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Genetics are awesomeeee.

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Genetics are awesomeeee. Structure of DNA Each DNA molecule is made up of two very long polymers Double helix: is the shape Nucleotides: are the building blocks ... – PowerPoint PPT presentation

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Title: Genetics are awesomeeee.


1
Genetics are awesomeeee.
2
Structure of DNA
  • Each DNA molecule is made up of two very long
    polymers
  • Double helix is the shape
  • Nucleotides are the building blocks
  • deoxyribose ( a 5 carbon sugar)
  • phosphate group
  • nitrogenous base

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DNA double helix
5
Nitrogenous bases
  • There are four different nitrogenous bases
    thymine (T), cytosine (C),
  • adenine (A), and guanine (G)
  • These four bases are the foundation of the
    genetic code.
  • These chemicals act as the cell's memory,
    instructing it on how to synthesize enzymes and
    other proteins. These four nucleotides encode
    everything an organism needs to live and protects
    this information with incredible accuracy.

6
  • In a human being
  • DNA is broken down onto 46 separate chromosomes
  • Each chromosome has about 160 million nucleotide
    pairs
  • This massive amount of information is stored and
    replicated almost flawlessly!

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DNA Replication
  • INTERPHASE Before a cell divides, its DNA is
    replicated
  • Semi Conservative replication Two strands of a
    DNA molecule are separated, each ONE can be used
    as a template to produce a complementary strand. 
  • Each template and its new complement together
    then form a new DNA double helix, identical to
    the original.

9
  • Before replication can occur, the length of the
    DNA double helix about to be copied must be
    unwound. INTERPHASE
  • The two strands must be separated, much like the
    two sides of a zippper helicase   
  • The enzyme DNA polymerase then moves along the
    exposed DNA strand, joining newly arrived
    nucleotides into a new DNA strand that is 
    complementary to the template.  

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Meiosis I
  • STEP ONE MEIOSIS I This is basically like the
    PMATI of a regular mitosis.
  • Pairs of chromosomes are lined up at the center
    of the cell and then (separated) and pulled to
    each side.
  • Meiosis is a bit different because there is
    something called crossing-over. This crossing
    over is an exchange of genes from 1 homologous
    chromosome to the other (genes from the
    chromosome you got from mom go onto the
    chromosome you got from dad. The genes are mixed
    up, not resulting in a perfect duplicate like
    mitosis.
  • This is why your children will not look exactly
    like their Nana or Grandpa. They will look like
    a combo.

12
  • The cell divides, leaving two new cells with a
    pair of chromosomes each. Normally the cell would
    begin to go about its business of living and
    slowly duplicate the chromosomes for another
    mitotic division. Since this is meiosis, there is
    a very short interphase and division begins
    again. The DNA is not doubled

13
Meiosis II
  • STEP TWO MEIOSIS II
  • In Metaphase II all of the chromosomes line up
    along the center of the cell
  • Anaphase II shows the chromosomes split and move
    to opposite sides of the cell.
  • They don't divide up the DNA between the new
    cells
  • Each daughter cell will get one-half of the DNA
  • The cell membrane begins to pinch. When it's all
    over, you are left with four haploid cells that
    are called gametes. The eventual purpose of the
    gametes will be to find other gametes with which
    they can combine. When they do, they will form a
    new organism.

14
Mendels First Law
  • Mendel's First Law is the law of "Segregation of
    Characteristics.
  • Humans are Diploid. This means you get two
    alleles for each trait. You get one allele from
    mom and one allele from dad.
  • This law basically says that you can only get ONE
    allele from mom. Only ONE from dad.
  • In eye color B Brown is dominant. Blue (b) is
    recessive.
  • If mom has Brown eyes she could be BB or Bb. She
    can only pass ONE allele on in her egg.

15
Independent assortment
  • Mendel's Second Law is the law of "Independent
    Assortment". This says that for two
    characteristics the genes are inherited
    independently.
  • Example Your shoe size and hair color are not
    inherited together. Meaning people with black
    hair do NOT necessarily have Big Feet.

16
  • - If mom had the genotype AaBb she would make
    four kinds of gametes(eggs) they would contain
    the combinations of either AB, Ab, aB or ab.
  • A is dominant (big feet) a is recessive (little
    ft)
  • B is dominant (black hair)b is recessive(blond)
  • So, mom would pass on either
  • Big feet black hair (AB),
  • big feet and blonde hair (Ab)
  • Little feet and black hair (aB)
  • Little feet and blonde hair (ab)

17
Punnett Square
  • A punnett square is used to predict an expected
    outcome of
  • a particular cross or
  • breeding experiment.

18
Non Mendelian Genetics
  • Some traits are not passed on the way the traits
    Mendel studied were.
  • Incomplete dominance
  • Co dominance
  • Multiple alleles

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Incomplete Dominance
  • Incomplete dominance is a form of intermediate
    inheritance in which one allele for a specific
    trait is not completely dominant over the other
    allele. This results in a combined phenotype.

20
Codominance
  • A condition in which both alleles of a gene pair
    in a heterozygote are fully expressed, with
    neither one being dominant or recessive to the
    other.

21
Multiple Alleles
  • Any set of three or more alleles or alternative
    states of a gene.
  • Only two of which can be present in an organism
    at a time.
  • Responsible for differences in expressions of a
    given trait. Example brown eyes v. green eyes.
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