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GENETICS NOTES_CHAPTER 11 Introduction to Genetics/More on Geneticschapters13,14
I.The work of Gregor Mendel
• _____________________=The scientific study of
heredity.
A. Mendel’s Pea Plants
a. Austrian monk whose statistical work w/ pea plants
yielded a greater understanding of biological
inheritance
b. He knew each flower produces pollen,containing the
male reproductive cells-sperm and female portion
produces egg cells.During sexual reproduction,male
and female cell join in ________-making a new
cell that develops into an embryo
c. Pea plants self-pollinating
d. He started w/ true-breeding plants-meaning that if
they are allowed to self-pollinate,they make offspring
_________ to themselves.
i. 1 group ____ plants
ii. 1 group ______
iii. 1 made only ______ seed
iv. 1 made ______ seeds
****Mendel wanted to produce seeds from male and female
reproductive cells from 2 different plants,preventing selfpollination by cross-pollination,with 2 different plants as
parents….This allowed him to cross- breed characteristics
B. Genes & Dominance
i. Mendel studied different characteristics.
ii. These characteristics are called
______________-such as seed or flower
color or height in humans
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iii. Studied 7 traits-see p.264-and he studied
the offspring
iv. The offspring are called F1(“first filial”…Filius
and filia are Latin words for son and daughter)
v. __________________are the offspring of
crosses of parents w/different traits.
****Mendel expected characteristics to blend-like
red+white=pink-This was not the outcome
•
•
•
•
• 2 conclusions:
– 1) biological inheritance is determined
by factors carried by one generation to
another.we now call these chemical
factors that determine
traits___________________.
Different forms of a gene are called
___________________
– 2) The Principle of Dominance states
some alleles are ________________and
some are recessive
Alleles occur in pairs and only one allele w/ a certain
trait needs to be present for a
_________________trait
2 alleles of that trait must be present for
_______________traits.
Tall plants were dominant and short recessive
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Section 11-1
P Generation
Tall
Short
Principles of Dominance
F1 Generation
Tall
Tall
F2 Generation
Tall
Tall
Tall
Short
C.Segregation
Mendel wondered if the recessive alleles had disappeared
or were they still present in the F1 plants .He allowed all 7
kinds of F1 hybrids to produce an F2 generation by selfpollination
• F1 cross-recessive traits reappeared(~ ¼ F2 showed
recessive trait)
• Mendel said the alleles for tall and short
segregated(separated) during formation of sex cells
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• Each gamete (Sex cell) carries a single copy of each
gene
• F1 produces 2 types of gametes-one has short allele and
one has tall allele.
• ______________letter stands for dominant allele and
lower case letter for __________________.example:Tt
T stands for tall and lower case for short.
PROBABILITY AND PUNNETT SQUARES
– Likelihood for occurrence for a particular
event is __________________________
– PAST OUTCOMES DO NOT AFFECT
FUTURE OUTCOMES
– Probability is used to determine genetic
occurrences using a diagram called a
___________________-which can
predict and compare genetic variations
that will result from a cross.
– ____________________means the
organism has the same 2 alleles for a
trait---TT—also called true-breeding
– _______________means the organism
has 2 different alleles for a certain
trait---Tt-also called hybrid.
– ______________is the observed physical
trait----example:tallness or shortness
– ________________=genetic makeup or
actual alleles----example:TT or Tt
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Tt x Tt
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Tt x Tt
T
t
T
t
Genotypes__________________________________
Phenotypes____________________________________
– Each offspring will have the same probability of a
genotype and phenotype because each is
____________or a single occurrence
– Larger the # of offspring ,the closer
to_________________
III. Mendelian genetics
• Mendel wondered if the segregation of one pr of alleles
affected another(?)
• A) Independent Assortment
– To answer his questions ,he performed a
______________.
• 1)Two-Factor Cross F1
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– Crossed truebreeders w/ only round yellow peas
(genotype RRYY) x plants w/wrinkled green
peas(rryy)
– Offspring were round yellow,establishing the
dominance of RRYY
• Resulting genotype RrYy
rryy x RRYY
ry
ry
ry
ry
RY
RrYy
RrYy
RrYy
RrYy
RY
RrYy
RrYy
RrYy
RrYy
RY
RrYy
RrYy
RrYy
RrYy
RrYy
RrYy
RrYy
RrYy
RY
2) The Two factor Cross:F2
– All F1 plants were __________.He wanted to see
how the alleles will segregate when F1’s are crossed
w/ each other to make an F2 generation
– F2 produced 556 seeds-315 round 7 yellow and 32
were wrinkled and green
– _____________seeds had a combination…Therefore
seed shape separated separately from color.
