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Bell Work Mitosis: • What occurs during mitosis? • What are the products of mitosis? • What is the purpose of mitosis?
3/8/18
Bell Work: Complete the pre-assessment on your Anchor Activity Unit 6 sheet. Get out your notebooks for Meiosis notes.
3/9/18
REPRODUCTION: THE NATURAL PROCESS BY WHICH NEW ORGANISMS ARE GENERATED
Asexual Reproduction
1. Requires only 1 parent
2. Offspring are identical to parent
3. Examples: Binary Fission (bacteria), Budding (Hydra and yeast)
A Hydra
budding
Sexual Reproduction
1. Requires 2 parents which each:
provides a gamete – sperm or egg
Give DNA to offspring
2. Two gametes fuse to create a new organisms → Fertilization
3. Offspring are different from both parents
4. Example: Meiosis
FERTILIZATION: Male & female reproductive cells (GAMETES) fuse to form a new cell (ZYGOTE) that develops into a new organism.
Gametes: • Have 1 copy of each
chromosome or gene • Haploid, n
Zygotes: • Have 2 copies of each
chromosome (1 from each parent)
• Diploid, 2n
haploid haploid
diploid
Somatic Cells: a. Have 2 copies of each gene – diploid b. Make up most of the cells in your body
MEIOSIS
Making the Reproductive Cells: Starts with Germ Cells
1. Interphase: • DNA replication
2. Prophase I: • Homologous chromosomes pair up • Crossing over occurs
Interphase and Meiosis I
HOMOLOGOUS CHROMOSOMES
• A pair of chromosomes, one from each parent
• Carry the same genes
• Are identical in shape
Sister Chromatids
Homologous Chromosomes
Crossover
Crossing Over: Homologous chromosomes exchange pieces
3. Metaphase I Homologous chromosomes line up at metaphase plate
4. Anaphase I Homologous chromosomes pulled to opposite ends of cell
5. Telophase I Nuclear envelope reforms
6. Cytokinesis 2 daughter cells with ½ number of chromosomes as parent.
End of Meiosis I: 2 new cells each with 2 copies of 1 chromosome (from only 1 parent)
1. Prophase II Nuclear envelope breaks down
2. Metaphase II Chromosomes line up at metaphase plate
Meiosis II
3. Anaphase II Sister chromatids pulled to opposite ends of cell
4. Telophase II: Nuclear envelope reforms
5. Cytokinesis: 4 daughter cells with 1 copy of each chromosome
4 Haploid Cells each genetically different
DNA replication
Meiosis I
Diploid Cell
Meiosis
Meiosis II
MITOSIS MEIOSIS
DNA Replication
Number of cell divisions
Number of daughter cells and genetic
composition
Role in the body
Once in Interphase Once in Interphase
One Two
2, diploid, identical to
parent
4, haploid, different from
parent
Growth & Repair Reproduction
Bell Work 3/12/18
Make a Venn Diagram comparing Mitosis and Meiosis
Complete your Meiosis on the Table
When you have completed your modeling of meiosis on the
whiteboard your options are:
1. Complete the Meiosis worksheet – due tomorrow
2. Take notes from the slides on the website (#21 to #26).
3. Do the Google Classroom Assignment (Chromosomes and
Karyotypes) – due Thursday
4. Work on “Identifying Genetic Disorders with Karyotypes” – due
Thursday
Bell Work 3/13/18
Make a Venn Diagram comparing Mitosis and Meiosis
2. Independent Assortment: Chromosomes are randomly segregated & sorted during metaphase I
Sources of Diversity in Meiosis & Sexual Reproduction
1. Crossing Over during Prophase I
3. “Random” Mating Combination of sperm & egg that form the zygote is random.
Chromosome Mutations
Deletion of a part of a chromosome
Duplication of a part of a chromosome
Inversion of a chromosome
Translocation between 2 different chromosomes
Breakage of a chromosome caused by errors in cell division or damaging agents such as radiation.
