making sense of dna. dna is a code for making proteins dna (gene) protein trait
TRANSCRIPT
Making Sense of DNA
DNA is a code for making proteins
DNA (Gene) Protein Trait
DilemmaDNA
• Contains sequence for protein
• Risky/Dangerous for DNA to leave nucleus
Protein• Made by ribosomes• Ribosomes stuck in
cytoplasm
Solution– SEND MESSENGER!
Step 1- Copy DNA Info on mRNA
• DNA creates a message for the ribosome called mRNA.
• Messenger RNA (mRNA):– Same structure as DNA (except different
type of sugar; ribose instead of deoxyribose)
Step 1- Copy DNA Info on mRNA
• DNA creates a message for the ribosome called mRNA.
• Messenger RNA (mRNA):– Same structure as DNA (except different
type of sugar; ribose instead of deoxyribose)
– Single stranded
Step 1- Copy DNA Info on mRNA
• DNA creates a message for the ribosome called mRNA.
• Messenger RNA (mRNA):– Same structure as DNA (except different
type of sugar; ribose instead of deoxyribose)
– Single stranded– Uracil replaces all the thymines.
Step 1- Copy DNA Info on mRNA
• Write the corresponding RNA strand
TAAGCTACCGAATGGACAACACTTCGACTAAUUCGAUGGUUACCUGUUGUGAAGCUGA
Step 1- Copy DNA Info on mRNA
• Transcription video• http://www.youtube.com/watch?
v=ztPkv7wc3yU
Step 1- Copy DNA Info on mRNA
Similarities between DNA and RNA:1. Sugar and phosphate make up the backbone2. They both have base pairs3. They both carry the same protein messages
Step 2- mRNA leaves nucleus
Step 3- mRNA attaches to ribosome at START codon (AUG)
• Ribosome finds the START sequence in the mRNA: AUG
Remember?
• Ribosome- ___________________
Remember?
• Ribosome- makes protein
Step 4- tRNA brings the correct amino acid
Step 4- tRNA brings the correct amino acid
• Each sequence of 3 bases corresponds to 1 amino acid
• Codon- sequence of 3 bases that codes for an amino acid
Step 4- tRNA brings the correct amino acid
• Transfer RNA (tRNA)- brings amino acids to the ribosome.
(Why sequence of 3?)
• There are 20 common amino acids.• Could you make 20 different combinations
with 2 bases?
• How many different combinations can you make with 3 bases?
Step 5- Amino Acids link to form Protein
Step 5- Amino Acids link to form Protein
• tRNA brings the next amino acid.• Peptide bonds- connect amino acids together to form
a protein• Protein- chain of amino acids that fold into a specific
shape.
Step 6- tRNA reaches STOP codon
• The process continues until the STOP codon: UAG, UAA, UGA
• Then the protein is complete.
Putting it all together
• Video 1
• Video 2
Ticket
1. How does the DNA code get to the ribosome?
2. Which amino acid would match the mRNA code: CCA?
Short cut
Practice
DNA code:TACGTTCGAATT
mRNA code:
Amino acid code:
Project-Based Assessment #3
Project choices:Cancer (any genes)