LS4001 - TOPIC 2 MOLECULAR & POPULATION GENETICS

UNIT 2 - MOLECULAR & POPULATION GENETICS

, Lecture 1 - DNA Structure, Genes & Chromosomes
LO: Understand the importance of DNA, The structure of DNA, and how genetic information
flows through the ‘Central Dogma’

Function of DNA:
Deoxyribose Nucleic Acid (DNA) stores a transmits the cells genetic into
storage
-



of main into

Must pass an exect copy ofall to each
its DNA daughter cell
-




* recovered from genetic testing.

fragments can survive for decades.
-
MUST:BE STABLE ACCURATELY COPY / CONTAIN CODED INFO.




History of DNA:
① MISCHER-1869

↳ used pos filled bandages to isolate substance rich in phosphorus oNitrogen from the nucleiof wic-named it nuclein/NA
② GUIffITH's EXPERIMENT -
1928

↳ Had Streptococcus pneumonial Bacteria -> smooth strain:virulent / rough strain harmless

-

only 5 strain virulent dead
=




strain harmless alive
only is
-
=




-
killed (strain (heat) = alive

-
livingReads - living found in heart.
dead



CONCLUSION:Achemical substance in dead'sis capable of transforming'n' into
becoming virulent.
③ AVERY, MACLEODO MCCARTY -
1944


↳ showed DNA is the chemical substance that transforms Bacteria




->remove lipids a sugars from heat killed's' cells:leave proteins/RNA/DNA



->
Treat with enzymes to destroy DNA/proleins/RNA



-> Add living's 'cells, observe transformation testpresence of virulent'scells)




↳ DNA is the chemical substance from dead's'strain that is capable to transfer is into virulent,

④ fRANRCINS 8 WICKINS -
1953

↳ used
X-ray diffraction to obtain images of DNA
⑤ WATSON UCHICK -
1953


Deduced DNAwas double Helix images.
after
x-ray diffraction
↳ a


- Wen nobel prize in 1962-100 years after pos.

, The structure of DNA:
↳ multiple nucleotides:Adenine/ Thymine/cytosine/avanine linked together by a
sugar phosphate backbone
-




7) I
polynucleotide strands run 'anti-parallel to eachother, held
by Hydrogen bands between bases.
strands are wound into 'double helix'.
↳ I a
v
↳ pyrimidines:Thymine, cytosine Corasil- UNA) each base has similar width
holding the backbone so is
↳ purines:Adenine, avanine the same distance apart.

Hydrogen bands
Thymine
complementary pailing
Adenine 2
+
=
base


Cytosine avanine+
3
=



Hydrogen bands




Deoxyribose (sugar) phosphate
+


Nitrogenous base
+




sO

·NCH, ↑ ↑M

↑!
0
Y
p=
o
li
↑
!n ↑in
phosphate joins to C4 of sugar o nitrogences base is linked to CI releasing MO
↳ polynucleotides formed via phosphodiester bands:
-
ot on 13 807 on phosphate joins releasing M28.
↳ Major aroove occurs where the backbones are far apart

↳ Minor arous occurs where they are close together
DNA
forms right-handed helix #


helix turn is 3.4
A nm with 10 bases perform

·naryotic
chromosomes:

↳ contain 2, double stranded, circular chromosome




Packaging Prokaryotic Chromosomes:
↳
By forming loops being supercoiled (non-relaxed
eukaryotes have multiple, linear chromosomes are complementary (diploid) 23 pairs Ihaploid each speciwegy 76 chromosomes
=
-
-




- Histone proteins bind to DNA
fold itinto coils(loops in an
organised way
-
between DNA protein
Complex is chromatin.


↳ Histones are
highly conserved, small basic proteins with the charge that bird to -ve DNA




↑ Nucleosomes play a
key role in chromatic
packing
↓
⑤Beads on
-
m string'
+