Wednesday, January 14, 2009

Three Question Thursday for 1-15-09

It is that time again! Send me your TQTQs as a comment to this post. As before, I will try to answer as many as I can.

Mr. Baker

32 comments:

ZS said...
This comment has been removed by the author.
ZS said...

1)What is Coleus?

2)I believe some organisms doesn't have gender or worms have both gender. How their chromosomes look like? Do they have a pair of both X and Y?

3)Cells deivde. When do they stop dividing? and How many cells can we hold in a body?

Shauna said...

To Zena, I asked Baker the same thing about when do cells stop dividing and this is what he said, "As you know, cell division is regulated by the levels of CDK. However, it is growth factors in the fluid surrounding cells that signal cells to proliferate (grow and divide). Interestingly, most cells in the human body are in G-zero stage but can be induced to leave G-zero and divide. Some cells like nerve cells are fixed in G-zero and this seems to be due to control switches that were set when the cell differentiated."

Shauna said...

1. How exactly do "genes program cells to synthesize specific enzymes and other proteins"?

2.Since we inherit thousands of genes, is it possible to carry the gene for every single eye color? Why do certain races mainly have brown eyes?

3. When a multicellular organism reproduces by budding does it essentially cue many of its cells to divide? In other words how exactly does budding occur? It is similar to cancer cells?

Mr. Baker said...

Perfect Shauna!

Inwoo said...

- What do they mean when a certain display is a "karyotype?".
- Is Meiosis regulated by CDK levels, just like mitosis?
- Is interracial breeding a safer guarantee of no human DNA defects?

Ana said...

Awsome okay here are MY TQT.
1. I never really understood how a characteristic can be dominant over another characteristic.
2. Mr. Baker, you said that in average a person has several mutations. Does that affect us in any way? Can there be a person with NO mutations?
3. A what point does a person, child, thing, start to develop or produce sperm or egg cells? After the two sex cells come together to create a being, when to the cells start to produce sex cells?

Ca said...

1. How exactly do the inherited instructions carry out to produce certain characteristics?
2. Why must meiosis and fertilization alter the sexual life cycles?
3. When the human cell divides, would there happen to be a cleavage furrow during cytokinesis just like animal cells division?

TahiraMadness said...

Good day fellow biology lovers. *pushes up glasses*

My curiosity has worked its magic, and in my brain three questions have formed. (Can I get any cornier?)

1)If we weren't mammals would the probability of being mutated be lower? I've never seen a bird with half a wing. Ya dig?

2)Lets say that theoretically our scientists were able to alter the genes of a child, would it then be possible to steal--or I mean ask permission then take--genes from amazing people in the world (containing but not limited to: Tahira, David Beckham, whoever won the noble prize, Anderson Cooper, etc. etc.) and create the ultimate human? Or can you only mix genes from two people?

3) Are our likes and dislikes dependent on our genes?

That is all..for now.

--Tahira

TahiraMadness said...

Oh wait...question two barely makes any sense to me. Scratch that.

Mr. Baker said...

Zena asked - What is Coleus? Coleus is the genus of a common household ornamental plant.

Zena asked - I paraphrase, "What do hermaphroditic species chromosomes look like. Well, there are many answers for this and we will discuss this later but in the worm C. elegans, self-fertilizing organisms have and XX karyotype. Whereas the rare male type has a XO karyotype (only one X chromosome).

Shauna asked - How exactly do "genes program cells to synthesize specific enzymes and other proteins"? Let me put this one off for chapter 17.

Shauna asked - Since we inherit thousands of genes, is it possible to carry the gene for every single eye color? Why do certain races mainly have brown eyes? First of all we do not completely understand the genetics of eye color so any answer would have to be somewhat speculative. I would think that one individual can not contain all the genetic variation that results in all the eye colors. this is because eye color is the result of the action of many genes and for each gene there are many alleles. So lets say 5 genes code for eye color and each gene has 3 alleles. Well one person heterozygous at each locus could possess only 10 alleles of the possible 15. As for why races have a typical pigmentation, this is an evolutionary question and you will have to wait.

