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2/22/2016, 10.1 – Intro. To genetics
• LT: Today I will…
– Differentiate between a
gene and trait
– Define some basic
genetics vocabulary
• ET: Read the chapter
mystery on pg. 307.
Write down the
question that is to be
investigated as we go
through the chapter.
Basic vocabulary to help
in our study of genetics
•
•
•
•
•
Genetics
Fertilization
Trait
Hybrid
Gene
• Allele
• Principle of
dominance
• Segregation
• gamete
Vocabulary cont…
• Gametes: These are sex cells
– Ex. Animals have sperm and egg
– Ex. Plants have pollen and ovum
• Fertilization: in sexual
reproduction, this is the joining
of gametes
– Ex. Sperm and egg form a cell that
develops into an embryo
Vocabulary
• Genetics: the study of
heredity – the passing
of genetic information
from one generation to
the next
• Trait: the physical
expression of a gene,
basically a characteristic
• Gene: the actual
information in the DNA
that determines traits.
This is what is passes from
generation to generation
• Allele: Different forms of a
trait
– The trait is height
– The different alleles for
height could be short or tall
Traits VS. Alleles
• The trait - eye color
– Alleles (forms): blue, brown, green
• The trait - thumb shape
– Alleles: bent or straight
• The trait - hair line
– Alleles: widows peak or straight
Vocabulary continued…
• Segregation: When homologous
pairs of chromosomes (one moms
and one dads) separate to make
gametes (haploid cells)
• Principle of Dominance: some alleles
are dominant over others
Lets look at some of these traits!
• Read through the “Quick
lab” on pg. 311
• Make the data table in
your notebook
• Make your prediction
according to step 2
• Figure out your features
• Survey your friends!
2/23/2016 11.1 - Gregor Mendel
• Learning Targets:
– Describe how Mendel
studied inheritance in
peas
– Summarize Mendel’s
conclusions about
inheritance
• Entry Task:
– Trait: fur pattern
– Alleles: ????
– Pick a trait and list the
possible alleles for that
trait
Gregor Mendel 1822
• Who: An Austrian monk
• What: developed an explanation for the
mechanism of evolution
What Mendel did…
P
Parental
F1
Generation
F2
Generation
Genotype VS. Phenotype
Genotype
• Homozygous – an
organisms has two identical
alleles, like “TT.” Both
parents gave a tall allele
– Homozygous dominant
– Homozygous recessive
• Heterozygous – an
organisms has two different
alleles, like “Tt.” Parents
gave different forms of the
height gene
Phenotype: what form of
the trait is expressed –
what they look like!
• Tall
• Short
• Blue eyes etc…
What every form of trait
you see in that individual
Lets practice!
For each set of alleles, write the genotype and phenotype.
• Straight hair is dominant over curly
– SS
– Ss
– ss
• Freckles recessive to no-freckles
– FF
– Ff
– ff
• Brown fur is dominant over white
– BB
– Bb
– bb
11.2 –
Genotypes
and
Phenotypes
• ET: Choose letters and write the
alleles for the given genotype
– Brown eyes is dominant over blue eye
• Homozygous dominant
• Heterozygous
• Homozygous recessive
– Widows peak is dominant over
straight hair line
• Homozygous dominant
• Heterozygous
• Homozygous recessive
– Attached ear lobes is recessive to
unattached
• Homozygous dominant
• Heterozygous
• Homozygous recessive
Mendel’s Conclusions
• Inheritance is determined by factors that
are passed from one generation to the
next, genes.
• Some forms of a trait (alleles) are more
dominant than others, the principle of
dominance
Biology – 2/24/2016
• LT: Today I will…
– Make predictions about
patterns of inheritance
– Use mathematical
methods for solving
genetics problems
(Punnett square)
• ET: Write the
genotype for an
individual who has
attached ear lobes,
has a widows peak,
and hairy fingers
– eeWWFF
– eeWwFw
Punnett Squares
• We will cross two homozygous parents
• TT – homozygous dominant
• tt – homozygous recessive
T
t
t
T
2/25/2016: 11.2/11.3 – Probability and
Patterns of Inheritance
• LT: Today I will…
– Explain the
principle of
independent
assortment
– Use Mendel’s
principles to solve
punnett square
problems
• ET: What are the possible
allele combination in the
following individuals gametes
– Genotype is TTRRGG
– Genotype is ttrrgg
– Genotype is TtRrGg
Lets practice making gametes!
• If the genotype is… • Possible gametes are…
1. Bbyy
By by
2. bbYY
bY
3. BBYy
BY By
4. HHJJII
HJI
5. Hhjjii
Hji hji
6. HhJjIi
HJI HjI Hji HJi hJI hji hJi hjI
Continued…
• Sex linked traits – some inherited traits are
located on the chromosomes that determine
gender, the X or Y.
• Females have two X chromosomes: XX
genotype
• Males have one of each: XY genotype
– EX. Hemophilia is an X-linked recessive disorder.
This means…
• If you’re a make, XY, and you inherit a recessive allele
it will show up because you do not have another X
chromosome with a normal dominant allele to over
power it.
The Two-Factor Cross: 2 traits
• P generation: RRYY homozygous dominant
for round yellow peas x rryy homozygous
recessive for wrinkled green peas
RY
RY
• RRYY Parent’s Gametes –
RY
• rryy Parent’s Gametes -
ry
ry
ry
ry
RY
Lets cross 2 F1 generation plants!
All the possible
combos.
RY
Ry
rY
ry
RY
RRYY
RRYy
RrYY
RrYy
Ry
RRYy
RRyy
RrYy
Rryy
rY
RrYY
RrYy
rrYY
rrYy
ry
RrYy
Rryy
rrYy
rryy
Other forms of Inheritance
• Incomplete Dominance = A blending of both alleles
– Ex. The allele for red petals is not completely
dominant over the allele for white petals so the
offspring has pink petals
Continued…
• Co-dominance = Both traits will show up. They are
not blended together, you actually see both
– Ex. The allele for black feathers is co-dominant
with the allele for white feathers so the bird is
black and white spotted
Biology 2/29/2016 – Meiosis Simulation
• http://www.biomanbio.com/GamesandLabs/
Genegames/snurfle_meiosis_and_genetics.ht
ml
Independent Assortment
• Genes for different traits can segregate
independently during the formation of
gametes (meiosis)
Crossing Over
Lets Model this Process!
• Get your bag of
chromosomes
• And pull out one set of
chromosomes
Polygenic Traits
• Traits controlled by two or more genes: eye and
skin color. So there are several different
combinations possible
*Incomplete dominance – In a heterozygote there is
a blending of the two traits ex. Red and white
produce pink
*Co-dominance – In a heterozygote both traits are
visible ex. Black and white speckled chickens