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Genetics
Gregor Mendel
Chapter 11
Mendel
• Austrian Monk
• Was a local high school science teacher
• Job was to grow food for the entire
monastery
• Became interested in how traits are
passed from parents to offspring.
Variations
Human Genetics
Principles of Inheritance
• E:\Early_Principles_of_Inheritance.asf
Mendel
• Crossed and controlled breeding of pea
plants
• Used burlap sacks to control pollination of
flowering pea plants
• Very controlled experiment
• Many generations in a short period of time
Mendel’s Work
• Crossed a tall pea plant with a tall pea
plant, produced all tall plants.
• Crossed a short pea plant with a short pea
plant, produced all short plants.
• Crossed a tall pea plant with a short plant,
produced all tall plants.
• Took seeds from the previous cross,
produced 3 tall plants and one short plant
Monohybrid Crosses
• E:\Introduction____Classical_Genetics_an
d_Monohybrid_Crosses.asf
Mendel’s Research
• E:\Gregor_Mendel_s_Research_and_Prin
ciples.asf
Mendel’s Discoveries
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asf
Mendel’s Hypothesis
• Traits are controlled by factors (genes)
which always occur in pairs
• Factors (genes) separate during the
formation of sex cells (gametes).
• In a pair of factors (genes) one may mask
or hide the effect of the other trait.
Possible Gametes
Punnett Square
Punnett Square
Punnett Square
Punnett Square
Punnett Square
Punnett Square
Punnett Square
Pea Plants
Mendel’s Crosses
Genetic Terms
• Homozygous- two alleles that are the
same, TT or tt
• Heterozygous- two alleles that are
opposite, Tt (hybrid)
• genotype- using letters to represent traits,
TT, Tt, tt.
• Phenotype-a physical description of a trait,
• Homozygous tall, heterozygous tall.
Genetics
• In pigs white coat color is dominant to
black coat color. Curly tails are dominant
to straight tails.
• Cross a heterozygous white coat,
heterozygous curly tail male with a
heterozygous white coat, heterozygous
curly tail female. Predict the possible
results.
Probability
• E:\Probability.asf
Mendel’s research on Pea Plants
• E:\Gregor_Mendel_s_Reseach_on_Pea_P
lants_and_His_Development_of_Theories
_of_Inheritance.asf
Dihybrid Crosses
• E:\Introduction___Dihybrid_Crosses.asf
Dihybrid Cross
Dihybrid Cross
Breeding Song Birds
• E:\Breeding_White_Songbird_Canaries_T
hrough_a_Dihybrid_Cross.asf
Incomplete Dominance
• E:\Incomplete_Dominance_in_Snapdrago
ns.asf
Genetics
• In four ‘o’ clocks, red is incompletely
dominant to white flower color. The
heterozygous condition results in pink
flowers.
• Cross a red flower with a pink flower and
predict the results.
• Cross a pink flower with a pink flower and
predict the results.
Multiple Alleles and Co-dominance
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n_Human_Blood_Types.asf
Incomplete dominance vs. Codominance
• Incomplete- you get a mixture. Red and
white, you get pink.
• Co-dominance- both traits appear. Red
and white to make roan.
• A and B blood types combine to make AB.
Human Alleles
• E:\Possible_Combinations_of_Human_All
eles.asf
Fruit Flies
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f_the_Fruit_Fly_Drosophila.asf
Human Sex Chromosomes
Sex Linked Inhertiance
• E:\Introduction___Sex_Linked_Inheritance
.asf
Sex Linked Inhertiance
• E:\Inherited_Human_Traits_and_Patterne
d_Sex_Linked_Inheritance.asf
Color Blindness
• E:\Color_Blindness.asf
Color Blindness
Hemophylia
• E:\Hemophylia.asf
Pedigree Charts
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ked_Inheritance_in_Pedigree_Charts.asf
Sex Linked Traits
• Traits carried on X or Y chromosome.
• Most are carried on X chromosome.
• Therefore a male is 70 times more likely to
have a sex-linked trait than a female.
Sex limited traits
• Traits carried by both sexes and controlled
by the presence of sex hormones.
• Secondary sexual characteristics.
