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Ch. 16 Genetics (Replication of DNA (replication fork (DNA uncoils and…
Ch. 16 Genetics
Replication of DNA
replicon
when separating
forms bubble
primer RNA
10 nucleotides long
polymerized
DNA polymerase
DNA-synthesizing
semiconservative replication
method of replication
strand of DNA acts as template for complementary strand
replication fork
DNA uncoils and separates
fork-like structure
ligated
attached by covalent bonds
two new molecules
replication forks run into another
Mutations
Causes of Mutations
mutagen
something that causes mutations
Insertion Sequences
few thousand base pairs long
code for enzymes that:
cut insertion sequence out
splicing it into DNA elsewhere
Transposon
longer than insertion sequences
carries out genes that code for proteins
not associated with transportation
Effects of Mutations
depends on its nature, position, and extent
almost always harmful
natural selection eliminates these
Somatic Mutations
can happen anytime in cell
does NOT lead to sex cell
offspring does not receive mutation
DNA Repair Processes
even one mutation can be harmful
must not be perfect
sexual reproduction would not be necessary
Definitions
mutation
#
any change in DNA
point mutation
base changed to different base
deletion
piece of DNA lost
insertion
addition of DNA
inversion
repaired DNA put in backwards
Monohybrid Crosses
Monohybrid Crosses with Incomplete Dominance
only single character is analyzed/studied
parental generation
"parents"
first filial generation (F1)
"kids"
F2
"grandkids"
homozygous
two identical alleles for this gene
exapmle: "rr"
heterozygous
two different alleles
example: "Rr"
incomplete dominance
neither parental trait dominates
Crossing Heterozygotes with Themselves
selfing
plant pollinates itself
Punnett square
#
Monohybrid Crosses with Complete Dominance
dominant
the trait that shows in heterozygous alleles
recessive
trait the does not go through in heterozygous alleles
Test Crosses
complete dominance
no recessive trait
hard to see genotype
test cross
plant being studied with homozygous recessive
pure-bred lines
special line of homozygous recessives
Multiple Alleles
X1, X2, X3, X4
more than R and r
Concepts
genetics
science of inheritance
gene
sequencing of DNA
alleles
gene occurs in multiple forms
differ by sequencing nucleotides
genotype
alleles that a single individual has
phenotype
physical characteristics
size, shape, metabolism
Dihybrid Crosses
Genes on Separate Chromosomes Independent Assortment
independent assortment
genes on separate chromosomes
alleles of one gene moves independently of other alleles
Crossing-over
independent assortment occurs when two genes located apart
prophase 1
Genes on the Same Chromosome Linkage
genes
linked
several types of heterozygote are possible
map unit
centimorgan
two genes studied/analyzed simultaneously
Multiple Genes for One Character
epistasis
having multiple genes for each trait
quantitative trait loci
genes with complex crosses, 100-1,000 progeny
have to be preformed to see what fraction of phenotype is related to gene
pleiotropic effects
multiple phenotype effects of one mutation
Other Aspects of Inheritance
maternal Inheritance
biparental inheritance
both parents transmitted equally
uniparental inheritance
maternal inheritance
zygote gets all plastid and mitochondrial genomes
pollen parent
ovule parent
variegation
plastid inheritance
spots; white, red, orange
Lethal Alleles
#
mutation can kill the plant
difficult to detect
Multiple Sets of Chromosomes and Gene Families
polyploid
more than two sets of chromosomes
nondisjunction
daughter cell gets two copies of chromosome
change in chromosome number per nucleus
paralogs
similar to wild-type allele
originated as duplicates
gene family
multiple copies of traits
effects
difference in squares
more in depth
