Evolution: Fundamental Genetics
- Created by: meg_lou
- Created on: 18-04-17 12:41
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- Fundamental Genetics
- Mendel's Experiments
- Crossed a line bred true for brown seeds with one bred true for white
- First generation all had brown seeds
- When first generation was bred, there was 3/4 brown and 1/4 white
- White (ww), brown (BB)
- Brown was the dominant trait and white was recessive
- If Bw is present in the genotype (traits in the genes) then it will be observed in the phenotype (observable traits) as brown seeds
- Brown was the dominant trait and white was recessive
- Mendelian genetics
- Two genes for each dichotomous trait are alleles
- Homozygous organisms possess identical genes e.g. BB
- Heterozygous organisms possess different genes e.g. Bw
- There are dominant (brown seed) and recessive (white seed) traits
- Crossed a line bred true for brown seeds with one bred true for white
- Chromosomes
- Reproduction
- Egg and sperm combine to form a zygote with 23 pairs of chromosomes present
- Mitosis - cell division that produces daughter cells with 23 pairs of chromosomes
- Meiosis - 23 pairs of chromosomes are randomly sorted into the 2 gametes produced
- Linkage - tendency of traits encoded on the same chromosome to be inherited together
- Crossing over - increases diversity and 'shuffles the genetic deck'
- Structure
- DNA molecules of double strands of nucleotide bases wrapped around each other
- A nucleotide on strand 1 pairs with a particular nucleotide on strand 2
- To replicate, the strands unwinds and each nucleotide attracts its matching base
- This makes 2 DNA molecules identical to the first
- Reproduction
- Gene Expression
- Mechanism
- 1. Strand of DNA unravels
- 2. Messenger RNA (mRNA) synthesised from DNA transcription
- 3. mRNA leaves nucleus and attaches to ribosome in the cell's cytoplasm
- 4. Ribosome synthesizes protein according to 3-base sequences of mRNA translation
- 3. mRNA leaves nucleus and attaches to ribosome in the cell's cytoplasm
- 2. Messenger RNA (mRNA) synthesised from DNA transcription
- 1. Strand of DNA unravels
- Regulation
- Enhancers - DNA that determines whether particular genes initiate the synthesis of proteins and at what rate
- Transcription factors - proteins that bind to DNA and influence extent the genes are expressed
- Epigenetics - pattern of actual gene expression vs genes possessed
- MitochondrialDNA
- Energy-generating structures found in the cytoplasm of all cells that have their own DNA
- Once believed to come from the mother but paternal mitochondrialDNA have been found in one case
- Mechanism
- Mendel's Experiments
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