Genetics 4 Flashcards
Genetics
study of how traits are inherited from one generation to the next
who first described the DNA structure
after whos work?
Watson & Crick in 1953, ~100 years after Mendel’s
work
where are genes located
chromosomes
what are chromosomes
segment of DNA that directs the synthesis of a protein
the nucleotide bases
guanine, adenine, thymene, cystosine
Sum of all DNA
genome
The genome also has lots of non___________
coding DNA
Not every gene is expressed in every
cell
Set of rules that translate nucleotide squence into amino acid sequence
genetic code
what is the genetic code based off of?
codons
codons are
3 nucleotides
what is each codon specific for?
one amino acid
how many amino acids to plants make vs us
plants make 20 we make 10
Genetic code is
universal
difference with amino acids in RNA vs DNA
T is replaced with U in RNA
how many genes does every humans genome have
> 20,000
what percent of human genes are nonecoding
> 98%
how many genes does cottonwood genome have
40000
what do plastids also have
DNA
many plants are
Polyploid
meaning they have more than 2 complete sets of chromosomems
Gregor mendel
-created field of genetics
-Rejected ideas of blending inheritance and genetic material being a fluid that mixes
-Crossed tall and short pea plants
results of mendels experiment with peas
-All offspring in F1 generation were tall.
-F2 generation (offspring of F1 plants): Ratio of three tall
individuals to one short individual
interpretation of Mendels experiment
Monohybrid cross
recessive and dominant alleles
allele
one of two or more versions of a DNA sequence at a genomic location
two alleles are the same
the individual is homozygous for that allele. tt, TT
An individual inherits
2 alleles
two alleles are different
Tt heterozygous
draw the thing square thinng
1/4 will be recessive the rest will be heterozygos or homozygous dominant
diagram used to predict gynotypes of cross
punnet square
o traits (determined by two genes) are passed to offspring
independently of each other
law of independent assortment
dominance may be
incomeplete
many traits are determined by
more than one gene
ie.fruit size, yield, disease resistance, drought
gene expression can be modified by
the environment
ny traits that are important in agriculture and forestry are so-called
quantitative traits
quantitative traits
Show continuous rather than discrete variation * Are determined by several genes
* Are influenced by environment
Darwin
1858, theory of evolution
Mendel
1866 publishes his work (overlooked until 1900)
Watson & Crick
1953 provide DNA model
Nirenberg
1961 cracks genetic code
2003
Human genome sequenced
Breeders look at traits like ;
these are all __________ traits.
yield, disease resistance, and stress tolerance (drought, frost)
quantitative
what are the 2 ways to potentially modify plants
-Traditional breeding (works well with crops)
-Transgenic plants
-genome editing(sci fi)
Plant Breeding
accelerated evolution guided by humans rather than nature, guiding the representation of good plants in subsequent generations
corn breeding what happened
Decrease in branching and increase in seed size were selected for in corn breeding
why is having genetically uniform plants risky
new traits may become important in the future.
Disease tolerance
green revolution
By crossing desirable parents, Norman Borlaug created smaller and disease-resistant plants.
what are a solution to preserving genetic diversity?
Gene banks, frozen dried seeds
produced by inserting genes from virtually any organism into plants
why?
Transgenic plants
primarily for resistance of insects and herbicides
the inserted genes are called
transgenes