I will get to the budding question later.

Inwoo asked - What do they mean when a certain display is a "karyotype?". A karyotype is simply a picture of an organisms chromosomes organized by size and shape - like you did in class.

Inwoo asked - Is Meiosis regulated by CDK levels, just like mitosis? Neat question, life does not like to throw things away. Rather it prefers to modify what it has. Though I do not know for certain, I would expect that meiosis uses many of the same chemical signals as mitosis with modification. I will see what I can find.
Inwoo asked - Is interracial breeding a safer guarantee of no human DNA defects? In general any outbreeding is better genetically than inbreeding. But there is much more to say about the genetics of race later in class.

Ana asked - I never really understood how a characteristic can be dominant over another characteristic. Well this has to do with the action of the gene product in the cell. Later we will talk about this but quickly, completely dominant/recessive traits are rare. Most traits have a more complex mechanism for their expression. Generally, in a dominant/recessive trait the recessive allele produces an ineffective protein while the dominant allele produces a fully functioning protein.

Ana asked - Mr. Baker, you said that in average a person has several mutations. Does that affect us in any way? Can there be a person with NO mutations? Many mutations are "silent" meaning they have no effect. Some mutations can have a positive effect and others can be maladaptive. And some humans could have no mutations, it is unlikely but possible.
Ana asked - A what point does a person, child, thing, start to develop or produce sperm or egg cells? After the two sex cells come together to create a being, when to the cells start to produce sex cells? In humans there is a difference between the two sexes. Males will not produce sperm until puberty begins. Females will have begun meiosis in their ovaries while in utero! They go into stasis at the end of meiosis 1 and will complete meiosis, one at a time, after puberty when the menstrual reproductive cycle begins.

Ca asked - How exactly do the inherited instructions carry out to produce certain characteristics? See my answer to Shauna's first question.

Ca asked - Why must meiosis and fertilization alter the sexual life cycles? This is because the chromosome number shifts from haploid to diploid at different points of the life cycle.

Ca asked - When the human cell divides, would there happen to be a cleavage furrow during cytokinesis just like animal cells division? You bet.

That's it for now.

Mr. Baker said...

I just read Tahira's questions and I am laughing. However they are interesting and I will answer them later.

Bulgan said...

1. So genetic variation means the shuffling of genes?
2. In figure 13.8,they cells start from 46 and end up 23?
3. In figure 14.4, why and how does the F1 generation alleles get segregated?

Mr. Baker said...

I think I will write a few answers during Biotech.

Tahirs asked - 1)If we weren't mammals would the probability of being mutated be lower? I've never seen a bird with half a wing. Ya dig? Not really, because mutation rate and half a bird wing are different questions and I am not sure how you are relating them. But I bet it makes sense to you. As for the first part of your question, in general the mutation rate is affected by many things and it is best to consider mutation in terms of populations. In population terms mutation rate is a function of population size and generation time.


Tahira asked - 2)Lets say that theoretically our scientists were able to alter the genes of a child, would it then be possible to steal--or I mean ask permission then take--genes from amazing people in the world (containing but not limited to: Tahira, David Beckham, whoever won the noble prize, Anderson Cooper, etc. etc.) and create the ultimate human? Or can you only mix genes from two people? Right now we can only do the mixing in humans the natural way (if you get my drift). But we have introduced single genes into other organisms. In theory, it is considered possible to what you ask but that will be way in the future and I for one am glad I will not be here. My question to you is, "Why Anderson Cooper?"

Tahirs asked - 3) Are our likes and dislikes dependent on our genes? I don't know.

Bulgan asked - 1. So genetic variation means the shuffling of genes? Perfect you got it. In all populations today there is a vasy supply of untested variation just because the deck is so vast and the cards have not been shuffled to make all the combinations yet.

Bulgan asked - 2. In figure 13.8,they cells start from 46 and end up 23? In humans, yes, the figure shows 4 and ending in two.

