5/11/20151 genetic fundamentals & gregor mendel dr. rick woodward chapters 9 & 10 (new/green...

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Genetic Fundamentals & Gregor Mendel

Dr. Rick Woodward

Chapters 9 & 10 (New/Green Text Book)

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January 12, 2011Wednesday

Today’s Agenda:

-Journal Questions: Why do you think the study of genetics is important?

What is your New Year’s resolution/goal?

-Turn in your gene mutation winter break project.

*1. Lecture: Genetics & Mendel’s Laws

–Slide 36

2. Genetic Traits Activity: How alike are we?

3. Work on page 43 in packet: Heredity

4. Video: “Ghost in your genes”

5. Homework: Read Chapter 9 “Mendel Genetics”

(page 164 - 183: Second page of packet)

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The Genesis of GeneticsA. Genetics was founded with

the work of Gregor Johann Mendel, an Austrian monk who experimented with garden peas.

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Mendel’s Experimental GardenMendel’s Experimental Garden

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Situating Mendel HistoricallySituating Mendel Historically

(1831-1836) (1859) (1866) (1892) (1910)Darwin on Darwin’s Mendel’s Weismann’s Morgan

Mendel born Beagle On the Origin Paper germ plasm finds white

Voyage of Species published theory fruit fly

1800 1815 1830 1845 1860 1875 1890 1905 1920

Napoleon Crimean Formation Mendel’s Sex defeated at War of German work re- chromo-Waterloo (1853-1856) Empire (1870) discovered somes

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Genetic TerminologyKey Concept!

A. Heredity is the transmission of characteristics from parents to offspring.

B. A trait is a specific characteristic such as height or eye color.

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Genetics TerminologyC. Molecular genetics is the

study of the structure and function of chromosomes and genes.

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Mendel’s Observations

A. Mendel observed seven characteristics in pea plants.

B. He looked at contrasting traits:

1. Plant height

(long or short stems)

2. Seed color

(yellow or green)

3. Flower color

(purple or white)

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Mendel’s Observations

C. Mendel studied each characteristic and its contrasting trait individually.

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Mendel’s Experiments: Crossed Pea Mendel’s Experiments: Crossed Pea Varieties with 7 Clearly Distinguishable Varieties with 7 Clearly Distinguishable TraitsTraits

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Mendel’s ObservationsD. He began by growing plants

that were pure for each trait.

(1) Plants that are pure for a trait always produce offspring for that specific “pure” trait.

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Mendel’s Observations

E. The term strain denotes plants that are pure for a specific trait.

F. The first strain is referred to as a parental generation, or P1 generation.

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Mendel’s Observations

G. When the plants matured, he recorded the number of each type of offspring produced by the P1 plant.

(1) He called the offspring of the P1 generation the first filial generation, or F1 generation.

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F1 x F1 Punnett square

F2 genotypes

1/4 SS1/2 Ss1/4 ss

F2 phenotypes

3/4 smooth1/4 wrinkled

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Terminology A. An allele is an alternative

form of a gene.

(1) Letters are used to represent alleles. (i.e. T, t)

(2) Dominant Trait: TT (Tallness)

(3) Recessive Trait: tt (shortness)

B. Gene: a segment of DNA that contains coding for a polypeptide or protein; a unit of heredity information.

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TerminologyC. Punnett Square: Used for predicting

the probability that certain traits will be inherited by offspring.

(1) Punnett Square = P for Probability

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Terminology D. Homozygous: When both

alleles of a pair are alike, or the same, the organism is said to be homozygous for that characteristic.

AA = RED

aa = BLUE

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Terminology E. Heterozygous: When the two

alleles in the pair are different, the organism is heterozygous for that characteristic. Tt

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Terminology

F. The genetic makeup of an organism is its genotype

(1) Combination of alleles (Rr, rr, RR)

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Genotypic Ratio

1. Cross (Tt) (Tt) using a Punnett square.

2. What is the genotypic ratio?

Genotypic Ratio = 1TT:2Tt:1tt

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Terminology G. Phenotype is the physical

appearance or expression of the genotype. (Flower Color)

(1) Flower Color is the physical appearance/phenotype.

