Mendelian Patterns of Inheritance Chapter 11

QOD:

c 1. Heredity i 2. Genotype e 3. Phenotype d 4. Dominant b 5. Recessive h 6. Alleles f 7. Homozygous

(Pure) a 8. Heterozygous (Hybrid) g 9. Genetics

Genetics Vocabulary Practice

a. The alleles of a particular gene are different b. Not expressed when the dominant form of the trait is present c. Passing of trait from parents to offspring d. The expressed form of a trait (cover up other forms) e. Physical appearance of a trait f. When the two alleles of a particular gene are the same g. Branch of a biology that studies heredity h. Different versions of a gene i. Set of alleles that an individual has

Ch 11

Sexual Reproduction and Genetics

Genetics: the study of heredity Heredity the passing of traits to the next generation. :

(from parent to child)

§ Trait: a physical feature (blue eyes)

Dominant trait: a trait that always shows, can cover the other allele. - represented by a Capital letter EX: Brown eye: B Recessive trait: a trait that only shows of both alleles are present. - represented by lower case letter EX: blue eye: b

Codominant: both alleles are expressed (shown) . EX: Bb: Brown (B) and Blue (b) eyes are both expressed

Sexual Reproduction and Genetics

§ Homozygous: Homozygous: two of the same alleles for a particular trait § ex: BB or bb also called pure § Heterozygous Heterozygous: two different alleles for a particular trait § Ex: Bb also called hybrid Gregor Mendel: the father of genetics, studies the traits of pea plants

11.1 Gregor Mendel “Father of Genetics”

• Developed the fundamental laws of heredity • He studied science and mathematics -chose to study genetics in garden peas (Pisum sativum)as as they are easily grown and their pollination is easily controlled. He controlled pollination by manually moving pollen between plants Developed True-breeding plants by selfpollination

Funfact: Mendel originally wanted to breed mice, but wasn't allowed to because it was considered scandalous

http://science.howstuffworks.com/life/29784-100-greatestdiscoveries-genetics-and-gregor-mendal-video.htm

Mendel examined varieties of peas for heritable characters and traits for his study. (stem length, pod shape, seed shape, seed color..etc) Developed hybrid plants by crossbreeding two plants of differing characteristics Tall v Short

Sexual Reproduction and Genetics

Mendel

P generation parents

F1 offspring 1 kids

F2 offspring 2 grandkids

11.2 Mendel's Law of Segregation (MONOHYBRID CROSS)

• A monohybrid cross

involves one (mono) character and different (hybrid) traits. The F1 seeds were all purple; the white flower trait failed to appear at all.

• 

Because the purple flower trait completely masks the white flower trait when true-breeding plants are crossed, the purple flower trait is called dominant, and the white flower trait is called recessive.

Creating the F2 generation *Cross the F1 generation together to create F2 *Ratio is always 3:1 Mendel proposed that the units responsible for inheritance were discrete particles - particulate theory of inheritance

In 1865, Mendel published his findings in a paper called Experiments on Plant Hybridization, which was mostly ignored at the time due to a number of reasons. First, Mendel was not well known in scientific community. Second, his theory ran against the popular model of blended inheritance.

As Viewed by Modern Genetics

• During production of gametes, only one of the pair

members for a given parent passes to the gamete. (LAW OF SEGREGATION) Mendel's units of inheritance are now called genes. Different forms of a gene are called alleles. Each allele is given a symbol:

•  •  • 

Parental Cross

PP x pp purple x white

Mendel’s Three Laws 1. Dominance & Recessiveness 2. Segregation: the two alleles for a trait separate (or

segregate) during the formation of gametes 3. Independent Assortment: during gamete formation,

alleles pair independently, meaning a particular allele for one character can be paired with either allele of another character

•  Two copies of same allele = homozygous. Homo means "the same"

• Therefore both PP and pp are considered homozygous, just one is purple and the other is white.

• Some purple-flowered plants could be Pp.

