1. DNA, RNA and Protein Synthesis
Sections 12-1 to 12-4

2. DNA & its structure

3. Chromosome Structure of Eukaryotes
Nucleosome
DNA
double
helix
Coils
Supercoils
I. DNA is:
into chromosomes
Found in ____
Histones
Nucleotides bundled
nucleus

4. DNA = deoxyribonucleic acid
Why is DNA important?
code for PROTEINS, which determine your traits
Monomer (building block) of DNA = NUCLEOTIDE

5. 3 Parts of a Nucleotide:
1. Sugar (deoxyribose)
2. Phosphate
3. A nitrogen base
(Adenine, Cytosine, Guanine & Thymine)

6. One Nucleotide

7. II. Structure of DNA
double-stranded molecule
double-helix (twisted) shape
Sugars & phosphates = BACKBONE of DNA strands

8. 2 nitrogen bases attach in center of DNA strands (HYDROGEN bond)

9. 2 Groups of Nitrogen bases :
1) Purines
Adenine & Guanine
2 chemical rings
2) Pyrimidines
Cytosine & Thymine
1 chemical ring

11. III. Complementary Base Pairing
Adenine bonds to Thymine (A-T)
Cytosine bonds
to Guanine (C-G)

12. Hydrogen bonds
Deoxyribose
Phosphate

13. DNA Model Activity Color each component a different color
Cut out pieces
Have a key for all pieces
Circle one nucleotide
QUES #1- How many nucleotides are there in your model?
QUES #2- How is this model an inaccurate representation of DNA? (List at least 3 ways)

14. IV. History of DNA
1. Rosalind Franklin
took x-rays of DNA crystals & determined its “spiral” helix shape
never recognized for her work

15. Franklin’s x-ray of DNA
Rosalind Franklin

16. 1st to “discover” & publish shape/structure of DNA in 1953
2. James Watson & Francis Crick
1st to “discover” & publish shape/structure of DNA in 1953
used Franklin’s x-rays to determine its shape
received Nobel Prize

17. James Watson & Francis Crick

19. V. DNA Replication
how DNA copies itself
Occurs in NUCLEUS
Importance = ensures new cells (made in mitosis) have same info.

20. VI. DNA Replication Steps:
Step 1: Separating the DNA
Helicase enzyme split the base pairings into two strands

21. Step 2: Constructing complementary bases of DNA
DNA polymerase enzymes construct new complementary bases & insert on the original DNA strand

22. There are many enzymes working at once so replication can occur quickly.

23. Step 3: Accuracy and Repair
Enzymes proofread and repair incorrectly bonded bases.
Any error is called a mutation

24. Mutations can have harmful effect Beneficial effect
No effect (junk DNA)

26. RNA, Transcription & Translation
PROTEIN SYNTHESIS

28. RNA = ribonucleic acid Why is RNA important?
1. Carries code from DNA (in nucleus) to make proteins (at ribosomes)
2. RNA acts like a messenger between DNA & proteins!

29. Differences between DNA & RNA
DNA vs. RNA
Double-stranded
Single-stranded
Double helix shape
Coiled strand

30. DNA vs. RNA
Sugar = DEOXYRIBOSE
Sugar = RIBOSE
A, C, G & T bases
A, C, G & U bases
U = uracil; pyrimidine that pairs with ADENINE

32. 3 Types of RNA:
1. Messenger RNA (mRNA) – brings info. in DNA to ribosome
2. Transfer RNA (tRNA) –binds to mRNA on 1 end & has specific amino acid on other end.

33. 3. Ribosomal RNA (rRNA) – makes up ribosomes where proteins are made
* All 3 RNA’s work together to make proteins!

34. I. TRANSCRIPTION = makes mRNA from DNA
Occurs in NUCLEUS
A. Steps:
1) DNA unwinds & separates
2) RNA nucleotides PAIR w/ bases on 1 DNA strand only

35. 3) When finished, new mRNA strand BREAKS AWAY & leaves nucleus; DNA strands REJOIN.

36. http://www. brooklyn. cuny. edu/bc/ahp/BioInfo/graphics/Transcription

37. II. TRANSLATION = forms PROTEINS using mRNA (code copied from DNA)
DNA-RNA-Protein Synthesis
II. TRANSLATION = forms PROTEINS using mRNA (code copied from DNA)
- Occurs at RIBOSOMES
A. Steps:
1) mRNA goes to ribosome
DNA-RNA-Protein Synthesis

38. 2) tRNA’s temporarily pair w/ mRNA.
a) ANTICODON (3 tRNA nucleotides ) pairs to CODON on mRNA
b) On opp. end of tRNA, AMINO ACID (for mRNA codon) is attached

39. 3) As tRNA’s attach, a.a. link/bond & each tRNA leaves
4) When STOP codon is reached, a.a. chain is complete.
* Chain of amino acids = PROTEIN!

40. Protein = amino acids linked together Anticodon Codon
tRNA
mRNA
Amino acid
Protein = amino acids linked together
Anticodon
Codon

42. III. Protein Synthesis (vocab)
A. PROTEIN (polypeptide) = chain of AMINO ACIDS (linked by PEPTIDE BONDS).
* Order of a.a. determines type of protein made

43. B. Amino acid determined by codon on mRNA
CODON = 3 consecutive mRNA nucleotides that code for 1 amino acid.

44. IV. What is the amino acid for the following mRNA codons?
CCC =
Pro (short for proline)
UGU =
Cys (short for cysteine)
AGU =
Ser (short for serine)

45. Mutations
= permanent change in DNA sequence
May be harmful
May have no effect
May be beneficial

46. Two types of DNA mutations:
1. Point mutation = one base is substituted in DNA
Only 1 codon/amino acid affected
May or may not affect protein

48. 2. Frameshift mutation = a base is added or deleted
All codons change (shifted)
Completely changes protein

50. U A A G G C A G U U U U A A C G G C A G U U U PRACTICE Original mRNA
mutation mRNA
What type of mutation?
Were all the a.a. affected?

51. A T T C C G T C A A A T A A G G C A G T T T
1. Write the complementary strand to the DNA under the process of REPLICATION.
A T T C C G T C A A A
T A A G G C A G T T T

52. A T T C C G T C A A A U A A G G C A G U U U
2. Write the complementary strand to the DNA under the process of TRANSCRIPTION.
A T T C C G T C A A A
U A A G G C A G U U U