Lecture #2 Flashcards
1
Q
Species hereditary :
A
genetic endowment members of a species have in common
2
Q
Individual heredity:
A
how genes contribute to differences
3
Q
The Genetic Code:
A
- Each cell has 46 chromosomes (23 pairs)
- The 23rd pair is the sex chromosome and is different for males (XY) and females. (XX)
- Except for egg and sperm cells which have 23 chromosomes
- The chromosomes of a cell are located in the cell nucleus and consist of a single strand of DNA helix on which thousands of genes are encoded.
- Alleles are pairs or series of genes on a chromosome that determine the hereditary characteristics.
4
Q
Meiosis
A
- Reduction division 46 to 23
- Makes sperm and egg cells as they only have 23 chromosomes
- one cell divides to produce 2 cells each with 23 chromosomes.
5
Q
Mitosis
A
- Usual cell division (growth and repair occurs)
- 1 cell divides to produce two identical cells with 46 chromosomes each)
6
Q
What are genes?
A
- located on a chromosome
- unit of DNA
- Variants of genes are referred to as alleles.
- Alleles are pairs or series of genes on a chromosome that determine the hereditary characteristics.
7
Q
Determination of sex
A
- Y has fewer genes
- When fertilisation occurs they always inherit the mother’s X chromosome and either the father’s X or Y chromosome determining the sex.
8
Q
Genotype
A
- The genes that an individual inherits
9
Q
Phenotype
A
- The way a person’s genes are expressed in observable or measurable characteristics, resulting from the interaction of genes and environment.
10
Q
Sex linked inheritance
A
- Males are more genetically vulnerable than females
- The Y chromosome is smaller than the X chromosome so fewer genes so, males don’t necessarily have a gene to counteract the genes on the opposite chromosomes so they have a possibility of having a greater number of genetic abnormalities.
11
Q
Polygenic Inheritance
A
- Multiple genes interact with one another and the environment
