Genes

Genes

What is a gene?
1. Definition
  1. heritable factor
  2. length of DNA
  3. influences specific characteristics
2. Genetics
  1. storage and transfer of information in living organisms
  2. comes from 'genesis' or 'origins'
  3. Experiments in 19th century
  4. Intense research in early 20th century
3. chemical composition
  1. 42 DNA molecules or chromosomes
  2. genes = shorter lengths of DNA
  3. chromosome = many genes
Where are genes located?
1. location
  1. specific position
  2. one type of chromosome
  3. called the locus
2. crossing over experiements
  1. genes linked in groups
  2. groups match one type of gene
  3. maps of the gene sequence produced
What are alleles?
1. definition
  1. specific forms of genes
  2. more than two alleles of a gene
2. Gregor Mendel: father of genetics
  1. difference between varieties = different heritable factors
  2. discovered alleles
3. position
  1. same locus as gene
  2. only one allele can occupy the locus of the gene
  3. expect two copies of the gene - different or same
Differences between alleles
1. one or a few bases differ
2. single nucleotide polymorphisms
  1. SNP
  2. position on gene where more than one base can be present
  3. several present
Mutation
1. forms new alleles
2. random changes
3. most common: base substitution
  1. one base in gene replaced with another
4. almost all neutral or harmful
  1. or lethal; cause mutated cell death
5. transferred to offspring only through gamete mutation
What is a genome?
1. whole genetic information in organism
  1. entire base sequence of each DNA molecule
2. human genome
  1. 46 molecules that chromosomes
  2. DNA molecule in mitochondrion
3. plant genome
  1. DNA molecules in chromosomes
  2. molecule in mitochondrion and chloroplast
4. prokaryote genome
  1. DNA in circular chromosome
  2. plasmids present
The Human Genome Project
1. timeline
  1. initiated 1990
  2. draft sequence 2000
  3. complete sequence 2003
2. Aim: find base sequence of entire human genome
3. junk DNA
4. satellite DNA
5. individual's genome only
6. revealed evolutionary history

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