chapter 9 genetics handout fall 2011

CHAPTER 9 PATTERNS OF INHERITANCE (GENETICS)

I. The Foundation of GeneticsII. Basic TerminologyIII. Modern Principles of InheritanceIV. Solving Genetics Problems

A. Monohybrid CrossV. Sex-Determination and Sex-Linked TraitsVI. Non-Mendelian Patterns of InheritanceVII. Human Genetic Disorders/ConditionsVIII. How Phenotypes are Affected by

Non-genetic Factors (Environment)

I. The Foundation of Genetics

______________(mid-1800s) - Austrian monk, Father of

Genetics

- studied inherited ________ in edible garden peas by

making hybrids

p. 141

Fig. 9-10

1884 – Mendel died

1900s – his work was _________________ by

Carl Correns

Hugo de Vries

Erich Tshermak

II. Basic Terminology

III. Modern Principles of Inheritance (Based on Mendel’s Work)

1. Each trait is determined by a ____________; an organism has two _____________ for each gene.

2. Law of Dominance genotype Aa Bb

3. Law of Segregation Aa Bb

4. Law of Independent Assortment AaBb

AA aa BB bb

AbAb aBaB ababABAB

gametesgametes

gametesgametes

IV. Solving Genetics Problems

A. Monohybrid Cross

V. Sex-Determination and Sex-linked Traits

X chromosome Y chromosome

Fig. 9-14Fig. 9-14

p. 144p. 144

VI. Non-Mendelian Patterns of Inheritance A. Multiple Alleles and Co-dominance

e.g., human blood types

GenotypeGenotype

AA, AoAA, Ao

BB, BoBB, Bo

ABAB

oooo

(Universal donor)(Universal donor)

Frequency in Frequency in the U.S.the U.S.

(Universal recipient(Universal recipient))

Table 9-1 p. 146Table 9-1 p. 146 Human Blood Group CharacteristicsHuman Blood Group Characteristics

B. Polygenic Inheritance - when several genes influence a ____________________

e.g., eye color skin color

father

mother

VII. Human Genetic Disorders or Conditions - mutations - A. Due to abnormal # of autosomes e.g., Down syndrome or ____________ Fig. 9-22aFig. 9-22a

p. 153p. 153

Baby with Down syndrome

Typical Down syndrome’s hands and feet

Genetic test for Down syndrome (Fluorescence In Situ Hybridization or FISH)

Fig. 9-23 p. 153Fig. 9-23 p. 153

Why are there 3 copies of chromosome # 21?

________________________:

- the failure of chromatids to separate during anaphase II

B. Due to chromosomal deletions or presence of several repeats of a DNA sequence

1) Cri-du-chat syndrome

- “___________________________” (French) - deletion of short arm of chromosome # 5 - severely impaired _____________________

2) Fragile X syndrome

- multiple copies of GAT can inactivate the entire _________________________- the most common form of inherited _________________________________- attention deficit, ____________________

- large ears, long face, flat feet

C. Due to imbalance in the # of the X and Y chromosomes

1) Turner syndrome - X 1/3000 live births (females)

2) Trisomy X - XXX 1/1500

3) Klinefelter syndrome – XXY 1/1000 males

4) Jacob Syndrome – XYY 1/1000 males

TURNER TURNER SYNDROMESYNDROME

KLINEFELTER SYNDROMEKLINEFELTER SYNDROME

D. Due to single gene mutations or defects

1) Due to X-linked recessive alleles a) hemophilia b) red-green colorblindness c) Duchenne muscular dystrophy d) cleft palate

2) Due to autosomal gene defects (recessive) a) sickle cell anemia

- abnormal ____________________

Normal red blood cellsNormal red blood cells Sickle cells Sickle cells (abnormal red blood (abnormal red blood

cells)cells)

b) Cystic fibrosis - non-functional _______________________ - produce excessive _______________ - lung infections

D. Due to single gene defects…continued

3) Due to dominant alleles

e.g., Huntington’s disease

- delayed onset disease - brain slowly deteriorates: ___________ - loss of ________________________ - painful paralysis - Huntington gene – Chro. # 4 (1993) - huntingtin protein forms aggregates in

__________________ which die off

VIII. How Phenotypes are Affected by Non-genetic Factors (Environment)

A) Himalayan rabbit genotype = BB or Bb

B = black fur

phenotype? = __________________________________

Why???Why???

- enzyme producing black pigment - ______________ at 93°F (34°C)

B) Colors of pea flowers

- ________________________________________

C) Height

- _________________________________

D) Skin color

- ________________________________

E) Intelligence

F) Susceptibility to cancer