Mistakes during Meiosis
Nondisjunction: An error that can occur during meiosis in which chromosomes DO NOT separate.
Human Fruit fly Karyotypes: • a photograph of
chromosomes grouped as homologous pairs
• Can be used to determine gender and diagnose disease
Sex Chromosomes: • All organisms have 1 pair, X
and Y • X and Y have different
genes • Females have 2 X
chromosomes • Males have 1 X & 1 Y
Autosomal Chromosomes: • Paired – 1 from each
parent • Each pair has the same
genes
Bell Work 3/14/18
1. What is the gender of the individual shown on the right?
2. Is the Karyotype normal? If not, where is the abnormality?
XYY Syndrome: • Male • Taller • Sexually normal • Increased risk of
learning disabilities
Turner Syndrome: • Short • Infertile • Female
Down’s Syndrome: Intellectual disability Weak muscle tone Increased risk of
other medical conditions
Edwards Syndrome • Low birth weight •Heart defects •Often die before
birth or in 1st month
Patau Syndrome • Severe intellectual
disabilities • Physical abnormalities • Small eyes • Extra fingers or toes • Many infants die in 1st
days
Klinefelter Syndrome: •Male •Produce less
testosterone •Delayed puberty •Breast enlargement • Sterile
Bell Work 3/14/18
1. What is the gender of the individual shown on the right?
2. Is the Karyotype normal? If not, where is the abnormality?
Triple X Syndrome: • Female •Often infertile •Otherwise normal
2. Independent Assortment:
What are 3 events that occur during meiosis and zygote formation that contribute to genetic diversity in a species?
1. Crossing Over during Prophase I
3. “Random” Mating
Bell Work 3/15/18
• Alleles: Different sequences of the same gene
Mendelian Genetics - Vocabulary
Alleles are either dominant or recessive
• Homozygous: both alleles in the organism are the same; Homozygous Dominant and Homozygous Recessive
• Heterozygous: each allele for a gene in the organism is different.
• Genetics: Study of heredity • Heredity: passing of traits from parent to offspring
• Genotype: the alleles an organism has for each gene
• Phenotype: the outward appearance of the genotype
• Trait: characteristic that varies from person to person, depends on
combination of alleles for each gene • Punnett squares:
diagram showing the allele combinations that MIGHT result from the fusion of 2 gametes to form a zygote.
R = violet, dominant r = white, recessive Genotype Phenotype Genotype ratio Phenotype ratio
RR = violet 1 Rr = violet 2 3 rr = white 1 1
R r male / sperm
R
r
fem
ale
/ e
ggs
Sample Cross:
Rr x Rr
R R
r r
R
R
r
r
Gregor Mendel (1822-1884)
• Austrian monk. • Studied inheritance of traits in
garden peas. • 1866: Defined the laws that govern
inheritance of traits.
Mendel’s Pea Plant Experiments
• Pollen – produced by the
stamen, contains the sperm
(male reproductive cell).
• Flower – contains the ovary or
egg (female reproductive cell).
a. Self-pollinated: pollen and ovary
from same flower fertilize
b. Cross-pollinated: pollen and
ovary from different flowers
fertilize
• Plants can be:
• Generations in breeding:
1. P1: Parental generation.
2. F1: 1st generation offspring (from breeding individuals in
P1 generation).
3. F2: 2nd generation offspring (from breeding individuals in
F1 generation).
• Observation: Offspring retain traits of
parents.
