Genetic Fundamentals & Gregor Mendel

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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

• Todays Agenda
• -Journal Questions Why do you think the study
  of genetics is important?
• What is your New Years resolution/goal?
• -Turn in your gene mutation winter break
  project.
• 1. Lecture Genetics Mendels 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 Genetics

• A. Genetics was founded with the work of Gregor
  Johann Mendel, an Austrian monk who experimented
  with garden peas.

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Mendels Experimental Garden
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Situating Mendel Historically

• (1831-1836) (1859) (1866)
  (1892) (1910)
• Darwin on Darwins Mendels
  Weismanns Morgan
• Mendel born Beagle On the Origin Paper
  germ plasm finds white
• Voyage of Species published
  theory fruit fly
• 1815 1830 1845 1860 1875 1890 1905
  1920
• Napoleon Crimean Formation Mendels
  Sex
• defeated at War of German
  work re- chromo-
• Waterloo (1853-1856) Empire
  (1870) discovered somes

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Genetic Terminology

• Key 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 Terminology

• C. Molecular genetics is the study of the
  structure and function of chromosomes and genes.

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Mendels 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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Mendels Observations

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

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Mendels Experiments Crossed Pea Varieties with
7 Clearly Distinguishable Traits
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Mendels Observations

• D. 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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Mendels 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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Mendels 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 SS
• 1/2 Ss
• 1/4 ss
• F2 phenotypes
• 3/4 smooth
• 1/4 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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Terminology

• C. 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 1TT2Tt1tt

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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 13 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 generationRatio9331
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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 Traits

• B. 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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Todays ActivityHOW ALIKE ARE OUR ALLELES?

• Find out the alleles you have for different
  traits
• For each trait, write down whether you express
  that trait and whether you are dominant or
  recessive.

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1. TONGUE ROLLING

• DOMINANT Trait
• The ability to roll up the sides of the tongue
  (RR, Rr)
• RECESSIVE Trait
• Not being able to roll up the sides of the
  tongue (rr)

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2. 2nd TOE LENGTH

• DOMINANT Trait
• 2nd toe is longer than the big toe
• (BB, Bb)
• RECESSIVE Trait
• 2nd toe is shorter than the big toe
• (bb)
• -note the presence of a toe ring.

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3. WIDOWS PEAK

• DOMINANT Trait
• Hairline has a point, widows peak is present
• (WW, Ww)
• RECESSIVE Trait
• Hairline has no point, no widows peak
• (ww)

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4. ATTACHED/FREE EARLOBES

• DOMINANT Trait
• Earlobes hang freely from the ear
• (EE, Ee)
• RECESSIVE Trait
• Earlobes are attached to the side of the face
• (ee)

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5. HITCHHIKERS THUMB

• DOMINANT Trait
• Thumb is straight slightly angled
• (HH, Hh)
• RECESSIVE Trait
• Thumb can be bent backwards
• (hh)

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6. HAIRY KNUCKLES

• DOMINANT Trait
• No hair on middle parts of fingers
• (HH, Hh)
• RECESSIVE Trait
• Hair is present on middle parts of fingers
• (hh)

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7. DIMPLES

• DOMINANT Trait
• Dimples present
• (DD, Dd)
• RECESSIVE Trait No dimples
• (dd)

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8. CLEFT CHIN

• DOMINANT Trait
• No cleft present in the chin
• (CC, Cc)
• RECESSIVE Trait
• Chin has a cleft or indentation
• (cc)

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9. STRAIGHT/BENT PINKIES

• DOMINANT Trait
• Pinkies are straight
• (SS, Ss)
• RECESSIVE Trait
• Pinkies are bent
• (ss)

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HANDEDNESS

• DOMINANT Trait
• Right-handed
• (HH, Hh)
• RECESSIVE Trait
• Left-handed
• (hh)

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Handedness The Brain
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January 13, 2011 Thursday

• Todays Agenda
• -Journal Question What is the difference
  between a genotype and a phenotype?
• -What is epigenetics?
• (1) Lecture on Mendels 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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Mendels Laws Other Key Concepts

• 1. Mendels Law of Segregation
• 2. Mendels Law of Independent Assortment
• 3. Mendels Law of Dominance
• 4. Mendels Law of Incomplete Dominance
• Other Key Concepts
• 1. Blood Types
• 2. Homologous Chromosomes
• 3. Crossing Over
• 4. Sex-Linked Traits (pedigree chart)
• 5. DNA versus RNA

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Mendels 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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Mendels Law of Independent 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 Mendels second
  principle Independent Assortment

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Independent Assortment
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Mendels 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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Mendels 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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Mendels 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 Over

• A. 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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Pedigree

• A. 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 Public

• A. 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 G CG

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Karyotype

• A picture of an Individuals 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 todays 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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Todays Lab

• Find 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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Todays 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.

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Todays AgendaJanuary 20, 2011

• Journal 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)

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DNA Replication

• When 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 Mutations
• 2. DNA Replication
• 3. Recombinant DNA Technology
• 4. Protein Synthesis
• -Comprehensive final exam with emphasis on
  genetics, the cell, organelles and their
  functions.