Gastrula, Blastula and the blastopore

 Embryonic development involves a zygote undergoing stages of development, making blastula and gastrula.  Have a look at these under the microscope and upload a pic of your drawing and photo of the following specimens:  blastula, gastrula, whitefish mitosis, human sperm specimen

Co-Dominance and human blood groups

 What if the heterozygous trait exhibited codominance?  in this case, two alleles can code for co-dominant traits.  That is, neither is dominant over the other.  Blood type is an example of this:

A is codominant to B
A is dominant over O
B is dominant over O

Possible genotypes:

heterozygous AB blood gives both type A protein and type  B protein on the erythrocytes.

homozygous AA gives blood type A  protein on the erythrocytes
homozygous BB is blood type B protein on the erythrocytes

Heterozygous AO is gives blood type A
Heterozygous BO is blood type B

homozygous recessive OO gives blood type O .

There is  neither A or B on erythrocytes.

You have heard that blood type is important for blood transfusions. That is because the immune system will always attack an unknown protein.  Thus

type A person can receive  type A blood, and will reject type B blood

type B person can receive type B blood and will reject type A blood.

type AB person can receive type A blood and Type B blood

Type O person can receive nobody's blood except from another type O

Everyone can receive type O, No-one can receive type AB

Blood type is heritable and that means you can sometimes deduce genotype by looking at phenotype. Here is a sample question:

What Colour is this Dress?

 

There is a very interesting dress. It has caused major arguments!  This dress causes your cells in your retinas to perceive it to be certain colours depending on the state of your retinas. Of course your genes determine what your retinas are like...but also your retinas change over time too!  

Your perception is also based on whether you think this dress is in shadow or light...Try this, 

 I would like you to ask  20 people you know "What colours do you see on this dress:  Is it :  

A. GOLD AND WHITE 

B.  BLACK AND BLUE

C.  GOLD AND BLUE

D.  NONE OF THE ABOVE...THEN what colour is it?  

What are the characteristics of the people who are more likely to say that it is any of the choices above?   

Remember you can poll people without meeting face to face. Ask a variety of people including old, young, male, female...put your results on a table and hypothesize why people see different colours

  

 

SEX LINKED ALLELES

 SEX LINKED GENES

The sex chromosomes are XX and XY in humans. Some alleles are located on the X chromosome. But very few on the Y chromosome.  Remember that people who are  females have the genotype XX and people who are males have XY.

The Y chromosome carries very little information, only enough to influence the embryo on the path towards male primary and secondary characteristics.

Meanwhile, many RECESSIVE ALLELES are located on the X chromosome, including
1. hemophilia, the inability to clot blood
2. colourblindness inability to tell the difference between red and green colour
3.  baldness

These characteristics are far more common in malea than females because males have only one X. And if that X contains the recessive allele, they will show the phenotype.  Meanwhile, females may have the recessive and their dominant genes on their other X will protect them.  For example

An example of using a punnet square to calculate probability is here:

Some things to note about sex linkage:  Signs of sex linked alleles are:
1. more males get the phenotype, but females can be carriers
2.  males can inherit from mother but not father (because males get their X from mom)
3.  females have an extra X and this protects them.  Females must be homozygous to show the sex linked phenotype.
Further reading on sex linkage here http://learn.genetics.utah.edu/content/pigeons/sexlinkage/

FYI if you were born a male and you want to know if you're colourblind:  Test yourself here: But careful, if you are a genetically male, you might find out you are colour blind!  Apparently most people find out they are colourblind from their science teacher !  
http://colorvisiontesting.com/home.html

Basic practice worksheet going over main concepts

Worksheet B

Vulcan Mating ritual

 

Vulcan Mating Ritual

Mating Lab: 

Purpose:  To have hypothetical offspring with at least 4 other individuals

In the class and calculate the probability of certain traits using a punnet

Square.  Next, you will perform a Vulcan mating ritual (pon farr) where

you randomly pick an allele from the other person and they randomly pick

one of your alleles.  Then observe the traits of your offspring.  Have 8 kids per mate

Keep track of the genotype of each kid.  By the end of the activity, you will have 32 kids

Method:

Write down your phenotype for the following characteristics:

Earlobe attachment or unattached.   E.   e

Tongue rolling or not                       T       t

Cleft chin or smooth chin.                C     c

Widow’s peak or not                          W  w

Natural curl or straight hair         N  n

Dimples or not       D    d

Righty or Lefty       R   r

Freckles or not       F  f

biologically female  XX or biologically male XY

For each trait, make the genotype as alleles on two small pieces of paper.

 Write your phenotypes now:

For each mate you have draw nine punnet squares  representing

 each trait and

calculate the Probability of each trait.

Mate 1’s  genotype:_Ff WW tt nn rr dd cc  Ee__XX_________________

Punnet squares: indicate probability

Actual genotypes of the offspring. Draw a cartoon of your kids. Name them

Offspring :

1.ff Ww Tt  Dd Cc EE rr

2.

3.

4.