1. Compare and Contrast: DNA and RNA
Bell Ringer
Compare and Contrast: DNA and RNA

2. Bell Ringer
What organelle is responsible for protein synthesis (making proteins)?
What types of cells have this organelle?
Where in the cell can this organelle be found?

3. What are the 3 types of RNA? What is the function of each type?
Bell Ringer (1)
What are the 3 types of RNA?
What is the function of each type?

4. Protein Synthesis: An Overview
Day 5 Unit 5
Goal: Students will be able to describe the processes of transcription and translation.

5. Protein Synthesis Foldable
Transcription
Translation
Where?
What molecules are involved?
What is produced?
Where does it go?
What happens?
Where?
What molecules are involved?
What is produced?
Where does it go?
What happens?

6. Back of Foldable Amino Acids & Nucleotides Central Dogma Types of RNA
Codons
Start =
Stop =

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Structure of RNA
Like DNA, RNA is a polymer of nucleotides. In an RNA nucleotide, the sugar ribose is attached to a phosphate molecule and to a base, either G, U, A, or C. Notice that in RNA, the base uracil replaces thymine as one of the pyrimidine bases. RNA is single-stranded, whereas DNA is double-stranded.
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8. Pathway to Making a Protein
DNA
mRNA
tRNA (ribosomes)
Protein
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DNA  RNA  Protein
Nuclear
membrane
Transcription
RNA Processing
Translation
DNA
Pre-mRNA
mRNA
Ribosome
Protein
Eukaryotic Cell
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10. Types of RNA Messenger RNA (mRNA) makes a copy of DNA
Transfer RNA (tRNA) decodes mRNA and transfers amino acids to the ribosome
Ribosomal RNA (rRNA) build the protein by bonding amino acids together. Ribosomes are made of rRNA.

11. Protein Synthesis 2 Steps Transcription Translation
Protein synthesis uses the information in genes to make proteins.
2 Steps
Transcription
Translation

12. Transcription: Where? mRNA is made in the NUCLEUS
mRNA will leave the nucleus through the pores in the nuclear membrane
(DNA does NOT leave the nucleus)

13. Transcription: Involved Molecules
DNA (instructions for making the protein)
mRNA (copy of the instructions)
RNA polymerase (enzyme that builds mRNA)

14. RNA Polymerase = The Enzyme responsible for Transcription
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15. Transcription: Produces?
mRNA (messenger RNA)
Long Straight chain of Nucleotides
Made in the Nucleus
Copies DNA & leaves through nuclear pores
Contains the Nitrogen Bases A, G, C, U ( no T )
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16. Remember the Complementary Bases
On DNA:
A-T
C-G
On RNA:
A-U
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17. Transcription: What Happens?
Big Idea: DNA is copied into a complementary sequence of mRNA.
RNA polymerase is the enzyme that is responsible for transcription
DNA = GCCATT
mRNA = CGGUAA

18. RNA polymerase DNA RNA Adenine (DNA and RNA) Cystosine (DNA and RNA)
Guanine(DNA and RNA)
Thymine (DNA only)
Uracil (RNA only)

19. Transcription: Goes to?
mRNA leaves the nucleus through the pores in the nuclear membrane and goes to the cytoplasm & ribosomes
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The Genetic Code
Each gene on a strand of DNA is read in 3 base sequences called codons
A codon designates an amino acid
An amino acid may have more than one codon
There are 20 amino acids, but 64 possible codons
Some codons tell the ribosome to stop translating
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The Genetic Code
Use the code by reading from the center to the outside
Example: AUG codes for Methionine
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Name the Amino Acids
GGG?
UCA?
CAU?
GCA?
AAA?
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23. Start/Stop Codons
There will always be a “Start” codon (AUG) at the beginning. It is like capitalizing the 1st letter of a sentence.
There will always be a “Stop” codon (UGA, UAA, UAG) at the end. It is like a period at the end of a sentence.

