Download CHAPTER 10.1

CHAPTER 10.1
GENETICS DEVELOPED FROM
CURIOSITY ABOUT
INHERITANCE
THE BLENDING HYPOTHESIS
OF INHERITANCE

Trait- a variation of a particular gene
TONGUE ROLLING
HITCHHIKERS THUMB
BENT PINKY
EARLOBES
WIDOW’S PEAK
DIMPLES
MID-DIGIT HAIR
THE BLENDING HYPOTHESIS
OF INHERITANCE




Blending Hypothesis- early 1800’s, offspring would
appear as a blending of parental traits
Example: Purple flower X White Flower = Pink
Flower
ACTUALITY: Purple flower
DISPROVED
MENDEL’S PLANT BREEDING
EXPERIMENTS

Gregor Mendel- Austrian monk, gave rise to
genetics, studied pea plants
GREGOR MENDEL
PEA PLANT CHARACTERISTICS
MENDEL’S PLANT BREEDING
EXPERIMENTS



Genetics- the study of heredity
True Breed- when a plant is crossed with itself, it
ALWAYS produces identical offspring
Cross-fertilization- sperm from the pollen of one
flower fertilizes the eggs in the flower of a
different plant
Class Work

1. Explain how Mendel's particulate hypothesis
is different from the blending hypothesis of
inheritance.
2. What is the difference between selffertilization and cross-fertilization?
3. Describe a pattern of inheritance that the
blending hypothesis fails to explain.
CHAPTER 10.2
MENDEL DISCOVERED THAT
INHERITANCE FOLLOWS RULES
OF CHANCE
MENDEL’S PRINCIPLE
OF SEGREGATION
 Hybrid- an individual with two different alleles


Pure Breed (true breed)- an individual with two of the same
alleles


Hh
hh or HH
Allele- alternate forms of a gene (letters)
MENDEL’S PRINCIPLE OF
SEGREGATION

Homozygous- when two alleles are the same


Heterozygous- when two alleles are different



HH or hh
Hh
Dominant- apparent, capital letter (H)
Recessive- masked, lower case letter (h)
MENDEL’S PRINCIPLE OF
SEGREGATION
Principle of Segregation- when two alleles separate
during the formation of gametes
 Punnett Square- a tool to predict the possible
outcomes

MENDEL’S PRINCIPLE OF
SEGREGATION

Test Cross- breed a
homozygous recessive
individual with a
dominant phenotype
MENDEL’S PRINCIPLE OF
SEGREGATION
Phenotype- an observable trait
 Genotype- genetic makeup, combination of alleles

MENDEL’S PRINCIPLE OF
INDEPENDENT
ASSORTMENT

Dihybrid Cross- cross organisms differing in two
characteristics, proves independent assortment
 Predict
the colors of the offspring of 2
true-breeding Mirabalis plants, one
white, and one red.
MENDEL’S PRINCIPLE OF
INDEPENDENT
ASSORTMENT

Principle of Independent Assortment- alleles for genes
are sorted independently of one another
Class Work

1. What are the two possible gametes produced
by a plant that has the genotype Aa? Give the
probability of each type of gamete.
2. Use a Punnett square to predict the genotypes
produced if the plant in Question 1 is selffertilized. Calculate the probability of each
outcome.
3. List all the possible genotypes of a pea plant
with purple flowers and round seeds.
4. List the four possible allele combinations in the
gametes of a plant with genotype PpWw.
CHAPTER
10.3/10.4/10.5
THERE ARE MANY VARIATIONS OF
INHERITANCE PATTERNS/MEIOSIS
EXPLAINS MENDEL’S PRINCIPLE/SEXLINKED TRAITS HAVE UNIQUE
INHERITANCE PATTERNS
INTERMEDIATE
INHERITANCE

Intermediate Inheritance- when a heterozygote has a
phenotype between both homozygous parents

Also known as incompelte dominance
MULTIPLE ALLELES


When several alleles exist in a population
Example: Blood
MULTIPLE ALLELES

Codominance- when a heterozygote expresses both
traits
 IaIb

How is this different than intermediate
inheritance?
POLYGENIC INHERITANCE

When two or more genes affect a single
character
IMPORTANCE OF
ENVIRONMENT


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Leaves vary in size, shape, and greenness from year to
year depending on exposure to wind and sunlight
Nutrition/Exercise influence on height, body build, and
skin color
Temperature and fur

Siamese Cats
CHROMOSOME THEORY OF
INHERITANCE

Chromosome Theory of Inheritance- genes are located
on chromosomes, inheritance patterns are based
on fertilization and meiosis
CHROMOSOME THEORY OF
INHERITANCE

Gene Locus- the location of a trait on a
chromosome
GENETIC LINKAGE AND
CROSSING OVER

Genetic Linkage- the tendency for alleles to be
inherited together
SEX-LINKED GENES
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Sex-linked gene- genes located on a sex
chromosome
In humans sex linked genes are on the X
chromosome (most of the time)
Why do you think?
Men: XY
Women: XX
Sex-linked
Inheritance
Why
are some diseases more common in men
than women?
Ex.


Color blind
8 % of males,
but only 0.5% females
Sex-Linked Traits
Male and Female
Sex-Linked Traits in Human
Red/Green
Colorblindness
Hemophilia
Hemophilia
Hemophilia

Queen Victoria
of England was
a carrier
 1819-1901


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XBXB Normal Female
XBXb Carrier Female (normal)
XbXb Disorder female



( you need two copies of the gene in females to
express)
XBY Normal male
XbY Disorder male

Why do you think sex linked traits effect men more
than women?
Exit Ticket
this person XH Xh have
hemophilia? Is this male of female?
 Would person XHY have
hemophilia? Is this male or female?
 Would
Sex- Linked Cross
 If
a mother who is a carrier for
Hemophilia has a child with a
father who has normal blood?
What percent of the children will
have Hemophilia? What percent of
the boys?
Sex-Linked Cross
 Cross
a female that has normal
vision with a male that is
colorblind. What percent of
their children will be colorblind?
Pedigree
Offspring:
Shade in the trait expressed
Problems with Chromosome Number
5.
6.
7.
Monosomy – only one of a particular type of
chromosome (2n -1)
Trisomy – having three of a particular type of
chromosome (2n + 1)
Polyploidy – having more than two sets of
chromosomes; triploids (3n = 3 of each type
of chromosome), tetraploids (4n = 4 of each
type of chromosome).