• Conclusion: Physical traits are inherited
as particles
• Mendel studied 7 traits in pea plants by:
1. Allowing plants to self-pollinate for
many generations to create a pure
strain (homozygous)
2. Cross-pollinating plants w/ different
traits
• Types of Genetic Crosses a. Monohybrid: Cross involving a single trait (for example
flower color). b. Dihybrid: Cross involving 2 traits (for example flower color
and plant height)
male / sperm
fem
ale
/ e
ggs Genotype:
Phenotype:
P1 Cross
Monohybrid
Trait: Seed Shape
Alleles: R – Round; r – Wrinkled
Cross: Round seeds x Wrinkled seeds
(RR x rr)
Genotype ratio:
Phenotype ratio:
male / sperm
fem
ale
/ e
ggs
Genotype:
Phenotype:
F1 Cross
Monohybrid
Trait: Seed Shape
Alleles: R – Round r – Wrinkled
Cross: Round seeds x Round seeds
(Rr x Rr)
Genotype ratio:
Phenotype ratio:
yellow round
green round
yellow wrinkled
green wrinkled
F1 Generation
Dihybrid cross – P1 generation
YYRR yyrr yr yr yr yr
YR
YR
YR
YR
YyRr
YyRr
YyRr
YyRr YyRr YyRr YyRr
YyRr YyRr YyRr YyRr
x
YyRr
YyRr YyRr YyRr
YyRr
Dihybrid cross – F1 generation
YyRr YyRr
YR Yr yR yr
YR
Yr
yR
yr
YYRR YYRr YyRR YyRr
YYRr YYrr YyRr Yyrr
YyRR YyRr yyRR yyRr
YyRr Yyrr yyRr yyrr
x yellow round
green round
yellow wrinkled
green wrinkled
F2 Generation
true-breeding yellow, round peas
true-breeding green, wrinkled peas
x
YYRR yyrr
YyRr
100% F1 generation
yellow, round peas
self-pollinate
F2 generation
9/16 yellow round peas
9:3:3:1
3/16 green round peas
3/16 yellow
wrinkled peas
1/16 green
wrinkled peas
Y = yellow
R = round
y = green
r = wrinkled cross-pollinate
Dihybrid Crosses
Mendel’s Laws of Inheritance:
1. Law of Dominance:
Some alleles are dominant and some are recessive – the dominant
alleles mask the recessive alleles.
2. Law of Segregation:
During gamete formation the 2
alleles that determine trait
separate from each other and
at fertilization are recombined.
3. Law of Independent
Assortment:
Alleles for different traits
are sorted randomly
during Metaphase I.
Each pair of alleles segregates into gametes independently
Gametes with different combinations of alleles are produced in equal amounts
YyRr
Yr Yr yR yR YR YR yr yr
Trait: Seed Shape and plant height
Alleles: R – round r – wrinkled
T – tall t - short
Cross: 1 round seed, tall plant
1 wrinkled seed, tall plant
(RrTt x rrTt)
Phenotype Ratio:
Bell Work 3/16/18
Bell Work 3/19/18
How do Mendel’s observations of the pea plant offspring support the Law of Dominance?
Corn Snake Genetics
Correction on the handout:
Under Albino snake, change the genotype:
It is NOT Bbrr – it SHOULD be bbrr
Bell Work 3/20/18
To determine the true genotype of your new ‘wild’ corn snake (B_R_), you cross it with an albino corn snake (bbrr). 1. What offspring phenotypes
are possible for each possible genotype?