Individuals that are purple, but had a white parent, are heterozygous: Pp. Hetero means "different". The F1 cross Pp x Pp purple x purple

Review Terms F1 vs F2 True Breeding vs Hybrid Self Pollination vs Cross Pollination Homozygous vs Heterozygous Particulate Theory vs Blending Theory Segregation

The physical appearance of an organism is its phenotype. Purple-flowered would be a phenotype. The actual composition of the organism's alleles for a gene is its genotype: Pp is a genotype.

GENOTYPE Pp

PHENOTYPE purple flowers

rr

wrinkled seeds

TT

tall

tt

short

Organisms have many different genes some have thousands, and complex organisms have 10 times that number.

BY CONVENTION: The dominant trait is given a capitol letter, the lowercase of that same letter is the recessive trait. DO NOT MIX LETTERS. Pick one and stick to it. Also, some letters are better than others. Capital S looks a lot like a lowercase (s). Pick a different letter... Okay Short hair = SS Short hair = Ss Long hair = ss Steps to solving genetics problems 1.  Key 2.  Parents cross 3.  Punnett Square 4.  Genotype and ratio 5.  Phenotype and ratio

Better (use H for hair) HH Hh hh

Punnett Square: to predict outcome of offspring Steps to solving genetics problems Cross heterozygous green pea 1.  Key (Gg) with heterozygous green pea 2.  Parents cross 3.  Punnett Square plant (Gg). Yellow is recessive. 4.  Genotype and ratio 5.  Phenotype and ratio

P = Gg x Gg G

g

G

GG Gg

g

Gg gg F1

Key: GG: Gg: green

gg yellow

Genotype: ¼ GG; 2/4 Gg; ¼ gg Genotype ratio: 1:2:1 Phenotype: ¾ green; ¼ yellow Phenotype ratio: 3:1

In dragons... Wings are a dominant trait, but some dragons are born wingless.

1. If a wingless dragon is crossed with one that is heterozygous, how many of its offspring will also be wingless? 2. What are the chances that two heterozygous dragons have a whelp that is wingless?

If a wingless dragon is crossed with one that is heterozygous, how many of its offspring will also be wingless? P = ff x Ff f

f

F

Ff

Ff

f

ff

ff F1

Key: FF: Ff: wings

ff wingless

Genotype: 2/4= ½ Ff; ½ ff Genotype ratio: 1:1 Phenotype: ½ wing; ½ wingless Phenotype ratio: 1:1

What is a test cross? Help, help! I don't know what my genotype is!! Am I Ff or FF?

Key: F= winged f=wingless

I can help you! Let's have offspring!

Practice with Punnett Squares 1. A round seeded plant (RR) is crossed with a wrinkle seeded plant (rr). What are the phenotypes of the offspring?

2. Two heterozygous purple flowered pea plants are crossed. What are the phenotypes of their offspring and in what proportion?

3. A plant with green seeds (yy) is crossed with a heterozygous plant. What percentage of their offspring have yellow seeds?

Why does the punnett square work? It all goes back to meiosis.. each side represents a sperm or egg. The boxes filled out simply give you the statistical chance that a certain sperm will fertilize a certain egg.

Probability: The chance that an event will occur - It is a prediction, and it could be wrong.

Mendel’s Laws of Probability -  Can use probability and math to solve genetic problems.

Ex: If two parents are heterozygous for nostril flaring. P= Ee X Ee Chance of E =½ Chance of e = ½ 1.  2.  3.  4. 

Chance of EE = ½ x ½ Chance of Ee = ½ x ½ Chance of eE = ½ x ½ Chance of ee = ½ x ½

=¼ =¼ =¼ =¼

Ee= ¼ + ¼ = ½

If a wingless dragon is crossed with one that is heterozygous, how many of its offspring will also be wingless?

P = ff x Ff ½½

Key: FF: Ff: wings

½½

1

fF= 1 X ½ = ½ ff=1 x ½ = 1/2

ff wingless

Incomplete Dominance

In Make believe flowers……. Incomplete Dominance Key: RR = red Rr = purple (BLENDING) rr = blue

CoDominance Key: RR = red Rr = red and blue (both are expressed) rr = blue

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Resources

Copyright © by Holt, Rinehart and Winston. All rights reserved.

