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DNA
Replication,
Transcription
and
Translation
Structure of DNA and RNA
DNA
Deoxyribonucleic Acids
are nucleotides made
of:
– Base pairs
(Adenine, Thymine,
Guanine, Cytosine)
– Deoxyribose sugar
group
– Phosphate group
– Double stranded, in
helix coil form
RNA
Ribonucleic Acids
are nucleotides made
of:
– Base pairs
(Adenine, Uracil,
Guanine, Cytosine)
– Ribose sugar group
– Phosphate group
– Single stranded
Base pairs come in two combinations:
C bonds to G
RNA uses Uracil, in place
of Thymine.
(A bonds to U)
A bonds to T
DNA structure
Makes a ladder shape
• Phosphates bond to
Sugars ( uprights )
• Base pairs bond
A to T, and C to G
between sugars
• The two strands twist
into double helix
form
DNA structure compared to RNA
• Both have a ladder shape
made when Phosphates
bond to Sugars (uprights
or backbone)
• Both Base pairs are
attached to this backbone
• Both the strands of DNA
or strand of RNA twist
DNA Replication - “Xeroxing”
- Happens in the nucleus
1.DNA unzip - with help of
enzymes
2.Two strands DNA form
(sense and anti-sense)
3.Enzymes help new
nucleotides pair with free
ends on single strand of
DNA: A-T and C-G
4. A-T and C-G form
hydrogen bonds between
new nucleotide and the
strand of DNA
Sense Anti- sense
DNA Replication
Final Product:
2 double helix DNA formations that are
exact copies of the original DNA strand
Transcription of DNAmonks re-writing manuscripts
letter by letter
(messenger writing down the plans before
they are carried away)
• Happens in nucleus
• Then mRNA exits into
cytoplasm carrying
message
• Involves DNA and
mRNA, and enzymes
(polymerase)
Transcription
• 1. DNA "unzips " enzyme breaks double and
triple bonds between
nitrogen base pairs (A-T,
C-G)
• 2. Two strands DNA
formed (sense and
anti-sense)
• 3. Enzyme reads DNA
base pairs and adds new
nucleotides to match base
pair (Uracil in place of
Thyamine) (A-U, C-G)
Transcription - Final stages
• 4. The nucleotides are
bonded at the phosphate
and sugar creating the
new strand of RNA.
• 5. RNA introns spliced
out, leaving mRNA.
• Final Product: coded
strand of mRNA
Translation of mRNAdeciphering the code, like spies in WWII
(builders building the structure,
using plans carried by messenger)
• Occurs in the cytoplasm
(Endoplasmic reticulum)
• Molecules involved
mRNA, tRNA, codons (3
bases), ribosomes, amino
acids, and enzymes
= Protein!
Translation - begins
• 1. First codon of mRNA
strand attaches to a
Ribosome (codon is 3 base
pair combination)
• 2. tRNA carrying a specific
amino acid, approaches
ribosome.
• 3. Enzyme helps tRNA
anti-codon to pair with
codon on mRNA.
• 4. tRNA remains with
amino acid attached to it.
Translation - continued
• 5. Next codon on mRNA
slides along to ribosome,
New tRNA anti-codon
with specific amino acid
is paired with codon on
mRNA.
• 6. Amino acid is bonded
with previous amino acid.
(peptide bonds) tRNA
breaks off, leaving
bonded amino acids.
Translation - Finale
• 7. Process continues as each codon is
paired with anti-codon, until STOP
codon on mRNA is reached.
Final Product:
Polypeptide chain also known as
Protein!
Summary of Transcription and Translation