Do Now
1. Where is the DNA located in the
cell?
2. Where are the proteins made in the
cell?
3. How do you think the information
gets between these two places?
• Topic: DNA to proteins
• Essential question: How is DNA the
instructions for making my body?
What are proteins made out of?
• Proteins are long chains of amino acids.
Proteins can be made out of 100s to 100,000s
of amino acids
• Many proteins are actually several proteins
(chains of amino acids) put together
• There are 20 types of amino acids
Turn and talk
• Explain to your neighbor: What is the
difference between a cell in your eye and a
cell in your knee?
• Topic: Transcription and translation
• Essential question: How is DNA
turned into proteins?
• DNA makes proteins in a two step
process
• First, DNA is transcribed into RNA
• Second, RNA is translated into amino
acids
• RNA is: (ribonucleuic acid)
– A long chain of nucleotides
• Phosphate
• Sugar is ribose
• Bases are G, C, A, and U (uracil)
– A single strand (DNA is a double strand)
– Can leave the nucleus
– Not self-replicating (DNA is self replicating)
– A temporary copy of DNA
On your white boards
Make a Venn diagram for DNA and RNA
DNA
RNA
Do Now
Go back to your “DNA to proteins” notes
from yesterday (the first ones, not the
second ones). Write a summary
underneath your notes. I will stamp your
summaries in three minutes.
Types of RNA
• mRNA – messenger RNA. Is a copy of the
DNA.
• tRNA – transfer RNA. Brings the amino acid
to the ribosome
• rRNA – ribosomal RNA. ribosomes are made
out of RNA and protein.
Which is RNA? How do you know?
1.
2.
Transcription
• Transcription is making a RNA copy of the DNA
• It happens in the nucleus
• Steps
1. Unzip the DNA
2. mRNA nucleotides match to DNA nucleotides
3. mRNA detaches from the DNA
4. mRNA leaves the nucleus
Transcription
Transcription
Transcription (h)
• Transcription is making a RNA copy of the DNA
• It happens in the nucleus
• Steps
1. The enzyme RNA polymerase binds to a
region of DNA right before the gene called a
promoter
2. RNA polymerase makes a RNA copy of the
DNA using complementary base pairing. This
copy molecule is called precursor mRNA
Transcription
• http://www.stolaf.edu/people/giannini/flasha
nimat/molgenetics/transcription.swf
Why precursor mRNA?
• Genes consist of regions called introns and
exons. Exons are part of genes that become
the protein, and introns do not.
• Enzymes called splicesomes splice out the
introns from the precursor mRNA
• The result is mRNA, which is ready to make a
protein
• http://www.dnalc.org/resources/3d/rna-splicing.html
On your white board
• What is the mRNA that matches this strand of
DNA (sequence for hemoglobin)?
ATGGTGCACCTGACT
Transcription
Just transcription
http://www.youtube.com/watch?v=5MfSYnItYvg
Translation
1. mRNA attaches to the ribosomes
2. mRNA is read in three-letter words called
“codons”
3. tRNA brings the amino acid that matches the
mRNA (remember, they are both RNAs, so can
match nucleotides)
4. The chain of amino acids grows as the mRNA
moves down the ribosome, three bases at a
time
5. When the ribosome reaches the end of the
mRNA, the chain of amino acids (protein)
detaches from the ribosome and goes off to do
its job in the cell.
•
http://www.youtube.com/watch?v=8dsTvBaUMvw
• What is the amino acid sequence made
from this RNA (for hemoglobin)?
UACCACGUGGACUGAGGAC
Do Now
1. What color is the DNA in this picture?
2. What color is the RNA in this picture?
3. What color is the RNA polymerase in this
picture?
• http://www.youtube.com/watch?v=8dsTvBaU
Mvw