Incomplete Dominance Traits appear to "blend" in offspring RR x WW RW (pink) Show: Pink x Red Pink x Pink White x White

Figure 11.14

This illustrates another style of "letters" to denote genotypes R1 and R2

Coloration in Rodents Black x White = Gray BB x WW = BW

Sickle Cell Trait in Humans Genotypes & Phenotypes

Pleiotropic Effect: a single mutant gene affects two or more seemingly unrelated traits - Sickle cell shape, and resistant to malaria parasite

Prevalence of Malaria In tropical Africa, where malaria is common:

homozygous dominant individuals die of malaria homozygous recessive individuals die of sickle cell anemia heterozygote carriers are relatively free of both reproductive advantage

Pleiotropic Effect: a single mutant gene affects two or more seemingly unrelated traits

Prevalence of Sickle Cell Anemia

Wavy hair is an example of incomplete dominance

Codominance

ROAN COW What happens when you cross a white and a red cow?

Roan is codominant - both alleles R and W are expressed

What happens when two Roan Cows are Crossed? R R

RR

r

Rr

r Rr rr

In Make believe flowers……. Incomplete Dominance Key: RR = red Rr = purple (BLENDING) rr = blue

CoDominance Key: RR = red Rr = red and blue (both are expressed) rr = blue

Ex: A brown bird crosses with a white one and all the offspring produced are Key: BB= Brown tan. If these offspring were crossed Bb = Tan and produced 16 birds, how many would be tan? bb = White

P = Bb x Bb B

b

Genotype: ¼ BB; ½ Bb; ¼ bb

B

BB Bb

Genotype ratio: 1:2:1

b

Bb

Phenotype: ¼ Brown ; ½ Tan ; ¼ White

bb F2

Phenotype ratio: 1:2:1

If these offspring produced 16 birds how many would be expected to be tan? 8

Keep in mind: in most real organisms, it is not that simple. More than one gene will code for a trait.

QOD: Mendel’s Properties 1. What does INDEPENDENT ASSORTMENT mean?

In your own words, describe what it means with regard to Mendelian genetics.

2. Mendel would have never developed this law if he'd chosen traits located on the same chromosome. Why do you think that would have altered his results? 3. What is the difference in complete dominance, codominance, and incomplete dominance and which did Mendel study? Why?

Dihybrid Cross

Mendel's Law of Independent Assortment – Illustrated by the DIHYBRID cross law describes the outcome of dihybrid (two character) crosses, or hybrid crosses involving additional characters. A dihybrid is an individual that is a double heterozygote (e.g., with the genotype RrYy - round seed, yellow seed). What are the gametes that can be produced by this individual?

Dihybrid Cross: RrYy x RrYy cross two traits at same time: remember independent assortment

Key: In pigs, T = curly tail t = straight tail Complete dominance

1a.

P = TtBb

B =brown coat b = white coat Complete dominance

x

G TB, Tb , tB, tb

X

TtBb TB, Tb, tB, tb

Phenotype

Genotype: TB,

Tb ,

tB,

1/16 TTBB

tb

9/16 curly tail & brown coat

2/16 TTBb

TB TTBB

TTBb

TtBB

TtBb

Tb TTBb

TTbb

TtBb

Ttbb

tB

TtBB

TtBb

ttBB

ttBb

tb

TtBb

2/16 TtBB 4/16 TtBb 1/16 TTbb

3/16 straight tail & brown coat

2/16 Ttbb

1/16 straight tail & white coat

1/16 ttBB

Ttbb

ttBb

ttbb

2/16 ttBb 1/16 ttbb

Pheno ratio: 9 : 3 : 3 : 1

3/16 curly tail & white coat

1a.

Continued….