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– This is known as ______________________-genes
segregate independently during formation of
gametes.This accounts for much of the variation in
color
B.Summary of Mendel’s Principles
• Inheritance of biological characteristics is controlled by
genes from the parents
• When there are 2 or more alleles of a gene,then one is
dominant and one is recessive
• Most sexually reproducing organisms have 2 adults w/ 2
copies of each gene-one from each parent.
• Alleles usually segregate independently.
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C.Beyond Dominant and Recessive alleles
Exceptions to the rules
****Majority of genes have more than 2 alleles.
****Some are neither dominant nor recessive and multiple
genes and alleles or genes control traits
1 ) Incomplete dominance-one allele is not completely
dominant over another one
• 2) ____________-both alleles contribute to the
phenotype—example –in chickens the allele for black
feathers is codominant with white---this results in
__________offspring
• 3) _______________-more than 2 possible alleles exist in
a population(not in one organism-example-rabbits have 1
gene for coat color,but 4 possible alleles for that gene….also
an example is genes for human blood type
• 4)_____________-traits controlled by 2 or more genes’
INTERACTION-4 different genes cover ….probably control
human skin color
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D.Applying Mendel’s principles
– _____________________started using fruit flies
to study genetics______________________________________The
y are easy to study because they produce many
offspring quickly….Mendelian genetics applied to
them
E. Genetics and the Environment
– Traits not determined solely by genes
• Traits determined by ____________________________
IV.Meiosis-already covered
V.Linkage & Gene Maps
Crossing –over during meiosis separates genes on the same
chromosome onto homologous chromosomes---This gives great
genetic ____________________.
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More on Genetics Notes➪ ____________________________- use desired
traits to produce the next generation-exampleselectively breeding dogs,horses,plants
➪ _____________________________crossing
dissimilar individuals—often useful in plants
➪ ________________________-continued breeding
of individuals w/similar characteristics
➪ Mutations are a source of genetic variation
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➪ DNA extraction-add chemicals that cause DNA to
uncoil from histones and burst out of nucleus
➪ ________________________________-making
changes in the DNA code of an organism
➪ _________________________________are
used to cut DNA into fragments and gel
electrophoresis is used to compare
____________________,or gene composition
➪ ________________________________-DNA
produced by combining DNA from different sources
➪ __________________In the process of
transforming bacteria,the foreign DNA is joined to
this small,circular DNA
➪ _____________________-contain genes from
other species---used for making insulin….
➪ A _____________is a member of a population of
genetically identical cells from a single source
➪ ___________________________is a picture of
chromosomes arranged in ordered pairs
➪ _______________________-chart that shows a
relationship within a family,usually tracking one
trait
➪ HUMAN BLOOD GROUPS1. Rh-single gene w/2 alleles---+ and -/+ is dominant
2. ABO blood groups – genes---IA,IB,and I or A,B,O
phenotype
genotype
Antigen on
RBC
Safe Transfusions
To
From
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A
B
AB
O
AA or AO
A
A,AB
A,O
BB or BO
B
B,AB
B,O
AB
A and B
AB
A,B,AB,0
OO
none
A,B,AB,O
O
➪ Autosomal Disorders-Albinism,Cysytic
Fibrosis,Galactosemia,PKU,Tay-Sachs
Achondroplasia,Huntington’s.hypercholesterolemia,Sick
le-cell disease
➪ 23 pairs of human chromosomes
➪ Xx=female and xy=male
➪ Sex-linked genes:
1. colorblindness is on x chromosome-rarely expressed in
females
2. hemophilia on x
3. muscular Dystrophy
➪ Chromosomal Disorder:
1. ___________________-homologous chromosomes
fail to separate
2. __________________-trisomy 21
3. Turners-only x
4. Klinefelter’s xxy,xxxy,xxxxy
➪ DNA fingerprinting
➪ Human Genome project-analyze human DNA
sequence
➪ a ______________- is a “generic” cell that can
make exact copies of itself indefinitely. It is a
precursor cell that has the ability to make
specialized cells for various tissues in the body
(such as heart muscle, brain tissue and liver tissue).
Stem cell research is expected to impact advances
in curing diseases such as Alzheimer’s and
Parkinson’s disease, diabetes, spinal cord injury,
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heart disease, stroke, arthritis, and cancer.
***Stem cells are primal, undifferentiated cells which
have the unique potential to produce any kind of cell in
the body. Medical researchers believe stem cells have
the potential to change the face of human disease by
being used to repair specific tissues or to grow organs
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