Introduction
As a trainee lab technician supporting the Histology Department in the Western Health and
Social Care Trust laboratory, I have been tasked with demonstrating how to set up a
microscope and prepare microscope slides to observe and draw the stages of mitosis and
meiosis.
In this report, I will provide evidence of my practical work, including detailed observations
and drawings of the cell division stages. Additionally, I will discuss and explain the structure,
function, and behaviour of the chromosomes during cell division and evaluate how these
processes lead to genetic variation.
Structure and Function of Human Chromosomes
Centromeres
Centromeres are critical to chromosome shape and function, particularly during cell division.
They bind sister chromatids together after DNA replication and act as an attachment point
for spindle fibres during division. This ensures that daughter cells have the correct number
of chromosomes, preventing diseases (Canvas, Class Notes, 2024).
Chromatids
Chromatids are necessary for cell division, especially during mitosis and meiosis. They are
made up of sister chromatids connected at the centromere and play an important function
in ensuring that genetic material is correctly transmitted to daughter cells (Canvas, Class
Notes, 2024). During mitosis, sister chromatids are separated during the anaphase stage, but
in meiosis, homologous chromosomes couple up and exchange genetic material,
contributing to genetic variation (Nature Education, 2014).
Autosomes
Autosomes are chromosomes that contain the majority of an organism's genetic material,
including genes that affect physical attributes and illness susceptibility. Humans have 44
autosomes, 22 of which are not directly involved in sex determination. During cell division,
autosomes behave similarly to sex chromosomes, ensuring that each daughter cell obtains a
complete complement of genetic material. During meiosis, homologous autosomes link up
to increase genetic variety for evolution and adaptation (Canvas, Class Notes, 2024).
Sex chromosomes
The sex chromosomes are another name for another pair of chromosomes. The 23rd pair of
chromosomes determine an individual’s sex.
Two X chromosomes cause individuals to develop as a woman. One X and one Y
chromosome will cause ones to develop as a man. However, these chromosomes also
contain additional genes that control physical traits unrelated to sex (Canvas, Class Notes,
2024).
Chromosome number
Typically, a person has 46 chromosomes, arranged on 23 pairs. Each chromosome in a pair
matches for size and gene loci, even though these chromosomes do not pair up in the body's
cell nuclei unless the cell is getting ready for meiosis.