What percentage of the offspring will be purebred dominant for both traits? 1/16 or 6% What percentage of the offspring will be hybrid for both traits? 4/16 or 25% Genotype:

Phenotype

1/16 TTBB

Key:

In pigs, T = curly tail B =brown coat

2/16 TTBb

t = straight tail b = white coat

1/16 TTbb

9/16 curly & brown

2/16 TtBB 4/16 TtBb 3/16 curly & white

2/16 Ttbb 1/16 ttBB

3/16 straight & brown

2/16 ttBb 1/16 ttbb

1/16 straight & white

All of these type of crosses will follow the same ratio

AaBb x AaBb both heterozygous for both traits 9 - (two dominant traits) 3 - (one dominant, one recessive) 3 - (one recessive, one dominant) 1 - (two recessive traits)

1b.

Key:

In pigs, T = curly tail t = straight tail Complete dominance

P = TTbb G

Tb Tb

x X

B =brown coat b = white coat Complete dominance

ttbb tb

Genotype: 100% Ttbb

tb

Ttbb

Pheno ratio: 0 : 1 : 0 : 0

Phenotype 100% curly tail and white coat

3.

Key:

In Drosophila fruit flies W = long wings w = vestigial wings Complete dominance

P = Wwhh G

Wh, wh Wh

WH

wh

WWHh WwHh

Wh

WWhh

Wwhh

H = hairless body h = hairy body Complete dominance

x

WWHh

X

WH, Wh

Genotype:

Phenotype

1/4 WWHh

50% long wings and hairless body

1/4WwHh

50% long wings and hairy body

1/4 WWhh 1/4 Wwhh

Pheno ratio: 1 : 1 : 0 : 0

What percentage of the offspring will have long wings and hairless bodies?

50%

2.

Key:

In pea plants L = long stems l = short stems Complete dominance

P = LLgg G

Lg Lg

lG

LlGg

x X

G =green pods g = yellow pods Complete dominance

llGG lG

Genotype:

Phenotype:

100% LlGg

100% long stems and green pods

Pheno ratio: 1 : 0 : 0 : 0

It may be faster to solve problems mathematically. This one is NOT 9:3:3:1

HhBb x hhBb How many off the offspring will be short haired and red eyed?

Try another mathematical model.. Winged, Fire breathing dragon DdFf x Wingless, Fire breathing dragon ddFf

Consider the cross between a plant with round seeds, purple flowers to one with wrinkled seeds and white flowers ...

RrPp x rrpp

Multiple Alleles

Multiple Alleles: more than two alleles in the population ex: Blood Types

Blood Type

There are 3 alleles that code for what type of blood you have. A, B, and O. A and B are Co-Dominant and O is recessive. Phenotype Genotype

Type A

IAIA, IAiO

Blood Donor Donate to Type A/AB

% of population 42%

Type B

IBIB, IBiO

Donate to Type B/AB

Type AB

IA IB

Universal recipient/Donate to AB

4%

Type O

iOiO

Universal Donor/ only receive O

44%

10%

Practice #1 Cross: Type A (AA) father with a type 0 mother. What are the possible blood types of the offspring?

P = AA x OO A

A

O AO AO O AO

AO

Genotype: 4/4 AO Phenotype: 4/4 Type A

Practice #3 Suppose two newborn babies were accidentally mixed up in a hospital, something that rarely happens. In an effort to determine the parents of each baby, the blood types of the parents and the babies were determined. Baby 1-type B Mrs. Davisson-type B Mrs. Morgan - type O Baby 2-type O Mr. Davisson- type B Mr. Morgan - type AB

A Name

Genotype

Mrs. D

BO

Mr. D Mrs. M Mr. M Baby 1 Baby 2

BB, BO BO BB, BO OO OO AB AB BO BB, BO OO OO

B

O AO BO O AO

BO

1.  Which baby belongs to Mr. & Mrs. Davisson? Baby 2 2. Which baby belongs to Mr. and Mrs. Morgan? Baby 1

Chapter 9

blood type is located on chromosome #9 •  Type A, B, AB or O RH factor is a separate gene that codes for another protein. This is the positive or negative part of the blood type, on chromosome #1.

