CHAPTER 10.1
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Transcript 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
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
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
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).