* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Download 6.6 Meiosis and Genetic Variation
Vectors in gene therapy wikipedia , lookup
Genetic code wikipedia , lookup
Polymorphism (biology) wikipedia , lookup
Medical genetics wikipedia , lookup
Pharmacogenomics wikipedia , lookup
Polycomb Group Proteins and Cancer wikipedia , lookup
Genetic drift wikipedia , lookup
Ridge (biology) wikipedia , lookup
Biology and sexual orientation wikipedia , lookup
Koinophilia wikipedia , lookup
Gene expression profiling wikipedia , lookup
Site-specific recombinase technology wikipedia , lookup
Genome evolution wikipedia , lookup
Minimal genome wikipedia , lookup
Y chromosome wikipedia , lookup
Genomic imprinting wikipedia , lookup
Artificial gene synthesis wikipedia , lookup
Behavioural genetics wikipedia , lookup
Gene expression programming wikipedia , lookup
Epigenetics of human development wikipedia , lookup
X-inactivation wikipedia , lookup
Neocentromere wikipedia , lookup
Quantitative trait locus wikipedia , lookup
Genetic testing wikipedia , lookup
Population genetics wikipedia , lookup
Public health genomics wikipedia , lookup
Biology and consumer behaviour wikipedia , lookup
Heritability of IQ wikipedia , lookup
Genetic engineering wikipedia , lookup
Designer baby wikipedia , lookup
Human genetic variation wikipedia , lookup
History of genetic engineering wikipedia , lookup
6.6 Meiosis and Genetic Variation KEY CONCEPT Independent assortment and crossing over during meiosis result in genetic diversity. 6.6 Meiosis and Genetic Variation • Objectives: – Students will be able to: *describe how sexual reproduction creates unique gene combinations *explain how crossing over during meiosis creates genetic diversity. 6.6 Meiosis and Genetic Variation Sexual reproduction creates unique combinations of genes. • Sexual reproduction creates unique combination of genes. – independent assortment of chromosomes in meiosis=223 – random fertilization of gametes 223x223 =64 trillion • Unique phenotypes may give a reproductive advantage to some organisms. 6.6 Meiosis and Genetic Variation Crossing over during meiosis increases genetic diversity. • Crossing over is the exchange of chromosome segments between homologous chromosomes. – occurs during prophase I of meiosis I – results in new combinations of genes 6.6 Meiosis and Genetic Variation • Chromosomes contain many genes. – The farther apart two genes are located on a chromosome, the more likely they are to be separated by crossing over. – Genes located close together on a chromosome tend to be inherited together, which is called genetic linkage. • Genetic linkage allows the distance between two genes to be calculated. 6.6 Meiosis and Genetic Variation • Review – Describe how sexual reproduction creates unique gene combinations. – Explain how crossing over during meiosis creates genetic diversity – Fruit fly gametes each have four chromosomes, representing 2^4, or 16, possible chromosome combinations. How many chromosome combinations could result from fertilization between a fruit fly egg and a sperm cell? – Suppose two genes are very close together on a chromosome. Are the genes likely to be separated by crossing over? Explain – You know that you get half your DNA from your mom and half from your dad. Does this mean you got one-quarter of your DNA from each of your grandparents? Explain – Mitosis creates daughter cells that are genetically identical to the parent cell. If crossing over occurred between sister chromatids during mitosis, would it increase genetic diversity?