Many Genes Have Multiple Alleles A population might have more than two alleles for a given gene. In Labrador retriever, coat color is determined by one gene with four different alleles. Five different colors result from the combinations of these alleles. (More on labradors later)

•  • 

Eye color is also controlled by multiple alleles

The simulation is a bit simplified, but the idea is that MULTIPLE ALLELES control a single trait (eye color)

It is likely that more than 2 alleles control eye color, this is simplified just made it simple to understand.

Polygenic Traits

• Individual heritable characters found to be controlled by groups of several genes, called polygenes. • Each allele intensifies or diminishes the phenotype. • Variation is continuous or quantitative (adding up) - also called quantitative inheritance • Seed Color in wheat - aabbcc, Aabbcc, AaBbcc, AaBbCc, AABbCc, AABBCC (light, intermediate colors, dark) • In humans - hair color, height, skin color

Pg 197

Polygenic Inheritance AABBCC x aabbcc (P) AaBbCc x AaBbCc (F1) Seven Possible Phenotypes in the F2 The more “dominant” alleles for dark pigmentation (caused by melanin), the darker the skin

Figure 11.16

Example polygenetic trait question:

In a cross AaBbCc AaBbCc, what is the probability of producing the genotype AABBCC? a. ¼ b.1/8 c.1/16 d.1/32 e.1/64 ANSWER: E

Environment and Phenotype Temperature, water, food sources can have an affect on how a gene is expressed = “multifactoral” Rabbits have a gene that codes for darker pigments - this gene is more active at low temperatures. Parts of the body that are colder will develop the darker pigmentation ears and feet

• SIAMESE CATS

Multiple Alleles control the combs of chickens.

Assignment: Multiple Alleles in Chickens

LEGHORN CHICKEN – SINGLE COMB

BUTTERCUP CHICKEN - BUTTERCUP COMB

Buckeye Chicken – Pea Comb

Wyandotte Chicken - Rose Comb

Lethal Genes (Not in book, added)

• Some genes are lethal when both

alleles are present. Lethality can occur before or after birth Huntington's disease in humans is caused by a lethal allele, death occurs later in life Other examples: Mouse coat color (yellow), Creeper legs in chickens, Manx Cats (no tails)

•  • 

An example is the "creeper" allele in chickens, which causes the legs to be short and stunted.

Manx cat

X- linked traits

Inheritance and Human Heredity X-linkedComplex traits: traits on the X chromosome •  Colorblindness •  Hemophilia •  Muscular Dystrophy More common in males

Colorblindness sex-linked recessive condition in which people can’t see certain colors don’t make some of the pigments in the eye that are necessary for color vision. The most common form is red-green colorblindness

Normal color vision : 29 Red green color blind : a bunch of spots!

Normal color vision : 56 Red green color blind : 56

Normal color vision : 8 Red green color blind : spots

Hemophilia: condition that impairs the blood’s ability to clot. Hemophilia is a recessive sex-linked trait. Also known as bleeders disease

Hemophilia: Royal Disease

Muscular Dystrophy (MD): disease that results in

progressive wasting away of skeletal muscle.   Caused by a defective protein known as dystrophin

Ex:

Colorblindness

Key: XX = female normal vision XY = male normal XXe = female carrier (normal vision vision) XeY = male colorblind XeXe = female colorblind

Cross carrier female with normal male X X

XX

Xe XXe

Y XY XeY

P = XY x X Xe Genotype Phenotype 1/4XX: female normal vision 1/4 XXe : female carrier 1/4 XY: male normal vision ¼ XeY: male color blind

What % of their boys will be expected to be colorblind?

50%

Hemophilia

Key: XX = normal female XY = male normal XXh = female carrier XhY = male hemphiliac XhXh = female hemophiliac MD

Key: XX = normal female XXm = female carrier XmXm = female with MD

XY = male normal XmY = male with MD

Carrier

1. XY male normal 2, XXe female carrier 3. XY male normal 4. XXe female carrier 5. XXe female carrier 6, XY male normal

7. XeY male colorblind 8. XXe female carrier 9. XX or XXe 10. XeY male colorblind 11. XY male normal 12. XeXe female colorblind

Complex Inheritance and Human Heredity

Pedigrees:

