Do Now• Show a diagram of how you would split/

unwind the following Base pairs of DNA

• Draw the two new strands of DNA after replication

Do Now Answer

“Unzipped” Replicated: (original strand black, new

strand red)

12-3Protein Synthesis

Transcription and Translation

• If all the DNA in ten human nuclei were enlarged to a full-sized continuous ladder, it could reach more than 30 million miles, or from the earth to the planet Mars:

•

I. Gene Expression

A. Each DNA molecule carries

directions to make the organism

B. DNA is the blueprint for the sequence of amino acids that make up a protein

DNARNA Amino AcidsProteinsYOU!

How does DNA make proteins?

II. Transcription

A. DNA can NOT leave the nucleus

B. A copy of the DNA “recipe”

needs to be madeC. DNA copies itself into Ribonucleic

Acid (RNA)

III. mRNAA. The disposable copy of DNAB. It has the same structure as

DNA but Thymine is replaced by Uracil (A-U instead of A-T)

C. The copy leaves the nucleus with the protein “recipe” it copied from the DNA

D. It is called messenger RNA (mRNA) because it brings the message from the nucleus to the ribosomes

Transcription continued…• An entire strand of DNA is not transcribed into

RNA at once.– Small segments of DNA are transcribed to RNA that

code for specific genes

• IntronsIntrons – parts of the DNA sequence that do not code for any

gene

• Exons – parts of the DNA sequence that code for different

genes – Only Exons will be used to create RNA!

http://www.stolaf.edu/people/giannini/flashanimat/molgenetics/transcription.swf

IV. Translation

A. The recipe now has to be read or translated

B. The ribosome (rRNA) attaches and travels along the recipe strand

C. The recipe is read in groups of

3 bases called codons

D. The codons represent the order of the amino acids in the protein that is being created

E. Transfer RNA (tRNA)anticodons are complimentary to mRNA

F. Carry amino acids to ribosome where they are linked together to

form proteins

mRNA basesamino acidsprotein

(polypeptide)

• http://www.sciencenetlinks.com/interactives/protein.html

http://www.youtube.com/watch?v=4PKjF7OumYo&feature=related

http://www.youtube.com/watch?v=xc2wbIDfO7E

A.

CUU?

Leucine!

1. Fill in the complimentary DNA strand using base pairing rules

DNA

Completed strand

DNA

Fill in the correct mRNA bases by transcribing the bottom DNA code

Completed m RNA

Fill in the paired tRNA anti codons

Completed tRNA

Using the mRNA strand, translate the codons and find the correct amino acid

using the Codon table

http://www.darienps.org/teachers/otterspoor/notes/mrna.pdf

12-4 Mutations – see dittoI. Chromosomal: involves pieces of chromosomes – several bases

1. Deletion

2. Inversion

3. Translocation

4. Duplication

II. Point (gene) mutations – involves one or only a few bases

1. Frameshift – due to deletion or insertion – shifts entire code