All about your DNA

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All about your DNA
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Structure of DNA

• Every DNA molecule is made in a twisted ladder
  shape called a double helix.
• The sides of the ladder are called the backbone
  of the DNA molecule.
• The backbone is made up of alternating sugar
  (ribose) and phosphate molecules.

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• The rungs or steps of the DNA ladder are made up
  of nitrogen base pairs
• Each rung is actually 2 individual molecules
  connected in the middle.
• There are 4 possible nitrogen base molecules that
  make the rungs of the ladder
• Thymine
• Adenine
• Cytosine
• Guanine

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• Thymine ALWAYS and ONLY bonds with Adenine.
• Cytosine ALWAYS and ONLY bonds with Guanine.

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Nucleotides

• Nucleotides link together and form DNA.
• Nucleotide One ribose (sugar), one Phosphate,
  and one nitrogen base.

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The DNA Hand Trick

• Palm Sugar (Ribose)
• Thumb (Phosphate)
• Fingers Nitrogen Bases (A,T,C,G)

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Genes

• 90 of your DNA is never used for anything that
  we know of.
• Genes are sections of the DNA code that are
  actually used by the cell to create proteins.
• Genes can be anywhere from 100s to 1000s of
  base pairs long.

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Chromosomes

• Chromo DNA
• Some Body
• Chromosomes are coils of DNA that are wound super
  tight and are X-shaped.
• Every human has 23 pairs of chromosomes- 46 in
  total. 23 from mom, 23 from dad.

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Boys vs. Girls

• The only genetic difference between males and
  females occurs on the 23rd chromosome pair.
• In boys, the 23rd pair do not match. One
  chromosome- the Y chromosome- is much shorter
  than the other. This XY combination makes the
  person male.
• Females do not have the Y- they have two
  regular shaped chromosomes (XX).

Girl
Boy
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Making Boys and Girls

• Women have XX, so they can only give an X to
  their offspring.
• Men have XY. They have an equal chance of giving
  either an X or Y to their child.
• If a male gives an X, that would create XX (girl)
  when combined with the mothers X. If the male
  donates Y, that means XY (boy).

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Chromosomes Jobs

• Chromosomes are giant clumps of DNA, so they
  carry the critical instructions for life.
• Genes are located on chromosomes.
• Chromosomes are the way information is passed
  from one generation to the next.
• Chromosomes are found in pairs- one from mom, one
  from dad.

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Other Organism Chromosome Totals

• Fruit Fly 8 Chromosomes

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Pea Plant 14 Chromosomes
Kangaroo 12 Chromosomes
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Algae 148 Chromosomes
Dog 78 Chromosomes
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• 1260 Chromosomes
• (Highest for Plants)

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• Wooly Mammoth (extinct) 58 Chromosomes
• Retrieved from frozen remains

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Protein Synthesis

• Protein Synthesis creating a protein by reading
  DNA code
• This is how DNA code comes to life.

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Unzipping?!

• The bonds in the middle of the steps of the
  double helix can come apart.
• This is called unzipping and must happen for
  the DNA code to be read.

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Step 1

• The DNA never leaves the nucleus. Why?
• The DNA is very safe in the nucleus. Even very
  small changes in the DNA molecule can be
  catastrophic.
• Step 1 DNA unwinds and unzips itself at a
  specific gene.

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Step 2

• A molecule called RNA Polymerase attaches to
  the unzipped DNA and reads the A, T, G, C code.

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Step 3

• Transcription- mRNA is created- a copy of the
  DNA code that replaces Thymine with Uracilto and
  can leave the nucleus.

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• RNA is a single strand that looks like a single
  twisted ribbon (a single helix).
• RNA, for some reason, does not use Thymine.
• Every place Thymine would be used, RNA uses a
  similar molecule called Uracil instead.

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Step 4

• mRNA Travels out of the nucleus and hooks onto a
  ribosome.

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Step 5

• Translation- The Ribosome reads the RNA and
  creates the protein.

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Step 6

• Amino acids are added to the Protein and is used
  by the cell for a body process or to create a new
  structure.

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Protein Synthesis Flow Chart p. 28
On your paper, write the title and explain how
the cell reads the DNA to make protein.
DNA unwinds and unzips itself at a specific
gene
RNA attaches to the unzipped DNA
mRNA makes a transcription of the DNA code
replacing Thymine with Uracil
mRNA travels out of the nucleus and hooks onto a
Ribosome
tRNA takes the mRNA to the ribosome. The
Ribosome reads the RNA code through translation
and creates a protein
Amino Acids are added to the protein. The protein
is used by the cell for a body process
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Protein Synthesis p. 28
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Determining Sex

• The gender of a person is determined by the
  passing down of the sex chromosomes from
  parents to offspring.

• Since females have two Xs, they can ONLY pass
  down an X to their offspring.
• Males have an X and Y chromosome, so they can
  pass either X or Y to their offspring.

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Sex-Linked Traits

• The X and Y chromosomes have genes on them, just
  like all the other chromosomes.
• The traits controlled by genes on these X or Y
  sex chromosomes are called sex-linked.
• Some diseases are sex linked, such as hemophilia.
  
• Ex All the physical and chemical differences
  that make someone a male are sex-linked traits
  because they are passed down on the Y chromosome.
  .
• hemophilacs

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Mutations

• Any abnormal change in an organisms DNA.
• Examples
• If the nitrogen bases arent kept exactly the
  same, large problems or changes occur.
• If a letter simply disappears, this mutation is
  called a deletion. This is very bad.
• If one letter accidentally switches to a
  different letter, it is called substitution.
• If extra letters are added to the code, it is
  called an addition mutation.
• All mutations on active genes can cause
  changes/problems in the organism.
• i.e.. Blue eye mutation, 6 fingers, 3 nipples,
  etc.