AgendaCheck in HW- have it on deskHeredity misconceptionsWhiteboard out HWHeredity PracticeHW: Finish GATTACA reflection?

Heredity MisconceptionsUnlearn these things

Genes code for traits Genes are instructions for building

proteins, which have major affects on traits

Genetics Determine Who I AmRemember GATTACA!Genes code for proteinsEnvironment, choices have huge effects!

Most Traits Are Controlled by a Single Gene E.g. eye color is controlled by at least 2

genes and is probably affected by many more

Because multiple proteins can affect this phenotype

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.

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?

Dominant Alleles Are BetterMost genetic diseases tend to be

recessiveWhy 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

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

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

What Actually HappensSome alleles are instructions for producing functional proteins

The other alleles produce no protein at all or a protein that does not function at all

A trait is dominant ifOne set of instructions produces enough proteins to have the trait

I.e. if you are heterozygous you have the trait

A trait is recessive ifOne set of instructions is not enough to cause the trait

I.e. if you are heterozygous you will not have the trait

Incomplete Dominance

Heterozygotes produce fewer proteins, so they have an intermediate phenotype

Co-Dominance

Multiple alleles produce functional proteins

Male v. FemaleMales XYFemales XX

What This Means Males have only one copy of genes on

the X chromosome Females have two

For Your Future Trivia Needs

XY system is only really in mammals

Some other fascinating sex determination systems

Birds and Some ReptilesZW system – females are ZW, males are ZZ

Kind of similar to our system, except roles are reversed

The egg determines the sex

In BeesMales have half as many

chromosomes If egg is fertilized, it becomes a

female, if it is not fertilized it grows into a male

In Some Reptiles (alligators) Temperature the egg is incubated at

determines sex Temperature seems to turn on or off

certain enzymes

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…

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

Hermaphroditic Snails and Slugs

Have male and female anatomies

But reproduce with others, not with themselves

This video will blow your mind!

https://www.youtube.com/watch?v=wG9qpZ89qzc

Whiteboarding – 5 minutes to have explanation readyAces – 5a2s – 23s – 34s – 45s – 5b6s – 67s - 7

DO NOT DOODLE WITH THE MARKERSNo more warnings, instant detention