Bulgan asked - 3. In figure 14.4, why and how does the F1 generation alleles get segregated? They become segregated because the alleles are on homologous chromosomes and the chromosomes are segregated during Meiosis I. As the homologous chromosomes move away from each other, the alleles they carry move away also.

Mr. Baker

Mr. Baker said...

Tahira, sorry about hitting the "s" rather than the "a".

Bulgan said...

"alleles are on homologous chromosomes?"? i don't get it.... :(

Bulgan said...

Mr.Baker, i have a question on the lab.
5. Why is meiosis important for sexual reproduction?
- is it because it produces more sex cells rather than somatic cells?

Bulgan said...

Another question,
is 2 centrioles called centrosomes?

Mr. Baker said...

Bulgan,

Allele is another name for gene and genes are on chromosomes. So when the chromosomes move apart (segregate) the alleles on the chromosomes are segregated also. Now, the reason meiosis is important for sexual reproduction is because it reduces the number of chromosomes by half. regarding the centrosomes, before a cell divides the microtubules are manufactured and begin to form the spindle. This region of microtubule manufacture and organization is called the centrosome. In animal cells a pair of centrioles is also found in this region, whereas in plants no centrioles are present.

Keely said...

Hello everyone! Sorry for the late Three Question Thursday Questions.
So here I go:

1. How do cells know when to undergo mitosis or meiosis? Is it by cell signaling or is it like a ticking time bomb that eventually a cell just does no matter what?

2. How is a trait determined if it’s dominant or recessive?

3. I understand there are dominant traits and recessive traits. Lets say B is brown and b is blue. I get that BB and Bb would both have a phenotype of brown and bb would have a phenotype of blue but how do people get green eyes or gray? I know it’s probably really complicated but what I really want to now is, is there more than just those two traits involved? Is there like a mutation that causes green and gray eyes or is there like a hidden trait g? Sorry if that was confusing.

Questions I have been wondering about (not necessarily related to the reading):

1. Is it scientifically possible for scientist to cross breed animals like a cow and a pig to create a cow pig? Or is it genetically impossible or is it just unethical? If it’s genetically impossible how can we cross breed plants like an apple and a grape to make a grapple?

2. Does Meiosis have any checkpoints? I know I have asked a question similar to this before but I’m curious?

Sorry about the extra questions. I am in a questioning mood today.

See you all tomorrow,
Keely

Keely said...

Mr.Baker. So I don't forget I am going to ask you now. Can you please explain how you could get a 2:4:2 arrangement by crossing over tomorrow if we have time. It's a question on the lab.

Thank you,
Keely

Mr. Baker said...

Keely, I will get to your TQTQ this weekend. As for the Sordaria, I will take more time to explain it tomorrow.

Keely said...

Thank you.

Shauna said...

Keely,
I don't know about cross-bredding different animals but I would think that it would mess up something. At this farm I volunteer at they bred a petite dairy cow to a Scottish Highland Bull which is a monster of a creature and the baby was too big for the mom so she almost died from the size of the calf.

Bulgan said...

OMG, that is soooooooooooooo scaryy!!!
poor mom.... :(
how is it possible thou??

Mr. Baker said...

Keely asked - 1. How do cells know when to undergo mitosis or meiosis? Is it by cell signaling or is it like a ticking time bomb that eventually a cell just does no matter what? I do not know but let me hazzard a guess until I can find out. Following fertilization the egg begins to divide. At this point the cells can become any type of cell - they are undifferentiated. As the mass of cells becomes an embryo then a fetus the cells do become differentiated and take on specific functions. Once a cell is a muscle cell it won't become a blood cell. Well, I figure that the same is true of the cells that become gametes. They differentiate and become cells that are to undergo meiosis. Just as all the other types of cells only do mitosis.

keely asked - 2. I understand there are dominant traits and recessive traits. Lets say B is brown and b is blue. I get that BB and Bb would both have a phenotype of brown and bb would have a phenotype of blue but how do people get green eyes or gray? I know it’s probably really complicated but what I really want to now is, is there more than just those two traits involved? Is there like a mutation that causes green and gray eyes or is there like a hidden trait g? Sorry if that was confusing. Yes, eye color is more complicated and is the result of many genes. let me talk about that in a bit more detatil in class.

