B1 - Variation and inheritance Flashcards
What is a gene?
A gene is a short section of DNA. Each gene codes for a specific protein by specifying the order in which amino acids must be joined together.
Give examples of inherited characteristics.
- skin colour
- hair colour
- eye colour
- size of nose
Give examples of characteristics that aren’t inherited.
- accent
- piercings
- scars
What is a gamete?
Gametes are sex cells. The male gametes are the sperm, and the female gametes are the eggs. Gametes contain one set of genetic information.
How many pairs of chromosomes are in a human body cell?
23 pairs.
What is variation caused by?
- genes being mixed up when gametes are formed
- genes coming from two parents
- mutations
What are the issues linked with a person with an inherited disorder?
- should they inform their partners, employers and insurers about their disorder?
- should they accept the risk if passing a genetic disorder to their next generation
- should they rely on new technology to select an embryo that does not carry the disorder?
Why are the number of chromosomes in a cell usually even?
This is because the paired chromosomes separate when egg and sperm are formed.
What do chromosomes carry?
Chromosomes carry genetic information in genes.
Where in a cell are chromosomes found?
In the nucleus.
What is an allele?
An allele is different versions of the same gene.
What does cross pollinated mean?
The transfer of pollen from the male reproductive organ of one plant to the female reproductive organ of another plant.
What does heterozygous mean?
Heterozygous means that a person carries two different alleles of the same gene.
What does homozygous mean?
Homozygous is when a person has either two dominant or two recessive alleles.
What is a genotype?
The genotype of an organism demonstrates the alleles present for a particular characteristic.
