RNA and Protein Synthesis
BIOLOGY
Chapter 10-2 and 10-3 (pgs 190-197)
Do Now
• What is the function of DNA?
• What are the 4 nitrogen bases in
DNA nucleotides and how do they pair
up (complimentary base pairing)?
• What are the two main enzymes
involved in DNA replication?
Review of DNA:
DNA?
•Organic molecule
(nucleic acid) that is
composed of repeating
subunits - nucleotides
•Stores and transmits
the genetic information
•Controls the
production of protein
FYI…
Each ‘gene’, or section of DNA, consists of a sequence
of nucleotides arranged in a specific order according to
our genetic ancestry.
The order of these base units makes up the genetic
information or “code” for specific characteristics
(proteins) in the body.
Review of Proteins
Proteins are also made up of a sequence of
subunits called amino acids.
Ribosome
And, in all cells, except for bacteria, DNA is
stored in the nucleus and protein synthesis
takes place in the ribosome in the
cytoplasm…
? Question ?
So, how do cells use the
genetic information, or
‘code’ stored in DNA to
make millions of
different
characteristics and
proteins the body
needs?
This is how we do it….
• The DNA (deoxyribonucleic acid) that contains the
genetic code to make all of your proteins is trapped
in the nucleus of the cell
• The ribosomes, enzymes, and amino acid building
blocks of protein are out in the cytoplasm
• RNA (ribonucleic acid) is responsible for getting the
‘code’ from the nucleus to the cytoplasm
• RNA Copies DNA and then moves outside the
nucleus to synthesize proteins in the ribosome
RNA – Ribonucleic Acid
Like DNA , RNA is a nucleic
acid made up of repeating
nucleotides
Differs in structure:
1. Sugar (ribose)
2. Phosphate
3. 1 of four different
Nitrogenous Bases (A, G,
C, U)
4. Single strand
FYI - RNA
RNA differs from DNA
in several ways.
–An RNA molecule has
only one side of the
ladder shape.
–RNA has the bases A, G,
and C. However, it has a
base U or Uracil, instead
of base T or thyamine.
–So when forming base
pairs, base A pairs with
base U.
Comparison of DNA and RNA:
Nucleotide Components
DNA
RNA
Function
Form/Structure
Sugar
Nitrogen Base
Deoxyribose
Adenine,
Guanine,
Cytosine,
Thymine
Store and transmit
genetic info. that
tells cells which
proteins to make
and when.
Adenine,
Guanine,
Cytosine,
Uracil
Move genetic
Single strand of
info. from DNA to nucleotides.
ribosomes;
assemble
Single Helix
polypeptide chains
(proteins)
Ribose
2 strands of
nucleotides.
Double Helix
3 Types of RNA:
RNA: ribonucleic acid. Use information
from DNA to make proteins.
1. mRNA – messenger RNA
2. tRNA – Transfer RNA
3. rRNA – Ribosomal RNA
Messenger RNA (mRNA)
• Single, uncoiled chain
of RNA that
transcribes DNA’s
information from
nucleus to cytoplasm
Transfer RNA (tRNA)
• Single chain of about
80 RNA nucleotides
folded into a hairpin
shape that bind to
specific amino
acids
• There are 45
different varieties
Ribosomal RNA (rRNA)
• Consists of RNA nucleotides in
globular form – most abundant RNA
type
• Along with proteins,
rRNA makes up the
ribosomes where
proteins are made
http://glencoe.mcgrawhill.com/olcweb/cgi/pluginpop.cgi?it=swf::550::400::/sites/dl/free/0078802849/383936/Vis_transcripti
on_translation.swf::Visualizing%20Transcription%20and%20Translation
2 Parts of Protein Synthesis
• 1. TRANSCRIPTION-mRNA is
produced from DNA in the nucleus.
• 2. TRANSLATION-Takes place in the
ribosome. mRNA is ‘read’ and amino
acids are transferred into the
growing chain of the protein by
tRNA.
Transcription
• Part 1 of protein synthesis
• Process by which genetic
information is copied from
DNA to mRNA
• An enzyme, RNA polymerase
initiates transcription by binding
to promoter regions on DNA
• DNA molecule separates
• Only one of the DNA strands
acts as a template
Transcription
• RNA polymerase connects
RNA bases to the growing
RNA strand
• The same as when DNA is replicated but
uracil is used instead of thymine
• It continues until it reaches a termination
signal
Transcription
• PROMOTER-beginning of the gene
being transcribed.
• TERMINATION SEQUENCE-end of
the gene being transcribed. Tells the
RNA polymerase “let go”.
Do Now
• How is RNA different from DNA?
• What are the three types of RNA?
• What is the purpose of
Transcription?
Translation
Part 2 of Protein Synthesis
•
•
•
•
WHAT ARE PROTEINS?
Proteins are polymers of amino acids
There are 20 different amino acids
The sequence of amino acids
determines the structure of the
protein
• The function of the protein depends
on its structure
Proteins:
Translation
Part 2 of Protein Synthesis
•The sequence of
nucleotides in an mRNA
strand is translated into a
sequence of amino acids to
make a protein
•A series of 3 nucleotides
(bases) on mRNA make a
codon. A codon codes for
one amino acid.
Codons
Translation
Part 2 of Protein Synthesis
•There are 64 codons and
only 20 amino acids, so
several codons can code
for the same amino acid
•There are also a start
codon (AUG) and stop
codons (UAA, UAG, UGA
Check for Understanding:
• 3 mRNA bases = code for 1 amino acid
• If you have 450 mRNA bases, how
many amino acids would you code for?
• How many codons would you have?
Translation
Part 2 of Protein Synthesis
•mRNA goes to ribosome and begins
translation from start codon
•As the ribosome reads each codon,
the corresponding tRNA will come
and match its anticodon to the
correct codon.
•The anticodon is complementary to
and pairs up with a corresponding
mRNA codon.
Translation
Part 2 of Protein Synthesis
•The amino acid
carried by the tRNA
will be linked to the
prior amino acid in
the chain. Ribosome
reads the stop codon
and the process
stops.
Translation
Part 2 of Protein Synthesis
Summary:
• Let’s watch protein synthesis in
ACTION!
• Or here…
• Now Play
“Drag and Drop Protein Syntheisis”