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If molecule Y represents a DNA molecule, then
molecule W represents what?

               1.        Glucose
               2.        Nucleotide
               3.        Amino Acid
               4.        RNA
               5.        Lipid

1    2    3         4    5   6   7   8   9   10   11   12   13   14   15   16   17   18   19   20

21   22   23        24
Where in the cell does
transcription take place?
     1.       Cytoplasm
     2.       Mitochondria
     3.       Nucleus
     4.       Golgi Body
     5.       Vacuole

1     2   3    4    5   6   7   8   9   10   11   12   13   14   15   16   17   18   19   20

21   22   23   24
mRNA is synthesized in the nucleus and
travels to the cytoplasm to meet up with
which organelle?

1.        Mitochondria
2.        Ribosome
3.        Golgi Body
4.        Lysosome
5.        Nucleus

1    2     3    4    5   6   7   8   9   10   11   12   13   14   15   16   17   18   19   20

21   22    23   24
Where in the cell does translation, the second
part of protein synthesis, take place?

1.        Mitochondria
2.        Nucleus
3.        Golgi body
4.        Cytoplasm

1    2     3    4    5   6   7   8   9   10   11   12   13   14   15   16   17   18   19   20

21   22    23   24
If molecule Y represents a protein, then
molecule W represents what?

               1.        Glucose
               2.        Nucleotide
               3.        Amino Acid
               4.        RNA
               5.        Lipid

1    2    3         4    5   6   7   8   9   10   11   12   13   14   15   16   17   18   19   20

21   22   23        24

   Deletion
       Occurs when part of a chromosome is left out
       Most are lethal
   Insertion
       Segment of a chromosome is removed and
        inserted into another one
   Duplication
       Segment of DNA is copied twice
   Inversion
       Occurs when part of a chromosome breaks off
        and is reinserted backwards
   Translocation
       Occurs when segments of DNA on
        2 chromosomes are rearranged
Some Vocab first
   Heredity
       The passing on of characteristics from parents to

   Trait
       Characteristic that is inherited
What is a gene?
   A region of DNA that controls a hereditary characteristic
   Give me an example:
     Let’s take the gene for hair color

     How many different genes are present in this room?

   Different forms of genes are called
     Alleles

   For the gene for hair color how many different alleles do
    each of you have?
     2
Where did it all begin?
   With Gregor Mendel
   Mendel used pea plants to study what
    genetics really was.
   He would cross pollinate them to see what
    kind of products he would get and then make
    assumptions as to what was happening to the

   Let’s look at how a plant reproduces
   What was Mendel seeing?

Let’s take a trip down history
        Mendel took two pea plants that were identical in every way
         except for their heights, one was short and one was tall.

        He called these two plants the parent generation, which
         is some vocab that we still use today. It’s abbreviated –
History Trippin
   He cross pollinated them and took a look at
    their offspring.
History Trippin
   When he planted the seeds from the cross pollination the plants that were
    produced were all tall.

   He called the offspring from this first cross between the parents – the F1
   Filial is latin for son or daughter
History Trippin
   Next, Mendel allowed the tall plants in the F1 generation to self pollinate.
    He then planted these seeds and grew 1000 plants.

   Mendel found in this F2 generation that ¾ of the plants grew tall and ¼
    were short.
Why was this a big discovery
for Mendel?

   1 trait of a pair seemed to disappear in the F1 generation, only to reappear
    unchanged in ¼ of the F2 plants.
Mendel’s Conclusions
    Gregor Mendel didn’t know much if anything about
     DNA or what it was, and he didn’t even know how
     much you know…so what was Mendel’s big
     conclusion after seeing his offspring?
    He figured out that each organism must have 2
     factors that control each of its traits.
The Rule of Dominance
   In Mendel’s F1 offspring plants, there were
    only tall plants even though one of the
    parents was a short plant.

   1 of the alleles is dominant over the other.
The Rule of Dominance
   The observed trait is DOMINANT and the trait that
    disappeared is recessive.
   In Mendel’s example which is the dominant trait and
    which is the recessive trait?

   The allele for tallness is DOMINANT
   The allele for shortness is recessive
What does it mean to
     be Dominant or
How many of you have 6
fingers on each hand?
   6 fingers are dominant
How many of you have a
widow’s peak?
   Widow’s peak is dominant
How many of you have
attached ear lobes?
   Attached earlobes are recessive
How many of you have the
ability to roll your tongue?
   Rolling your tongue is dominant
How many of you have a
straight thumb?
   Straight thumb is recessive
How many of you have blue
   Blue eyes are recessive
How many of you can taste
PTC paper?
   PTC tasting is dominant
How many of you have
   Having freckles are dominant
How many of you have a cleft
   Having a cleft chin is recessive
How many of you have a
second toe longer than your
big toe?
   Having a longer second toe is dominant
How many of you when clasping
your hands together, the left thumb
is on top of the right thumb?

