Practice

1)  What is an aneuploid?  Give some examples of aneuploidy.  (Remember the karyotypes we looked at on the smartboard.)
2)  What is the only human aneuploid condition (that could result in a live birth) in which the person has 45 chromosomes?
3)  In humans, normal hearing requires at least one dominant allele at two different loci (genes):   D__ E__.  Knowing this, how could two deaf individuals have children who all have normal hearing?
4)  In cocker spaniels, black fur is dominant to brown, and spotted is dominant to solid.  What would be the phenotypic ratio of a cross between a homozygous black, spotted male and a homozygous brown, spotted female?
5)  A woman has blood type A and man has blood type B.  Without knowing their actual genotypes, list all the possible blood types their children could have.

Read over linked genes and how to calculate recombination frequency.  I hope to get to this tomorrow.  If you left for the math competition today, try to get with a classmate to catch up and complete your graphic organizer.  I'll be checking in.

Practice

Here are a few questions for practice/review.

Match the following F2 phenotypic ratios with the inheritance pattern they are most common in:

1)  1:2:1                          a.  complete dominance
2)  3:1                             b.  dihybrid
3)  9:3:3:1                       c.  incomplete dominance and codominance

4)  What is the type of inheritance in which both alleles are equally expressed?  Give an example discussed in class.
5)  What is the type of inheritance in which two pure-breeding phenotypes produce offspring that have a phenotype that is intermediate between the two parental types?  Give an example discussed in class.
6)  In hamsters, black fur is dominant to brown.  A friend gives you a black hamster.  How could you determine if its genotype is BB or Bb?  (What type of cross would you perform?)
7)  What is the difference between the terms sex-linked gene and linked gene?  (See p. 176 and p. 172.  These terms do not mean the same thing!)  We will begin discussing linked genes tomorrow and calculating recombination frequencies, so I need you to know the difference between these terms.

I will be checking in until around 10:30 if you have questions.  These are good practice, so try them.  If you get stuck, that's okay.  If I can't answer your questions on the blog because you need to see a punnett square or detailed explanation, I will definitely answer them tomorrow. 

Questions

Here are some questions to help you practice tonight, just in case you are uneasy about the problems from class today.

1)  A paternity issue has come up.  The child has blood type A, the mother has blood type B, and the alleged father has blood type O.  Can this be his child?  Justify your answer with a punnett square.
2)  In cats, a condition called manx exists.  Manx cats have a naturally occurring mutation of the spine, which usually causes them to be tailless (no tail.)  When pure breeding long tail cats are bred with tailless manx cats, cats with tails that are short and stubby are usually produced.  Based on this information, what can you conclude about the inheritance pattern of tail length in cats?
3)  For the following conditions, determine if they are inherited as autosomal dominant, autosomal recessive, or sex-linked recessive:  Sickle cell disease, cystic fibrosis, achondroplasia, Huntington's disorder, hemophilia, PKU, colorblindness, Tay-Sachs.

If you have questions, I will be checking in until around 9:30.  I'm pretty tired tonight.:)

Tonight's Reading/Studying

I hope everyone feels comfortable with the genetics problems we discussed and worked in class today.  We will be adding more types of crosses tomorrow, so go through the chapter and look for examples of:

1)  incomplete dominance (such as red and white flowers producing pink)
2)  sex linkage (such as hemophilia and colorblindness)
3)  codominance (such as human blood types, which is also an example of multiple alleles)
4)  epistasis (which is a variation on the dihybrid cross we did in class today; you get a different phenotypic ratio, such as 9:3:4 ,  9:7  , or some other ratio)

It is critical that you understand the basic vocabulary:  trait, allele, homozygous, heterozygous, genotype, phenotype, hybrid, true-breeding, dominant, recessive, P generation, F1 generation, F2 generation, autosome, sex chromosome.  Without this vocabulary, working the problems is pretty much impossible. 

We will continue to go through the study guide packet tomorrow and add examples of Punnett squares to your notes.

Fall Break/Next Week

I hope everyone enjoys their much deserved break!  If you find yourself bored and in need of entertainment, break out your iPOD and listen to the mitosis, meiosis, and Mendelian genetics tutorials on  Kahn Biology.  I will be around online, so post questions as they come up. 

I have left a packet for chapter 9 for you next week.  Some of it is easy, some is not.  I highly recommend using a pencil to complete the study guide packet so you can make changes (if necessary) when I get back.  A lot of chapter 9 will be stuff you already know and just need to review, but there is a good bit of information that I am pretty sure you've never heard before.  Don't stress over it, but don't ignore it either.  READ, re-read,  talk to each other, and try to work through the problems.  And as always, I'll be checking in.

Tonight's Reading

Well, here's the new blog page.  I may have created two accidentally, but google has not been my friend these past few days.  Anyway...join up so you can post questions.  Read the rest of chapter 8 tonight and be ready to finish up the discussion in class tomorrow.