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Phenotypic Ratio

1. What is the phenotypic ratio of a cross between (Tt)(Tt)?

- Use a Punnett Square to assist you.

2. The phenotypic ratio is

3 Tall: 1 Short

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Ratios

F1 x F1 crosses:

Mendel also discovered that traits that disappear in the F1 generation reappear in the F2 generation in a 1:3 ratio.

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Hybrids A. A hybrid is…..B. A monohybrid cross is a

cross between individuals that involves one pair of contrasting traits (TT)(tt)

C. A Dihybrid cross is a cross between individuals that involve two pairs of contrasting traits. (BBSS) (ssbb)

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Dihybrid cross: F1 generation

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Dihybrid cross: F2 generation

Ratio:

9:3:3:1

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Hybrid Cross

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Dominant versus Recessive Traits

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Recessive Traits versus Dominant Traits

A. Recessive Trait: Referring to an allele that is masked by the presence of another allele for the same characteristic.

(1) Example: T = Tall

t = Short

tt = Short (recessive trait)

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Recessive Traits versus Dominant Traits

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Recessive Traits versus Dominant TraitsB. Dominant Trait: The dominant

trait dominants over a recessive trait unless the recessive trait is homozygous tt = shortness.

(1) Example: T = Tall

t = Short

TT = Tall (Dominant Trait)

Tt = Tall (Dominant Trait)

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Epigenetics

A. May control the expression of our genes.

B. Involves the modifications of the activation of certain genes, but not the basic structure of DNA

C. Possible Epignetic Processes:

1. Gene silencing

2. Chromosome inactivation

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Today’s Activity:Today’s Activity:HOW ALIKE ARE OUR ALLELES?HOW ALIKE ARE OUR ALLELES?

Find out the alleles you have for different traitsFind out the alleles you have for different traits For each trait, For each trait, write downwrite down whether you express whether you express

that trait and whether you are that trait and whether you are dominant or dominant or recessive.recessive.

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1. TONGUE ROLLING1. TONGUE ROLLING

DOMINANT Trait: DOMINANT Trait:

The The ability to roll up the sides ability to roll up the sides of the tongue (RR, Rr)of the tongue (RR, Rr)

RECESSIVE Trait:RECESSIVE Trait:

Not being able to roll up the sides Not being able to roll up the sides of the tongue (rr)of the tongue (rr)

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2. 2nd TOE LENGTH2. 2nd TOE LENGTH

DOMINANT Trait: DOMINANT Trait:

2nd toe is longer than the big toe2nd toe is longer than the big toe

(BB, Bb)(BB, Bb)

RECESSIVE Trait: RECESSIVE Trait:

2nd toe is shorter than the big toe2nd toe is shorter than the big toe

(bb)(bb)

--note the presence of a toe ringnote the presence of a toe ring..

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3. WIDOW’S PEAK3. WIDOW’S PEAK DOMINANT Trait: DOMINANT Trait:

Hairline has a pointHairline has a point, widow’s peak is present, widow’s peak is present

(WW, Ww)(WW, Ww) RECESSIVE Trait: RECESSIVE Trait:

Hairline has no point, no widow’s peakHairline has no point, no widow’s peak

(ww)(ww)

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4. ATTACHED/FREE EARLOBES4. ATTACHED/FREE EARLOBES

DOMINANT Trait: DOMINANT Trait:

Earlobes hang freely from the earEarlobes hang freely from the ear

(EE, Ee)(EE, Ee)

RECESSIVE Trait: RECESSIVE Trait:

Earlobes are attached to the Earlobes are attached to the side of the faceside of the face

(ee)(ee)

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5. HITCHHIKER’S THUMB5. HITCHHIKER’S THUMB

DOMINANT Trait: DOMINANT Trait:

Thumb is straight slightly angledThumb is straight slightly angled

(HH, Hh)(HH, Hh)

RECESSIVE Trait:RECESSIVE Trait:

Thumb can be bent backwardsThumb can be bent backwards

(hh)(hh)

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6. HAIRY KNUCKLES6. HAIRY KNUCKLES

DOMINANT Trait: DOMINANT Trait:

No hair No hair on middle parts of fingerson middle parts of fingers

(HH, Hh)(HH, Hh)