    Left thumb on top is dominant
How many of you have
broad/fuller lips?
   Full lips are dominant
How many of you have an
immunity to poison ivy?
   Poison ivy immunity is dominant
The Rule of Dominance
   We label or designate alleles with letters.
       (For example, a letter T for the trait of height)
   An uppercase letter is used for the
    Dominant allele (T for tall)
   A lowercase letter is used for the recessive
    allele (t for short)
    The Rule of Dominance

   Using the letter
    T what can you
    say about the
    possible alleles
    that the
    following people
    have on the
    genes on their
Mendel’s Law of Segregation

 What happens during Meiosis?
 Mendel’s law of segregation
 explains the results of his cross
 between F1 tall plants. He
 concluded that the 2 alleles for
 each trait must separate when
 sex cells are formed. A parent,
 therefore, passes on at random
 only one allele for each trait to
 each offspring.
Let’s Make Another Baby!
   How many chromosomes do we have in our cells?
   How many came from Mom?
   How many from Dad?
   How many alleles for hair color did you receive from your mother?
   How many alleles for hair color did you receive from your father?
   If you have 2 alleles for hair color how come half of my head isn’t
    blonde and half isn’t brown?
Genetics Vocabulary
   Phenotype
       The way an organism looks
       Give me an example
   Genotype
       The gene combination an organism has
       Give me an example
       *Problem: You can’t always know an organism’s
        genotype simply by looking at its phenotype
   Homozygous
       An organism’s 2 alleles are the same
       2 capital letters would be homozygous dominant
           Give me an example
       2 lowercase letters would be homozygous
           Give me an example
   Heterozygous
       An organism’s 2 alleles for a trait are different
       Give me an example
Let’s revisit Meiosis again
   What happens in Metaphase 1
       The law of independent assortment
   Genes for different traits (for example seed
    shape and seed color) are inherited
    independently of each other.
   In our class example we used hair color,
    number of toes, and eye color
       We saw depending on how they randomly lined
        up with each other that you could tons of different
Punnett Squares
     In 1905, Reginald Punnett, an English
      biologist, devised a way of finding the
      expected proportions of possible
      genotypes in the offspring of a cross.

     If you know the genotypes of the parents,
      you can use a Punnett square to predict
      the possible genotypes of their offspring.
Monohybrid Cross
   Let’s consider Mendel’s first monohybrid cross between his true-
    breeding Tall plants and his true-breeding short plants. (P1 -> F1)
   Each letter (allele) separates into a possible gamete (sex cell).
Mendel’s Second Monohybrid
   Now let’s look at Mendel’s second
    monohybrid cross between his heterozygous
    F1 generation self-pollinating themselves.
    (F1 -> F2)
   Punnett squares show all of the possible
    combinations of gametes and the likelihood
    that each will occur.
       In reality, however, you don’t get the exact ratio of
        results shown in the square. That’s because
        genetics is like flipping a coin, meiosis leaves it up
        to chance.
   After completing a punnett square you are
    able to calculate the probabilities of what
    offspring will be produced.
   Let’s calculate some probabilities
Sex Linked Inheritance
Sex Linked Genes
   The X and Y chromosomes carry the genetic
    information that makes us male and female
   They also contain genetic information for
    some other traits

   What combination of sex chromosomes do
    girls have?
   What combination of sex chromosomes do
    boys have?
Sex Linked Genes
   Who determines the gender of the baby?
Sex Linked Genes
   Since men only have 1 X chromosome they will display
    the characteristics of these traits even if they are caused
    by a recessive allele

                           Male                     Female
                  The "a" recessive allele   The "a" recessive allele
                           will be                   will not
                     expressed in his         be expressed in her
                       phenotype                   phenotype
Sex Linked Genes
   There are about 1,098 human X-linked genes.
   Most of them code for something other than female
    anatomical traits.
   Many of the non-sex determining X-linked genes are
    responsible for abnormal conditions such as hemophilia,
    red-green color blindness, congenital night blindness,
    some high blood pressure, duchene muscular dystrophy,
    fragile-X syndrome, and male pattern baldness.
Sex Linked Genes
            If a woman is a carrier of an X-linked
            recessive allele for a disorder and her
            mate does not have it, their boys will
            have a 50% chance of inheriting the
            disorder. None of their girls will have
            it, but half of them are likely to be

            If a man has an X-linked recessive
            disorder and his mate does not carry
            the allele for it, all of their girls will be
            carriers. None of their boys will
            inherit the allele. Only girls receive X
            chromosomes from their fathers.
Sex Linked Inheritance
   In humans, red-green colorblindness is a
    recessive sex-linked trait. It is found on the X
    chromosome, not the Y. Because, males only
    have one X chromosome, they have a much
    greater chance of having red-green
    colorblindness. Females would have to be
    homozygous recessive in order to have red-
    green colorblindness.

   Normal vision – 8 red green color blind - 3
Sex Linked Inheritance
Sex Linked Inheritance
   A recessive allele on the X chromosome is
    responsible for red-green color blindness in
    humans. A woman with normal vision whose
    father is color-blind marries a color-blind
    male. What is the probability that a son of this
    couple will be color-blind?
     A pedigree is a diagram of family relationships
      that uses symbols to represent people and lines
      to represent genetic relationships.
     These diagrams make it easier to visualize
      relationships within families, particularly large
      extended families.
     Pedigrees are often used to determine the
      mode of inheritance (dominant, recessive, etc.)
      of genetic diseases.
   Squares represent Males
   Circles represent Females
   Horizontal lines connecting a male and female
    represent mating
   Vertical lines extending downward from a couple
    represent their children
   Oldest individuals are found at the top and youngest
    on the bottom
   Completely shaded in individuals posses the trait
   Half shaded in individuals are carriers of the trait

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