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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. RNADNA & RNA differ from each other in several important ways. See if you can fill in the following chart for DNA
DNA vs. RNADNA RNA
Full Name
Sugar in Nucleotide
Nitrogen Bases
# of Strands
Compliments/Pairing
What is this structure called?
PhosphateGroup
NNitrogenous base(A, G, C, or )
Sugar( )
RNA Nucleotide – a nucleotide is the three component parts together
PhosphateGroup
NNitrogenous base(A, G, C, or )
Sugar( )
RNA – Ribonucleic Acid
RNA is like DNA except…
- it is single stranded
- it has uracil instead of thymine
- it has ribose instead of deoxyribose
Nitrogen Bases
Sugars
&
Phosphates
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 SynthesisThe 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 SynthesisThe 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 - mRNAThe 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
TranscriptionTry 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 - mRNADNA’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)
Steps of Protein Synthesis
4. Next a molecule of Transfer RNA (tRNA) attaches to the mRNA strand
Steps of Protein Synthesis4. 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)
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)