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)

Anatomy of a (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)

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)