24. Translation

26. Translation: Where? Ribosome
Free floating ribosome in cytoplasm (makes proteins for that cell) OR
attached ribosome on the Rough ER (makes proteins to be exported to other cells)

27. Translation: Involved Molecules
mRNA (copy of the instructions)
tRNA (translates the instructions)
rRNA (builds the protein)

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Transfer RNA
amino acid
attachment site U A C
anticodon
Decodes (translates) the mRNA
Transfers amino acids to the ribosome
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Codons and Anticodons
The 3 bases of an anticodon are complementary to the 3 bases of a codon
Ex: Anticodon UGA
Codon ACU
UGA
ACU
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Ribosomal RNA (rRNA)
rRNA is a single strand 100 to 3000 nucleotides long
Globular in shape
Made inside the nucleus (nucleolus) of a cell
Associates with proteins to form ribosomes
Site of protein Synthesis
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32. Translation: Produces?
Chain of amino acids
Polypeptide (protein)

33. Translation: What Happens?
tRNA translates the mRNA using “anticodons.” (complementary to the codon)
Each tRNA molecule has an anticodon on one end and an amino acid on the other.
tRNA transfers the amino acids to the ribosome in the correct sequence.
rRNA forms peptide bonds between the amino acids. This links them together to build the protein.

34. Translation: Where does it go?
The protein will do one of 2 things
Stay inside the cell to carry out functions for that cell OR
Be exported to other cells
Rough ER  Golgi  Exocytosis

35. mRNA Nucleus Messenger RNA Lysine Phenylalanine tRNA Transfer RNA
Messenger RNA is transcribed in the nucleus.
Transfer RNA
The mRNA then enters the cytoplasm and attaches to a ribosome. Translation begins at AUG, the start codon. Each transfer RNA has an anticodon whose bases are complementary to a codon on the mRNA strand. The ribosome positions the start codon to attract its anticodon, which is part of the tRNA that binds methionine. The ribosome also binds the next codon and its anticodon.
mRNA
Start codon
Ribosome
Methionine
Phenylalanine
tRNA
Lysine
Nucleus

38. The Polypeptide “Assembly Line”
The ribosome joins the two amino acids—methionine and phenylalanine—and breaks the bond between methionine and its tRNA. The tRNA floats away, allowing the ribosome to bind to another tRNA. The ribosome moves along the mRNA, binding new tRNA molecules and amino acids.
mRNA
Ribosome
Translation direction
Lysine
tRNA
Growing polypeptide chain
Completing the Polypeptide
The process continues until the ribosome reaches one of the three stop codons. The result is a growing polypeptide chain.

41. Mutations Gene Mutations — result from a change in a single gene
Chromosomal Mutations — the whole chromosome is changed

42. Gene Mutations: result from a change in a single gene
Point Mutations = affect 1 nucleotide; switches one nucleotide for another
This only affects 1 amino acid in the protein sequence
May also be called Substitution
Example
THE CAT ATE THE RAT (normal)
THE CAT ARE THE RAT (mutation)

43. Gene Mutations: result from a change in a single gene
Frameshift mutations affect how the entire gene is read.
Insertion or Deletion—a nucleotide is inserted or deleted from the sequence
This changes the codons FROM THAT POINT ON! All the remaining amino acids will be affected.
Example
THE ACA TAT ETH ERA T. (insertion mutation)
THE CAT ATE THE RAT. (normal)
THC ATA TET HER AT. (deletion mutation)

44. Protein Synthesis Activity
Step 1: Transcription
Copy the “gene” into the complementary sequence of mRNA.
This must be done in the “Nucleus.”
Step 2: Translation
Translate the mRNA using the “tRNA cards” posted around the room. The codon should match up with a word.
If you have done this correctly, your sentence should make sense!!!
Don’t forget the punctuation (Start/Stop codons)!!

45. What happens during transcription? What happens during translation?
QOD (1)
What happens during transcription?
What happens during translation?