Genetics Flashcards
Genes
- Segment of DNA
directs synthesis of protein- Located in chromosomes
not every gene expressed in every cell
- Located in chromosomes
Genome
Sum of all DNA
Genome has lots of non coding DNA
Genetic code
Set of rules that translate nucleotide sequences into amino acid sequence (guanine, adenine, thymine, cytosine)
What is based on codons
Genetic code
What is 3 nucleotides?
Codon
Each codon specific for
one amino acid
human gene count
humans 20k genes 98% nonecoding
How can the genetic code be defined?
universal
Mendel
- Created genetics field
Crossed tall and short peas
Offspring in F1 gen were tall
Offspring in F2 ratio of 3 tall to one short
what ideas did mendel regect
- Reject ideas of blending inheritance
- Reject idea of genetic material being fluid that mixes
Monohybrid cross
Parents differ in alleles for one gene
Dihybrid cross
Parents differ in alleles for 2 genes
Law of independent assortment
Two traits are passed to offspring independently of eachother
Law of independent assortment does not
always apply
Environment can modify
gene expression
Dominance may also
be incomplete
Many traits are determined by
more than one gene
Many traits that are important in agriculture and forestry are
quantitative
Genetic breakthrough timeline
1858 - Darwin
- Theory of evolution
1866 - Mendel
- Work published-peas and shit
1953 - Watson and Crick
- DNA model
1961 - Nirenberg
- Cracks genetic code
2003 -
- Human genome sequenced
Traditional breeding
○ Accelerated evolution guided by humans rather than nature
Transgenic plants
○ Produced by inserting genes from another organism in plants
○ Increase resistance etc.
Gene banks
- preserve agricultural diversity
- Form of dried seeds frozen plant parts
gene bank example
KEW Gardens - millennium seed bank prodect
quantitative traits
- Show continuous rather than discrete variation *
-Are determined by several genes - Are influenced by environment
