Notes Compiled by Giorgia Lobban (2021)
Meiosis
Life at a Molecular, Cellular and Tissue Level
SAGS List
Candidates should know:
The location of chromosomes in cells and their structure.
The significance of chromosomes in cell division.
The difference between haploid and diploid number and understand the significance of each
Where, when, and why meiosis takes place in animals and flowering plants
The process of DNA replication as part of interphase. (Suggest covering here to avoid
confusion with protein synthesis)
The process and terminology of meiosis. Only names of basic phases (e.g., Prophase I) are
required.
About chromosomal mutations that can arise as a result of abnormal meiosis, (use Down
syndrome as an example).
How to work with karyotypes
1|Page
, Notes Compiled by Giorgia Lobban (2021)
CHROMOSOMES
Long, thread-like structures that form part of the chromatin network in the nuclei of cells. They are
made up of a strand of DNA wound around proteins called histones.
In somatic (body) cells of diploid organisms:
- Number of chromosomes in each cell is the same
- Chromosomes are made up of two sets
- One chromosome of each pair comes from the mother (maternal chromosome)
- One chromosome comes from the father (paternal chromosome)
- They are called diploid cells, 2n for short.
For each paternal chromosome, there is a matching maternal chromosome, forming a
homologous pair
Chromosomes forming a pair are the same size and shape and have the same genes in the
same place
Alleles for each trait may not be the same
There are two types of chromosomes in humans
- 22 pairs of autosomes
- 1 pair of gonosomes
A haploid chromosome number is found in gametes
Replication DNA is especially important to ensure that, as a cell divides, each daughter cell
receives a full complement of all the genetic material
Diploid= having two sets of chromosomes in each cell
Haploid= having one set of chromosomes in each cell
Somatic cells= all body cells except sex cells
Gamete= sex cells (sperm or egg/ovum)
Autosome= chromosome that does not determine sex of an individual
Gonosome= sex chromosomes, X and Y
2|Page
Meiosis
Life at a Molecular, Cellular and Tissue Level
SAGS List
Candidates should know:
The location of chromosomes in cells and their structure.
The significance of chromosomes in cell division.
The difference between haploid and diploid number and understand the significance of each
Where, when, and why meiosis takes place in animals and flowering plants
The process of DNA replication as part of interphase. (Suggest covering here to avoid
confusion with protein synthesis)
The process and terminology of meiosis. Only names of basic phases (e.g., Prophase I) are
required.
About chromosomal mutations that can arise as a result of abnormal meiosis, (use Down
syndrome as an example).
How to work with karyotypes
1|Page
, Notes Compiled by Giorgia Lobban (2021)
CHROMOSOMES
Long, thread-like structures that form part of the chromatin network in the nuclei of cells. They are
made up of a strand of DNA wound around proteins called histones.
In somatic (body) cells of diploid organisms:
- Number of chromosomes in each cell is the same
- Chromosomes are made up of two sets
- One chromosome of each pair comes from the mother (maternal chromosome)
- One chromosome comes from the father (paternal chromosome)
- They are called diploid cells, 2n for short.
For each paternal chromosome, there is a matching maternal chromosome, forming a
homologous pair
Chromosomes forming a pair are the same size and shape and have the same genes in the
same place
Alleles for each trait may not be the same
There are two types of chromosomes in humans
- 22 pairs of autosomes
- 1 pair of gonosomes
A haploid chromosome number is found in gametes
Replication DNA is especially important to ensure that, as a cell divides, each daughter cell
receives a full complement of all the genetic material
Diploid= having two sets of chromosomes in each cell
Haploid= having one set of chromosomes in each cell
Somatic cells= all body cells except sex cells
Gamete= sex cells (sperm or egg/ovum)
Autosome= chromosome that does not determine sex of an individual
Gonosome= sex chromosomes, X and Y
2|Page
