Download DNA with Nitrogen Bases

DNA
A Snapshot of DNA
DNA from a few Angles
• Cell: Every cell contains a nucleus which is filled with the directions
for cell function, DNA.
• Chromosome: When DNA is tightly coiled and wound it becomes
visible in the form of chromosomes. Chromosomes contain our
genes which determine our traits. Each chromosome contains over
100 million base pairs (DNA nitrogen bases)
• Histone: A type of protein which creates a strong bond to DNA
allowing it to coil up tightly into chromatin which makes up
chromosomes.
• DNA Double Helix: Composed of a twisted ladder of chromatin.
• DNA with Nitrogen Bases: There are four nitrogen base pairs that
make up the steps or rungs of the DNA ladder: Cytosine pairs with
Guanine and Thymine pairs with Adenine. The sides of the ladder
are made of phosphate and deoxyribose sugar molecules.
Which is which?
DNA DOUBLE
HELIX
CELL
CHROMOSOME
HISTONE
DNA W/ NITROGEN
BASES
A REAL snapshot of DNA
Rosalind Franklin
• As a physical chemist at King’s College, Franklin
studied DNA’s structure using x-ray photography /
crystallography alongside Maurice Wilkins.
Wilkins was not fond of Franklin but her research
was intriguing to him. She proved that the
phosphate groups were found on the outside of
DNA and she noted the possibility of a helix
shape. It was at this time that Wilkins took
Franklin’s photographs to Watson and Crick. After
publishing many papers and even continuing her
research throughout her illness, Rosalind died in
1958 of ovarian cancer.
Watson and Crick DNA Model
Watson, Crick and Wilkins
• Near Franklin’s college, Watson and Crick worked
together at Cambridge trying to determine the
structure of DNA. When Wilkins approached
Watson and Crick with Franklin’s photographs it
became their proof of the double helix structure
with two chains of nucleotides going in opposite
directions and nitrogen bases in the middle,
making the rungs of the ladder. They published
their findings in 1953 and in 1962, Watson, Crick,
and Wilkins won the Nobel Prize for their
discovery. By this time, Franklin had died and she
could not receive the prize posthumously.
DNA – deoxyribonucleic acid
• Resides in the nucleus
• Shaped like a twisted ladder (Double Helix)
• Sides of the ladder are made up of sugars and
phosphates
• The steps of the ladder are made of PAIRS of
molecules called nitrogen bases.
• Nitrogen Base + Sugar + Phosphate =
NUCLEIC ACID
Nitrogen Bases
• The are 4 bases
Adenine
Guanine
Purines
Thymine
Cytosine
Pyrimidines
Purines and Pyrimidines
purine
pyrimidine
He found the same amount of Adenine and Thymine AND
the same amount of Cytosine and Guanine exist in our cells.
This provided evidence that certain bases pair with certain bases!
Basic Structure
Nucleotide
Proteins
• Proteins are one of the most important parts
of all living things
• Large, complex molecules that do most of the
work in a cell, AND
• Provide for the structure, function and
maintenance of the body’s tissues and organs
• Made up of amino acids (20 types that
combine to make different proteins)
Protein Synthesis
• Protein synthesis or creation is important for
cellular function. Proteins are made of amino
acids and our DNA provides the instructions
for assembling amino acids in the proper
order, thus creating proteins that can do their
jobs correctly.
• The nucleus holds the key for protein
synthesis, a process that takes place within
every cell of every living thing.
DNA and RNA
• DNA and RNA work together to make sure the
protein synthesis occurs in our cells
• Both are Nucleic Acids
• Both have Adenine, Cytosine and Guanine
DNA has Thymine but RNA has Uracil
RNA
• Messenger RNA – carries a message based off
of the DNA
• Transfer RNA – transfer the message
• Ribosomal RNA – work in the ribosomes to
make proteins
REPLICATION
• When cells of the body divide, the DNA double
helix duplicates itself within the nucleus.
• An enzyme called Helicase unwinds the two
strands and the enzyme DNA polymerase reads a
the strands and lays down complimentary
nitrogen bases.
• Finally Helicase zips the DNA back up creating
TWO daughter strands from one parent strand.
TRANSCRIPTION
• The synthesis of messenger RNA (mRNA)
using DNA as a template.
• Helicase unzips DNA and RNA polymerase
copies the DNA message into a single strand
of mRNA where uracil is substituted for
thymine as a pair to adenine.
• mRNA is small enough to leave the nucleus so
the DNA message can reach the ribosomes in
the cytoplasm.
TRANSLATION
• The synthesis of protein using mRNA as a
template.
• mRNA travels to a ribosome (rRNA) where it is
read in triplets (a codon).
• Each triplet codes for a specific amino acid
which transfer RNA (tRNA) provides. The
amino acids link up at the ribosome until an
amino acid (polypeptide) chain is created
which builds up to make a protein.
Mutations
MUTATIONS
• What is a mutation? It is a permanent
alteration in a sequence of DNA that makes up
a gene.
• Mutations can be so small that they affect a
single base pair or so large that it involves
multiple genes.
• Mutations can affect individuals differently
depending on where they occur and the type
of proteins that are created as a result.
Deletion
• changes the number
of DNA bases by
removing a piece of
DNA.
Inversion
• an entire section of DNA is reversed
Translocation
• a whole
chromosome
or
chromosome
segment
attaches to
another
chromosome
or segment
creating a
hybrid.
Insertion
• increases the number of DNA bases in a gene
by adding a piece of DNA
Duplication
• a piece of
DNA that is
copied one
or more
times