2. How will this tell you what the genotype of your snake is?
BbRr
br
br
br
br
BBRR
BBRr
BbRR
Sex Chromosomes: Chromosomes with genes that determine gender. X-Linked Traits: Genes carried on the X Chromosome
Autosomes: Chromosomes with genes that do not determine gender. Autosomal Traits: Genes carried on these chromosomes
There are 2 types of chromosomes:
Gene notation for X-linked traits:
Xupper-case letter : For the dominant
allele on X-chromosome (XH)
Xlower-case letter : For the recessive
allele on X-chromosome (Xh)
Y : For the male chromosome
Females have 2 X chromosomes:
XX with allele shown by upper- or lower-case letter for each
X. Heterozygous female: XRXr
Males have 1 X which is paired with 1 Y chromosome:
XY with allele shown by upper- or lower-case letter on the
X. Male with recessive trait: XrY
Male with dominant trait: XRY
Offspring Ratios
Gender:
Genotype:
Phenotype:
In Fruit Fly, eye color is X-linked:
Xr = white eyed (recessive)
Cross white-eyed female fruit fly w/ red-eyed male fruit fly:
White-eyed female genotype:
Red-eyed male genotype:
Practice
Cross a female carrier of Hemophilia and a normal male
1. Normal (XH) is dominant over hemophilia (Xh)
2. Parent Genotypes
Mom:
Dad:
3. Offspring ratios
Gender:
Genotype:
Phenotype:
Hemophilia is an X-linked Trait: Practice
Background: Sickle cell Anemia is a recessive trait carried on chromosome 11. In regions where malaria is common, individuals who are heterozygous for sickle cell anemia have a 60% survival advantage compared to individuals who are homozygous dominant (AA). Individuals who are homozygous recessive for sickle cell anemia (SS) live on average to ~45 years.
Problem: Two heterozygous parents living in Madagascar have children. What is the probability that they will have children who will survive to the age of 65 years?
Bell Work 3/22/18
Co-dominant Alleles:
Alleles – B and W
BB = Black
WW = white
BW = Multi-colored
Both alleles contribute to the
phenotype B B
W
W
BW
BW
BW
BW
In some chickens neither black nor white
feathers is dominant – chickens with
both alleles are checkered
Blood Type has 3 alleles: IA, IB, i
IA and IB: co-dominant
i: recessive
Multiple Alleles
Genes with more than 2 alleles
These alleles represent the antigens that are expressed on the
surface of your red blood cells
Antibodies in your
plasma will attack only
those red blood cells
(RBCs) with an antigen
different to the one on
your own RBCs.
Blood Type and
Blood donors
Red Blood Cell
antigen Plasma
antibody
Blood
type
Genotypes
IA IA
IA i
IB IB
IB i
IA IB
i i
Phenotype
A
A
B
B
AB
O
RBC*
Antigen
A
A
B
B
A & B
none
Plasma
Antibody
B
B
A
A
None
A & B
Malaria and the Inheritance of Sickle Cell Anemia
Sickle Cell is an example of a co-dominant trait:
Individuals w/out the disease have 2 normal alleles – AA
Individuals w/ 1 diseased allele have the “trait” – AS
Individuals w/ 2 diseased alleles have the disease – SS
The Ghost in Your Genes
Bell Work: 4/2/18
About 70% of Canadians get a bitter taste from the chemical phenyl
thiocarbamide (PTC), while the other 30% do not. The ability to taste PTC (T)
is a dominant characteristic, while ‘taste-blindness’ to it is recessive (t).
Tongue-rolling is dominant (R); inability to roll the tongue is recessive (r).
A tongue-rolling woman who is taste-blind for PTC has a father who could
not roll his tongue but could taste the PTC chemical. She marries a man
who can taste PTC but cannot roll his tongue. His mother was taste-blind to
the chemical. Show the possible children this couple could produce. Use a
Punnett square to illustrate your answer.
Daughter Genotypes:
Her Fathers Genotypes:
Husband Genotypes:
His Mothers Genotypes:
A tongue-rolling woman who is taste-blind for PTC has a father who could not roll his tongue but could taste the PTC chemical. She marries a man who can taste PTC but cannot roll his tongue. His mother was taste-blind to the chemical. Show the possible children this couple could produce. Use a Punnett square to illustrate your answer.
Daughter Genotypes: Her Fathers Genotypes:
Husband Genotypes: His Mothers Genotypes:
Offspring Genotype Ratio: Offspring Phenotype Ratio:
Incomplete dominance:
One allele is not completely
dominant over another
Some flowers show incomplete
dominance in flower color:
Alleles – R and W
RR = red
WW = white
RW = pink
Polygenic Inheritance:
The inheritance pattern is controlled by two or more
genes each with two alleles.
• Polygenic inheritance shows up as a range of variation such has height, skin color or hair color.