• Females- estrogen and progesterone
• Female traits- higher % of body fat vs.
lower % of muscle tissue. Breast growth
and production of eggs.
Sex Limited Traits cont.
• Males
• Voice change, growth of beard, production
of sperm, Higher % of muscle tissue vs.
lower % of body fat.
Sex Influenced Traits
• Traits that are dominant in one sex and
recessive in the other trait.
• Male pattern baldness.
Polygenic Inheritance
• More than one pair of alleles codes for a
trait.
• Skin color
• Hair color
• Eye color
• The more dominant traits, the darker, more
recessive, lighter the color.
Selective Breeding
• Luther Burbank worked with potato plants
to produce a potato that was resistant to
disease.
• You take the best two individuals with
qualities that are favorable, and allow
them to mate.
• Hopefully the traits are passed to
offspring.
Hybridization
• Crossing of two different organisms and
trying to pass the traits to the offspring.
• Cross between a cow and a buffalo and
producing a beefalo.
• Done with some domestic animals hoping
to produce a new breed.
• Many hybrids are sterile.
Hybrids
• Crossing of two closely related but
different individuals
• The goal is to get the best qualities of
each individual
• Example beefalo
• Goal was to get an individual that had
good tasting meat but was able to survive
extreme harsh weather conditions.
Hybrids
Genetic Disorders
• Human disorders can be caused by
dominant, or recessive genes. Some may
exhibit co-dominance.
• Many of these disorders are from
particular areas of the world. They have
become more prevalent due to the
breaking down of geographic and social
barriers.
Genetic Disorders
• Most genetic disorders are autosomal,
which means they occur on an autosome
or any chromosome other than sex
chromosome.
• Sex linked- occur on X or Y chromosome
• Color blindness, hemophilia
Sickle Cell
Nondisjunction
• Failure of a pair of chromosomes to
separate during meiosis
• Trisomy- three chromosomes instead of
the normal pair.
• Monosomy- one chromosome instead of
the normal pair.
• May occur in any pair of chromosomes
Trisomy 21
• Downs Syndrome- results from
nondisjunction in the 21st pair of
chromosomes, they have 3 chromosomes
instead of the normal pair.
Karotypes
• Used by Geneticist to determine genetic
disorders.
• Take a photograph of chromosomes and
then line them up to see if correct number
exists or if part of a chromosome is
missing.
Karotypes
• E:\Karyotype___A_Key_to_the_Study_of_
Sex_Linked_Inheritance.asf
Karotypes
Cloning
• E:\Cloning.asf
Human Genome
• E:\An_Introduction_to_the_Human_Geno
me.asf
Becoming an Identical Twin
• E:\Becoming_an_Identical_Twin.asf
Identical Twins
• E:\Identical_Genes__The_Science_of_Ide
ntical_Twins.asf
Twins and Environment
• E:\Separated_at_Birth__Environment_vs_
_Heredity_in_Identical_Twins.asf
Genetics and Behavior
• E:\Novelty_Genes__Genetics_and_Behavi
or.asf
Hunting Down Genes
• E:\Hunting_Down_the_Genes_Involved_in
_Disease.asf
Tracking Traits
• E:\Tracking_Specific_Traits_Through_Gen
etic_Code.asf
Mutation
• Any change in the genetic code.
• Most mutations are harmless
• Most mutations correct themselves during
the next cell division.
• Mutations may cause an abnormal growth
of some types of cells, this may lead to
various types of cancer.
Mutations cont.
• Mutations can be on the DNA level, allele
level, or the chromosome level.
• Mutations may be harmful or lead to a
genetic change.
• Some genetic change may be positive.
Genetic Engineering
• Manipulating DNA
• Gene Splicing, cut DNA at a specific point
so that a new sequence of DNA can be
introduced. Ex. Injecting the gene to
produce insulin into bacteria so that it will
produce insulin.
Gene Splicing
DNA to Solve Crimes
• E:\Using_DNA_Evidence_to_Solve_Crime
s.asf
X Chromosome turned off
Aging
• E:\The_Molecular_Process_of_Aging__Tel
omeres_and_the_Death_of_Cells.asf