October 27, 2009

• Write down objectives and activities!

• Record your test grade (MAJOR) on your new gradesheet for the 2nd nine weeks!!

• Review power standards for Photosynthesis, Cellular Respiration and DNA…

Protein Synthesis*Gene Expression*

After replication…

TRANSCRIPTION and

TRANSLATION

Transcriptionand

Translation

DNA RNA (Transcription)

RNA Protein (Translation)

Where do replication and transcription take place? Why?

RNA – The “Other” Nucleic Acid

Differs from DNA :

1. RNA is a single strand of nucleotides DNA is a double strand of nucleotides (helix)

2. Ribose is sugarDeoxyribose is sugar in DNA

3. No Thymine, Uracil (U) replaces Thymine

•Messenger RNA (mRNA)

•Ribosomal RNA (rRNA)

•Transfer RNA (tRNA)

Three Forms:

Key Players:

Ribosome - rRNAtRNA – transfer RNA

mRNA – messenger RNALeaves nucleus with instructions!

Transcription

**Occurs in the nucleus

1. Different enzyme binds to the start signal on DNA

2. Unwinds and separates DNA

3. One side of DNA is used as the templateto make the copy of RNA

4. RNA Nucleotides bind with complementary bases

(U pairs with A)

5. Complete when enzyme reaches the stop code

TTATGCATCG

What will be the complimentary RNA sequence?

New RNA dangles off the enzyme

DNA closes back to a double helix shape

Working copy of RNA is edited

Introns – Noncoding (intervening) sequences– edited out

Exons – Code for amino acids – (exit nucleus) spliced together

Example: ACAAUGGACAGU

is the RNA code

If the code for the protein is ACUGGU, what are the introns/exons?

mRNA – Blueprint for protein synthesis travels from nucleus to ribosome

Three Types of RNA Made in Transcription

tRNA – Translates mRNA code to amino acids

(monomers of protein!)

rRNA – Makes up ribosomes

October 29, 2009• Write down your objectives and activities!• Turn in your “Challenge Questions” if you finished it…

if not, get a ZAP pass NOW!

Warm Up: (Write the questions!!!)1. What are the 3 differences between DNA and RNA? 2. Is this DNA or RNA? – TATTAGCTAG3. Is this DNA or RNA? – AUAAUCGAUC4. What two processes occur in the nucleus? 5. What is the end result of replication? 6. What is the end result of transcription? 7. What is the end result of translation? 8. What is the end result of protein synthesis?

The Genetic Code

Instructions for building a protein come from:

Codon – 3 base code on mRNA – codes for amino acids or is a stop

signal

Genetic code is nearly universal for all organisms!!

20 Different kinds of amino acids

Sequence of three bases gives enough different combinations to code for all of them = CODONS!

64 possible codons – 61 code for amino acids

3 are stop signals

Each codon codes for one AA, but there is more than one codon for most AA.

Codons

The Genetic Code

November 2, 2009• Write down objectives and activities. • Turn in homework. • Get a ZAP pass if you don’t have it!Warm Up: 1. What is the end result of replication? 2. What is transcription? 3. What is translation? 4. Where are codons located? 5. Where are anticodons located? 6. What kind of RNA is used in transcription? 7. What kind of RNA is used in translation?

Remember the Key Players…

ribosometRNA

mRNA

Translation*Occurs in cytoplasm on ribosomes!

*Strings Amino Acids together to form protein that will express a gene!

tRNA

RNA folded with three loops

One loop has three nucleotide sequence (Anticodon)

which is complementary to mRNA codon

For example, if codon is CAAanticodon would be GUU…

“End” of tRNA carries AA that corresponds with

the mRNA codon (remember: codon comes

from wheel/chart!)

No anticodon for codonsUAG, UAA, OR UGA

(Stop Codons)

1. mRNA leaves nucleus & binds to ribosome

2. tRNA with anticodon UAC and AA Methionine binds to start codon

Translation

3. Next tRNA comes to ribosome

4. Enzyme joins two AA

Ribosome

mRNA tRNA

5. 1ST tRNA leaves

6. 2ND tRNA slides over bringing the mRNA and AA chain along tRNA

mRNA codon

tRNAanticodon

Amino AcidChain

7. Next codon in ribosome is ready for new tRNA anticodon (Process continues…)

Finally, Step 9…. Ribosome complex falls apart releasing new protein!!!

8. Continues until stop codon

from to to make up

Concept MapSection 12-3

also called which functions to also called also called which functions towhich functions to

can be

RNA

Messenger RNA Ribosomal RNA Transfer RNA

mRNA Carry instructions rRNACombine

with proteins tRNABring

amino acids toribosome

DNA Ribosome Ribosomes