Genetics & Inheritance
No description yet. This curated deck is ready for daily study.
Card preview (22)
Define inheritance?
Is the passage of hereditary traits from one generation to another
Define genetics?
Is the branch of biology that deals with inheritance
Define genotype?
Is the genetic make up of an individual
Define phenotype?
Is the physical characteristics determined by the genotype and the environment e.g blue eyes and brown hair
Define mutation?
Permanent change in a gene
Define Autosomes?
Any chromosome other than the sex chromosomes
Explain what is meant by recessive and dominant alleles?
Dominant: The dominant allele is an allele that is always expressed in a person. It does this by over-riding the influence of the corresponding allele on the other homologous chromosome. E.g. Pp Recessive alleles: The recessive allele is an allele that is completely hidden or masked by the presence of a dominant allele. A recessive allele is only expressed when no dominant allele is present. E.g. pp (homozygous recessive)
Explain what is meant by recessive and dominant alleles?
Dominant: The dominant allele is an allele that is always expressed in a person. It does this by over-riding the influence of the corresponding allele on the other homologous chromosome. E.g. Pp Recessive alleles: The recessive allele is an allele that is completely hidden or masked by the presence of a dominant allele. A recessive allele is only expressed when no dominant allele is present. E.g. pp (homozygous recessive)
Explain Autosomal dominant?
Caused by mutation of a single gene chromosome (Pp) e.g Huntington’s Disease
Define Autosomal recessive?
Caused by mutations of two gene pairs on a chromosome (pp) e.g cystic fibrosis
Define X-linked recessive?
Caused by the mutation on the X chromosome, usually expressed in males as they only have X chromosomes e.g colour blindness and haemophilia
Most inherited traits are not controlled by one gene but by: the combined effects of two or more genes OR combined effects of many genes and environmental factors. Give examples?
Example: Skin colour, hair colour, height, body build. Environmental factors: Skin colour affected by sun exposure. Height affected by malnutrition or disease. Body build affected by malnutrition or obesity
Describe the difference between autosomes & sex chromosomes?
Autosomes: Autosomes are any chromosomes other than a sex chromosomes. Sex chromosome: Sex chromosomes are the 23rd pair. In females, the 23rd pair consists of XX. In males, the 23rd pair consists of XY
Explain the term trisomy?
There are three chromosomes not two as normal. Downs syndrome.
Explain the term monosomy?
There is a missing chromosome e.g 45 instead of 46 chromosomes. An example of this is Turner’s syndrome when a female is born with only one X chromosome
Somatic cell division results in?
2 genetically identical cells
An example of a sex linked disorder is?
Haemophilia
An example of an autosomal dominant condition is?
Huntington’s Disease
The end result of Meiosis is the production of cells that have?
23 chromosomes
State two functions of a nucleus?
Control cellular structure Control cellular activites
Describe somatic division and the number of chromosomes involved?
Productions of two genetically identical cells to replace dead, injured cells or add new cells each with the same number of chromosomes as the original cells e.g 23 pairs or 46 total
Describe reproductive division and the number of chromosomes involved?
Production of gametes for sexually reproducing organs. Number of chromosomes in half the nucleus in half meiosis e.g 23