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unit 2 genetics.docx

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Biological Sciences
Mark Fitzpatrick

Genetics 1. Human karyotypes are used to show all the chromosomes in a cell. They can detect chromosomal abnormalities such as a missing chromosome. There are 22 chromosomes and a pair of sex chromosomes, ordered from largest to smallest, all in pairs and all the centromeres have to be lined up. 2. Human Karyotypes are created by staining all 23 pairs of chromosomes with a chemical dye called Giemsa. Staining these chromosomes reveal a banding pattern that is unique to that chromosome, which allows for identification, called G-banding.Karyotypes are mostly created with blood or fetal, although any tissue can be used. These fetal cells are obtained by amniocentesis or chronic villi sampling. 3. Some examples of disorders are Down syndrome, which is trisomy 21, Klinefelter syndrome, which is an extra x chromsome in males and gives fewer sexual traits and turner syndrome, which is a missing sex chromosome (missing Y) and reduces female traits. 4. Examples of non-disjunction of sex shromosomes are syndromes such as Turner or Klinefelter syndrome. These syndromes typically result from chromsomes failing to separate in Meiosis 1 or 2. 5. A mutation is an error in the DNA sequence molecule that can be caused by various factors, such as viruses. 6. 3 types of mutations are aneuploidy, which is an extra or missing chromosome, translocation, which is chromosome pieces being mixed up and deletion, which is when a part of a chromosome has gone missing. 7. Prenatal genetic screening occurs when mother’s would like to see if their future babies have any mutations or defects. This way, doctors can catch these problems early and try to heal them. 8. Chorionic villi sampling is when a doctor takes a very tiny piece of placenta from a mother’s baby in her womb and takes it to detect for mutations by placing them as a karyotype. Amniocentesis is when the doctor extracts a little amount of amniotic fluid from the mother’s womb, which has blood cells that the baby has shed, and detects mutations with karyotypes. 9. genetic trait-a charateristic of an individual that is determined from alleles and genes, height gene- part of chromosome that is responsible for particular trait,such as using letters AA or Aa allele- form of a gene located on a chromsome, such as the letter A in AA purebred- having descnded from common ancestors where all share similar traits, such as size P generation- the parent generation, with all of the original traits, such as mother AA, dad BB F1 generation- offspring from the cross of P generation, first filial generation, such as AB F2 generation- offspring from cross of F1 generation, second filial generation, such as AA Dominant Allele- where the traits are always expressed in an individual, such as brown eyes Recessive Allele- having an allele that is present but inactive such as blue eyes Phenotype- appearance of a trait in an organism, such as the colour white Genotype- appearance of a letter to represent the trait, such as W to represent colour white Homozygous genotype- having 2 alleles for a trait that are the same, like AA or aa Heterozygous genotype- having 2 letters that are different, such as Aa Hybrid genotype- an
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