1. DNA and Modern Genetics

2. DNA Makes Proteins
DNA stores information that cells need to function, grow and divide.
However, DNA doesn’t DO any of the things a cell needs to do-proteins do!

3. DNA Makes Proteins Proteins are made up of amino acids.
There are 20 different amino acids
They combine in different ways to make up the thousands of proteins in the human body.

5. DNA Makes Proteins Some proteins are small
Lysozyme is made of 129 amino acids
Some proteins are very large
Dystrophin is made of 3685 amino acids

6. DNA Makes Proteins
DNA stores the information that tells the cell how to combine amino acids to build proteins.
DNA is like a code that the cell can use as instructions for building proteins.

7. DNA and the Genetic Code
DNA is in the shape of a double helix (spiral ladder)
The rungs of the ladder are made up of pairs of bases.
Adenine (A) always pairs with Thymine (T)
Cytosine (C) always pairs with Guanine (G)

8. DNA and the Genetic Code
The order of bases in the DNA strand is the code for making proteins.
3 nucleotide bases codes for 1 amino acid.
T-C-T  Arginine

10. DNA and the Genetic Code
Try it: using the table, write down the sequence of amino acids that this strand of DNA would code for.
T-C-T-C-C-A-C-G-A-T-T-T-G-T-A

12. DNA and the Genetic Code
T-C-T-C-C-A-C-G-A-T-T-T-G-T-A
Arginine-Glycine-Alanine-Lysine-Histidine

13. DNA and the Genetic Code
A gene is the entire sequence of bases that codes for all the amino acids in a protein.
The average human gene is made up of 8,446 bases (A’s, T’s, C’s, and G’s)!
Each human has about 20,000 genes.

14. Mutations Look at the sentence below, made up of 3 letter words.
One day the cat ate the rat.
Insert an extra a into the word “cat,” then rewrite the sentence, putting a space after every 3 letters.
One day the caa tat eth era t

15. Mutations
Our genes control our traits by controlling what proteins we produce.
For example, skin color comes from a protein called melanin.
The amount of melanin an individual produces (determined by our genes) will determine their skin color.

16. Mutations
Sometimes, the sequence of DNA base pairs can be changed due to:
Errors in replication (when the DNA is copied)
Exposure to radiation
Toxins
A change in DNA is called a mutation.

17. Mutations 3 possible outcomes for a mutation:
Mutation causes no effect
Only 5% of our DNA is our genes. Mutations on non-gene DNA are neutral.

18. Mutations Mutation has a minor effect
Change in appearance, like hair or eye color
Does not help or harm the organism

19. Mutations Mutation has a major effect Genetic disorder
Increased resistance to disease

20. Mutations
Some genetic disorders are caused by mutations that are inherited (passed from parent to offspring).
Examples: albinism, cystic fibrosis, sickle cell anemia

21. Mutations
Some people may inherit a tendency to develop some genetic disorders, like diabetes, Alzheimers, or emphysema.
Their environment and behavior can affect whether they develop the disease, including:
Diet
Exercise
Smoking

22. Mutations
Some disorders, like most cancers, occur due to DNA mutations that happen during a person’s lifetime, from:
Ingesting carcinogens
Exposure to radiation
Errors in DNA replication

23. Mutations
Cancer is characterized by uncontrolled cell division.

24. Change Over Time Organisms change over long periods of time.
New traits can be introduced to a species through DNA mutations.

25. Selective Breeding
Humans can change the traits in a species of animal or plant by selecting and breeding them for certain traits.
Examples: faster horses, sweeter corn, cows that produce more milk

26. Selective Breeding
Thousands of years of selective breeding have created all the different dog breeds, though all dogs are the same species and descend from the same ancestor (the wolf).

27. Genetic Engineering
Genetic engineering is the process in which the DNA of an organism is directly changed by inserting another organism’s DNA.
The result of genetic engineering is a genetically modified organism (GMO).

28. Genetic Engineering
One use of genetic engineering in crops is to make them insect- resistant, so farmers don’t have to use chemical pesticides on their crops.

29. Genetic Engineering
Other crops have been genetically modified so that they can grow in places they otherwise wouldn’t be able to.

30. Genetic Engineering
Some people worry about the risks of genetic engineering
How will genetically modified organisms affect natural populations?
Should genetically modified food be labelled so people know they are eating it?

31. DNA Identification
Each person’s DNA is like a fingerprint, unique to them (except for identical twins).
DNA found at a crime scene can be matched to an individual, which can help solve crimes.

32. Studying Genomes Genome: all the genetic material in an organism.
Human Genome Project: goal was to determine the entire 3 billion letter sequence of a human’s genome.

33. Studying Genomes The project was completed in 2003.
Now scientists are working on identifying the 20,000 individual genes in the human genome.

34. Studying Genomes
There are many ethical questions that arise from changing DNA.
In the future, we will have to decide when and how this technology is used in our society.