1. DNA & GENES
DNA
RNA
PROTEIN SYNTHESIS
MUTATIONS

2. Griffith’s Experiments
Study suggested that DNA was probably the genetic material

3. Hershey and Chase Experiments
Radioactive 32P was injected into bacteria!
Hershey & Chase proved that DNA was the cell’s genetic material!

4. Hershey & Chase Which radioactive marker is found inside the cell?
Protein coat labeled
with 35S
DNA labeled with 32P
Hershey & Chase
T2 bacteriophages
are labeled with
radioactive isotopes
S vs. P
bacteriophages infect
bacterial cells
bacterial cells are agitated
to remove viral protein coats
Which radioactive marker is found inside the cell?
Which molecule carries viral genetic info?
35S radioactivity
found in the medium
32P radioactivity found in the bacterial cells

6. James Watson and Francis Crick
Chargaff
Discovered that amts of Adenine = Thymine, and Guanine = Cytosine
James Watson and Francis Crick
Double helix …..held together by hydrogen bonds

7. DNA RNA
1. Sugar deoxyribose 1. Sugar ribose
2. Phosphate Phosphate
3. Nitrogen base Nitrogen base
-thymine -uracil

8. Base Pairing T A G C DNA Thymine (T) – Adenine (A)
Guanine (G) – Cytosine (C)
PYRIMIDINE PURINE G C
PURINE PYRIMIDINE
A or G
Weak hydrogen bonds
T or C

9. DNA P O 1 2 3 4 5 P O 1 2 3 4 5 G C T A

10. Base Pairing U A G C RNA Uracil (U) – Adenine (A)
Guanine (G) – Cytosine (C)
PYRIMIDINE PURINE G C
PURINE PYRIMIDINE

11. DNA Replication
DNA unzips (hydrogen bonds between the nitrogen bases are broken by enzymes).
Free nucleotides pair with exposed bases. DNA Polymerase bonds the nucleotides together.
3. Two identical double stranded DNA molecules are formed. (ClassZone)

12. Differences Between DNA & RNA 1. RNA is single stranded DNA is double
2. RNA can leave the nucleus and enter the cytoplasm DNA can not.
3. RNA has the sugar ribose, DNA has the sugar deoxyribose
4. RNA- uracil, DNA- thymine

13. 3 Types of RNA 1. mRNA: messenger RNA, a copy of DNA from the nucleus.
Reads DNA and copies it into RNA T A
RNA
DNA A U C G

14. 2. rRNA : ribosomal RNA, found on the. ribosomes and functions in
2. rRNA : ribosomal RNA, found on the ribosomes and functions in attaching to mRNA to assemble the correct order of amino acids.
Binds to mRNA
Binds to tRNA

15. 3. tRNA : transfer RNA, located in cytoplasm
it picks up amino acids and like a factory worker it puts the correct amino acid in place to build a protein.
Each tRNA has an anticodon on it that corresponds to the mRNA codon read off of the DNA.
Serine
(amino acid)
tRNA A G U U C A
mRNA

16. Protein Synthesis (steps)
I. Transcription:
DNA unzips with the help of RNA Polymerase
mRNA reads the DNA, RNA Polymerase bonds the RNA nucleotides together.
3. mRNA breaks off and leaves the
nucleus and travels to the ribosomes in the cytoplasm.
DNA strand TAC GCT TAG TTA ACT
mRNA strand AUG CGA AUC AAU UGA

17. PROTEIN SYNTHESIS CONT
II. Translation:
mRNA attaches to ribosome. The ribosome
reads 1 codon at a time. The process begins with a
start codon.
2. tRNA with an amino acid finds its anticodon
complement on mRNA’s codon.
mRNA : AUG UUU CCC CGA - codons
tRNA : UAC AAA GGG GCU - anticodons

18. PROTEIN SYNTHESIS CONT
3. Ribosomes continue to read the codons
and another tRNA attaches leaving another
amino acid.
4. Step 3 continues until the whole strand of
mRNA is read, when the stop codon is reached
the protein is completed.

20. Protein Synthesis Animation
Synthesis

21. Gene Expression/Regulation
Prokaryotic Transcription:
Operon – a region of DNA that contains a promoter,
operator, and structural genes.
Promoter – DNA segment that allows a gene to be
transcribed, RNA Polymerase binding site.
2. Operator – DNA segment that turns a gene “on” or “off”

22. *The lac operon was one of the earliest exps of gene
regulation in bacteria
Lactose absent
Lactose present

23. The lac operon is “off” when lactose is not present.
The lac operon is “on” when lactose is present.

24. Gene Expression/Regulation
Eukaryotic Transcription:
*Transcription is controlled by regulatory DNA sequences and
protein transcription factors.
Most eukaryotes have a TATA box promoter.
Enhancers and silencers speed up or slow down the rate of transcription.

25. mRNA Processing 3 Steps Addition of the cap Addition of the tail
Removal of introns with the splicing together of exons
Exons - code for parts of the protein
Introns – nucleotides that occur between exons

26.
Gene Mutations
Gene mutations: a change in the sequence of nucleotides within
a gene.
When do mutations occur?
- most often during DNA replication.
Different Types (pg 253 Fig 8.20)
1. Point Mutations- 1 nucleotide is changed to another, thus
coding for a different amino acid. Single base
pair substitution.
2. Frameshift mutations- add or delete a nucleotide to cause
the other bases to move up or down the
DNA molecule.

27. Chromosomal Mutations
(Change in chromosome structure)
Different Kinds
1. Deletion: when part of a chromosome is left out.
2. Insertion: part of a chromosome breaks off and inserts into
another causing a duplication in the other
chromosome.
3. Inversion: genes break off and are reinserted backwards
4. Translocation: genes break off and add to a different
chromosome.(pg 253)
Causes: mutations are random events. Most often though
environmental factors play a huge role in gene mutations

29. Read p254-255 and answer Apply Q on p254, and Summarize Q on p255

30. Chromosomal Mutations
*Many chromosome mutations result when chromosomes fail to
separate properly during meiosis.
Nondisjunction - occurs when homologous chromosomes or
sister chromatids fail to separate.
Causes: Down syndrome, Turners syndrome, Klinefelters
syndrome, cancer, etc.
NOVA video (RNAi)

32. copyright cmassengale

33. DNA is made up of a long chain of nucleotides.
Each nucleotide has three parts.
a phosphate group
a deoxyribose sugar
a nitrogen-containing base
phosphate group
deoxyribose (sugar)
nitrogen-containing
base