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Unit 11 Assignment 11.2 Chromosomes
- Institution
- PEARSON (PEARSON)
This is the second assignment from unit 11 BTEC. This assignment was awarded a distinction grade and it covers all the criteria needed to complete the specification.
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Chromosome:They are formed from chromatin fibres through eukaryotic
cell division. Found in the nucleus of a eukaryotic cell (in
humans containing 23 pairs of chromosomes and 46 in total)
with a thread-like structure which contains lots of
chromatids. These chromatids are made up of single length
of DNA which is wrapped and histone proteins which form
nucleosomes of 8. Nucleosomes coil to form chromatin
loops. These chromatins are joining together to form a
condense chromosome.
Chromosomes generally carry genetic information from one generation to other. They are
involved in in the process of cell division, replication and creating daughter cells, and become
visible during the 1st stage of mitosis; prophase where the nuclear membrane plus the
nucleolus disappears.
Chromatids
Chromatid:
Start as one chromatid and in DNA replication of a chromosome, two identical sister
chromatids are created, and they are attached to one another forming a whole chromosome
of 2 identical sister chromatids. They are becoming chromosomes only when mitosis or
meiosis occurs which makes them separate.
In order to pass into the stage of cell division, chromatids allow each cell to hold two copies of their
information inside.
They are visible during prophase when the DNA condenses into sister chromatids and
the nucleus is disappearing.
Centromere:
Located where the two chromatids join, they attach to spindles during cell
division.
Made of DNA sequences. Centromere
Homologous chromosome:
Pair of chromosomes which have identical size, identical genes at the same location, gene loci on the
two chromosomes. But they might have different alleles.
One homologous come from one parent(mom) and the other comes from another Two sister chromatids=
parent(dad). chromosome
They take part in mitosis or meiosis where it allows the genetic material from both
parents to combine into new cells.
They pair up in the stage of prophase 1 and exchange their genetic material
by crossing over each other. They also can be visible.
Non-homologous chromosome:
Chromosomes which have alleles of different types of genes.
X and Y Chromosomes are known as non-homologous.
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