Download DNA Notes

DNA Structure and Function
Watson and Crick
• An Englishman and
an American
discovered the
structure of DNA in
1954.
• DNA is to small to see
so they had to build a
model using x-Rays
and chemical
information about
Nitrogen bases
They Had Some Help
• Roselyn Franklin took this x-ray picture of DNA
which lead Watson and Crick to the double helix
structure of DNA but they failed to give her credit
until much later.
Double Helix
• DNA consists of
two strips, made of
sugars and
phosphates,
twisted around
each other and
connected by
nitrogen bases.
• Looks like a spiral
staircase or a
twisted ladder.
Sugar Backbone
• The backbone of DNA
is made up of
Deoxyribose (Sugar)
molecules connected
to each other using
Phosphates
Nitrogen Bases
• DNA contains 4
nitrogen bases that
make up the “code”
for all living things.
A = Adenine
T = Thymine
G = Guanine
C = Cytosine
A always bonds to T
G always bonds to C
Nucleotide
• The combination of a sugar, phosphate and
nitrogen base is called a Nucleotide. These are
the building blocks of DNA.
DNA Facts
• There is 6 feet of DNA in EVERY cell in
your body
• Your DNA contains over 3 Billion base
pairs
• Your DNA has over 23,000 genes which
means you can produce 23 thousand
different protiens.
RNA
• Two types
a.
mRNA=messenger
b. tRNA = transfer
• Single strand
• Ribose backbone
• Substitutes Uracil (U)
for Thymine (T)
Key Words for Protein Synthesis
• Gene- section of DNA that codes for a
specific protein.
• Messenger RNA (mRNA)- nucleic acid
that copies the DNA and takes it to the
Ribosome.
• Ribosome- Organelle that builds proteins
using mRNA and tRNA.
• Transfer RNA (tRNA)- nucleic acid that
matches up codon to anticondon and drops
off amino acids in the correct order.
Key Words Continued
Codon- Group of three nitrogen bases
found on the mRNA that codes for a
specific amino acid.
Anticodon- Group of three nitrogen bases
found on the tRNA that matches up with
the codon and drops off the correct amino
acid.
Amino Acid- Building blocks of proteins that
are placed in the correct order by
matching codon to anticodon along the
length of a gene.
Steps to Protein Synthesis
Transcription
• DNA Opens one Gene
• One side of the DNA is copied by the mRNA
• mRNA travels outside the Nucleus to the
Ribosome
Translation
• Ribosome attaches to the mRNA.
• tRNA matches up codon to anticodon and
drops off the correct amino acid
• A chain of amino acids is created which is a
protein
Translantion
Protein Synthesis Models
• https://www.youtube.com/watch?v=NJxob
gkPEAo&list=FLEezLUmpa3vfMmQGp1aPTQ&feature=mh_lolz
• https://www.youtube.com/watch?v=Nmqhd
ozuf7Y&list=FLEezLUmpa3vfMmQGp1aPTQ&index=1
Genetic Mutation
• Point mutation- substitution, addition or
removal of a single nucleotide.
- substitution can cause a change in the
amino acid sequence
- Deletion and addition mutation can cause
a frameshift which means that the order of
amino acids changes.
Sickle Cell Anemia