1. Environmental Influence,
Genetics PowerPoint #2
Co-Dominance and Blood-typing, Incomplete Dominance, Genetic Disorders and Karyotyping, Pedigrees and Genetic Inheritance
Environmental Influence,
Sex-Linked Traits

2. In this presentation
Slides 3-4: Punnett Square Slide 5-7: Co-Dominance and Blood-typing Slide 8: Incomplete Dominance Slide 9: Sex Linked Traits (X-Linked Traits) Slides 10 & 12: Meiosis Slides 13-25: Karyotypes and Genetic Disorders Slides :Pedigrees and Genetic Inheritance Slides 28 & beyond: Assignments From EOC coach book

3. Monohybrid Cross (Punnett Square)
Used to determine phenotype and genotype of offspring (F1 generation).
Phenotype = physical (color, shape, appearance)
Genotype = gene or allele (Aa, AA, aa)
Dominant = trait always displayed (AA, Aa)
Recessive = trait always masked; only expressed when homozygous (aa)
Allele
Meaning AA
Homozygous Dominant Aa
Heterozygous
Homozygous recessive

4. Monohybrid Cross (Punnett Square)
Example: The trait for brown eyes is dominant to blue eyes (b). Show a cross between a parent (P1) with blue eyes, and a parent that is heterozygous for brown eyes. B b Bb bb
P1: Bb x bb
F1:
50% Bb (brown eyes),
50% bb (blue eyes)

5. Co-Dominance All traits are DOMINANT (no recessive; lowercase alleles)
In co-dominance, both traits are expressed.
Red Fish(R) x Blue Fish (B) = Red/Blue Fish

6. Co-Dominance and Blood Typing
Blood Type
Allele A
AA (dominant) or Ai (heterozygous) B
BB (dominant) or Bi (heterozygous) AB O ii
Always assume that in blood-typing, that the question is referring to the heterozygous allele (Ai or Bi), unless otherwise stated
Use the Punnett Square to determine blood type

7. Co-dominance and Blood Typing
What do you think? Is it possible for a mother with Type A blood and a father with Type B blood to produce a child with Type O blood?
Yes, it’s possible!
If both parents are heterozygous for the blood type

8. Incomplete dominance
All traits are DOMINANT (no recessive; lower cased alleles)
In incomplete dominance, traits blend together.
Ex. Red flowers (R) x White flowers (W) = Pink Flowers

9. Sex-Linked Traits “X-Linked Traits”
Affects the sex chromosomes (pair #23)
Most Sex Linked Traits affect the X chromosome.
Males are more affected by sex-linked traits because they only have one X chromosome
Females are often carriers because they have two X chromosomes
Female Sex Chromosomes XX
(carrier)
Male Sex Chromosomes XY
(affected)
She has an extra X, so she’s safe
He only has one X, so he has the disease

10. Meiosis Makes Gametes (sex cells)
Divides adult chromosome number in half (haploid); so that parents only pass 23 chromosomes to offspring.
Meiosis I: Homologous chromosomes
a) Crossing Over (swapping of chromosomes from mom & dad). Occurs in Prophase I
b) Law of Independent Assortment: states that alleles (genes) that you receive from your parents sort RANDOMLY; during Meiosis when your gametes are being made. The reason why you are genetically different, and look different from parents.
c) Non Disjunction (chromosomes do not separate properly), adding one chromosome, causing Down Syndrome, Klinefelter’s, Turner Syndrome
Meiosis II: Sister Chromatids
End result; four daughter cells with 23 chromosomes. Meiosis II and Mitosis are similar

11. Meiosis II II Crossing Over
Divides chromosomes number in half so there are only 23 chromosomes in gametes
23 mom + 23 dad = 46 you!
Crossing Over
Two diploid daughter cells with 46 chromosomes
Chromosomes break apart, exchanging genetic material
Law of Independent Assortment states that the chromosomes you get from mom and dad (23 Mom + 23 Dad) sort randomly as your gametes are being made during Meiosis II II
Four haploid daughter cells with 23 chromosomes

12. Events in meiosis
Crossing Over: Occurs in Prophase I, where the chromosomes break, and exchange genetic material
Why organisms look different than parents
Non-disjunction: failure of chromosomes to separate properly, causing organism to have extra chromosome (Trisomy 21)

13. Karyotypes and Genetic Disorder
Karyotypes are mapping of human chromosomes
A normal human karyotype has 46 chromosomes (diploid), and 23 pair (haploid).
Chromosomes 1-22 are called autosomes.
The sex chromosomes are the 23rd pair
Males are XY; females are XX

14. Normal Male Karyotype (XY)

15. Male (XXY) Klinefelter’s Syndrome
Males have an extra X Chromosomes
Smaller genital region
Develops breasts
47 chromosomes total

16. Klinefelter Male

17. Female Down Syndrome Karyotype
Trisomy 21
(Down Syndrome)
Extra pair #21

18. Down Syndrome (Trisomy 21)

19. Female Turner Syndrome (XO)
Female with 45 chromosomes total.
Missing and X chromosome.
Infertile
Does not go through puberty
Non-functioning reproductive organs

20. Female (Turner Syndrome) XO

21. Cystic Fibrosis Thick mucus in the lungs and digestive tract
Mainly affects Caucasian population
1 in 28 Americans carries the trait.
Caused by defective protein in cell membrane.
Treated with special diet, and physical therapy.

22. Tay-Sachs Disease Caused by recessive trait
An important enzyme (protein) is missing that breaks down lipids (fat) in the central nervous system.
Fat (lipids) accumulates in the CNS causing damage

23. Sickle Cell Anemia Primarily affects the African-American Community
Red blood cells are crescent shaped
Pain in the extremities
Caused by Point (substitution) mutation
Patients with SCA are immune to Malaria

24. PKU (Phenylketonuria)
Recessive disorder
Missing an enzyme that converts the amino acid Phenylalanine into Tyrosine.
Phenylalanine cannot be broken down by the body and causes damage to the CNS
Patients treated with diet low in phenylalanine
Phenylalanine is found in many diet sodas.

25. Huntington’s Disease Degeneration of Nerve Cells (neurons)
Cognitive impairment
Inability to focus
Muscle rigidity
No treatment
Death in 1-5 years
Neuron Apoptosis
(neurons die)

26. Pedigree Key Male Female Carrier Affected Male Affected Female
Marriage (Union)
A pedigree is a mapping of genetic inheritance. A family tree of disease.
Carrier

27. Pedigrees and Genetic Inheritance

28. Independent Assignment List
Green EOC Coach Book: COACH BOOKS DO NOT GO HOME!!!!!
Read each lesson, and answer the questions that follow. Write the question AND the answer! QUIZ GRADE. Due Tuesday, April 29th.
Lesson 20: The Structure and Function of DNA. Pp Answer Questions 1-4 on page 146-7
2) Lesson 21: The Structure and Role of RNA. Pp Answer questions 1-5 on page 153.
3) Lesson 22: Genetics: Pp Answer questions 1-4 on page 161
Lesson 23: Meiosis and Genetic Variation. Pp Answer questions 1-4 on pg. 166
4) Lesson 25: Genetic Disorders. Pp Answer questions 1-3 on page 177
5) Lesson 26: DNA Technology. Pp Answer questions 1-3 on page 185.
6) Chapter 4 Review: pp ; answer questions 1-18