A diagram that traces the inheritance of a particular trait through several generations

Human Disorders

Pg 192

Autosomal Recessive vs Autosomal Dominance

Aa

Aa

aa

Aa

Aa

aa

Figure 11.10

Figure 11.11

Hereditary Genetic Disorders Name of Disorder

Tay Sacks Cystic Fibrosis PKU Sickle Cell Disease Neurofibromatosis Huntington's Disease Achondroplasia

Type (autosomal, sex linked, dominant, recessive)

Description/ Symptoms

Type of people group/ treatment / other

Tay Sachs Autosomal recessive -progressive deterioration of nerve cells and of mental and physical abilities Young children begin showing signs of slowed development Severe impairment and death strikes 1 in 3600 births 100 times greater than incidence among non-Jews

non-functional enzyme fails to breakdown lipids in brain cells fats collect in cells destroying their function symptoms begin few months after birth seizures, blindness & degeneration of muscle & mental performance child usually dies before 5yo

Cystic Fibrosis autosomal recessive -More common in Caucasians -Mucus in respiratory tract, difficulty breathing extreme salty sweat -Mucus may cause secondary infections http://www.redorbit.com/news/video/health_2/1113011363/miracle-drug-for-cystic-fibrosis-11222013/

Effect on Lungs normal lungs

airway

Cl–

Chloride channel transports salt through protein channel out of cell Osmosis: H2O follows Cl– Cl– channel

H 2O cells lining lungs

cystic fibrosis

Cl–

bacteria & mucus build up

H 2O thickened mucus hard to secrete

mucus secreting glands

Phenylketonuria (PKU)

• Lack enzyme for normal metabolism • Phenylalanine builds up and causes brain damage • Newborns are routinely tested • Changes in diet lead to normal life

Phenylalanine Hydroxylase is the enzyme needed, absent in those with PKU

http://www.youtube.com/watch? v=XKSoMi4U-1k http://www.youtube.com/watch? v=w3L2SPj7alQ

autosomal recessive

Sickle Cell Disease • More common in Africans (African-Americans) • Causes blood to be sickle shaped • Affects oxygen flow to organs, causing weakness, pain, anemia, etc Heterozygotes are resistant to malaria

• 

AA = normal Aa = sickle cell trait aa = sickle cell disease

Neurofibromatosis -Autosomal dominate -carry high risk of tumor formation -Tumors form under skin and can cause skeletal deformities, blindness "The Elephant Man" Several years ago, research teams located the exact position of the NF1 gene on chromosome 17. The product of the NF1 gene is a large and complex protein called neurofibromin, which is primarily active in nervous cells as a regulator of cell division. Intensive efforts have let to the identification of the NF2 gene on chromosome 22. The NF2 gene product is a tumor-suppressor protein called merlin.

http://www.bcnf.bc.ca/learn/about-the-charity/

Huntington's Disease HH = Huntington's Hh = Huntingtons hh = normal Symptoms appear later in life, often starting with poor muscle control Autosomal Dominant

neurodegenerative genetic disorder that affects muscle coordination and leads to cognitive decline

There are different types of dwarfism. Achondroplasia is caused by a dominant allele.

Meet Kenadie Two dwarfs can have a normal child. Dd x Dd

http://www.youtube.com/watch? feature=player_embedded&v=_QBy8DFaLR4

Primordial Dwarfism

Genes and crossing over: the higher the crossing over frequency, the farther apart the genes The following crossover frequencies were noted via experimentation for a set of five genes on a single chromosome:

A and B → 35% B and C → 15% A and C → 20% A and D → 10% D and B → 25% A and E → 5% B and E → 40% Pick the answer that most likely represents the relative positions of the five genes.

29. In a cross AaBbCc AaBbCc, what is the probability of producing the genotype AABBCC? a. ¼ b.1/8 c.1/16 d.1/32 e.1/64 ANSWER: E

Goals 1.  Finish Pedigree worksheet staple into QOD 2.  Grid in questions in Genetics FRQ packet can check answers with yellow answer key 3.  Finish lab(s)