Download DNA Replication, Transcription and Translation Power Point

Something to Think about ……
Did you know that some of
your cells are dying right
now? You may live to the
ripe old age of 100, but
most of your cells will have
been replaced thousands
of times before you blow
out the candles on that
birthday cake. Every time
cells divide to produce new
cells, DNA must first be
copied. Before we
replicate some DNA, let’s
recap …………………………….
Chromosomes, Genes, and DNA
• Chromosomes and genes are made of DNA.
• Genes are stretches of DNA that code for a trait such as hair
color or eye color.
Hair Color
Eye Color
• Chromosomes are threadlike structures found in the nucleus
that contain genetic information (genes).
Chromosomes, Genes, and DNA
chromosome
cell
genes
nucleus
base pairs
DNA (double helix)
DNA Replication
• Why does DNA need to replicate?
DNA is located inside the nucleus and NEVER leaves the
nucleus. However, ALL cells need the genetic code (DNA) to
function. DNA will make a copy of itself and that copy
“leaves” the nucleus.
• Do you remember “who/what” goes in the nucleus to copy
the DNA?
RNA
• When in the cell cycle does the DNA get replicated?
The S-Phase of Interphase
How does DNA replicate?
• The process by which DNA
is copied during the cell
cycle is called replication.
• When DNA is copied, every
cell has a complete set of
DNA.
• DNA simply stores the
genetic information.
Enzymes and other
proteins do the actual work
of replication.
DNA Polymerase:
enzymes that form bonds
between nucleotides
(phosphate, deoxyribose,
nitrogen base) during
replication.
• Before DNA replicates, do you
remember:
1. What are the 4 nitrogen bases of
DNA?
Adenine, Guanine, Thymine, Cytosine
2. How do these nitrogen bases pair
up?
AT
GC
DNA Replication
Original
DNA Strand
1. The original strand of
DNA “unzips” and
nucleotides base
pairs separate.
2. The enzyme Helicase
is responsible for the
“unzipping.”
3. New DNA strands
forms.
Quick Illustration
New DNA
Strand
DNA Replication
Video & Quick Question
During DNA replication,
what is the complementary
strand of the original
DNA strand below?
A T G G C T A
DNA Replication YouTube Video
After Replication……Transcription Begins….
• Remember, DNA never leaves the nucleus so RNA makes a copy of
the DNA.
• The process of RNA making a copy of DNA inside the nucleus is
called transcription.
• mRNA (messenger RNA) sends the message/copy of DNA to the
cytoplasm of the cell. RNA gets the message out 
• How does mRNA tell the cell what to do?
mRNA codes for a protein and proteins keep a cell alive
• What are the nitrogen bases for RNA?
Adenine, Guanine, Uracil, Cytosine
• How do RNA nitrogen bases pair up?
AU
GC
RNA Transcription
• DNA unzips again (seperates)
• The enzyme RNA polymerase
bonds nucleotides together in
a chain to make a new RNA
molecule
• When complete, RNA
detaches and DNA zips back
together
• Transcription produces
mRNA, rRNA, and tRNA
• Once in the cytoplasm, mRNA
attaches to a ribosme to make
a protein
• Remember ….. Protein
synthesis takes place in
ribosomes
Transcription
Illustration and Questions
Quick Illustration
Complete the following base
pairing. Pay
attention to which process you
are pairing up
with.
Original DNA:
A A T G C T
DNA Replication: ____________
Transcription:
____________
Translation
• Translation is the process that translates a mRNA message
into a polypeptide. The translator is tRNA.
• Polypeptide??????? Polypeptides make up proteins.
• The building blocks of proteins are amino acids.
• During the process of translation, 3 nitrogen bases
sequenced together are referred to as a codon.
• Codons will code for an amino acid.
• In addition to coding for amino acids, there are stop codons
and a start codon.
• Start and Stop codons begin and end
the translation process.
Brain Teaser
Can you handle it?
Suppose an mRNA
molecule in the
cytoplasm had 300
nucleotides. How
many amino acids
would be in the
resulting protein?
Translation
How does a cell translate a codon into an
amino acid?
Set of 3 mRNA’s is a
codon which codes
for an amino acid.
tRNA forms an
anticodon that pairs
to the codon
Coding for Amino Acids
• Let’s try it 
• AUA:
______________
• GAG:
______________
• UUA
______________
• AAC:
______________
• UGA:
______________
Another Brain Teaser 
Think about this Base Pairing……
• Original DNA:
T G A C C T
• DNA Replication:
______________
• Transcription mRNA: ______________
( set of 3 = codon )
• Translation tRNA:
( anticodon )
______________
• Amino acids: ____________________
Transcription and Translation
Quick Video
http://www.youtube.com/watch?v=983lhh20rGY
Why all this just for amino acids?
• Amino acids are used in every cell of your body
to build the proteins you need to survive.
• Amino acids repair tissues, build cells, form
antibodies, carry oxygen …. Just to name a few!
• There are 20 amino acids used to make proteins
in your body.
• Amino acids form long chains which are called
proteins.
To put it simply 
Thank goodness!!!
This was just way toooooo
much information !!!!!
1. DNA replicates
inside the nucleus
( AT GC )
2. The enzyme RNA
polymerase goes in
to make a copy …..
( AU GC )
3. mRNA goes back into
the cytoplasm and
attaches to a
ribosome
4. tRNA brings the
correct amino acid to
the ribosome
( AU GC )
Replication
Transcription
Translation