1. Hereditary

2. Gregor Mendel
- Austrian
- Used Peas in for experiments
Heredity
- Passing of traits
- From Parents to Offsprings
Offspring
- Product or child
- From reproduction

3. - Have male and female reproductive structures
Self- Pollinating Plant
- Can fertilize itself
- Can self-pollinate
True-Breeding Plant
- Offspring is identical to parent
- Involves two different plants
Cross-Pollination
- One plant fertilizes another

4. 3. 1. 2.

5. Characteristic
- Feature
- in different forms
- Ex: Hair color, Eye color, Height
Trait
- Different forms of characteristics
Breed
- To mate or fertilize with another organism

6. Mendel’s First Experiments
- Crossed pea plants
- Focused on 7 characteristics
- One trait seemed to always disappear
- One trait seemed to always stay
Dominant Trait
- The trait that stayed
- The trait that disappeared
Recessive Trait

7. - Mendel studied one characteristic at a time
- Mendel only used true-breeding plants
- So he would know what to expect

8. Mendel’s Second Experiments
- Investigating recessive traits
- First generation offspring were bred
- Some recessive traits reappeared
- Recessive traits didn’t show up as much as the dominant traits
- 3:1 ratio
- Realized two sets of instructions were needed
- Opened the doors to modern genetics

9. Traits and Inheritance
Chapter 5: Section 2

10. Genes
- Provide instructions
- Control inherited traits
Alleles
- Different forms of genes
- Can be the same or different details
Phenotype
- An organism’s appearance
- Physical features
- Determined by genes
Genotype
- An organism’s genes
- Different combinations of alleles

11. - Used to organize different combinations Punnett Squares
- Possible genotypes of offspring
- Dominant traits  Capital Letters
- Recessive traits  lower case letters
- Two alleles per trait (two sets of instructions)
- Helps calculate probability
Probability
- Mathematical chance something will happen
- Expressed in a fraction or percentage
Homozygous
- Both alleles are the same, dominant or recessive
Heterozygous
- Have one dominant and one recessive allele

12. - Used to organize different combinations
Punnett Squares
- Possible genotypes of offspring

13. - Both traits appear
Incomplete Dominance
- Neither trait is dominant nor recessive
Ex: Red flower + White flower = Pink flower
- One gene ONLY
One gene – Many traits
- Can influence many traits
- Several genes involved
One trait – Many genes
- ONLY one trait influenced
Ex: Skin color, Hair
- Environment can influence traits too
- Sometimes genes are not the only factor

14. Meiosis

15. - Only one parent needed
Asexual Reproduction
- Offspring is identical to parent
Mitosis
- Method used for eukaryotic cells to divide
- Asexual reproduction is a type of mitosis

16. - Involves two parents
Sexual Reproduction
- Needs sex cells
- Offspring are different from parents
- Pair of chromosomes
Homologous Chromosomes
- Carry the same genes
- Sex cells only have one of the pair
Meiosis
- Making of sex cells
- Sex cells have half as many chromosomes as non-sex cells

17. Walter Sutton
- Studied meiosis in grasshoppers
- Determined that genes are located on chromosomes
Steps in Meiosis
- Two phases: Phase A and Phase B
- Chromosomes are copied only once
- Chromosomes divide twice
- New cells have half as many chromosomes

18. Meiosis Interphase
Meiosis is preceded by interphase. The chromosomes have not yet condensed.

19. Meiosis Interphase
The chromosomes have replicated, and the chromatin begins to condense.

20. Meiosis Prophase I
The chromosomes are completely condensed. In meiosis (unlike mitosis), the homologous chromosomes pair with one another

21. Meiosis Metaphase I
The nuclear membrane dissolves and the homologous chromosomes attach to the spindle fibers. They are preparing to go to opposite poles.

22. Meiosis Anaphase I The chromosomes move to opposite ends of the cell.

23. Meiosis Telophase I & Cytokinesis
The cell begins to divide into two daughter cells. It is important to understand that each daughter cell can get any combination of maternal and paternal chromosomes.

24. Meiosis Prophase II The cell has divided into two daughter cells.

25. Meiosis Metaphase II
As in Meiosis I, the chromosomes line up on the spindle fibers.

26. Meiosis Anaphase II
The two cells each begin to divide. As in Meiosis I, the chromosomes move to opposite ends of each cell.

27. Telophase II & Cytokinesis
With the formation of four cells, meiosis is over. Each of these prospective germ cells carries half the number of chromosomes of somatic cells.

28. - Carry genes that determine traits
Sex Chromosomes
- Carry genes that determine traits
- Determine sex of organism (male or female)
- Females have 2 X chromosomes (XX)
- Males have 1 X and 1 Y (XY)
- During meiosis, on of each of the chromosome pairs end up in a sex cell.
- Y chromosome does not carry all of the genes of the an X. Females have 2 X chromosomes, so they carry 2 copies of each gene found on the X. Back up gene available if one gets damaged.
Sex-Linked Disorders
- Sex chromosomes carry genes for certain disorders
Ex: Color blindness is on the X chromosome
Mutation in a gene on the X chromosome.

29. Pedigree
- Diagram used to trace traits
- Studies family history of traits
- Used by genetic counselors
- Traits are selected or desired
Selective Breeding
- Organisms with those traits are bred

30. A circle represents a female A square represents a male
Mom
Marriage
Dad
On a pedigree:
A circle represents a female
A square represents a male
A horizontal line connecting a male and female represents a marriage
A vertical line and a bracket connect the parents to their children
A circle/square that is shaded means the person HAS the trait.
A circle/square that is not shaded means the person does not have the trait.
Children are placed from oldest to youngest.
A key is given to explain what the trait is.
Has the trait
Male- Son Male-Son Female-Daughter Male – Son
Oldest to Youngest
Unaffected male Unaffected Female
Affected male Affected Female

31. I II
III IV
A pedigree chart shows an x linked disease if most of them males in the pedigree are affected.

32. Congenital colorblindness is much more common in males since males have one X and one Y chromosome and females have two X chromosomes. Females are typically carriers for the disease because only one of their chromosomes are infected. It is very rare that both X chromosomes in a sex-linked disease are mutated since both parents would have to have be infected and give the disease on both of the daughter's X chromosomes. A female with the colorblindness defect in one X chromosome is a carrier of colorblindness. Male children of a female carrier are likely to be colorblind. Male children of a male with colorblindness and a female carrier are extremely likely to be colorblind (Web Exhibits). Notice that when the mother is a carrier then she has a 50% chance of passing off her "bad" gene to her children. If she is colorblind then she will cause her sons to be colorblind but her daughters will be carriers. If both parents are colorblind then it is impossible for their children not to be colorblind as well.

33. Appears in both sexes with equal frequency, both sexes transmit the trait, does not skip generations, affected offspring must have an affected parent unless new mutation. When one parent is affected (heterozygous, and the other parent is unaffected, approx ½ the offspring will be affected. Unaffected parent do not transmit
A pedigree chart shows an autosomal disease if there is a 50/50 ratio between men and women inheriting disease. An autosomal recessive disorder means two copies of an abnormal gene must be present in order for the disease or trait to develop.