Genetics
- Created by: Former Member
- Created on: 10-09-19 21:13
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- Section 3 - Genetics
- Sexual Reproduction and Meiosis
- produces genetically different cells
- gametes are haploid
- fuse to produce zygote (diploid)
- mitosis and develops into embryo
- fuse to produce zygote (diploid)
- gametes are haploid
- gametes are produced by meiosis
- 1st division
- duplicates DNA, chromosomes line up and pulled apart, each cell has mixture from mother and father - genetic variation
- 2nd division
- chromosomes line up, arms pulled apart - 4 haploid daughter cells
- 1st division
- produces genetically different cells
- DNA
- Made up of nucleotides
- double helix structure
- DNA strands are polymers with repeating units - nucleotides
- sugar molecule, phosphate molecule, base
- ATCG (adenine, thymine, cytosine, guanine)
- complementary base pairing A+T C+G (weak hydrogen bonds)
- sugar molecule, phosphate molecule, base
- stored as chromosomes and contains genes
- long coiled molecules of DNA
- DNA makes up genome
- gene codes for particular protein
- Made up of nucleotides
- Genetic Diagrams
- Alleles are different versions of the same gene
- inherited genes control characterisitics
- 2 versions of every gene in your body
- Dominant capital C recessive smaller c
- dominant alleles overule
- homozygous - two alleles
- heterozygous - two different
- to be a recessive characteristic, both must be recessive
- genetic diagrams can show the influence of a single characterisitic
- monohybrid inheritence
- can be shown in a monohybrid cross or a punnett square
- monohybrid inheritence
- Alleles are different versions of the same gene
- More Genetic Diagrams
- a genetic diagram can show how sex is determined in humans
- 23rd pair of chromosomes ** or XY determine the sex
- males XY females ** - equal chance of a boy or a girl
- All eggs have an X chromosome, but sperm can have X or Y
- Family Pedigrees can also show monohybrid inheritance
- family tree of genetic disorders
- e.g. cystic fibrosis
- for children to inherit the disorder, both parents must have it or be carriers
- recessive allele
- a genetic diagram can show how sex is determined in humans
- Variation
- organisms of the same species have differences
- genetic or environmental
- genetic variation caused by different alleles, which can lead to differences in the phenotype
- new alleles through mutations
- sexual reproduction causes alleles to be combined in offspring
- e.g. different breeds of dog
- genetic or environmental
- Alleles arise due to genetic mutations
- changes to base sequence of DNA
- little or no effect on the phenotype
- new combinations of alleles may interact to produce new phenotypes
- organisms of the same species have differences
- Human Genome Project
- researchers managed to map over 20000 human genes
- started 1993
- complete map of human genome (20500 genes) completed 2003
- 1800 genes related to disease
- medical applications
- prediction and prevention of diseases
- testing and treatment for inherited disorders
- new and better medicines
- researchers managed to map over 20000 human genes
- Sexual Reproduction and Meiosis
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