Wednesday, January 28, 2009

TQT Time and What is Up for Tomorrow


Again, I encourage you to post comments to the posts of the other authors. It could start interesting conversations.

Now to school - Tomorrow is TQT and you should send them as comments to this post. We will begin tomorrow with a few comments on FRQ-12 then we will see if you have questions regarding FRQ-13. After, we will take a look at the fruit flies. I will demonstrate how to anesthetize the flies and show you how to sex and distinguish the phenotypes. Finally, you will have an opportunity to work with and observe the flies. If we have time we will discuss how the experiment will be conducted.

Be reading the text. You should be through chapter 14 and beginning 15. Read, Read, Read. Trust your intelligence and keep pushing. The AP test is on May 11.

Mr. Baker


Ca said...

1. In Mendel's studies, he didn't observe any linkage between seed color and flower color although these genes are on the same chromosome. Why is that so?
2. How exactly do linkage between genes affects the inheritance of 2 different characters?
3. What are the significances of the SRY gene in humans?

Mr. Baker said...

Great questions Ca. Let me get to number one later (I may address this in class) and I will definitely be talking about two in class. I will address number three now. SRY (Sex-determining Region Y-chromosome) is a gene on the Y-chromosome that produces a protein which interacts with the DNA molecule and begins a series of events that causes the testis to develop in males. So you could say it is pretty important to at least half of the humans!

Ca said...

Oh I see~ So is the SRY gene is on both male and female? How come no one post their questions?

Inwoo said...

1. Is there a higher chance that a child will receive more genes from a parent than the other?
2. Do genes determine even aspects of our organs and body functions?
3. Could you match a person's gene and trace it back to an ancestor wayy wayy back?

Mr. Baker said...


The SRY gene is normally only on the Y-chromosome though it can translocate to the X-chromosome. This will result in a XX male.

As for no questions, we can ask in class tomorrow.

Mr. Baker said...


Question 1 - Nope, in sexually reproducing organisms, the offspring receive half their genes from mom and half from dad.

Question 2 - With qualification, you bet. Genes either determine or play a big part in the development of organs and how they function.

Question 3 - Yes, we can trace the ancestry of genes by comparing gene sequences within and between species.

Jimmy said...

(6 Questions because I forgot my other 3 last week.) >_<
1. Can you explain the second gene locus in epistatis?
2. On the pedigree sheet we had in class I saw 2 heterozygous recessive produce a child that was not affected by the trait. Is that possible? If so how is it?
3. How do diseases affect a certain race more than others?
4. Are the SRY chromosomes only in humans?
5. How does the woman's age affect the probability of the child being born with down syndrome?
6. What is genomic imprinting?

Ana said...

Okay here are my QUESTIONS... Mostly they are terms.
1. I am not quite sure how TRANSLOCATION happens.
2. AH... How are viruses able to infect bacteria?
3. THis one is asking for an opinion... If you COULD go and fix any errors that result in harmful disorders while the embryo is developing .. would you allow it?

Keely said...

Hello all. Well Mr.Baker I am going to post six this week. Three for this week and three for the week I missed a while ago. I can give you the actual date tomorrow.

1.Is it possible that a Drosophila Melanogaster could be female and have white eyes?
2.I have a theoretical question. With cats or any animal that can have one or more mates at the same time how would you define that cross? Would it be the genotypes of the female X male X male? Would you use a Punnett Square or would you just have to wait and see?
3.With sex-linked traits how is it decided if its linked to the X chromosome or Y chromosome? Not how we can tell what one it's linked to but why is it linked to that chromosome.
4.Could a zygote end up with something other than XX or XY? If yes what would it be? Is one more dominant than the other?
5.Does the chromosomes from the dad decide different things than the chromosomes from the mom? I know this sounds dumb but doesn't the chromosome that determines the sex of the zygote come from the dad. Is there any thing that the chromosomes from the mom specifically determine?
6.What causes nondisjunctions?

I would like to apologize for my abstract questions. They sounded good in my head but now that I read a few of them they sound a little dumb but I am still curious.


TahiraMadness said...

Yellow folks,

I'm too tired to make a fancy introduction.

1)Does the blending inheritance happen in humans? Or is that reserved for plants only?

2)Is there some kind of test where they can test you to see if you are a carrier for all abnormalities or something magical like that?

