Warm-Up 2/23 -2/24

Choose one of the three enzymes from DNA replication. Explain what it is doing, including the molecules it is working on (substrate) and the terms active site and activation energy. I am stamping 12.2 Book Notes and the

Strawberry Lab

DNA Replication Journal Activity Line up according to your confidence with DNA

Replication Wait for me to give you a partner Critique each other’s journal writes for:

All 3 enzymes and what they do Labeling of 5’ and 3’ ends of all strands An explanation of why original strand one’s copy can

be built continuously while original strand two’s must be built in fragments

The finished product

Transcription and Translation:

Making Proteins

Making a protein

DNA contains the directions for assembling amino acids (they make up proteins).

DNA cannot leave the nucleus Protein synthesis occurs outside of the

nucleus, on a ribosome.Ribosome

How do we get directions to the ribosome?

Using RNA

RNA is used to send the information to the ribosomes

Ribonucleic acid (RNA): Is a single strand only Is made of a nucleotide containing a ribose

sugar, a phosphate and a nitrogenous base: Uracil (instead of Thymine), Adenine, Cytosine and

Guanine.

Transcription

Transcription: making an RNA copy of DNA to send to the ribosomes

Copy is disposable! Step One: RNA Polymerase (enzyme)

unwinds DNA double helix Step Two: RNA Polymerase builds a

complimentary strand of messenger RNA (mRNA) using the DNA template

Once the mRNA is made, the double helix winds back up!

Self Test!!!

You are making a strand of mRNA using the following DNA template:

TTCGCAAT

What would the order of the mRNA strand be?

Transcription movie

http://www.youtube.com/watch?v=5MfSYnItYvg&feature=relmfu

Translation

Translation: nucleotides on mRNA are translated into amino acids (and then proteins)

This occurs on a ribosome

Steps of Translation

1. mRNA moves from nucleus to the ribosomes

2. Ribosomal RNA (rRNA) on the ribosome binds to the mRNA and starts “reading” codons. Codons – 3 letter piece of mRNA that specifies a

particular amino acid Ex: AGU or GCG is a codon

Ribosome has two parts (large and small) and two binding sites

Steps of Translation

3. Transfer RNA (tRNA) links amino acids together and transfers them to the ribosome to make a protein

- tRNA contains an anti-codon on one side and an amino acid on the other

- an anti-codon is the opposite of

the three letter code of mRNA

Steps of Translation

4. The ribosome releases the protein and the mRNA

- protein to be used by the cell - mRNA to synthesize more protein

http://www.youtube.com/watch?v=8dsTvBaUMvw&feature=relmfu

In Summary…

Transcription (making mRNA) and Translation (making amino acids from mRNA) is how DNA makes protein

Sections of DNA are called ‘genes’, and they make certain traits by coding for proteins

Those proteins go out and build the traits of living things!

mRNA-amino acid chart

• Knowing a DNA strand, we can predict the amino acids in the protein that is made

•This chart helps us out:

•Watch a demo on the board