Summary Biology Chapter 5 (5.4–5.7) Year 3 Biology – Genetics and Pedigree Analysis Notes

​Biology Notes Ch5.4-5.7 Y3​


​5.4​
​​
● ​ he​​dominant allele​​only needs one in order to show​
T
​●​ ​The​​recessive allele​​would need two to show​
​●​ ​A pair of matching alleles is a​​homozygous pair​
​●​ ​A pair of not-matching alleles is a​​heterozygous pair​
​●​ ​A​​chromosome​​is a thread like structure of DNA found in the nucleus​
​●​ ​A​​gene​​is a small piece of DNA that encodes a protein​
​●​ ​An​​allele​​is a variant of a gene​


​A​ ​a​
​A​ ​AA​ ​Aa​
​a​ ​Aa​ ​aa​


​A​ ​A​
​a​ ​Aa​ ​Aa​
​a​ ​Aa​ ​Aa​


​A​ ​A​
​A​ ​AA​ ​AA​
​A​ ​AA​ ​AA​


​a​ ​a​
​a​ ​aa​ ​aa​
​a​ ​aa​ ​aa​

, ​5.5​
​●​ M ​ utations​​are changes in genes\chromosomes​
​~ more specifically, the nucleotides in DNA change​
​~ the protein completely changes​
​●​ ​When mutations occur in sex cells, they can be passed on to​
​offsprings​​and future generations​
​●​ ​Mutations can also be neutral\good!​​Beneficial mutations​​are part of​
​what causes species to adapt & change​
​●​ ​Cancer is caused by mutations​
​●​ ​Cells divide to keep you alive​
​Sometimes a mutation occurs, which disrupts that process (over​
​division)​
​That often leads to cancer.​
​●​ ​Normal cell division: normal cell → cell division → healthy tissue​
​●​ ​Mutation snowball effect: 1st mutation → 2nd → 3rd → 4th →​
​malignant cells tumour growth​​(cancer)​




​5.6​
​●​ W
​ hen a characteristic is inherited in a​​sex linked manner​​, the​
​inherited characteristic is located on one of the sex chromosomes (x​
​chromosome, not y)​