RECESSIVE Trait: RECESSIVE Trait:

Hair is present on middle parts of Hair is present on middle parts of fingers fingers

(hh)(hh)

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7. DIMPLES7. DIMPLES

DOMINANT Trait:DOMINANT Trait:

Dimples presentDimples present

(DD, Dd)(DD, Dd)

RECESSIVE Trait: No dimplesRECESSIVE Trait: No dimples

(dd)

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8. CLEFT CHIN8. CLEFT CHIN

DOMINANT Trait: DOMINANT Trait:

No cleft present in the chinNo cleft present in the chin

(CC, Cc)(CC, Cc)

RECESSIVE Trait: RECESSIVE Trait:

Chin has a cleft or indentationChin has a cleft or indentation

(cc)(cc)

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9. STRAIGHT/BENT PINKIES9. STRAIGHT/BENT PINKIES

DOMINANT Trait: DOMINANT Trait:

Pinkies are straightPinkies are straight

(SS, Ss)(SS, Ss)

RECESSIVE Trait: RECESSIVE Trait:

Pinkies are bent Pinkies are bent

(ss)(ss)

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10.10. HANDEDNESSHANDEDNESS DOMINANT Trait: DOMINANT Trait:

Right-handedRight-handed

(HH, Hh)(HH, Hh)

RECESSIVE Trait: RECESSIVE Trait:

Left-handedLeft-handed

(hh)(hh)

Handedness & The Brain

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January 13, 2011: Thursday Today’s Agenda:

-Journal Question: What is the difference between a genotype and a phenotype?

-What is epigenetics?

*(1) Lecture on Mendel’s Laws (finishing unit)

–slide 85

(2) Start Face Lab (last pages of your packet.)

(3) HW: Finish pages 44, 46, 48 in your packet.

(4) Study guide given out next class.

-Bring flash cards if you need them.

(5) Exam next week on Mendel & Genetics

-All work is due on the day of the exam

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Mendel’s Laws & Other Key Concepts

1. Mendel’s Law of Segregation 2. Mendel’s Law of Independent

Assortment3. Mendel’s Law of Dominance4. Mendel’s Law of Incomplete

DominanceOther Key Concepts:1. Blood Types2. Homologous Chromosomes 3. Crossing Over4. Sex-Linked Traits (pedigree chart)5. DNA versus RNA

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Mendel’s Law of Segregation

A. Law of Segregation states that a pair of factors (alleles) is segregated, or separated, during the formation of gametes (reproductive cells)

(1) When two gametes combine during fertilization, the offspring have two factors controlling a specific trait (Gg)

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Law of Segregation and Recombination

A. Each trait is transmitted as an unchanging unit, independent of other traits, thereby giving the recessive traits a chance to recombine and show their presence in some of the offspring.

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Mendel’s Law of Mendel’s Law of Independent AssortmentIndependent Assortment

1. Traits are not inherited together.

2. In forming the gametes, the “Factors” for any two traits assort independently from one another

3. This became known as Mendel’s second principle: Independent Assortment

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Independent Assortment

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Mendel’s Law of Dominance

C. Law of Dominance

1. Of two contrasting characteristics, the dominant one may completely mask the appearance of the recessive one.

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Mendel’s Law of Incomplete Dominance

D. Incomplete Dominance

1. Pattern of inheritance in which neither allele is dominant

2. Three totally different phenotypes can occur.

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Incomplete Dominance

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Mendel’s Law of Co-dominance

E. Incomplete dominance is also called Co-dominance

1. Co-dominance occurs when one allele is not dominant.

2. Both alleles are expressed equally.

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Co-Dominance: Blood Types

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What are Blood Types?

Everybody has a blood type. The most common blood type classification system is the ABO (say "A-B-O") system discovered by Karl Landsteiner in the early 1900s. There are four types of blood in the ABO system: A, B, AB, and O. Your blood type is established before you are born, by specific genes inherited from your parents. You receive one gene from your mother and one from your father; these two combine to establish your blood type. These two genes determine your blood type by causing proteins called agglutinogens (a-GLOO-tin-a-gins) to exist on the surface of all of your red blood cells.

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Blood Types

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Blood Types

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What is the most common blood type?

