1. DNA, Protein Synthesis, Mutations
Unit 5 Review
DNA, Protein Synthesis, Mutations

2. Griffith
Bacterial Transformation

3. Hershey and Chase
DNA is the hereditary material

4. Watson, Crick, Franklin Franklin: X-Ray crystallography Image of DNA
Watson and Crick: Built the 3D Model of DNA

5. Chargaff
A-T C-G

6. Nucleic Acids Polymers Made of nucleotides 5-Carbon Sugar
Phosphate Group
Nitrogen Base
The bases are the INFORMATIONAL part of DNA!!

7. BOTH are built from nucleotides
DNA vs. RNA
DNA
RNA
Usually double stranded (some viruses have single stranded DNA)
Stores Genetic Info
2 strands held together by weak H bonds
THYMINE
Deoxyribose sugar
Single stranded
mRNA – carries instructions for making proteins-transmits genetic info
tRNA – transfers AA
rRNA – assembles AA
URACIL
Ribose sugar
BOTH are nucleic acids
BOTH are built from nucleotides
BOTH have A, C, and G

8. Replication Facts
DNA has to be replicated (copied) before a cell divides
DNA is replicated during the S phase (or synthesis phase) of the cell cycle
New cells will need identical DNA strands

9. Enzymes involved with Dna replication
Helicase – unzips the DNA helix Dna Polymerase- synthesizes the new DNA strands by adding DNA nucleotides Ligase- joins okazaki fragments

10. Protein Synthesis Anabolic Proteins are built of Amino Acids
Genes code for proteins
Transcription (RNA synthesis)
Translation (assembling amino acids into proteins)
Are all proteins the same size? Why or why not?

11. Genetic Code UNIVERSAL Suggests a common ancestor
Although living creatures are diverse and unique the components of their genetic code are the same.
Suggests a common ancestor
Specific order of nitrogen bases (or nucleotides) determines what proteins are made, and therefore, what traits are expressed.

12. Codon Chart = Universal

13. Gene Expression Gene expression is a regulated process
Gene regulation results in a conservation of cell resources
Even though ALL of your cells have the same genes, liver cells express different genes than cardiac muscle cells, resulting in cell differentiation

15. Lac Operon Inducible system
Lactase is only produced in the presence of lactose
So if no lactose, no lactase produced…
Gene regulation results in conservation of cell resources

16. Genes code for proteins
But not ALL of a gene is expressed
Only EXONS code for proteins
INTRONS are removed by RNA splicing

17. Mutations Heritable mutations occur in gametes
Somatic mutations cannot be passed down

18. Types of Mutations – mistakes Point Mutations – effects a single gene
i. Substitution
-Missense
-Nonsense
ii. Frameshift
-Insertion
-Deletion
b) Chromosomal mutations – most drastic, change in structure or # of chromosomes (affects many genes)many are due to non-disjunction.

19. The Effects of Point Mutations
Gene Mutations
The Effects of Point Mutations
A point mutation is a change in a single base pair in DNA.
A change in a single nitrogenous base can change the entire structure of a protein because a change in a single amino acid can affect the shape of the protein. (SUBSTITUTION)
mRNA
Normal
Protein
Stop
Replace G with A
mRNA
Point mutation
Protein
Stop

20. Frameshift Mutations Gene Mutations
What would happen if a single base were lost from a DNA strand?
A mutation in which a single base is added or deleted from DNA is called a frameshift mutation because it shifts the reading of codons by one base.
As a result, every codon after the deleted base would be different.
Deletion of U
mRNA
Protein

21. Mutations can be Good Bad Have no effect (silent) Fixed by enzymes
Result in same AA
Occur in a non-coding region of DNA (such as an intron)
Occur in a gene that is not expressed(such as a recessive trait)

22. Recombinant DNA and Biotechnology
Genetic Engineering (Gene Therapy)
Recombinant DNA-the genes of an organism are changed by recombining its DNA with the DNA (or genes) from another organism.
Purpose- By inserting genes into the genome of an organism, the scientist can induce the organism to produce a protein it does not normally produce. This can help improve the quality of life for that organism.
Uses-bacteria that carry recombinant DNA can be released into the environment to increase the fertility of the soil, serve as an insecticide, or relieve pollution.

23. How it works-Restriction enzymes catalyze the opening of a DNA molecule at a “restricted” point, regardless of the DNA's source. Certain restriction enzymes leave dangling ends of DNA molecules at the point where the DNA is open. Foreign DNA can then be combined with the carrier DNA at this point. An enzyme called DNA ligase is used to form a permanent link between the dangling ends of the DNA molecules at the point of union (Figure 1).

24. Genetic Engineering

25. Techniques used to study genomes:
Genetic modification – involves scientists identifying and isolating genes that code for specific traits, and then manipulating those factors that affect the genes’ expression.
“GMOs” (genetically modified organisms) may have the genes of another organism inserted to add a desired trait. (For example, insect resistant GM cotton uses a gene from a naturally occurring soil bacterium to provide it with built-in insect protection.)
Gene therapy is a form of genetic modification used to treat patients with genetic disorders. In theory, a patient with a defective gene could have it replaced with a working version of the gene.

26. Techniques used to study genomes:
DNA fingerprinting- is a process in which a small sample of human DNA is cut with a restriction enzyme. The DNA fragments are separated according to size using gel electrophoresis and DNA probes. This creates a series of bands based on the size of the persons DNA fragments. The banding pattern created is unique, with the exception of identical twins. Banding patterns produced by two samples can be compared to establish whether the sources are related (paternity case) or come from the same person (crime scene.) DNA fingerprinting is also valuable for identifying the genes that cause genetic disorders.
Think “Who stole the Cheese?”

27. Chromosomal analysis- involves using karyotypes to identify chromosomal mutations in which an individual has an extra chromosome or is missing a chromosome. These types of mutations are caused by nondisjunction during meiosis. Karyotypes can be used to identify the possible location of a gene or a genetic abnormality on a chromosome.