AP Biology Discussion Notes
Wednesday 01/28/2015
Goals for Today
• Be able to describe how DNA & RNA
molecules differ from each other.
• Be able to name and describe the two
major steps of protein synthesis (how
proteins are made)
• Be able to list the molecules & structures
involved in Transcription & Translation.
Question of the Day 1/28
• What do you know about DNA &
Proteins?
– What is similar or true for both?
– What is different?
Question of the Day 1/28
• What do you know about the
relationship between DNA & Proteins?
Be Dogmatic!
Genetic Information is:
Encoded in DNA;
Transmitted through DNA Replication
(did this!);
Transcribed into RNA; this is called
TRANSCRIPTION;
Translated into Protein; this is called
TRANSLATION
Importance
• GENOTYPE becomes a PHENOTYPE
• Gene Expression
Chapter 17
Protein Synthesis: The Big Picture
Protein Synthesis
• The first step in protein synthesis
involves DNA & a very similar molecule,
RNA that is also made of ___________.
• Before we talk about the individual
steps in making proteins, lets compare
DNA & RNA
DNA vs. RNA
DNA & RNA differ from each other in several
important ways. See if you can fill in the
following chart for DNA
DNA vs. RNA
DNA
Full Name
Sugar in
Nucleotide
Nitrogen
Bases
# of Strands
Compliments/
Pairing
RNA
What is this structure called?
Phosphate
Group
N
Nitrogenous base
(A, G, C, or )
Sugar
(
)
RNA Nucleotide – a nucleotide is
the three component parts together
Phosphate
Group
N
Nitrogenous base
(A, G, C, or )
Sugar
(
)
RNA – Ribonucleic Acid
RNA is like DNA except…
- it is single stranded
Nitrogen
Bases
- it has uracil instead of
thymine
Sugars
&
Phosphates
- it has ribose instead of
deoxyribose
RNA
DNA
DNA or RNA?
• How could you tell, what is your evidence?
DNA or RNA?
• It is DNA because there are “T”s in it for
Thymine
DNA…. what is good for?
• DNA has 2 major functions in our
body:
1. Make more DNA
2. Make Protein
DNA holds the directions for protein synthesis
Protein synthesis -making proteins
Gene section of DNA that carries the code for
making one protein
Protein Synthesis
• Gene section of DNA that carries the
code for making 1 protein
• There are thousands of genes on each
chromosome.
• Everything in your body is made of AND by
proteins! Ex. Enzymes are proteins! 
Steps of Protein Synthesis
The first step of Protein Synthesis is known as
Transcription
• If you ordered a “Transcript” what would that
be?
• Would it be the same?
Steps of Protein Synthesis
The first step of Protein Synthesis is known as
Transcription
1.DNA is transcribed into messenger RNA
(mRNA) by an enzyme known as:
RNA polymerase, which builds an RNA
strand that is complimentary to the DNA
strand.
Transcription
RNA polymerase, which builds an RNA
strand that is complimentary to the
DNA strand.
Steps of Protein Synthesis
• If DNA is what is being transcribed, then
what part of the EUKARYOTIC cell would
this occur in?
• Transcription occurs in the _____________
Transcription – Practice!
RNA polymerase, which builds an RNA strand
that is complimentary to the DNA strand.
Messenger RNA - mRNA
The message of mRNA is carried in
“codons”
A codon is a three base sequence that
will code for one Amino Acid (the
__________ _______ /________
of ____________.
Together the codons in the mRNA strand
code for 1 protein (typically hundreds
or thousands of Amino Acids for a
single protein)
Protein Synthesis: The Big Picture
Transcription
Try to pick out the molecules:
–RNA Polymerase
– mRNA
–Nucleotides
–DNA
•Real Time animation of Trancription
Lets Review
• What process makes an mRNA molecule?
• What is needed to produce it?
• What sets mRNA apart from DNA?
Steps of Protein Synthesis
• The next major process in protein synthesis
is known as “translation” in this process
mRNA is translated into protein.
2. Before translation can happen mRNA must
move out of the nucleus ( in ______
organisms) and into the cytoplasm.
Messenger RNA - mRNA
DNA’s “recipes” are transcribed by the
enzyme ____ ____________ to make a
molecule of mRNA.
mRNA is like a different language then DNA
mRNA is the language that the ribosome (protein building machine) can read.
Steps of Protein Synthesis
•
The next step of Protein Synthesis is
TRANSLATION
If someone asked you to “Translate” something what
would that mean?
Steps of Protein Synthesis
•
The next step of Protein Synthesis is
TRANSLATION
3. Once the mRNA strand leaves the nucleus and
enters the cytoplasm the mRNA Attaches to a
ribosome (our cell’s protein making machine)
Steps of Protein Synthesis
3. Once the mRNA strand leaves the nucleus
and enters the cytoplasm the mRNA
Attaches to a ribosome (our cell’s protein
making machine)
4. Next a molecule of Transfer RNA (tRNA)
attaches to the mRNA strand
Anatomy of a
Transfer “t” RNA (tRNA)
Anatomy of a (tRNA)
Steps of Protein Synthesis
4. Next a molecule of Transfer RNA (tRNA)
attaches to the mRNA strand
Steps of Protein Synthesis
4. Next a molecule of Transfer RNA (tRNA)
attaches to the mRNA strand
5. Amino acids are linked together by the
ribosome to form the final protein (which is
really just a long chain of amino acids)
Translation
• Real Time Animation
Protein Synthesis
Lets put it all together!
Create the mRNA, tRNA and find the Amino
Acid coded for on mRNA
Protein Synthesis Story
Quiz & Quiz Corrections
• If your quiz corrections were ALL correct,
they are in the grade book. If there was
anything left to fix, they are not.
• Double check that your quiz grade and
corrections are in if you have finished
both.
Species of the Day 1/28
• Leopard Seal
– Hydrurga leptonyx
Species of the Day 1/28
• Leopard Seal
– Hydrurga leptonyx
What do you know about the
RNA of this leopard seal?
(You should have a pretty good
list by now, including processes
that the RNA is involved in)