9| DNA STRUCTURE AND ANALYSIS

Question 1

The genetic material must exhibit these four characteristics

Answer 1

1. Replication; transcription when three major RNAs are synthesized
2. Information storage
3. Expression of Information; information flow within a cell
4. Variation by mutation; could effect specific proteins in transcription or translation

Question 2

Each is the specific product of a gene and directs synthesis of a protein

Answer 2

mRNAs

Question 3

How are the different RNAs distinguished

Answer 3

By their Sedimentation Rate, the Svedberg Coefficient (S)

Question 4

A type of RNA that assists in processing mRNAs

Answer 4

snRNA (small nuclear RNAs)

Question 5

The three types of RNA involved in gene regulation

Answer 5

1. antisense RNA
2. miRNA
3. siRNA (short interfering)

Question 6

This type of RNA is involved in replication of the DNA ends, at the telomers

Answer 6

telomerase RNA

Question 7

Griffith’s experiment with II-R (avirulent, no capsule) and III-S (Virulent, capsule) concluded that

Answer 7

Heat killed bacteria, and that II-R strands had been transformed into the III-S lethal strain by a “Transforming Principle” which modified the cell.

injecting II-R into mice = lives
injecting III-S into mice = dies
injecting heated III-S = lives
injecting live II-R strand and heat killed III-S from a dead mouse = dies

Question 8

Who concluded DNA was the genetic material and how?

Answer 8

Hershey- Chase by injecting T2 phages with 35P and 32S

35P (DNA only contains phosphorous not sulfur); radioactivity inside cell

32S radioactivity outside cell on the protein coat

Question 9

Concluded that: transformation cannot occur unless DNA is present. Therefore, DNA must be the genetic material

Answer 9

avery-mcleoid- mccarty

Tested and concluded that DNA is the substance that causes transformation per heat killed assay with protase(-), RNASE(-), DNASE(+) and control (+)

Question 10

Name indirect evidence

Answer 10

1. distribution: should be found where it functions (gametes n and somatic 2n)
2. Mutagenises (UV); DNA absorbs at 260nm; while protein at 280nm without mutaiton

Question 11

Direct Evidedence

Answer 11

Recombinant studies; proved DNA was the mechanism of heredity

Recombinant; ability to splice an organisms DNA to another, transgenetic animals

Question 12

If DNA is subjected to heat, the double helix is denatured and unwinds, termed

Answer 12

hyperchromatic shift

Question 13

The mid point where 50% of the strands have been unwound is termed

Answer 13

the Tm, melting templerature

Question 14

Who proposed that DNA exists in the form of a rt-handed double helix composed of two long antiparallel polynucleotide chains, held together by hydrogen bonds formed between complementary nitrogenous base pairs

Answer 14

Wattson and Crick

Question 15

The semiconservative mode says

1
(2)

Answer 15

(1) the storage of genetic information in the sequence of bases
(2) mutations resulting in alternations of bases

Question 16

Base + Sugar, can be termed as a

Answer 16

neucloside

Question 17

Base + Sugar + Phosphate, can be termed as a

Answer 17

neucleotide

Question 18

Base + Sugar, can be termed as a neucloside but a nucleoside monophospahte (NMP) is temed as a

Answer 18

neucleotide; Base + Sugar + Phosphate

nucleic acid components

Question 19

This bond makes the backbone of the nucleic acid strands

Answer 19

phospodiester bond

Question 20

A+G =

Answer 20

= T + C

Question 21

A + C =

Answer 21

=T + G

Question 22

A + T = G + C

Answer 22

not 100% true

Question 23

If purines= pyrimidines, what are they?

Answer 23

A=T
G=C
purines=pyrimidine
9=6

Question 24

cahrgaff’s rule

Answer 24

A+G = T + C

his base pattern was critical to the W and Crick model

Question 25

What does each show us

1. X- Ray Diffraction:
2. Electrophorisis:
3. Transformation:
4. FISH (Florescent in Situ Hybridization):

Answer 25

1. X- Ray Diffraction: over all molecular structure
2. Electrophorisis: size of the fragment
3. Transformation: genetic material or gene transfer between cells
4. FISH (Florescent in Situ Hybridization): chromosome location

Question 26

DNA stabilizing factors, name three

Answer 26

1. H- bonds
2. hydrophobic nitrogenous bases (horizontal interior)
3. hydrophillic sugar back bone (outside axis)

Question 27

Why where 32P and 35S chosen in the Hershey-Chase experiment? What was the rationale and conclusion of this experiment

Answer 27

1. bacteriophage was composed of 1:1 protein coat and DNA
2. phages attach to the host cell by absorption
3. new phage produced inside the cell

they proved DNA carries the genetic instructions not protein

Question 28

What observations prove DNA is the genetic material in eukaryotes

Answer 28

direct evidence:
1. recombinant DNA technology
indirect evidence:
2. Mutagenises (UV)
2. Distribution of haploid and diploid cells

Question 29

what is a retrovirus, exception to the DNA is genetic material rule

Answer 29

a single stranded RNA virus containing mRNA as its genetic material