1. RNA & Protein Synthesis
Essential Question:
How do our cells determine who we are?

3. Why are proteins important to living things?
Control rate of chemical reactions as _e__________
Building materials for skin, bone, and _m_________
Help fight infections as _a__________________
Help control what goes in and out of cell through cell _m____________________
nzymes
uscles
ntibodies
embranes

4. 1. What is a gene?
Small section of DNA that holds code for making a particular protein, or for particular trait.

5. 2. What is RNA? How is it different from DNA?
Ribonucleic acid.
DNA has two strands, RNA only has one.
RNA has U (uracil) instead of T (thymine). The other bases are the same (A, G, C).

6. 3. What happens to DNA in the process of transcription?
DNA in nucleus is “unzipped.” A copy of one strand is made in the form of messenger RNA (mRNA)
Adenine (DNA and RNA)
Cystosine (DNA and RNA)
Guanine(DNA and RNA)
Thymine (DNA only)
Uracil (RNA only)
mRNA
DNA

7. 4. Proteins are made by joining ___________________ into long chains called polypeptides.
amino acids
Protein
molecule

8. 5. Each polypeptide contains a combination of how many different amino acids? __________20

9. 6. “Words” in the genetic code of DNA and RNA are made up of how many bases? __________3

10. 7. How are codons translated into different amino acids?
Codon made up of 3 nucleotide bases, e.g. AAG, CUA, etc.
Each set of 3 bases translates into different amino acid, e.g. AAG = lysine,
CUA = _________
leucine

11. 8. What do “start” and “stop” codons do?
Start = beginning of polypeptide
Stop = end of polypeptide.
If protein = paragraph, polypeptide = sentence, amino acids = words.

12. Quick Lab: How does a cell interpret DNA?
1. A certain gene has the following sequence of nucleotides: GACAAGTCCACAATC Write this sequence on your sheet of paper. 2. From left to right, write the sequence of the mRNA molecule transcribed from this gene: C U G U U C A G G U G U U A G

13. Quick Lab: How does a cell interpret DNA?
3. Look at Figure Reading the mRNA codons from left to right, write the amino acid sequence of the polypeptide translated from the mRNA.
CUGUUCAGGUGUUAG
CUG = ______________
UUC = ______________
AGG = ______________
UGU = ______________
UAG = ______________
Leucine
Phenyl-alanine
Arginine
Cysteine
Stop

14. Quick Lab: How does a cell interpret DNA?
4. Repeat step 3, reading the codons from right to left.
CUGUUCAGGUGUUAG
Aspartic acid
GAU = ______________
UGU = ______________
GGA = ______________
CUU = ______________
GUC = ______________
Cysteine
Glycine
Leucine
Valine

15. Analyze and Conclude
1. Why did steps 3 and 4 produce different polypeptides?
Reading bases from left to right produces different codons from reading right to left.

16. Analyze and Conclude
2. Do cells usually decode nucleotides in one direction only or in either direction?
Usually one direction only

17. 9. What happens to messenger RNA (mRNA) in the process of translation?
mRNA is translated into chains of amino acids that form proteins.

18. 9. What happens to messenger RNA (mRNA) in the process of translation?
mRNA is translated into chains of amino acids that form proteins.

19. 10. Explain the role of the following in protein synthesis: a. gene
Contains code for making a protein

20. 10. Explain the role of the following in protein synthesis: b. mRNA
Copy of gene that can be taken out of nucleus into cytoplasm.
Adenine (DNA and RNA)
Cystosine (DNA and RNA)
Guanine(DNA and RNA)
Thymine (DNA only)
Uracil (RNA only)
mRNA
DNA

21. 10. Explain the role of the following in protein synthesis: c. tRNA
Transfers amino acids over to mRNA, where they can be joined together to form protein.

22. 10. Explain the role of the following in protein synthesis: d. codon
3-letters/bases on mRNA that holds code for 1 amino acid

23. 3 letters/bases on tRNA that match with codon on mRNA
10. Explain the role of the following in protein synthesis: e. anticodon
3 letters/bases on tRNA that match with codon on mRNA
anticodon
codon

24. Helps join amino acids together to form protein/polypeptide
10. Explain the role of the following in protein synthesis: f. ribosome
Helps join amino acids together to form protein/polypeptide
ribosome

25. Molecules that join together to form protein
10. Explain the role of the following in protein synthesis: g. amino acid
Molecules that join together to form protein
Protein
molecule

26. Video: Protein Synthesis

27. GCU = __________ CAA = __________ UGG = __________ AUG = __________
Pop Quiz: Copy the codons below and identify the corresponding amino acids. p. 303
GCU = __________
CAA = __________
UGG = __________
AUG = __________
CAU = __________
alanine
glutamine
tryptophan
methionine
histidine
Your name at bottom