1. DNA & Genes CHAPTER 11 relating the structure of DNA to its function
the role of DNA in protein production
distinguish amongst different types of mutations.

2. DNA Molecule of Life
Proteins are important components of living cells.
Metabolism of cells is controlled by proteins called enzymes.
Proteins are essential for life.
Every cell is capable of making all the thousands of different kinds of proteins it may need.

3. Modern Genetics
DNA of the chromosomes is the genetic material that is passed from generation to generation.
Genes are sections of DNA.
DNA controls cellular activities by controlling the production of enzymes.

4. Think On This… How does the cell synthesize proteins?
What determines the kinds of enzymes present in each cell?

5. The molecule that controls the production of proteins is a nucleic acid called Deoxyribonucleic Acid (DNA).
DNA is found in the chromosomes in the nucleus.
DNA carries information for running the cell.
DNA is made of nucleotides.

6. DNA is made up of nucleotides
DNA Structure
DNA is made up of nucleotides
Nucleotides Have Three Parts
Simple Sugar (5-carbon sugar)
Phosphate group
Nitrogen Base

7. Looking at the Structure of DNA
In 1953 Watson and Crick solved the puzzle (p. 290 Fig. 11:3)
These two scientists viewed x-ray images of DNA crystals that were created by Rosalind Franklin and Maurice Wilkins.
DNA Structure
Resembles a ladder
sides: sugar and phosphate
rungs (steps): complementary pairs of nitrogen bases

8. The structure (shape) of the DNA
is referred to as a double helix.

9. DNA Bases In DNA, there are four possible nitrogen bases: adenine (A)
guanine (G)
cytosine (C)
thymine (T)

10. 4 Possible Nitrogen Bases
Purines
Adenine (A)
Guanine (G)
Pyrimidines
Thymine (T)
Cytosine (C)
Base Pair Rule
Adenine (A) to Thymine (T)
And
Guanine (G) to Cytosine (C)

11. DNA Replication

12. Replication of DNA DNA molecules can build an exact copy of itself.
This is called Replication. (ATP is the energy source)
Replication is important for reproduction and must occur every time a cell divides.
That way each cell has a complete set of instructions for making proteins.

13. : Protein Synthesis REMEMBER: DNA is in the Nucleus
Proteins are synthesized in the Ribosomes
“ How can the information get to the ribosomes?”
By coping a near message >>mRNA
(messenger RNA)
The process of transferring the information from DNA to RNA is called transcription

14. Transferring the info….
To carry the genetic message from the nucleus into the cytoplasm we have
mRNA.
Any RNA strand is a direct order from the DNA.

15. RNA Structure (looks like one half of a zipper)
The Sugar is Ribose
Single Strand
Bases are:
Adenine (A) to Uracil (U)
Guanine (G) to Cytosine (C)
**Thymine is NOT found in RNA **
Thymine is substituted with Uracil

16. 3 Types of RNA mRNA (messenger RNA) *Carries genetic information from
nucleus to ribosomes.
rRNA (ribosomal RNA)
*Found in ribosomes
*binds to mRNA and uses instructions to assemble the
amino acids in the correct order
tRNA (transfer RNA)
* Found in the cytoplasm
* Carries amino acids in the cytoplasm
to the ribosomes

17. DNA….to Proteins
DNA Replicates….mRNA carries message to the Ribosome…

18. The Genetic Code EXAMPLE There are 4 bases
There are 20 different kinds of
amino acids in cells
(A.A. are the building blocks of proteins)
The groups of three bases (3 letter code) in mRNA are called codons or triplets.
AUA,
Codon Or
Triplet
EXAMPLE
UUU,
Codon Or
triplet
ACG,
Codon Or
Triplet

19. The Genetic Code Each codon codes for a particular A.A.
Each codon always codes for the same A.A
The sequence can be different…this gives rise to different proteins.
There are 64 possible 3 letter code words.
Only 20 common A.A.
Some codons do not code for A.A., they provide instructions for making the proteins
Example: UAA (is a stop codon)
this indicates that the protein ends at this point
Example:AUG (is a start codon and codes for an A.A.)

20. TRANSLATION (see p. 294) Bonding A. A. to form proteins is called
Translation (from mRNA to Protein)
tRNA:
* Is shaped like a cloverleaf (Fig. 11:8)
*one end has an attached site for an A.A.
* the other end has an exposed base
triplet called and anticodon

21. Information is decoded
Translation:
Information is decoded
* If a codon (3 bases on mRNA)
is AUC …..then
Its’ anticodon (3 bases on tRNA) is UAG
*In the cytoplasm are the A. A. necessary
for building proteins. tRNA will carry the
proper A.A. to the mRNA and line them
in the correct order.
* Once the RNA attaches to its’ specific
A.A. the combination moves toward a
ribosome (protein factory)

22. Transfer RNA (tRNA) (p. 293)
Three base anticodon

23. Amino Acid Codons

24. Effects of Mutation: (p. 298)
Genetic Changes (11:3)
Mutation: any change in the DNA
sequence.
Mutagen: any agent that can cause a change in
DNA…(radiation, chemicals, and even high temperatures.
Effects of Mutation: (p. 298)
Point mutation: Change in a single base
pair in DNA
Frameshift Mutation: A single base is added or deleted from DNA

25. Four Kinds of Chromosomal Mutations (see.p. 300)
Deletion: part of the chromosome is left out
Insertion: part of the a chromatid breaks off and attaches to its sister chromatid
Inversion: part of a chromosome breaks off and reattaches backwards
Translocation: part of one chromosome breaks off and is added to a different chromosome