• The results of an average population will yield a bell-shaped curve.
Height is an example of an incompletely dominant trait that is
determined by more than one gene.
TTHH: very tall TtHh: med.
TtHH or TTHh: tall
TtHh, ttHH, TThh: med.
tthh: short
What is the probability that 2 medium
height parents will have tall or very tall
children?
Example of inheritance of height: keeping it simple, we will only
consider only 2 genes (T & H).
Eye Color in Humans: Polygenic Trait • At present, three gene pairs controlling human eye color are known.
• Two of the gene pairs occur on chromosome pair 15 and one occurs
on chromosome pair 19.
• One gene, on chromosome 15, has a brown and a blue allele.
• The second gene, located on chromosome 19, has a blue and a green
allele.
• The third gene, located on chromosome 15, is a central brown eye
color gene.
Bell Work
A
B
1. What is happening in diagram A?
2. What phases of meiosis does diagram A
represent?
3. What is happening in diagram B?
4. What phases of meiosis does diagram B
represent?
4/3/18
Metaphase I Anaphase I
Metaphase II Anaphase II
Essential Question Notecard: What is the role of meiosis in sexual reproduction and genetic variation?
Bell Work 4/4/18 & 4/5/18
Possible vocabulary: Crossing over, Random mating, Haploid, Diploid, Gametes, Independent assortment
Essential Question Notecard: How can the ratio of offspring be predicted from patterns of inheritance?
Bell Work 4/5/18 & 4/6/18
Possible vocabulary: Allele, co-dominance, Punnett Square, gametes, trait, dominance, recessive, genotype, incomplete dominance, phenotype
Essential Question Notecard: How does the environment influence the expression of genetic traits?
Bell Work 4/6/18 & 4/9/18
Pedigree Charts
Show how a trait is passed from one generation to the next.
Can be used to
Infer the genotypes of family members
Study the inheritance of genetic disorders
Parts of a Pedigree Squares: males Circles: females Horizontal lines: breeding
couples Vertical lines: connect
parents to children
Shading: individuals with the trait being studied
Diagonal line: death Roman numerals: generations Numbers: identify individuals
in a generation
Half shading or a dot: “carriers” of the trait
No shading: individuals without the trait being studied
Interpreting Pedigrees
1. Is the trait dominant or
recessive?
• Trait skips a generation?
Most likely Recessive
• Trait occurs every
generation?
Most likely Dominant
2. Is the trait autosomal or
sex linked?
• Affects males & females
equally? Autosomal
(i.e. Aa)
• Affects one sex more
than the other (i.e.
mostly males)? Sex-
linked (XAXa, XaY)
Pedigree Chart for Eye Color (autosomal)
What are genotypes of individuals 8 & 9?
Huntington’s Disease Autosomal Dominant (H, h)
What is genotype of individuals 1, 2, 3, & 4?
1 2
3
4
Hemophilia: X-linked recessive trait (Xh)
What are the genotypes of the following individuals:
1:
5:
7:
8:
Individuals with hemophilia are shaded
The pedigree chart shows the blood types of three generations of family members. Some of the phenotypes are shown.
Bell Work 4/9/18
1. What is the genotype of individuals 1 -6?
2. Give the probable genotype of all other family members.
Building a Pedigree Chart: The father, Tom, & mother, Diane, have 3 children. The 2 oldest children are
Anna and Mary and the youngest is Teddy. The oldest, Anna, is married &
has an older son, Will, and a younger daughter, Vanessa. Mary is also married
and has a son, Patrick. Teddy is not yet married. Everyone in this family is
right-handed except the father, the oldest daughter, and the granddaughter.
Right-handedness is dominant.
Cystic Fibrosis: What is the pattern of inheritance? What are the Genotypes of the individuals?
Hypercholesterolemia (H, h) Autosomal or X-linked trait? Dominant or Recessive? What are the Genotypes of the individuals?