1. From DNA to RNA to Proteins 2 Types of nucleic acids And Protein
Chapter 8
From DNA to RNA to Proteins
2 Types of nucleic acids
And Protein

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

3. Identifying DNA as the genetic material
Frederick Griffith – Experimented with two forms of bacteria that cause pneumonia on mice
Smooth (S harmful) and Rough (R non harmful)
Demonstrated Transformation
His conclusion: some factor changed the bacteria
“Transforming Principal”

4. Identifying DNA as the genetic material
Oswald Avery – Was puzzled by Griffith’s discovery and worked for 10 years to find the answer.
Directly observed transformation of R bacteria (harmless) into S bacteria (harmful)
Proteins do not contain phosphorous – tests showed phosphorus present
Performed chemical tests which indicated there was no protein present, and DNA was present.
Concluded that DNA is the transforming principal
DNA = Genetic material

5. Identifying DNA as the genetic material
Hershey and Chase- supported the conclusion - DNA is the source of genetic information
Bacteriophage – a virus that infects and replicates within bacteria.
Used bacteriophage infected with radioactive phosphorus atoms on DNA.
Radioactivity found in bacteria
Used bacteriophage infected with radioactive sulfur atoms on protein.
No radioactivity found in bacteria

6. 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.

7. DNA Structure What is the monomer that makes up DNA?
phosphate group
deoxyribose (sugar)
Nitrogen
containing
base
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 ( )
2. Phosphate ( )
3. Nitrogen Base
Adenine (A)
Guanine (G)
Cytosine (C)
Thymine (T)

8. Structure of DNA A  T G  C Double Helix – Spiral ladder
Discovered by Watson and Crick in the 1950’s with the help of Rosalind Franklin’s x-ray crystallography pictures
Double stranded
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

9. 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?

10. DNA Replication
Remember: DNA is always copied during cell reproduction
Mitosis
This takes place during the S phase of Interphase

11. 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.
nucleotide
The DNA molecule unzips in both directions.

12. Steps to DNA Replication
3. Complementary bases are added to each individual strand by DNA polymerase (enzyme).
DNA polymerase
new strand
nucleotide

13. Steps to DNA Replication
4. Each new cell can now get a complete copy of all the DNA.
One of the original strand, one new strand
original strand
new strand
Two molecules of DNA

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

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

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

17. 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

18. Transcription Occurs in the nucleus 1. DNA is again unzipped by
helicase.
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.
start site
nucleotides
transcription complex
DNA

19. Transcription 2. RNA Polymerase adds complementary RNA nucleotides
This makes mRNA
mRNA = messenger = carries the message
The DNA helix winds again as the gene is transcribed.
DNA

20. Transcription
3. The mRNA strand detaches from the DNA once the gene is transcribed.
mRNA leaves the nucleus.
RNA

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

22. Transcription

23. 3 Types of RNA

24. 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

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

26. Translation mRNA carries the DNA instructions for making protein
mRNA goes into the cytoplasm
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 strand - ACC
tRNA strand =
mRNA strand - GUC
Polypeptide chain = protein

27. Translation
An anticodon is a set of three nucleotides that is complementary to an mRNA codon.
An anticodon is carried by a tRNA.
Ribosomes consist of two subunits.
-1. The large subunit has three
binding sites for tRNA.
-2. The small subunit binds to mRNA.

28. Translation

29. Translation

30. 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?

31. Mutations There are two types of mutations
Sex cell mutations: affect the offspring
Body cell mutations: affect the individual only
Lethal mutations vs. beneficial mutations
Most mutations are good
DNA Polymerase can usually detect errors

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

33. Point Mutations 1. Substitution – also known as a point mutation
Point where one nitrogen base is substituted for another
Sickle Cell Anemia: substitute A for T
mutated
base

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