Lecture 2 & 3 DNA intro

Question 1

what are DNA 3 functions?

Answer 1

(SRM)
1. store info
2. replicated
3. mutates

Question 2

what is the central dogma ?

Answer 2

DNA (TRANSCRIPTON
RNA (REPLICATION AND TRANSLATION)
Protein

Question 3

what initiates gene expression

Answer 3

transfer of info

Question 4

what is a semi conservative model?

Answer 4

same 1 double dna strand converts to
1. 2 dna both with a new dna strand and an old dna strand
2. after replication the previous 2 dna that have old and new along with 2 dna that complete have two new strands together

Question 5

what is a conservative model ?

Answer 5

same 1 double dna strand
1. 2 dna one with a dna with both original stands and the second dna with both completely new dna strands
2. after replication 4 dna ( 3 all new) (1 is the original )

Question 6

what is the dispersive model

Answer 6

same 1 double dna strand
1. 2 dna stands that are MIXED with both old and new
2. after replication 4 more dna stand that both strands are mixed with old and new

Question 7

what did meselson and stahl do in 1958

Answer 7

meselson and stahl first grew ecoli in heavy nitrogen (15n) and transferred it to (14n) medium nitrogen and put it in a cetrifuge tube and the cetrifuge seperated it with the concetration of cscl, heavy dna at bottom
medium dna in middle
light dna at top

Question 8

what did meselson and stahl prove ?

Answer 8

dna replication is semi conservative

Question 9

why are 5 reasons mutation in dna important

Answer 9

1.to alterate protein or rna
2. evolution
3.form new allees
4. no product (protein or rna)
5.altered regulation of a product

Question 10

what are the 4 things a nucleic acid structure is comprised of
?

Answer 10

1.nitrogenous base
2. ribose sugar
3. phosphate group
4.nucleoside(tides)

Question 11

what are the 5 nitrogenous bases ? and which is one is for rna only and dna only

Answer 11

adenine
guannine
cytosine
thymine (DNA)
uracil (rna)

Question 12

what is the difference of the ribose sugars between dna and rna ?

Answer 12

dna has one alcohol groupd
rna has 2 alcohol groups

Question 13

what is a polynucleotide chain and how does it link ?

Answer 13

is multiple nucleitide and is linked via a phospherdiaster bond

Question 14

how is nucleic acids read

Answer 14

5’ end to 3’end

Question 15

what did watson and crick do

Answer 15

figure out the 3d structure of dna

Question 16

what is chargaff rule ?

Answer 16

number of A=T
Number of G=C

Question 17

what is B-dna

Answer 17

dna that has a major and minor goove and complete one turn in 10.5 base pairs

Question 18

what are three things major and minor grooves are good for ?

Answer 18

1.binding sites for different factors
2. recognizing specific nucleotides sequences on dna
3. has a distrubution of acceptors and donors

Question 19

what are the 5 forces that help form the double helix ?

Answer 19

1.phosphate back bone
2. stacking interaction (vanderwalls)
3. hydrophobic interactions
4. ionic interactions
5. hydrogen bonding

Question 20

what are the three forms of dna ? which is the only one that is left handed

Answer 20

A
B
Z - left handed

Question 21

what is the rise/base pair along the helix axis for (A) for b-form

Answer 21

0.34 nm

Question 22

what is the mean bp/turns for b-form

Answer 22

10

Question 23

what is the diameter for b-form ?

Answer 23

2nm(nano meteres)

Question 24

what are 5 things that denature dna

Answer 24

1.heat
2. low ionic strength
3. agents that influence hydrogen bonds
4. agents that enhance solubility of hydrophobic substances
5.high pH

Question 25

how can you monitor dna denature

Answer 25

via absorbance

Question 26

how does an absorbtion spectroo.. work ?

Answer 26

when dna is is double stranded absorption is low , which single stranded it increases

Question 27

what is hypochomic

Answer 27

when dna is still double standed and absortion is low

Question 28

what is hyper chromoic

Answer 28

when dna is single stranded and absorption is high

Question 29

in absorption sepc.. what is temperatue (tm)/ based on ?

Answer 29

the GC content , more gc conetent more temperatuve needed