we will explore an intriguing and fascinating topic: how DNA is packaged into chromosomes. Together, we will delve into the magical process that occurs inside our cells, where complex genetic codes are transformed into organized and tightly regulated structures known as chromosomes. We will show you the amazing process of how DNA is intricately folded inside the cell nucleus and shaped into a chromosomal structure. You will learn about the proteins and incredible mechanisms involved in this process, and how the precise arrangement of genes within cells is achieved. Join us on this exciting journey into the small and intricate world inside our cells, and uncover the secret behind how DNA is packaged into chromosomes. Don't forget to subscribe to the channel and hit the notification bell to stay updated with all the latest and exciting content. Thank you for your continuous support and for watching us.

1. Packaging DNA into
Chromosomes

2. “Chromosomeslookdifferentatdifferentstagesof
cellcycle”

3. • Chromatin → the overall mixture that chromosomes are composed
(chromosomes are about half proteins, half DNA)
• Proteins → responsible for packaging the DNA in a regular fashion
within the chromosome
• When cell isn’t dividing, chromatin is in a less condensed iffuse state
• As cell prepare to divide, the chromatin condense, further into visible
chromosome
• There must be a highly organized packaging system to fit a lengthy
DNA molecule into chromosomes

4. Chromatin
proteins
Histone
proteins
Non-histone
proteins
➢ Positively charged
➢ Associate most intimately with DNA
➢ very basic proteins
➢ Group of 5 proteins :
o H1
o H2A
o H2B
o H3
o H4
➢ Negatively charged
➢ Made of heterogenous mixture of
molecules

6. •Chromatin
purification
•multimers
of about
200bp in
length
1973

7. •Chromatin
purification
•multimers
of about
200bp in
length
1973
•first electron
microscopic
observations of
chromatin
• showed linear
arrays of spherical
structures (beads
on a string)
the
following
year
Beads on string
Describe appearance of
chromatin under a microscope,
when DNA is in les condensed
form, it look like a string with
regulatory spaced :beads” on it.

8. • Chromatin
purification
• multimers of
about 200bp in
length
1973
•first electron
microscopic
observations of
chromatin
• showed linear
arrays of
spherical
structures (beads
on a string)
the
following
year
Kornberg
showed that
each
nucleosome is
made up of
equal amounts
of each histones
except H1
1975
Between
1977 and
1980

9. •Chromatin
purification
•multimers of
about 200bp in
length
1973
•first electron
microscopic
observations of
chromatin
• showed linear
arrays of
spherical
structures (beads
on a string)
the
following
year
•Kornberg showed
that each
nucleosome is
made up of equal
amounts of each
histones except
H1
1975
•Aaron Klug
(microscope)
•Characterization
of second level of
chromatin
structure
Between
1977 and
1980

10. • Nucleosome is the fundamental
unit of chromatin structure
• Each nucleosome is made up of
histone around which a segment of
DNA is wrapped