GENETICS

							Biology Agenda –Intro to
Genetics

    1.   Catalyst: Meiosis Review
    2.   QUIZ: Meiosis [Obj. #1-5]
    3.   Notes – Intro to Mendelian Genetics
    4.   Practice genetics problems!
    5.   HW: Genetics Packet pg: 3-4
Which of the following
disorders is fake?
   “Werewolf Syndrome”
       Congenital generalized hypertrichosis – a rare
        disorder characterized by excessive hair growth
        on the face and the upper body
   “Vampire Syndrome”
       Familial photodermatitis - When exposed to the
        sun, the skin blisters and gives pain, drinking
        blood relieves symptoms
   “Blue-Skin Syndrome”
       Methomoglobinemia – the enzyme diaphorase is
        absent from the red blood cells, and doesn’t allow
        for the conversion from methomoglobin back to
        hemoglobin
   Vampire syndrome is the FALSE
    syndrome


Congenital generalized hypertrichosis…
The Fugate family of Troublesome Creek,Kentucky…
GENETICS
 Analyzing Heredity
Introduction
 Heredity:    the transmission of
    traits from parents to offspring
       Ideas of heredity have been around for all of
        recorded history
       It’s always been noticeable that children
        resemble their parents
   There are several famous examples…
   The Hapsburgs, the ruling family of Austria (1200s – WWI)
       One relative, the Archduke Francis Ferdinand, was shot by a
        Serbian rebel. This assassination began WWI.
       The “Hapsburg Lip” was a protruding lip that’s
        evident in portraits of the family that span over
        400 years…
   Royal families of Europe,
    beginning with Queen
    Victoria of England
       Passed on hemophilia
           Excessive bleeding due to
            an ineffective clotting
            factors
       It was passed on to the
        families of other nations as
        Victoria’s ancestors were
        married to others of their
        social status
•1800’s: Most scientists believed in the
blending model of inheritance
-Offspring are a blend of both parents
-The characteristics of the blended offspring are passed on to the next generation
-Variation is washed out over time
Basic Vocabulary before we begin:
   Chromosomes
   Genes
   Alleles
   Heterozygous
   homozygous
Genetic Symbols
    Female symbol:
        Represents the hand
         mirror & comb of
         Venus



    Male symbol:
        Represents the shield
         & spear of Mars
Who’s Gregor Mendel?
   1822: Born into a low-
    income family in what would
    become Czechoslovakia
   Entered the monastery to
    receive an education
   Eventually became an abbot
    for the church, meanwhile
    carried on experiments
Mendel, cont’d…

   Was creative in his approach to science
     Took quantitative (numerical) data
      and analyzed it mathematically
   His work was ignored until after his
    death
     Why Garden Peas?
   Mendel worked with Pisum sativum, garden peas, to study
    inheritance
     they come in a many varieties

     The male and female parts are in the same flower – an
      individual can self-pollinate itself or cross-pollinate with
      another individual
Pollination
Mendel’s Monohybrid Traits
    Mendel’s Experiments:
    He allowed each variety (ex:
     purple-flowered vs. white-
     flowered) to self-pollinate for
     several generations 
     Purebred varieties
    Question: Is inheritance blended
     or particulate?
    Hypothesis: If 2 purebred plants
     for contrasting characters are
     cross-pollinated then…
(P generation)
                             P:          x
1.   He crossed 2 varieties
     from the P
     generation… called the
     offspring the first filial,
     or F1 generation
                                   F1:
1.   Allowed the F1
     generation to self-
     pollinate… called the
     offspring the second
     filial, or F2, generation
                                   F2:
Monohybrid Cross – a cross that tracks a single trait
(ex: flower color)


   P generation:                 x


                                     All purple
                                      -called purple
   F1 generation:                      “dominant”
                                      -called white
                                       “recessive”

                                             -705 purple
   F2 generation:                            -224 white
                                               ~ 3:1 ratio
           F2:

   When Mendel self-pollinated the white
    flowered F2 individuals, ALL offspring were
    white
   When he self-pollinated the purple F2
    individuals, he found only 1/3 to be true-
    breeding
       The other 2/3 gave another 3:1 ratio of p:w
   From this he devised a theory…
Mendel’s Theory:
1.   Parents pass on
     genes, not
     necessarily traits
2.   Alternative forms of a
     gene that govern a
     specific trait ( hair
     color) are called
     alleles and are
     represented by by
     lower case or          In this plant,
     capitalized letters.   these might be
     (H,h)                  the individual’s
                             two genes for
                             flower color
Remember, chromosomes come in homologous
pairs, which have the same types of genes, but not
the exact same genes, since one chromosome in
each pair is from the mother of the organism, one
is from the father.
Chromosome 1     2                    Chromosome 3   4


                                                         Weight
 Eye color
                                                         Insulin
                         Homologous Pair =
                         2 chomosomes with
 Height                                                  Lips
                         same genes


 Hair Color


Chromosomes 1 and 3 were from Mom, 2 and 4 were from Dad.
 …more theory
3. For every trait, an individual has two genes
      -If the alleles are the same, it is “homozygous.”
     -If they are different, it is “heterozygous.”
4. Your set of alleles is your genetic make-up or
    “genotype.” Your appearance is your “phenotype.”
5. You get one allele for each trait from each parent,
    and then pass on one of these two to each child.
6. In heterozygous individuals, only the dominant allele
    is expressed. The recessive allele is there but is not
    expressed.
Mendel’s Laws of Inheritance:
   Law of Segregation: The members of each
    pair of alleles separate when gametes form
     You only give one of each homologous pair
      of chromosomes to each gamete
   Law of Independent Assortment: Pairs of alleles
    separate independently (ex: flower color is independent
    of seed color)
     Exception to the rule: We now know this does not
       hold true if both genes are located on
       the same chromosome!
Biologists use specific terms to talk about
different types of organisms.
   They use the term homozygous to mean
    purebred. Let’s see why:
       Homo- = _______, zygous = _____


   They use the term heterozygous to mean
    hybrid. Let’s see why:
       Hetero- = _________
Let’s practice that…
   Let’s create examples of each:
       Homozygous dominant for flower color: _____
       Heterozygous for flower color: _____
       Homozygous recessive for pea shape: _____
       Homozygous dominant for pod color: ______
       Heterozygous for stem height: _____

   NOTE: there are two ways to get a dominant
    trait to show up:
       _________
       _________
Phenotypes and Genotypes
   We need to distinguish between what
    something looks like and what genes it
    has.
       A pea plant that looks tall can be _______ or
        _______.
       Therefore, the pea plant’s PHENOTYPE is
        ____________ and the GENOTYPE could be
        ______ or ______.
   Pheno = ________________________
   Geno = _________________________
Analyzing Heredity
   Capital letters represent dominant alleles
   Lower-case letters represent recessive alleles

What is dominance?
 A dominant allele is the version of a gene
 that is expressed in an individual who has
 both alleles of that gene.
Is “dominant” the same as “common” or
“stronger”?
   No. Many genes are rare but dominant.
    Achondroplasia, a form of dwarfism
Practice and End of Class Reminders

   CLASSWORK: Complete pages 2 & 3 with
    your partner – show Ms. Reynolds when you
    are done

   HOMEWORK: Read 8.1 and 8.2, complete
    Genetics Packet page 4

   Obj. 6-8 Mastery QUIZ: Friday 3/4