1. DNA Replication and Protein Synthesis
From DNA to Proteins
2 Types of nucleic acid

2. DNA -> RNA -> Protein
DNA- Life’s Code
DNA -> RNA -> Protein

3. Influential Scientists
Frederick Griffith – Experimented with two forms of bacteria that cause pneumonia on mice
Smooth (S) and Rough (R)
Demonstrated Transformation
His conclusion: some factor changed the bacteria
“Transforming Principle”

4. Influential Scientists
Oswald Avery – Was puzzled by Griffith’s discovery and worked for 10 years to find the answer.
Directly observed transformation of R bacteria into S bacteria
Concluded that DNA is the transforming principle
DNA = Genetic material

5. Influential Scientists
Hershey and Chase- supported the conclusion - DNA is the source of genetic information
Used bacteriophage infected with radioactive sulfur atoms on protein.
Bacteriophage – a virus that infects and replicates within bacteria.
Minimal radioactivity found in bacteria
Used bacteriophage infected with radioactive phosphorus atoms on DNA.
Radioactivity found in bacteria

6. The Hershey-Chase experiment

7. 2 Types of Nucleic Acids DNA and RNA
DNA stands for Deoxyribo Nucleic Acid
DNA is genetic material that determines inherited characteristics/traits
The job of DNA is to code for proteins in the body.

8. DNA Structure What is the monomer that makes up DNA?
DNA is made up of long chains of Nucleotides.
Nucleotides- make up genes that code for a specific trait.
What makes up a Nucleotide?
1. Deoxyribose sugar ( S )
2. Phosphate ( P )
3. Nitrogen Base
Adenine (A)
Guanine (G)
Cytosine (C)
Thymine (T)

9. Nitrogen bases come in two types:
PURINES
Purines have two rings
And come in two types:
1. Adenine
2. Guanine

10. Pyrimidines have ONE ring
Nitrogen bases come in two types:
PYRIMIDINES
Pyrimidines have ONE ring
And come in two types:
1. Cytosine
2. Thymine

11. Structure of DNA A  T G  C Double Helix – Spiral ladder
Discovered by Watson and Crick in the 1950’s with the help of Franklin’s x-ray pictures
Double stranded (Antiparallel)
Complementary base paring – the nitrogen bases on one side of the ladder ALWAYS pair up with the same nitrogen base on the other side of the ladder.
Discovered by Chargaff
The pairs are held together
with hydrogen bonds
A  T
G  C 3’ 5’ 5’ 3’

13. Complete the other side of the DNA molecule
Circle a nucleotide

14. Review
How many different types of nucleotides are there? How do they differ?
What is the monomer of DNA?
What does DNA stand for?
DNA’s shape can be described as a ______________?
What makes up the sides of DNA?
What makes up the rungs?

15. Do Now….
How many different types of nucleotides are there? Name them. How do they differ? 4 – Adenine, Guanine, Cytosine, Thymine. A and G have 2 rings, C and T have 1 ring.
What is the monomer of DNA? Nucleotides
What does DNA stand for? Deoxyribonucleic Acid
DNA’s shape can be described as a Double Helix
What makes up the sides of DNA? Phosphates and Sugar
What makes up the rungs? Nitrogen base pairs

16. DNA Replication Remember: DNA is always copied during cell cycle
Mitosis & Meiosis
This takes place during the S phase of Interphase

17. Steps to DNA Replication
1. The DNA molecule is split down the middle (at the nitrogen bases) by helicase, breaking the hydrogen bonds.
Similar to a zipper
2. The nitrogen bases on each side of the molecule are used as a pattern for a new strand.
3. Complementary bases are added to each individual strand by DNA polymerase (enzyme).
Each new cell can now get a complete copy of all the DNA. – Semi-conservative
One of the original strand, one new

18. DNA Replication
Animation

20. DNA Replication
Helicase enzymes untwist and unzip the DNA helix. (A replication fork is now formed.)
Binding Proteins: Hold open the two DNA strands so that they don’t fold back onto each other
DNA Primase enzyme adds a primer to each side of the open strand.

21. DNA Replication DNA polymerase adds the new nucleotides one at a time.
Lastly, DNA ligase enzyme “glues” nucleotides together on the lagging strand.

22. Overall:
Both nucleotide chains separate and serve as a template for a new nucleotide chain.
The open structure is often referred to as a replication fork.
The leading strand requires fewer steps and therefore is synthesized more quickly.
The lagging strand is done in pieces since the helix uncoiling occurs in the opposite direction the polymerase is working. These pieces are called Okazaki fragments.

25. Original strands of DNA
***You are left with 2 exactly identical molecules of DNA double helix.***
New
New
Original
Original strands of DNA
Original O N N O
Semi-conservative Model

26. P A C T P A C T P T G A P T G A

27. Practice Base-Paring Original strand: ATTCCG Complement:
Original strand: GCTAAG
Complementary strand:
Original strand: CTACCA
Original:
Strand A: GACCTA
Strand B:

28. Review What is the purpose of replication?
How does DNA serve as its own template?
DNA polymerase
new strand
nucleotide

29. Central Dogma Transcription DNA  RNA Translation RNA  Protein
DNA  RNA  Protein
Transcription
DNA  RNA
Translation
RNA  Protein

