15. Genetics and the study of variation Flashcards
Define gene
The physical and functional unit of heredity, which carries
information from one generation to the next; a segment of DNA.
Define genotype
The specific allelic constitution of an organism, either of the entire organism
or for a certain set of genes or a certain gene.
Define phenotype
The morphological, biochemical and behavioural properties of an organism
resulting from a specific genotype and its interaction with the environment.
Define genome
The total set of different DNA molecules in an organisms
• the total amount of genetic material in a chromosome set - (in humans one set of chromosomes)
What is genetics?
Study of variation among living things and how this variation is inherited
What is the use of sequencing genomes?
- establish ways variation between/within species is inherited
- Identifying how genes are expressed
- examining inheritance at the population level
Variation may be due to…
- en/v factors
- genetic factors
- a combination of both - most common
Example of variation caused by en/v factors only
• Fetal Alcohol Spectrum Disorder (FASD)
factor - alcohol during pregnancy
Symptoms of FASD
- growth retardation
- characteristic facial features
- CNS anomalies (including intellectual impairment)
Example of variation from genetics only
- Huntington’s disease
- gene for huntingtin protein - we all have 2 copies
- if there are 42 repeats of CAG you have huntington’s (normal is ≈ 35)
Epigenetics
- Changes in gene expression that do not involve changes in DNA
- they may be passed from parent to offspring
Examples of variation from epigenetics
Mothers who were extremely stressed during pregnancy may have children who have more behavioural problems during the teens than others
