1. Heredity Misconceptions
Having misconceptions is actually a good thing – it means that you’ve been thinking!
However, it’s time to unlearn a few things … 

2. Misconception 1: Genes code for traits
ACTUALLY … Genes are instructions for building proteins, which have major affects on traits.

3. Misconception 2: Genetics Determine Who I Am
ACTUALLY …
Remember GATTACA!
Genes code for proteins
Environment, choices have huge effects!

4. Misconception 3: Most Traits Are Controlled by a Single Gene
ACTUALLY … multiple proteins can affect this phenotype
E.g. eye color is controlled by at least 2 genes and is probably affected by many more

5. Misconception 4: There are only 2 alleles for each gene, dominant and recessive
There can be many different alleles for each gene
E.g. blood type, there is the IA allele, IB allele and i allele.

6. Misconception 5: Dominant Alleles Are More Common
Not true at all
Examples: 6 fingers, a certain type of dwarfism, Huntington’s Disease,
Why might a dominant trait be really rare?

7. Misconception 6: Dominant Alleles Are Better
Most genetic diseases tend to be recessive
Why would dominant lethal diseases tend to disappear rather quickly?
But in general a trait being dominant DOES NOT in any way mean it is better

8. Misconception 7: There is a Gene for Diseases
Diseases are mostly the result of mutated alleles for necessary genes
Thus the person does not produce a necessary protein, or produces a deformed protein

9. Misconception 8: Dominant Alleles Shut Off Recessive Alleles
The alleles are on separate chromosomes and do not interact with each other at all
I’m going to talk about what REALLY happens for your own piece of mind/knowledge/trivia – not for the quizzes (next slide)

10. What Actually Happens
Some alleles are instructions for producing functional proteins
The other alleles produce no protein at all or a protein that does not function at all

11. A trait is dominant if
One set of instructions produces enough proteins to have the trait
I.e. if you are heterozygous you have the trait

12. A trait is recessive if
One set of instructions is not enough to cause the trait
I.e. if you are heterozygous you will not have the trait

13. Incomplete Dominance
Heterozygotes produce fewer proteins, so they have an intermediate phenotype
Ex: flower color is “new” color. Heterozygous (Red allele & white allele) = Pink

14. Co-Dominance
Multiple alleles produce functional proteins pretty equally…
Ex: Black chicken (BB) and white chicken (WW) = heterozygous (BW) is a speckled black and white chicken
Also blood type! AB blood both proteins show up on the blood cell. O is simple dominance…just FYI. Blood type has 2 types of inheritance!

15. Male v. Female
Males XY
Females XX

16. What This Means Males have only one copy of genes on the X chromosome
Females have two X chromosomes

17. For Your Future Trivia Needs
XY system is only really in mammals
Some other fascinating sex determination systems

18. Birds and Some Reptiles
ZW system – females are ZW, males are ZZ
Kind of similar to our system, except roles are reversed
The egg determines the sex

19. In Bees Males have half as many chromosomes
If egg is fertilized, it becomes a female, if it is not fertilized it grows into a male

20. In Some Reptiles (alligators)
Temperature the egg is incubated at determines sex
Temperature seems to turn on or off certain enzymes

21. In Some Fish (clownfish)
The largest member of a school becomes the reproductive female
The next in line is the reproductive male
All others are non-reproductive
When Nemo’s mother died he would have become a man… because his dad would have become a woman…

22. Parthenogenesis (asexual)
Some animals lay eggs that require no fertilization
Interestingly in these snakes individuals still “mate” with each other, even though there is no exchange of DNA, before laying eggs
Not really having sex, just dancing

23. Hermaphroditic Snails and Slugs
Have male and female anatomies
But reproduce with others, not with themselves
This video will blow your mind!