WARM UP

• What is the Central Dogma?

• What are the 3 differences between RNA and DNA?

• Where does transcription occur?

http://pubs.acs.org/cen/_img/85/i08/8508translation.jpg

Protein Synthesis Notes (Day 2)

***DURING THE PROCESS OF TRANSLATION

mRNA IS MADE INTO PROTEIN***

CHAPTER 10 NOTES (DAY2)

STEPS TO TRANSLATION

1) mRNA LEAVES THE NUCLEUS.

2) mRNA GOES TO THE RIBOSOMES IN THE ER.

3) WORKER MOLECULES CALLED tRNA PICK UP AMINO ACIDS. THE TYPE OF AMINO ACID PICKED UP (THERE ARE 20) DEPENDS ON THE SEQUENCE OF 3 NUCLEOTIDES ON tRNA (CALLED THE ANTICODON).

4) The RIBOSOME SITS ON mRNA.

5) The RIBOSOME READS THE mRNA SEQUENCE.

6) TheRIBOSOME READS mRNA BY EVERY 3 NITROGEN BASES CALLED A CODON.

7) FOR EVERY CODON, THE RIBOSOME GRABS A tRNA THAT HAS AN ANTICODON THAT MATCHES.

8) THE RIBSOME TAKES THE AMINO ACID AND ADDS IT TO A PEARL-LIKE STRING OF AMINO ACIDS.

REMEMBER: THE TYPE OF AMINO ACID DEPENDS ON THE ANTICODON, WHICH PAIRS UP WITH THE CODON ON MRNA, WHICH WAS MADE FROM DNA.

http://library.thinkquest.org/C0123260/basic%20knowledge/images/basic%20knowledge/RNA/translation%20steps.jpg

tRNA

DNA sequence – AAT CCC GTA ACG TTA TTC

mRNA sequence – UUA GGG CAU UGC AAU AAG

tRNA sequence - AAU CCC GUA ACG UUA UUC

Amino acids - Leu Gly His Cys Asp Lys

Transcription & Translation Decoding

Objective: List the types of DNA mutations and their affect on the translation/activation of DNA.

http://news.softpedia.com/images/news2/Researchers-discover-how-to-detect-mutations-2.jpg

Introns and Exons

Eukaryotes have spans of DNA that do not code for genes, followed by lengths of DNA that do code for genes.

Introns are longs segments of DNA that do not code for a gene. Often called “junk DNA”.

What good are introns?

Exons are spans of DNA that do code for a gene.

Processing mRNA in Eukaryotic Cells • mRNA must be processed, or prepared for

translation

• Intron – non-coding gene regions that are cut out of the RNA molecule in the nucleus

• Exons – expressed sequences of the RNA molecule; codes for a protein

• The introns are cut out and the exons are spliced together to make a final mRNA

Mutations

• Mutations – changes in the DNA sequences that affect genetic information

.

DNA POINT MUTATIONS

•POINT MUTATION: CHANGE IN A SINGLE NITROGEN BASE PAIR IN DNA. (EXAMPLE: INSTEAD OF AN “A”, THERE IS NOW A “G”).

•FRAMESHIFT MUTATION: CAUSED BY THE ADDITION OR DELETION OF A SINGLE NITROGEN BASE. THESE MUTATIONS CAN BE VERY DEADLY

TYPES OF MUTATIONS

•DELETION MUTATIONS: A NUCLEOTIDE IS CUT OUT. EFFECT: CHANGED PROTEIN (FRAMESHIFT MUTATION)

•INSERTION MUTATION: A NUCLEOTIDE IS ADDED. EFFECT: CHANGED PROTEIN. (FRAMESHIFT MUTATION)

•SUBSTITUTION MUTATION: ONE NUCLEOTIDE REPLACES ANOTHER NUCLEOTIDE IN A STRAND OF DNA. EFFECT: OFTEN LITTLE OR NO CHANGE TO THE PROTEIN.(POINT MUTATION)

http://www.members.cox.net/amgough/Mutation_frameshift-01_03_03d.jpg

http://staff.jccc.net/PDECELL/evolution/mutations/mutypes.gif