Answer: Type O Positive

Everyone can accept type O blood.

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Blood Types

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Blood Types

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Homologous Chromosomes

A. Two copies of each autosome are called homologous chromosomes.

(1) They are the same size, shape, and carry genes for the same traits.

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Homologous Chromosomes

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Homologous Chromosomes

B. Homologous pairs of chromosomes segregate during meiosis.

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Crossing OverA. Portions of chromatids may

break off and attach to adjacent chromatids on the homologous chromosome = a process called crossing over.

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Sex-Linked Traits

A. Sex-linkage is the presence of a gene on a sex-chromosome.

B. Sex Chromosomes:

XX = Female

XY = Male

C. X-Linked Traits:

(1) Colorblindness

(2) Hemophilia

(3) Duchenne Muscular Dystrophy

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Sex-Linked Traits

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PedigreeA. A pedigree is a family record that

shows how a trait is inherited over several generations.

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Review: DNA vs. RNA

DNA RNA

1. Location: Nucleus Ribosome

2. Function: Directs activities Protein Synthesis

of the cell

3. Nitrogen Bases: ATCG AUCG

4. Structure: Double Helix Single Strand

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Genetic Testing Kits for the PublicA. Genetic Testing kits are

available to check your DNA for possible anomalies.

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Parts of a Nucleotide

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Nitrogen – Base Pairing

A bonds with T:AT

C bonds with GCG

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KaryotypeA picture of an Individual’s Chromosomes

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Polyploidy

A. When organisms contain some multiple of the normal number of chromosomes, they are called polyploid organisms.

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y

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Recombinant DNA Technology

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Face Lab (January 18, 2011)- Journal Question: What genetic traits do

you think that you get from your parents? (Name/Identify 2 traits)

1. Find a friend to perform today’s lab with.2. Lab: Data Table & Diagram Your

Results.(Last pages of your packet)

-Diagram your offspring as a teenager. (use color pencils)3. Write a brief biography of your teen.4. Homework: Finish your packet & Face

Lab Portrait

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Today’s LabFind a partner to work with and perform the

face lab on human genetics.

Materials:

1. Coin

(Heads = Dominant. Tails = Recessive)

2. Lab

3. Color Pencils and paper to diagram face.

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Today’s Lab

1. Each of you must diagram a portrait of your child as a teenager.

2. Name your child

3. On the back of your portrait write a brief life history of your child.

Today’s AgendaJanuary 20, 2011Journal Questions:

-How do the nitrogen bases pair up in DNA?

-What are the three parts of a nucleotide?

*1. Brief Lecture: DNA Replication

2. Complete Face Lab –Draw your teen and write a brief biography.

3. Work on Study Guide for Exam VI

4. Exam on Monday (Jan. 24, 2011)

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DNA Replication

A. The process of copying DNA in a cell is called replication.

(1) During replication, the two nucleotide chains separate by unwinding, and each chain serves as a template for a new nucleotide chain.

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DNA Replication

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Steps of DNA Replication (1) Separation of two nucleotide chains.

a. Point of separation = Replication fork

(2) Chains are separated by enzymes called helicases.

(3) Helicase enzymes move along the DNA molecule, they break the hydrogen bonds between the complementary bases, and the chains separate.

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Steps of DNA Replication

(4) DNA Polymerases bind to the separated chains of DNA.

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Steps of DNA Replication(5) As DNA Polymerases move along

the separated chains, new chains of DNA are assembled using nucleotides that are complementary to the existing DNA chains.

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Steps of DNA Replication

(6) The complementary nature of the two chains of DNA is the foundation for accurate DNA replication.

-Nitrogen Base Pairing Rules:

A – T

C – G

GATTACA

CTAATGT (Complementary Strand)04/18/23 93

DNA ReplicationWhen DNA replication is

completed,

(1) Two new exact copies of the original DNA molecule are produced

(2) The cell is now ready to undergo cell division (P.M.A.T).

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Next Topics for the End of the Semester: January 27, 2011 (Thursday)1. Gene Mutations2. DNA Replication3. Recombinant DNA Technology 4. Protein Synthesis

-Comprehensive final exam with emphasis on genetics, the cell, organelles and their functions.