Q

To satisfy Chargaff’s rule, purines pair with pyrimidines to result in?

A

a uniform width between backbones of the strand

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21
Q

where can were replicate DNA?

A

test tube!

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22
Q

** what is the recipe to replicating/copying DNA?

A
  1. Salts and a pH buffer
  2. Nucleotides monomers of DNA (A,G,C,T) …. aka building blocks
  3. Templates
  4. Enzyme called DNA polymerase
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23
Q

***** what was the 1st possible DNA replication possibility? (DRAW THIS)

A

Semiconservative… each strand serves as a template strand to build a NEW strand

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24
Q

** what is the 2nd possible DNA replication possibility? (DRAW THIS)

A

conservative… the OG molecule serves a template strand ONLY and remains intact so the other 2 strands are NEW strand

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25
***** what is the 3rd possible DNA replication possibility?(DRAW THIS)
dispersive... DNA is cut into fragments and those fragments are the templates in both DNA molecules BOTH strands are old and new (mixed)
26
meselson & stahl showed? _______ replication possibility was the correct patter of DNA replication
semiconservative
27
E coli is?
bacteria
28
*** explain the experiment that concluded semiconservative replication is the correct pattern... (DRAW THIS)
took E coli(bacteria) grew it in N15 then transferred it into a N14 and those samples were WEIGHED
29
mechanisms of DNA replication: there are #__ main phases in DNA replication and this takes place in the ___ phase of the cell cycle (DRAW THIS)
3 S
30
**** name the phases and what it does in DNA replication
1. Initiation: double helix of DNA is unwounded which makes 2 template strands 2. Elongation: (elongation of new strand) the complimentary base Paris are linked together by special covalent bond called phosphodiester bond 3. Termination: DNA synthesis ends
31
DNA replication starts when there is? & why is it simple in prokarytoes?
a large protein complex that binds to the ori region because there is only 1 ori region
32
START: replication complex comes into the ____ region > __ begins to ___ in ____ directions > ___ strand is built on each template strand > until reaches the?
ori , DNA ... unwound BOTH , NEW termination region
33
in eukaryotes chromsomes are?
much longer and a lot more ORI regions of replication
34
**** ENZYME involved in DNA replication: 1st enzyme is? and what does it do?
DNA helicase: it is responsible for unwinding DNA using ATP as a source of energy (DNA helicase + ATP + DNA molecule ... hydrolyze ATP... to help uzip the 2 strands of DNA)
35
**** SSB proteins stands for what in DNA replication and what does it do?
single strand binding proteins: prevent strands from coming back to each other once they are unzipped
36
DNA polymerase requires 2 things what are they?
template strand and a primer
37
____ _____ makes the primer that DNA polymerase requires
DNA primase
38
what is a primer?
short strand of RNA made of DNA primase that helps DNA polymerase build onto this short strand
39
____ _____ links DNA fragments that are called _____ _____
DNA ligase Okazaki fragments
40
OG/ TEMPLATE DNA strand runs #__' prime to #___' prime so it is read in copy in this direction
5 - 3
41
NEW DNA strand runs/built in the #__' prime to #__' direction
3 - 5
42
1 phase/sage of DNA replication called ____.... : _____ _____ uses energy from ____ to unwind the 2 DNA strands : ___-____ _____ protein will prevent the strands from coming back to each other (unbind/apart) : the _____ ____ is the open area between both DNA strands where replication/construction of the NEW DNA strand can happen
initiation DNA polymerase ATP single-strand binding replication fork
43
*** why does DNA polymerase require a primer?
because the shape of its active site will ONLY allow nucleotides to another nucleotide which means it cannot start a strand out of nowhere
44
DNA polymerase ONLY ADDS.....
new nucleotides to a pre-existing strand which requires a primer (short strand start made up of RNA)
45
What does DNA primase do that DNA polymerase cannot do?
can start a standout of nowhere
46
2nd stage of DNA replication:____ (based not he activity of the DNA polymerase) DNA polymerase will bind to??? ............ and then it will?
elongation the strand where RNA primer ends read which nucleotides is where and add the the complementary base (adenine- thymine or guanine - cytosine)
47
complimentary base paring is?
A always binds to T G always binds to C
48
If DNA polymerase reads C it will add a G and add it to the end of the 3 prime end by a _____ reaction which form the _____ linkage
condensation phosphodiester
49
the _____ strand is where the replication fork allows for?
leading the 3 prime end to keep going
50
**** the other antiparallel strand called the ____ strand d runs into an issue so then what happens?
its further from the fork so it has to work backwards and it leaves gaps that are unreplicated called Okazaki fragments and so they each have their own primer so now multiple primers are added to this strand
51
the 3rd/final stage of DNA replication:______ explain.
termination where DNA polymerase adds nucleotides to the 3 prime end of the lagging strand UNTIL it reaches the primer of the previous fragment
52
in the termination phase: DNA polymerase replaces?
the primer with DNA
53
The final enzyme in termenation is called ____ ____ and it will do what?
DNA ligase fill/catalyze the gaps (fills in gaps)
54
what is the issue that occurs in the lagging strand and how does the cell survive this?
once the terminal primer is removed NO DNA can be synthesized (lose hanging nucleotides) SNIP off the 3 prime end piece
55
as cell divides as we age what happens?
our chromosomes become smaller, genes get lost, and the cell eventually dies off
56
eukaryotic chromosomes have ___ ____ @ the very end of their chromsomes (repetitive sequence) called ____
end caps telomeres
57
_____ are the part that get cut off because they don't actually code for anything [TTAGGG]
telomeres
58
telomeres will bind to the ____ to stop?
proteins chromsomes from being recognized as a mistake or issue SO THE CELL DOESNT KILL ITSELF
59
We have continuously dividing cells in our bodies called ___ cells( that are ____ _____ that produce ____ cells) so they quickly lose their _____ and so the cells become ___-_______
stem bone narrow blood telomeres non-functional
60
so uncertain cells that divide continuously need an extra ____ called _____ which is capable of?
enzyme telomerase adding and building more telomeres
61
DNA polymerase can make _____ (this is how ____ occur)
mistakes mutations
62
**** when DNA polymerase is adding new nucleotides to the growing strand on the 3' prime end the wrong ______ can be added in the sequence BUT _____ can be damaged by?
nucleotides DNA UV radiation and other threats
63
**** there are #___ repair mechanisms what are they and what do they do?
3 1. proofreading- done by DNA polymerase it will double check and make sure the correct nucleotide is added catching 99% or more mistakes (spelling correction) 2. mismatch repair: AFTER DNA polymerase is already done its work...new enzymes come in to scan DNA for any mistakes and if there is it will cut it our and DNA polymerase will fix it by adding the correct bases 3. Excision repair: different enzymes scan DNA for damage(so no mismatches) BUT actual damage to the bases and be removed and then DNA polymerase comes back to repair it

BIO EXAM #5 (3 decks)

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