3)How come people with Down syndrome also tend to develop leukemia and Alzheimer's?

Good night!


ZS said...

1) Why marrying with different race has higher chance of producing a child with some genetic errors (autism children, syndromes...)?
2)Um.. I was going to ask about SRY too... um... but you already answered. so....Do animals have SRY too? Do bugs have SYR-type things in their body? ^- ^;
3)Are the monkeys have a probability of getting down syndrome like we do?

I am still don't feel comfortable about this blog. I always forget my passwordXP. Well I wrote it down so it won't matter anymore. Yay! half day tomorrow~! Mr. Baker did you say when is the fruit fly quiz?

Cintia said...

T-Q-F :|
1. Where does amniocentesis begin?

2. For alleles that are the cause of certain hereditary diseases. can some of the victims, or people have the syptoms but not know it?

3. How is it that polydactyly allele is more dominant?, How is it that most of us are recessive homozygotes?

4. Can someone have a disease it's whole life, yet not know, until the have issues with their body?

Kiran said...

Hi Mr. Baker,

I have some long-winded questions, so please bear with me:

In fragile x syndrome, the tip of the chromosome is said to be attached to the rest by a thin strand of DNA. How does that interfere with the function of the chromosome, since it is still attached?

The book talked about how certain genes can express themselves differently based on whether or not they inherited from the mother or the father. Why so?

How does mitochondrial DNA differ than that of the nucleus? Also, is there a possible way for a male to pass down their mitochondrial DNA traits?

Also, these are some things I've been seeing on the news lately:

What is resveratrol, and how does it work to promote heart health? There was a segment on 60 minutes last week, about researchers trying to create a Resveratrol supplement that people can take to prolong life; what do you think?

On Komo 4 news I saw a story on gender selection in babies. How is gender selection possible?


Kiran said...

Also, to respond to Keely's first question:

There is a way to get a white-eyed female drosophila melanogaster. You can cross a white-eyed male with a heterozygous female that is a carrier for the white-eyed trait. The male x-chromosome with the white-eyed gene can combine with the female x with the gene as well. This has a 25% chance of occuring.

WeNdY said...

Here we are with the TQFs:

1) during deletion, where does the "lost" chromosome go?

2)I don't completely understand what Barr bodies are. what is their purpose?

3)does the word syndrome mean that the person has something specific like mental retardation or can it be applied to anyone who has a genetic abnormality?

Mr. Baker said...

Good morning everyone,

While the coffee is brewing, the dog is chewing his bone, and my stomach is growling I will knock off a few low hanging fruit.

Wendy (3), a syndrome is a disorder that is characterized by a number of symptoms. For example Down syndrome, having an extra chromosome 21, is characterized by mild to severe mental retardation, heart defects, vision defects, hearing problems, and more. Navigate to for more.

Kiran (3), Both Chloroplasts and mitochomdria have there own, small, genome (DNA), The DNA is circular and contains genes that code for the cytochromes and coenzymes that are involved in photosynthesis and respiration. The circular DNA and many other characteristics of chloroplasts and mitochondria have led to the endosymbiont theory. This theory describes the evolution of the eukaryotic cell. More on this when we study evolution.

Cintia (2), yes, many hereditary traits have variable penetrance and expressivity. These are measures of the number of individuals that have the allele express the trait and how fully the allele is presented in an individual. So it is possible to have a disease allele and yet have a mild enough expression that may go unnoticed.

Kiran, thanks for the answer to Keely's white-eyed female question.

There a many good questions that I will get to later.

Bulgan said...

sorry for my late TQT!!!
1. If nondisjunction occurs during the meiosis, can it affect the sex of the baby?

2. Since nondisjunction can cause disorders in humans, we cannot determine if it was in the parents gene or no right, how can we know then?

3. So does this mean the parents' doesn't have to have the Prader-Willi and Angelman syndrome, but thier babies can? Are these not a inherited disorder?

4. I've always wondered what causes some people to be more feminine or masculine.

p.s Mr.Baker, or Ca, i don't quite get this one "The SRY gene is normally only on the Y-chromosome though it can translocate to the X-chromosome. This will result in a XX male." There is XX male too? i thought only Y was male.

Cintia said...

Same question as Bulgan, with the SRY, i really do't understand the XX male.?