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Genetics - Coggle Diagram
Genetics
Monohybrid Crosses
Monohybrid Crosses with Incomplete Dominance
study of only a single character
white/red flower example
when both traits are expressed fractionally in offspring=incomplete
paternal generation
F1
F2
homozygous=same allele for gene
heterozygous=different alleles for gene
Crossing Heterozygotes with Themselves
selfling=crossing a plant with itself
selfling heterozygotes -> 3 F1 possibilities
rr, Rr, RR
Punnett square is useful to model this
allows the probability of phenotypical expression to be determined
Monohybrid Crosses with Complete Dominance
only one allele is expressed
characters will be:
all dominant (Rr,RR)
all recessive (rr)
Test Crosses
pairs made to determine a plants alleles from phenotype
cross unknown with known and see what is expressed
Multiple Alleles
the many forms in which a gene exists
cross=sexual reproduction between two individuals
Mutations
changes are more obvious with more traits studied
Causes of Mutations
mutagen=something that causes mutations
UV, chemicals, radiation
transposable elements
insertion sequences
few thousand base pairs
genes code for enzyme that physically rearranges sequence
transponson
similar to insertion sequence
may be longer, carries code for other types of proteins
Effects of Mutations
complicated process, mistakes are made
many mutations have little or no effect
point mutations may not even be noticed
codon may be for the same AA
different amino acid may work as long as it is not a critical piece
more often they are harmful
disrupt protein function
can result in death of the organism
Somatic Mutations
any mutation that occurs NOT in a sex cell
mutation is not passed on to offspring
DNA Repair Processes
enzymes search for anomalous coding
repair damaged sections
very important as thousands of errors can occur
DNA would in no way resemble orginial if left unchecked
mutation=any change in DNA
point mutation=single base converted into another
deletion=removal
insertion=adding
inversion=180degree rotation
Replication of DNA
replicon
small region cut from double stranded helix
exposed nucleotides attract their conjugate bases
form primer RNA
substrates for DNA polymerase
semiconservitave replication
one set from the original strand is conserved in new one
replication fork
appearance caused by splitting DNA
overall replication process occurs in less than 3 hours
occurs at many loci at a time
Dihybrid Crosses
differ in size of study
Genes on Separate Chromosomes: Independent Assortment
two genes on separate chromosomes
genes move independently of each other
yields looots of possibilities
Crossing Over
the random mixing of chromosomes
the further the genes are from each other, the greater the probability they will be separated
Genes on the Same Chromosome: Linkage
two genes located close to one another
rarely will be separated by independent assortment
recombinant chromosomes
formed when crossing over recombines alleles
parental type chromosomes
the same thing as the parent generation
each 1% of chromosome
map unit
=centimorgan
used to determine probability of seperation
2 genes are studied at the same time
e.g. petal color and shape
Multiple Genes for One Character: Quantitative Trait Loci
many genes can effect a single trait
complex enzyme combinations result in characteristics
epistasis
having multiple genes for each trait
quantitative trait loci
genes associated with the complex traits
pleiotropic effects
multiple phenotype effects of one mutation
e.g. phytochrome mutation->lots of problems
