Sunday, February 8, 2009

Finally, TQT - for Monday


I have finally found the time for the TQT post. Please write your TQTs as a comment to this post.

What sex is this fly?

Considering the class content, let me take a minute to review what you should , in general terms, know by now.
1. Offspring obtain genes from their parents by inheriting chromosomes.
2. Like begets like - sort of.
3. Meiosis; know the stages and what role it plays in life cycles.
4. What meiosis has to do with the origin of genetic variation.
5. Mendel's principles and how they lead to predicting probabilities.
6. Exceptions to simple Mendelian transmission.
7. Mendelian inheritance in humans and pedigree analysis.
8. Genes and chromosomes; TH morgan and his "Fly Lab", Morgan traced a gene to the behavior of a chromosome.
9. Linked genes, how they alter Mendelian expectations, crossing over produces recombinants, and using recombinants to map genes.
10. Chromosomal errors.
That takes us through chapter 15. I am planning to test chapters 13-21 on or around February 27. Get to reading.


Inwoo said...


1. DNA replication, why is one strand unable to replicate like the other one?
2. Why is the Ozaki one, forced to replicate backwards?
3. What does 5' and 3' mean?

Mr. Baker said...

Well Inwoo, all of your questions are related and have to do with the 5'-3' orientation of the complementary strands. We will cover this specifically in class but quickly, DNA can only replicate in the 5'-3' direction. The 5'-3' nomenclature has to do with the numbering of the carbon atoms of the deoxyribose sugar component of the nucleotide. See figure 16.12 of your text for the numbering scheme. Clearly, you are reading your text - good.

Ca said...

1. When a deletion occur in the chromosome structure, what is going to replace the missing gene? This is the one from chapter 15.
2. Why are the X-ray diffraction photo of DNA needed for DNA molecule configuration?
3. What does the backbone structure of a DNA helix made of? In other words, what exactly is forming it?

Mr. Baker said...

Ca, when a deletion occurs, the genes on the lost part of the chromosome are gone. X-ray diffraction photos allows chemists to infer the 3-dimensional configuration of molecules. The x-ray image of DNA made by Rosalind Franklin helped Watson and Crick realize that DNA is a helix. The "backbone" of DNA is a chain of alternating sugar and phosphate molecules.

Bulgan said...

i think we should watch the videos that we watch in Biotech to get chapter 16.
Anyways, here's my TQT.
1. Xeroderma pigmentosum is inherited from their partens? Then as soon as you find out that you have skin cancer, you can't go out in the sun?

2.D dont get 16.19 (b), so telomere is the part where one side is short and one side is long. telomerase enzyme helps extend one of the end (in this case '3) and RNA comes and match. What does it mean by the Primer is removed?

3.What does it mean to be minimal medium or complete growth medium?

and Ca, i think the backbone structure of a DNA helix is made of sugar-phosphate. Is this right, Mr. Baker?

Bulgan said...

oh, when did Mr. Baker post this?
That was fast.

ZS said...

1. May be I wasn't paying attention well on the text book, what is T2?
2. I know that DNA is given from parents' gene, but do you know the birth of the DNA's? According to evolution, how Darwin explains the DNA transformation from the apes' to us?
3. Where DNA polymerases created and what is it made of?

Mr. Baker said...

Hey Bulgan, we will watch the same videos and I will present a similar power point covering the structure of DNA, DNA replication , and the fabulous Okazaki fragments!

Ana said...

MALE (it has combs)

1.What causes the spontaneous loss of amino groups?? IS it plainly spontaneous?
2.I also had a question about the 5' and 3' but its already answered!!! =)
3. I dont understand why it is called "lagging strand" (in DNA)

Jimmy said...

1. How is it that the dead smooth cells and live rough cells kill the mouse, when both made it live?
2. Can you explain the 5'-3' directions?
3. What is the Okazaki fragment?

Shauna said...

I vote msle since it has a darker butte!
Anyways my questions show that I am still stuck in the Chapter 15 mindset.
1.) How are things like cancer and high cholesterol hereditary? is it that they carry a gene for not producing enough of something or something like that?
2.) What is the difference between genes and allels?
3.)The book say that a person who usually inherits two X chromosomes will usually become female...what do they mean by usually, is there a chance that the two x thing will be male?

Mr. Baker said...

Good, it is a male. It does have a darker butt (abdomen) and notice the sex combs on the front legs. They will never let you down.

TahiraMadness said...

Hi...I come bearing questions.

1) So viruses also infect bacteria? Why? Are we more prone to contracting viruses because we're loaded with bacteria? SHOULD WE WEAR PROTECTIVE GEAR?! Oh, also what kind of viruses are we talking about here?

2)The process where bases are separated, and then paired is all replication? Or is that just when it divides in half?

3)What do the three models of DNA replication have to do with anything? It happens in 3 different ways? Is it random?

--Tahira. Tahira. Tahira. Tahira. Tahira.

Mr. Baker said...


You should be very afraid of the viruses and no amount of protective wear will help. Just kidding. Yes viruses infect bacteria because like they do to all cells, they inject their DNA or RNA and hijacks the cell's machinery to make more virus particles. You are not necessarily more prone to viral infection because of your bacteria. They "like" your respiratory and other systems just fine. I do not understand question 2. The author uses the three models of DNA replication to illustrate how science develops models and tests them. The model that best describes the experimental evidence is the winner. I will discuss these models in class - maybe tomorrow.

Ana, I don't follow question 1 and 2 is answered. As for 3, the lagging strand gets it name because it is constructed in pieces rather than continuously. I will also show you this in class.

Jimmy, question 1, at the time this was discovered, it was not known, they simply said that the live smooth cells had become transformed. In fact we use that term to this day. Since that time we have found that the smooth cells possess accessory DNA called plasmids which convey the pathogenic trait. It was these small pieces of DNA that transformed the rough bacteria.

Shauna, genes and alleles. They are somewhat interchangeable. Alleles are alternate forms of a gene. For example in Drosophila, there is a gene called eye color and two alleles, wild type and sepia. Regarding the X-chromosomes and sex determination, there are many different chromosome arrangements due to chromosome anomalies such as nondisjunction. For example, an XO individual is a female, XXY, male.

Thanks for the questions. More answers later.
Be sure to participate in the daily Science Week question!

Mr. Baker signing off

Bulgan said...

Do we still post TQT here for tomorrow???

ZS said...

We don't have TQT for February 12th?

Shauna said...

No I asked Baker today