2. It takes about eight hours for one of
your cells to completely copy its DNA.
The human DNA code is made up of
about thirty billion A,T, C, and Gs on
each side of the DNA strand.
3. If the total DNA in one person were laid
in a straight line, it would stretch to
the sun and back over 600 times (it's 93
million miles from here to the sun).
You could fit one million threads of
DNA across the period at the end of
this sentence.
4. Our genes are remarkably similar to those
of other life forms. For example, we share
98% of our genes with chimpanzees, 90%
with mice, 85% with zebra fish, 21% with
worms, and 7% with a simple bacterium
such as E. coli.
5. The highest point in Kings
Park, the DNATower
(pictured) is so named
because it resembles the DNA
double-helix molecule.The
15m high staircase has 101
steps and was inspired by a
double staircase in a chateau
at Blois in France.
9. Meischer (1869)- discovered nuclein from leucocytes…but didn’t know
that it was nucleic acids
Chargaff (1952)- Gave his findings toWatson & Crick
Phoebus Levene (1905)- Russian scientist- Polynucleotide model,
tetranucleotide model
Erwin Chargaff (1950)- Chargaff’s rule; Showed that different species
contain different DNA sequence
Jerry Donohue (1952)- Suggested different cardboard cutouts to
Watson & Crick
Meischer 1869
10. GENES – units of genetic material that
CODES FOR A SPECIFICTRAIT
Called NUCLEIC ACIDS
DNA is made up of repeating molecules
called NUCLEOTIDES
16. Units combine by 3’-5’ phosphodiester
bonds to polymerise
3’- hydroxyl of one sugar is combined to 5’-
hydroxyl of another sugar through a
phosphate group
Bases jot in
Sugar phosphate skeleton
Sequence of nucleotides are of paramount
importance- Genetic code
5’-3’ polarity
17. Listen to the faintest sound, for opportunities knock only once
20. 1. Right handed double helix
2. Base pairing rule- complementary strands
A-T & G-C
Chargaff’s rule
3. Hydrogen bonding-
A-T– 2 H bonds
G-C– 3 H bonds
21. 4. Antiparallel strands
5. Each strand acts as a template for the
synthesis of the opposite strand
during synthesis
6. Pitch- 3.4 nm
10 bp / turn
Adjacent bases- 0.34 nm apart
Width- 20 A0
22. Major groove –
1.2nm
Minor groove- 0.6
nm
Tm- Melting
temperature of DNA
Annealing
24. Human diploid genome- 7109 bp-
distributed over 46 chromosomes
When placed end to end- 2meters
If one nucleotide added per second- 250
years to synthesize whole DNA of a
human cell
Length of DNA is compressed 10,000 fold
to generate chromosomes
Bacterial DNA- closed circular
25. Each chromatid- one strand of DNA
Hence 46 DNAs in 1 cell
Each DNA-2 strands
Hence total 92 strands of DNA
31. ‘Beads on String
appearance’
1.75 superhelical
turns- 146 bp
Nucleosomes →
solenoids
→chromatins
32. H2A & H2B- Lysine rich
H3 & H4 – Arginine rich
Histone synthesis stops when
DNA synthesis ceases
Chemical modifications-
acetylation, methylation, ADP
ribosylation, phosphorylation
Acetylation and methylation of
Lys residues- MC modification
33. Acetylation- activation of transcription
Deacetylation- depression of transcription
Phosphorylation- condensation of
chromosomes
ADP-ribosylation- DNA repair
Methylation- gene is repressed
Sumolytion of histones- repression of
transcription
(SUMO- Small ubiquitin related modifier)
34. 3 structural forms
A-E & Z
Change in structure helps in
different processes like
transcription, gene expression
35.
36. Characteristi
c property
A- DNA B-DNA Z-DNA
Shape Broad Intermediate Narrowest
Type of helix Rt handed Rt handed Lt handed
Base pair per turn 11 10 12
Tilt of the base
pairs relative
200 10 90
Diameter of helix 25.5 A0 23.7A0 18.4A0
Pitch per turn 25.3A0 35.4A0 45.6A0
Major groove Narrow Wide Flat
Minor groove Very broad Narrow Very narrow
Occurrence High salt medium
(Na, K, Cs)
Physiological form
In 92% HUMIDITY
Unusual DNA
37. A -form is meta-stable and quickly changes
to D form
C-DNA- found in 66% humidity, Li+ ions are
found- 9.33bp
D-form- 8bp/turn; 8-fold symmetry;
pronounced negative tilt
Z-DNA- initially synthesised in the lab; a
transient form; may have some regulatory
function. Repeating unit is a dinucleotide as
compared to B-DNA
38. ↑Temp or ↓salt concentration- splitting of 2
strands
Along with H bonds, the N bases also fall off
↑optical absorbance- Hyperchromicity
DNA loses viscosity after denaturation
Tm- exactly half of DNA is denatured
↑cations- ↑Tm; 10-fold increase will increase
16.60 Tm.
39. Separated strands tend to renature
Need base pair matching
Post-transcriptional joining- physiological
phenomenon
40. 1% of cellular DNA
2-10 copies
Circular double stranded
Heavy & light chain strands
16,569 bp
Genes code for 13 proteins of respiratory
chain
(54 out of 67 are coded by nuclear genes)
Genetic code different (UGA forTrp & AGA,
AGG of Arg as stop codons)
41. 2 r RNAs & 22 t-RNAs
No introns
High mutation rates
Stays in a relaxed or super-
coiled state- preferable mode
Maternal Mendelian
inheritance
OXPHOS diseases
42. Find out the OXPHOS diseases
Compare and contrast cellular and
mitochondrial DNA