Chromosomes are threadlike structures found in cells that carry genetic information in the form of genes. Each chromosome contains DNA and proteins. There are 22 pairs of autosomes that contain most genes and are identical between sexes, as well as two sex chromosomes, X and Y, that determine sex. Chromosomes are made of two chromatids joined at the centromere and have telomeres at the ends to protect the DNA. Chromosomes condense into chromatin and further condense during cell division. Histone proteins help package DNA into nucleosomes and chromatin within the nucleus.

1. Chromosome
By: MNV BioScie

2. What is a Chromosome?
a threadlike structure of nucleic acids and
protein found in the nucleus of most living cells,
carrying genetic information in the form of
genes.
Chromosome means: chroma - colour; some - body)
 First described by Strausberger in 1875.
 The term “Chromosome”, however was first used by
Waldeyer in 1888.

5. Autosome
• An autosome is any chromosome that is
not a sex chromosome.
• Each autosome stores many thousands
genes, each of which performs a
unique function in the organism's cells.
• 22 autosomes (chromosomes)
• Both identical both the two sexes.

6. Sex Chromosomes
• Sex chromosomes (Gonosomes) –
Chromosomes involved in sex
determination. 1 sex chromosome.
• Humans and most other mammals have
two sex chromosomes, the X and the Y.
• Females have two X chromosomes in their
cells,
• Sperms have both X and a Y chromosomes
• Egg cells all contain an X chromosome

7. Chromosome number
• Diploid cells (2N) where N- chromosome number have
two. Homologous copies of each chromosome.
• The body cells of animals are diploid.
• Haploid cells (N) have only one copy of each chromosome.
In animals, gametes (sperm and eggs) are haploid.

9. 2 parts:
Chromatids: two
identical parts of
a chromosome
Centromere:
Joins chromatid
together.
• Primary
Constriction

10. Telomere:
• A telomere is a region of repetitive DNA sequence at the
end of chromosome.
• Protects the chromosome from deterioration of rom fusion
with neighboring chromosomes.
Each chromosome has two arms
• p (the short arm)
• q (the long arm).

11. Kinetochore
• A kinetochore is a protein
structure that forms on a
chromatid during cell division
and allows it to attach to a
spindle fiber on a
chromosome.
• Its proteins also help to hold
the sister chromatids together
and play a role in

12. Karyotype
• A karyotype is simply a
picture of a
person's chromosomes
• Two chromosomes
specify sex, XX for female
and XY for male. The rest
are arranged in pairs,
numbered 1 through 22,
from largest to smallest.

13. Types of Chromosomes based on the position of Centromere
1. Metacentric Chromosomes
• The two arms are equal in length
• Appears in ‘V’ shape.
2. Sub metacentric Chromosomes
• Chromatids of one side are slightly longer than the other side
• Resemble the letter ‘L’.
3. Acrocentric Chromosomes
• Centromere is located closer to the end of chromatid
• The small round structure is termed as satellite
• Resemble the letter ‘J’
4. Telocentric Chromosomes
• Centromere at the end of chromosomes
• Not seen in human cells
• Resemble the letter ‘i’

14. Histone
• Histones are a family of basic
proteins that associate with DNA in
the nucleus and help condense it into
chromatin.
 Histone can be grouped into five major
classes: H1/H5, H2A, H2B, H3, and H4
 These are organized into two super-classes
as follows:
 Core histones – H2A, H2B, H3 and
H4
 Linker histones – H1 and H5

15. • A nucleosome is a section
of DNA that is wrapped
around a core of proteins.
Inside the nucleus, DNA
forms a complex with
proteins called chromatin.
• Histones help in order to
fit inside of the nucleus and
take part in the formation
of chromosomes.

16. Chromatin
• Chromatin is a mass
of genetic material
composed of DNA and
proteins that
condense to form
chromosomes.

17. DNA (deoxyribonucleic acid)
• the chemical inside the nucleus of a cell
that carries the genetic instructions for
making living organisms.
• The material inside the nucleus of cells that
carries genetic information.
GENE
• A gene is the functional and physical unit
of heredity passed from parent to
offspring.
• Genes are pieces of DNA, and most genes
contain the information for making a
specific protein