Distinction assignment from BTEC Applied Science Unit 11- genetics and genetic engineering. unit 11B includes the structure and function of human chromosomes, behaviour of chromosomes during meiosis and mitosis, and how the behaviour of chromosomes leads to variation.
, Structure of a chromosome:
A chromosome is a structure that is made up of long chains of DNA molecules and genetic
material from an organism. The main components that help to make up a chromosome are
2 chromatids, short and long arm, centromere, telomere, and DNA molecules.
Chromosomes are also known to be threadlike structures and are usually found within the
nucleus of the cell. The chromosome within a cell usually consists of genetic material (DNA)
which is needed for replication of the cell. A chromosome is made up of proteins as well as
one molecule of DNA (Genome research, 2015). It is essential that within cell division and
replication, that the chromosomes are not damaged, as well as ensuring that the overall
number and structure of the chromosomes do not change. This is important because it
helps to prevent any occurrence of disorders within the cell mainly caused by damaged
chromosomes.
Role of the components:
The first component of a chromosome is the chromatids. In each chromosome there are
two identical chromatids. Their main function of the sister chromatids is to pass on
chromosomes to the new daughter cells produced during cell division. In addition, they are
also important for helping the cell to store copies of their information which is essential for
replication of the cell during mitosis or meiosis (Biology Dictionary, 2016). Chromatids are
made up of one chromosomes and form two identical chromatids – sister chromatids – they
are also attached to each other through a centromere, and they are also pulled apart during
cell division in order to pass on one copy of the chromosome to the new daughter cell
produced (Biology dictionary, 2016). The main function of the sister chromatids is to assist
with DNA repair as well as duplicating their DNA during the process of interphase.
The centromere is another component of a chromosome. At the point of the centromere,
the sister chromatids are constricted, furthermore, the centromere also splits the
chromosome into the long and short arm. The main function of the centromere is to hold
together the chromosomes during the process of mitosis or meiosis, and this is important
because it helps to ensure that during DNA replication the sister chromatids do not lose
each other. The centromere separates the chromosome into the long and short arm and is
referred to as primary constriction. In addition, the long arm of the chromosome is known
as the q arm and the short arm is known as the p arm.
The telomere is another component of a chromosome and is known as the end section of
the chromosome. The telomere becomes much shorter in its length as the cell replicates
each time. Because the telomere is made up of non-coding DNA, the main function is to
help prevent the chromosome undergoing any damage. In addition, as the telomere
become shorter each time the cell divides, the chromosome will eventually be unable to
divide and replicate itself (Genome, n.d).
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