1. Heredity
Unit 5, Lesson 4

2. What is Heredity?
HEREDITY is the passing of physical characteristics from parents to offspring
Brain Pop: Heredity (2:28)
Brain Pop: Heredity

3. MENDEL’S DISCOVERY
Mendel worked with Pea Plants He discovered that a characteristic is a feature that has different forms in a population (seed color, flower position…) The different forms are called Traits (green, yellow, flower low, flower high…)

4. Checkpoint…. Characteristic
Is flower color a characteristic or a trait?
Characteristic

5. To review…. Plant pollination…
How to plants reproduce
They can reproduce asexually and sexually
Fruits and seeds are produced via sexually
In sexual reproduction, they have gametes (sex cells) and rely on animals/insects (bee/butterfly) or wind to pollinate them /transfer the gametes

8. Process…

9. Traits depend on inherited Factors
Mendel took 2 sets of plants and pollinated them to look at the outcome….
True breeding= always produces the same outcome
EX: green crossed with green always gives green

10. What he found….
each plant has 2 heritable ‘factors’ for each trait- one from each parent
Which pod color is recessive?
Yellow

11. DOMINANT AND RECESSIVE ALLELES
Individual factors, or sets of genetic information control the inheritance of TRAITS
The factors that control each trait exist in PAIRS
One factor comes from FEMALE parent and one factor comes from the MALE parent
One factor is dominant and the other factor is recessive

12. How are traits inherited?
Genes are passed form parents to offspring
GENES are segments of DNA found in the chromosomes and give instructions for producing characteristics.
ALLELES are the different versions of a gene

13. A dominant gene is represented by an uppercase letter and a recessive gene is represented by a lowercase letter
If BOTH letters are uppercase OR if BOTH letters are lowercase, then the gene is HOMOZYGOUS
If the letters are mixed (one lowercase and one uppercase) the gene is HETEROZYGOUS

14. Complete dominance

15. Genes influence Traits
Genotype
Combination of alleles you inherited from your parents
Phenotype
OBSERVABLE traits

16. Influences
Many genes can influence a single trait (eye color, skin color, hair color)
The environment can influence traits (artic fox has a gene that determines fur color, but the light effects the gene causing the fur color to change)
A single trait can influence many traits
(a tigers single gene effects his fur color AND eye color)

17. Incomplete and Complete Dominance
Incomplete dominance
The alleles of a gene have an influence on the trait
They BLEND
Snapdragon flower color
Codominance
The alleles of a gene have an contribute to the trait
They work TOGETHER
EX: Blood type

18. Checkpoint….

19. FYI….
* sex-linked characteristic