RNA and Protein Synthesis

Mr. CobbGCA Fall 2011

Review DNAWhat is a nucleotide?

What shape does DNA have?

What are the nitrogen bases in DNA?

Where do you find DNA?

Review DNAWhat is a nucleotide?

Sugar, phosphate, and base

What shape does DNA have?Double Helix

What are the nitrogen bases in DNA?ADENINE, THYMINE, GUANINE AND CYTOSINE

Where do you find DNA?NUCLEUS

BASE PAIRING• ADENINE – THYMINE (URACIL IN RNA)

• GUANINE – CYTOSINE

• A – T

• G – C

ALWAYS!!

Complete the DNA strand:

A - ___

G - ___

C - ___

C - ___

T - ___

G - ___

T - ___

G - ___

C – ___

G - ___

A - ___

A - ___

RNARibonucleic Acid

Contains Ribose as its 5-carbon sugar

Single strand-not double helix

Nitrogen Bases are A, C, G, and U (Uracil)

NO Thymine in RNA!!!!!

If you are looking at:A strand of bases and you are told to identify them as DNA or RNA,

IF you see Uracil, you will KNOW that it is RNA!!!

WHY TALK ABOUT PROTEIN SYNTHESIS

• CELL FUNCTIONS DEPEND ON ENZYMES (BIOLOGICAL CATALYST), WHICH ARE PROTEINS!

• MOST SUBSTANCES MADE BY CELLS CONTAIN A PROTEIN.

• UNDERSTANDING THIS PROCESS, SCIENTISTS CAN MAKE CHANGES TO WHAT PROTEINS ARE PRODUCED (ANTIBIOTICS)

PROTEIN REVIEW

• POLYPEPTIDE CHAINS OF AMINO ACIDS (AA)

• 21 AMINO ACIDS

• 2 THINGS MUST BE CORRECT FOR PROTEIN TO BE FUNCTIONAL

• 1. SEQUENCE OF AA

• 2. SHAPE

PROTEIN SYNTHESIS

THE CELL CAN MAKE THOUSANDS OF DIFFERENT PROTEINS

OR

THE CELL CAN MAKE THOUSANDS OF THE SAME PROTEIN.

PROTEIN SYNTHESIS STEPS

• 2 STEPS to making Proteins:

• STEP 1 TRANSCRIPTION: Getting the information from the DNA copied onto a mRNA strand.

• STEP 2 TRANSLATION: The mRNA strand goes out to a ribosome and builds a AA strand with the help of tRNA.

Protein Synthesis in a nutshell

Here’s a better look:

THE CODE OF LIFE

• COMPARE TO ALPHABET

• DNA’S CODE IS THE 4 NUCLEOTIDE BASES OF ADENINE, GUANINE, CYTOSINE, AND THYMINE

• THREE OF THESE BASES COME TOGETHER TO MAKE A CODE FOR AN AMINO ACID.

THE CODE OF LIFE

• THREE BASES MAKE A CODON.

• (THINK OF IT AS A 3 LETTER WORD MEANING A SPECIFIC AMINO ACID)

• A CODON CODES FOR A SPECIFIC AA.

THE CODE OF LIFE

• COMPARE TO THE ALPHABET CODE WE DISCUSSED.

• EX. THE DOG CAN RUN

• EACH LETTER IS A NUCLEOTIDE BASE.

• EACH THREE LETTER WORD IS A CODON THAT CODES FOR A SPECIFIC AMINO ACID.

• A STRING OF AMINO ACIDS MAKE A FUNCTIONAL PROTEIN, JUST LIKE A STRING OF WORDS MAKE A SENTENCE.

THE CODE OF LIFE• LETS SEE WHY THE SEQUENCE IS

IMPORTANT!

• THE RUN CAN DOG

• ONE AMINO ACID CHANGE CAN CHANGE THE PROTEIN, JUST LIKE ONE WORD CAN CHANGE THE SENTENCE.

• THE CAT CAN RUN

• THE DOG CAN SIT

• THE DOG CAN HOP

Amino Acid Chart

Amino AcidsThere are 21 Amino Acids, but as you

can see 64 combinations.

So, there are multiple codons per amino acid.

Also “stop” and “start” codons.

3 kinds of RNA:

Ribosomal RNA (rRNA) –makes up ribosomes

Messenger RNA (mRNA)

Transfer RNA (tRNA)

Why do we need RNA?

RNA is the key mechanism behind:

PROTEIN SYNTHESIS

Your characteristics are determined largely by the kinds of proteins your cells make out of amino acids.

PROTEIN SYNTHESIS

Where are proteins made? What organelle?

Where are ribosomes located?

Where are the directions for making proteins found?

OK, if the directions are in the nucleus, but the ribosomes

are in the cytoplasm or on the E.R.,

How do the directions get to the ribosomes????

That’s why we needmessenger RNA

(mRNA)mRNA is made in a process called TRANSCRIPTION

• Transcription is “the process of copying the DNA code onto a strand of mRNA”

“-scribe” means “write” so the code is copied or written onto mRNA during transcription

mRNA

Is made from a DNA strand pattern.

DNA “unzips” just the section that codes the directions for the needed protein.

RNA nucleotides come in and bind with the DNA nitrogen bases

So, transcription is

“Writing” the mRNA code from a strand of DNA

Occurs in the nucleus so the message can be sent from DNA to the ribosomes

DNA never leaves nucleus!

Cool facts about mRNA

• mRNA has a “cap” on one end and a Poly A tail on the other end.

• There are parts that are not used caused “introns” that are edited out before the mRNA gets to the ribosomes.

• The “exons” are the parts that are not edited out and thus used to make the protein.

Here’s a better look:

Now that we have our message,

The mRNA can move through the nuclear pores to go to ribosomes

Ribosomes will “read” the mRNA to build a protein

mRNA moves to ribosome

mRNA is read 3 letters at a time—codons

So, in our example, the first codon would be GUA

Codons become important in the next step

When mRNA gets to the ribosome:

The third kind of RNA comes into play.

Transfer RNA (tRNA)

Notice the 3-letter anticodon & amino acid

TRANSLATION

mRNA is read in codons (3 letters at a time)

A tRNA anticodon matches up with the mRNA codon

tRNA has an amino acid attached at the top

See your amino acid chart

Translation is:

The process of synthesizing amino acids into proteins with the aid of RNA

Protein Synthesis in a nutshell

Translation(this is not in the

notes)• The mRNA brings the DNA blueprints

(plans) to the cytoplasm.

• The rRNA (ribosomes) bind to the mRNA. This is the construction site, where we build the protein.

• The tRNA brings the materials (Amino Acids) to the construction site (ribosomes).

Metabolism

• Metabolism is the sum of all of life’s processes of an organism. For example: You take energy in and you expend energy by life’s activities.

• Young people have higher metabolism than adults because of the processes of growing.

• Plants use less energy during the night because they are not doing photosynthesis. So, a plant’s metabolism is higher during the day.

• Which one has higher metabolism?

Athlete versus video gamer

Anabolism

• Anabolism is the building of molecules and storing energy. What is one example of this?

• Catabolism is processes that break molecules down to release energy. What is one example of this?

We are finished!!!!

• Test is on Monday!!!!