ippie

ippie
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How many chromatids are present in a diploid (2n) cell of 36 chromosomes throughout the prophase stage of mitosis?

The solution is as follows...
Chromosomes are replicated during the S phase of a cell cycle. In the case of a (2n = 36) diploid cell, 36 x 2 = 72 chromatids will appear observable when chromatin fibers begin to condense at prophase of mitosis.

However, I think as follows...
The question said 2n=36 in prophase, so S phase is already passed. And the replicated chromosome # is 36. One chromosome = 2 chromatid. They are asking the # of chromatid. That's why 36*2=72. I mean it's not because of replication but because of 1 chromosome = 2 chromatid

Anybody explain?
 

Dr. Konfetka

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ippie said:
How many chromatids are present in a diploid (2n) cell of 36 chromosomes throughout the prophase stage of mitosis?

The solution is as follows...
Chromosomes are replicated during the S phase of a cell cycle. In the case of a (2n = 36) diploid cell, 36 x 2 = 72 chromatids will appear observable when chromatin fibers begin to condense at prophase of mitosis.

However, I think as follows...
The question said 2n=36 in prophase, so S phase is already passed. And the replicated chromosome # is 36. One chromosome = 2 chromatid. They are asking the # of chromatid. That's why 36*2=72. I mean it's not because of replication but because of 1 chromosome = 2 chromatid

Anybody explain?
I think they meant that 36 is the cells diploid number...thus the number of chromosomes it usually has. So, during prophase it would have twice as mcuh since it passes S phase before prophase. Crazy wording.
 
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ippie

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I got it. I have to read more carefully. thank you~
 
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ippie

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Then, what is the # of chromosome, not chromatid? Is it 36?
 
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ippie

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How about this problem?

How many chromosomes will be found in each gamete if the diploid parent cell consists of 36 chromatids at Prophase I?
 

tom_servo_dds

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ippie said:
How about this problem?

How many chromosomes will be found in each gamete if the diploid parent cell consists of 36 chromatids at Prophase I?
If 2n=36, then n=18 for the gamete (which is its haploid number). What happens though during meiosis is that all chromosomes duplicate which means you end up with 72 chromosomes total which then get split twice. During meiosis I it splits into two cells with homologous chromosomes and during meiosis II each of those split into separate sister chromatids. Meiosis II is therefore a lot like mitosis. Thus at the end of meiosis you will have 4 haploid gametes.

Quick way to check this is to ask yourself: if the parent has a diploid number of 2n=36 and the gamete needs to fuse with another gamete to produce the viable zygote, then in total they too will need to have a 2n=36 just like the parent.

Back to your second question then: if the parent has 36 chromosome at Prophase I that means its diploid number is 2n=18 and the number in each gamete is half that, or 9.
 
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ippie

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Which of the following statements pertaining to the versatility of catabolism is INCORRECT?

A. Starting materials for cellular respiration can all be derived from carbohydrates, fats, or proteins.
B. Glycerol from fats may enter the Krebs cycle upon its conversion to acetyl CoA.
C. Amino acids in excess may be deaminated to serve as intermediates for glycolysis or Krebs cycle.
D. Sugars in excess can be converted to fats through intermediates of glycolysis or Krebs cycle.
E. Certain amino acids can be synthesized through intermediates of glycolysis or Krebs cycle.
 
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ippie

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The answer is B. I know B is wrong, but how about C,D,E?
 

sonysonysony

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So is B wrong?

I think C is the answer too, since catabolism is breaking down of complex materials to its less comples forms.

C
aminoacids are broken down and the amine portion is separated from the acid counter part

D
Sugars being converted to fats is anabolism, since longer carbon chains are created from small carbon chains of sugars

E
Synthesizing materials like amino acids from intermediates of glycolysis is anabolism


ippie said:
The answer is B. I know B is wrong, but how about C,D,E?
 
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