Then keely asked -A question I have been wondering about (not necessarily related to the reading):

Is it scientifically possible for scientist to cross breed animals like a cow and a pig to create a cow pig? Or is it genetically impossible or is it just unethical? If it’s genetically impossible how can we cross breed plants like an apple and a grape to make a grapple?

Great question and one of my favorite subjects - hybrids. There are a few questions here so let me tick them off one-by-one. First, is it possible to hybridize two species? From the developmental aspect, a general rule in animals is that if the two species are rather similar, hybridization may happen. A pig and a cow have diverged evolutionarily too much for this to work. But hybridization between a rainbow trout and cutthroat trout can happen. Why it does not work is that as there has been more divergence, the genomes are less compatible and even if fertilization occurs, the embryo can not develop. You also have to consider physical barriers. The cow and pig parts just don't match (if you get my drift). Of course you could artificially inseminate. Or as Shauna cited, in the case of mammals there may be problems during birth. Now all of this does not preclude a future when we know more about how genes work and we could create a cow/pig hybrid in the lab.

Now the ethics question, that is for you to determine. Personnaly, I do not favor hybridization of wild species followed by their reintroduction into the wild. I do favor the hybridizing of strains of domestic animals and plants. There are many examples of human caused (anthropogenic) hybridization of wild species that has had a significant negative impact on ecosystems and species.

Last, you wondered why is it a problem in animals (see above answer) and not so in plants. Well, the answer is in your question. Plant genomes are less rigid and plants have naturally hybridized freely forever. it is just the way they are. Therefore it is easy for us to hybridize plants to suit our interest.

TahiraMadness said...

Whoa so using artificial insemination we can create flying mammals?

Oh and Anderson Cooper is the best! Just look at his hair.

Mr. Baker said...

Hey, I thought you were sick! And I said nothing about flying mammals. Besides, there are bats and Anderson Cooper is a Ken doll.

Keely said...

Thank you Mr.Baker and Shauna.
That makes more sense now.

Shauna thanks for telling me about the cow mishp or the cow complication story (sorry I am trying to phrase it in a nice and correct way). I never thought about the size differences which seems obvious now. Haha something the size of a horse can't be coming out of something like a goat. I know odd combo but you get the visual.
Did you know you can breed a german shepherd to a long haird dachound? My friend has a puppy that was that mix. I don't know which was the dad and what was the mom but I just thought it was interesting.

But thank you again. It makes more sense now.
Keely

Bulgan said...

Mr.Baker, i have a question on Free Response,
if you have it, it is #14. But if you don't, then what does it mean by Rh negative children and positive children? is this the gene?

Kiran said...

Hi Mr. Baker,

This is for the three-question-thursday/friday that I forgot to post:

You had said in class that race is biologically irrelevant, but how come there are certain diseases that are more common to certain races than others? The book somewhat explained sickle-cell disease in African Americans, but what about Tay-Sachs disease in Ashkenazic Jews? While the sickle-cell allele is beneficial in certain environments in Africa, is there a benefit with carrying the Tay-Sachs allele?

Also, the book mentions Huntington's disease, which is a late-acting lethal dominant allele. Why is it late-acting?

The book also discusses how it is difficult to differentiate if phenotypes are due to genetic or environmental factors, so phenotypes have ranges and are broadly defined. So, how is it possible to differentiate from environmental and genetic affects?

(By the way, Anderson Cooper is not a ken doll...)

Shauna said...

I know..how does it work in dog land cause I have seen that before, the mom must be the bigger dog.
(since there is a reoccuring talk about Anderson Cooper I must say that I agree with Tahira.. he is a cutie)