1. No Bell work

2. I can describe what a trait is.
Learning target
I can describe what a trait is.
Today I am…
learning about trait inheritance.
So that I’ll be able to…
understand how a parent passes traits onto their offspring.
I’ll know I’ve got it when…
I can write 1-2 sentences describing what a trait is.

3. Review
Genes are made of DNA, and different patterns of A, T, G, and C code for the instructions for making things your body needs to function (like the enzymes to digest food or the pigment that gives your eyes their color).
As your cells duplicate, they pass this genetic information to the new cells.

4. Good to know…
Individuals in every population vary from one another by their traits.
Traits: Distinguishing characteristics that are inherited, such as eye color, leaf shape, and tail length.
Heredity: The passing of traits or information from one generation to the next. This is also known as “Inheritance”.
The study of biological inheritance patterns and variation in organisms is known as Genetics.

5. Gregor Mendel
Known as “The Father of Genetics”, Mendel was an Austrian Monk who played an important role in the understanding biological inheritance.
He studied pea plants because of their ability to reproduce quickly.
Law of Segregation (Mendel’s first law):
Organisms inherit two copies of each gene, one from each parent.
Organisms donate only one copy of each gene in their gametes. Thus, the two copies of each gene separate during gamete formation.

6. Chromosomes
DNA is wrapped together to form structures called chromosomes.
Write: Most cells in the human body have 23 pairs of chromosomes, making a total of 46.
Write: Male chromosomes are XY and females are XX.

7. A specific characteristic that varies from person to person.
Trait
A specific characteristic that varies from person to person.

8. Heredity
When certain traits are passed from the parents to the children. Heredity is passed through genes in the DNA molecule.

9. Some characteristics come from a single gene, whereas others come from gene combinations. Because every person has about 25,000 different genes, there is an almost endless number of possible combinations!
Because you have a pair of each chromosome, you have two copies of every gene (except for some of the genes on the X and Y chromosomes in boys, because boys have only one of each).

10. Allele
One of a number of different forms of a gene. They are located at a specific position on a specific chromosome.
Examples: The gene for seed shape in pea plants exists in two forms, one form or allele for round seed shape (R) and the other for wrinkled seed shape (r).

11. Gene mutations
A person can be born with gene mutations, or they can happen over a lifetime. Mutations can occur when cells are aging or have been exposed to certain chemicals or radiation. Fortunately, cells usually recognize these types of mutations and repair them by themselves. Other times, however, they can cause illnesses, such as some types of cancer.
If the gene mutation exists in egg or sperm cells, children can inherit the gene mutation from their parents. When the mutation is in every cell of the body (meaning a child was born with it), the body is not able to "repair" the gene change.

12. Dominant alleles
Produces a dominant phenotype in individuals who have one copy of the allele, which can come from just one parent.

13. Recessive alleles
Produces a recessive phenotype, the individual must have two copies, one from each parent.

14. Dominant vs. Recessive
The allele or gene that shows up is called “dominant,” and the allele that is masked is called “recessive.”

15. Genotypes vs. Phenotypes
BB, Bb, or bb are the three genotypes from the picture below. Genotypes refer to the genetic makeup of a specific set of genes.
Purple flowers or white flowers are the two possible phenotypes from the picture below. Phenotypes are the physical characteristics, or traits, or an individual organism.

16. Homozygous vs. Heterozygous
Homozygous – Term used to refer to an organism that has two identical alleles for a particular trait (TT or tt)
Heterozygous - Term used to refer to an organism that has two different alleles for the same trait (Tt) RR rr Rr

17. Punnett Squares
Punnett Square – Diagram showing the gene combinations that might result from a genetic cross
Used to calculate the probability of inheriting a particular trait
Probability – The chance that a given event will occur

18. Punnett Square
Parent
Offspring
Parent

19. How to Complete a Punnett Square

20. Incomplete Dominance
Incomplete Dominance - Situation in which one allele is not completely dominant over another.
Example – Red and white flowers are crossed and pink flowers are produced.

21. Examples of Multiple Alleles
Blood Type – 3 alleles exist (IA, IB, and i), which results in four different possible blood types
Hair Color – Too many alleles exist to count
There are over 20 different shades of hair color.

22. Codominance
Codominance - Situation in which both alleles of a gene contribute to the phenotype of the organism.
Example – A solid white cow is crossed with a solid brown cow and the resulting offspring are spotted brown and white (called roan). +

23. Video – 7 mins