Nucleus
Parts of nucleus
•
Nuclear membrane
•
Nucleolus
•
Chromatin & nucleoplasm
Nuclear membrane
•
It is a double layer membrane. The outer layer of membrane attached with
ribosomes and continuous with rER.
•
Pores present
Nucleolus:
1. It is a structure found in the nucleus of
cells.
2. It is formed by proteins and nucleic acids.
3. It is occupies about 25% of the volume of the cell
nucleus.
Function:
It transcribes ribosomal RNA (rRNA)
The synthesis of RNA is regulated by five different chromosomes (13, 14, 15, 21, and 22).
Malfunction of nucleoli :
mutation causes malfunction of nucleus and it is related to following disease like Weine syndrome, Treacher Collins Syndrome and dyskeratosis.
Chromatin / Chromatin
granule-
The readily stainable substance of a non dividing
cell nucleus consisting of DNA and RNA and various
proteins; during mitotic
division it condenses into chromosomes
•
They are two types:
Heterochromatic
Densely packed
portion of chromatin which is genetically inactive.
Bluish in
colour.
Euchromatic
uncoiled portion of chromatin which is genetically active.
Lightly stain
uncoiled portion of chromatin which is genetically active.
Lightly stain
What is chromosome?
•
it is a
threadlike structures, which visible
during cell division and is composed by
•
DNA,
•
Small
RNA,
•
histone
and non-histone protein. (consisting
of genes that are responsible for the transmission of hereditary
characteristics)
Types of chromosome:
•
The
genes which regulate body character.
•
They are
22 pairs
•
The
genes which regulate sex character.
•
They are
1 pair
•
In male one X and one Y .
XY
•
In female two X.
XX
Chromosomes number in
human body
•
46
•
/23
pairs
•
22 pairs autosomes + 1pair sex chromosome
Diploid: A cell or an organism
consisting of two sets of chromosomes:
Usually, one set from the mother
and another set from the father.
In a diploid state,
the haploid
number is doubled, thus,
This condition is also known as 2n.
Haploid: The number of chromosomes
in a gamete
of an organism, symbolized by n.
Parts of a chromosome
Each chromosome has
a constriction point called the centromere, which divides the chromosome into
two sections, or “arms.”
The short arm of the chromosome is labeled the
“p arm.”
The long arm of the
chromosome is labeled the “q arm.
Chromatid - one of two identical strands into which a chromosome splits
during mitosis
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