30. RNA and Protein Synthesis
Why make proteins?
Skin, muscles, nails, hair, hormones, enzymes
How do we make proteins?

31. DNA makes RNA RNA is the 2nd type of Nucleic Acid
RNA is made of nucleotides, just like DNA
1. Ribose is the sugar
2. Phosphate
3. Nitrogen Bases
Adenine (A)
Guanine (G)
Cytosine (C)
Uracil (U): NOT Thymine (T)
Single Stranded
When RNA is assembled based off of DNA’s pattern, this is called Transcription

32. RNA and Protein Synthesis
Types:
mRNA – messenger
tRNA – transfer
rRNA - ribosomal

33. 3 Types of RNA

34. RNA and Protein Synthesis
Comparing DNA and RNA
DNA
RNA
SUGAR
BASES
STRUCTURE
LOCATION
Deoxyribose
Ribose
A T C G
A U C G
Double Helix
Single Stranded
Nucleus. Cytoplasm, Ribosomes
Nucleus

35. Transcription Occurs in the nucleus DNA is again unzipped by
RNA Polymerase.
RNA Polymerase adds complementary RNA nucleotides
Starting at a region called the promoter
This makes mRNA
mRNA = messenger = carries the message
mRNA leaves the nucleus
DNA is too large to get out of the nucleus, RNA carries DNA’s message out of the nucleus to a ribosome.
Ribosome – where the protein will be made.
DNA

36. RNA Polymerase makes mRNA RNA Polymerase breaks H-bonds
Deoxy-ribose P
Thymine
Cytosine
Adenine
Ribose P
Uracil
Ribose P
Guanine
Uracil
Adenine
Adenine
Deoxy-ribose P
Guanine
Thymine
---H---
Transcription
Ribose P
Guanine
RNA Polymerase makes mRNA
Strands move apart
mRNA exits nucleus
RNA Polymerase breaks H-bonds
DNA re-coils
---H---
Ribose P
Adenine
---H--- P

37. RNA complimentary base pairing during Transcription
DNA strand = AATTTGCGCGGCT
mRNA strand =
DNA strand = TATGCGCACTG
DNA strand = CGATCAGCCTAT

38. Fill in the missing information

39. Transcription

41. Transcription: RNA Editing
Many RNA molecules require a bit of editing before they leave the nucleus.
Introns- not involved in coding for proteins
These get taken out
Exons- are expressed

42. Translation RNA to Protein
Translation converts mRNA messages into Polypeptides
String of amino acids held together by a peptide bond
A codon is a sequence of three nucleotides that codes for an amino acid.
Examples:
AUG= Methionine
CUU= Leucine

43. The Genetic Code
The genetic code matches the mRNA codon with the tRNA anticodon to link amino acid or action
AUG= Start/ Methionine
UAA, UGA or UAG= Stop
Codon GCA =
Codon AAG =
Codon CGA =

44. Translation mRNA carries the DNA instructions for making protein
mRNA goes into the cytoplasm through nuclear pores
mRNA attaches to a ribosome to be “read”
Ribosomal RNA (rRNA)
Appropriate amino acids are strung together to build a polypeptide chain by reading codons.
Amino acids are attached to Transfer RNA (tRNA)
tRNA is complementary to mRNA
mRNA codon- ACC
tRNA anti-codon =
mRNA codon - GUC
tRNA anticodon =
Polypeptide chain = protein

45. Translation

46. Translation

47. Translation Mechanism
MET
This process continues until a stop codon is reached, at which point the mRNA strand, tRNA units, and rRNA subunits all are released.
MET
ISO
PRO A U G C
tRNA
U A U
tRNA
U A C
tRNA
U A C
tRNA
U A U
tRNA
G G G
Start Codon (Methionine)
Large Ribosomal Subunit (rRNA)
E Site
A Site
P Site
mRNA A U G C
Small Ribosomal Subunit (rRNA)

48. Translation

49. Process: A U G G U C C G A U C A G ribosome mRNA tRNA A. A. A. A.
Codon: 3 nucleotides of mRNA
AntiCodon: 3 nucleotides of tRNA U G C G
A. A. A U C
A. A. G A
A. A.
Amino Acid
tRNA

50. Number the 4 anti- codons in the order they occur
TRANS-LATION
Process of assembling polypeptides from information encoded in mRNA; Interpreting the code!
Number the 4 anti- codons in the order they occur

51. Only 20 Amino Acids 1 START codon 3 STOP codons 6/24/2018 7:28 PM
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52. 1. Which two mRNA codes correspond to histidine?
2. How many different mRNA codes correspond to arginine?

53. Protein Synthesis
Summary

54. Review What are the three parts to the Central Dogma?
How is RNA similar to DNA?
How is RNA different from DNA?
What are the 3 types of RNA?
How do amino acids differ from each other? (going back to the biochem unit)
What are the bonds that hold together the amino acids?

55. Mutations There are two types of mutations
Sex cell mutations: affect the offspring
Body cell mutations: affect the individual only
Mutations that cause a disorder or silent mutations
DNA Polymerase can usually detect errors

56. Causes of Mutations Mistakes in base paring during DNA Replication
Cause of many genetic disorders
Chemicals: like tobacco
Can lead to cancer because it changes the genes that regulate mitosis
Radiation: including UV (sun) and X-ray

57. Point Mutations 1. Substitution
Point where one nitrogen base is substituted for another
Sickle Cell Anemia: substitute A for T

58. Frame Shift Mutations 2. Deletions and insertions
When a nitrogen base is deleted or added
Frame shift mutations- because it moves the
codon up or down
Changes the sequence of amino acids