Genetics are awesomeeee.

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Genetics are awesomeeee.
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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
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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.

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• 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.

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• 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.

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• 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

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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.

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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.

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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.

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• - 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)

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Punnett Square

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

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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.

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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.

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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.