3. DEFINITION:-
Genome is a complete set of genetic material with in a organism
CHROMATIN :- It is in nucleus and thread like coiled structures and it is further
undergoes condensation to form chromosomes and suspended in nucleosome.
It has 2 varied categories are
EUCHROMATIN — uncoiled and active
HETEROCHROMATIN —condensed and inactive
Chemical composition of chromatin
•DNA — 22-40%
•RNA — 5-10%
•PROTIEN — 55-60% —> Histones (60%) and Non-histones(20%)
4. HISTONE:-
It is one of the major protiens in chromatin. These are also present in amino acids and
facilitate to bind with negatively charged DNA
In these also we have some varieties depends upon her nature are H1, H2A, H2B, H3 &
H4
NUCLEOSOMES :-
It is combination of 200 base pairs of chromatin and it is united of DNA packaging in
eukaryotes
5. EUKARYOTIC CELLS :- DNA is associated with basic proteins to form cytoplasm in
nucletiod region and structural protiens are named as histone.
HOW GENOME IS IN CELLS :-
PROKARYOTIC CELLS :- DNA is single circular chromosomes without basic protiens
and no de
f
ined nucleus
6. INFO IMAGES SIZES
A short region of DNA
double helix
2nm
Beads on a string forms a
chromatin
11nm
30 nm of chromatin
f
ibre
packed nucleosomes is
called solenoid
f
ibre
30nm
7.
8. CHROMOSOME:-
The chromatin material is thin thread like interwined mass of chromosome material
usually present in the nucleus and is composed ofthe genetic substance. Chromatin
material is composed of DNA (deoxyribonucleic acid) and proteins (histone and acidic
proteins). Chromatin is formed of repeating subunits, the nucleosomes, each of which
has a DNA molecule coiled around a disc of histones. The chromatin is condensed into
chromosomes during the cell division. Chromosomes are visible as rod-shaped
structures only when the cell is about to divide.
Chromosomes contain hereditary information of the cell in the form of genes. DNA
stores al the information necessary for the cell to function e.g. metabolism, growth
and reproduction.
