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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