9| DNA STRUCTURE AND ANALYSIS Flashcards
The genetic material must exhibit these four characteristics
- Replication; transcription when three major RNAs are synthesized
- Information storage
- Expression of Information; information flow within a cell
- Variation by mutation; could effect specific proteins in transcription or translation
Each is the specific product of a gene and directs synthesis of a protein
mRNAs
How are the different RNAs distinguished
By their Sedimentation Rate, the Svedberg Coefficient (S)
A type of RNA that assists in processing mRNAs
snRNA (small nuclear RNAs)
The three types of RNA involved in gene regulation
- antisense RNA
- miRNA
- siRNA (short interfering)
This type of RNA is involved in replication of the DNA ends, at the telomers
telomerase RNA
Griffith’s experiment with II-R (avirulent, no capsule) and III-S (Virulent, capsule) concluded that
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
Who concluded DNA was the genetic material and how?
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
Concluded that: transformation cannot occur unless DNA is present. Therefore, DNA must be the genetic material
avery-mcleoid- mccarty
Tested and concluded that DNA is the substance that causes transformation per heat killed assay with protase(-), RNASE(-), DNASE(+) and control (+)
Name indirect evidence
- distribution: should be found where it functions (gametes n and somatic 2n)
- Mutagenises (UV); DNA absorbs at 260nm; while protein at 280nm without mutaiton
Direct Evidedence
Recombinant studies; proved DNA was the mechanism of heredity
Recombinant; ability to splice an organisms DNA to another, transgenetic animals
If DNA is subjected to heat, the double helix is denatured and unwinds, termed
hyperchromatic shift
The mid point where 50% of the strands have been unwound is termed
the Tm, melting templerature
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
Wattson and Crick
The semiconservative mode says
1
(2)
(1) the storage of genetic information in the sequence of bases
(2) mutations resulting in alternations of bases
Base + Sugar, can be termed as a
neucloside
Base + Sugar + Phosphate, can be termed as a
neucleotide
Base + Sugar, can be termed as a neucloside but a nucleoside monophospahte (NMP) is temed as a
neucleotide; Base + Sugar + Phosphate
nucleic acid components
This bond makes the backbone of the nucleic acid strands
phospodiester bond
A+G =
= T + C
A + C =
=T + G
A + T = G + C
not 100% true
If purines= pyrimidines, what are they?
A=T
G=C
purines=pyrimidine
9=6
cahrgaff’s rule
A+G = T + C
his base pattern was critical to the W and Crick model
