Feb 1 2013

Dr. Pandya is not here… how do we learn day?

Watch the clips. Take notes, rewind them and listen carefully! We are making proteins today! Get all the details!!!

PS. If you have time go back and review the RNAi video (Nova science now)

HHMi TranscriptionBasic Detail

Define what the following terms do:

Promotor:RNA Polymerase:Activator Proteins:Enhancer regions:

What was the Central Dogma of biology mentioned?

What are the three stages of transcription?

• Initiation: RNA polymerase binds to the DNA promoter. Fig 17.8– TATA box is the area that transcription factors recognize

within the promoter. – Creates a transcription initiation complex (transcription

factors & RNA polymerase bond on promoter)• Elongation: DNA template continues to grow as RNA

polymerase separates DNA strand. – Transcribed part: Transcription unit (made of codons) (1

gene transcribed many times in caravan fashion)• Termination: mRNA is cut free from DNA template

Tata Box ExplainedTranscription in Detail

Watch the clip. Go to the quiz. Write down the question and correct answer.

If you picked the wrong choice initially please write an extra sentence correcting it.

How do Eukaryotes control Gene expression?

• Transcription creates Pre-mRNA. Fig 17.10• Pre-mRNA includes Introns and Exons• Introns= Fillers (intervening sequences)

• Exons= Code for proteins (expressed sequences)

• mRNA is just the Exons

Eukaryotic Transcription

How else is mRNA processed for translation?

• Background Info• snRNP’s (“snurps”) & splicesomes remove introns, creating

the final mRNA sequence= Exons only. Fig. 17.11• What stops the mRNA from degrading by hydrolytic

enzymes & binds it to the ribosome?– 5’ cap: modified guanine nucleotide is added to the 5’

end. – A poly tail: 30-200 adenine nucleotides on the 3’ end.

(Also helps release mRNA into the cytoplasm. • Enhancer’s causes the gene it is enhancing to be expressed.

Transcription occurs in eukaryotes when an enhancer site is activated.

snRNP’sSplicesomes

CapsAnd Tails

Take notes on: What is an Intron What is an Exon What is an 5’ cap What is an 3’ poly A tail What are a snurps? What is a spliceosome. What is gene splicing? What is Exon Shuffling. How is it important to evolution?

Where does it all go?

This one First This one Second

Take notes on:What happens when it leaves the nucleus.

Reminder and Review…yes you saw this before…. But its not the same!!!!

• Initiation: mRNA’s AUG codon (methionine) attaches to the ribosome. tRNA attaches.

• Elongation: forms the polypeptide chain as tRNA’s continue to attach.• Termination: mRNA reaches a stop codon. Release factor hydrolyzes

the bond. mRNA is degraded. Polypeptide is freed from ribosome. – After this the polypeptide will fold or pleat (secondary structure),

Chaperonine will complete the tertiary structure.

What process was this for????Translation

What about when a mistake occurs?• They can effect the species gene pool.• Point mutation= single base-pair substitution. (sickle cell)• Insertion or deletion= frameshift mutations. The Dog -> HeD og• Missence Mutation= If a codon within a gene turns into a stop codon

translation is altered.

Transcription full on with all the details!!!!Last set of questions:

What is the P siteWhat is the A site?What is the E site?How does the ribosome know were to begin and end translation.Why is this called translation?

That’s it. You’ve done it. CONGRADULATIONS

and THANK YOU!!!