M
Mark M
Guest
I just need to get a few things straight. The following are statements about my understanding of topics relating to genetics and DNA replication. For the examples let's pretend that chromosome 6 codes for, among many many other things, eye color. These are my conclusions please correct me if I am wrong.
Here's the format:
X) Subject
*My Understanding
-Here's Why
As I understand it:
1) Diploid (2n)
*The cell has enough DNA to code for two complete humans
- Notice the word code. I'll use a hypothetical example for this conclusion. Consider 1 trait - eye color: Mom's are blue and dad's are green. I get one chromosome 6 from each parent and the trait that displays is the dominant one, nevertheless I have two chromosomes coding for the same traits.
2) Haploid (1n)
*Cell has enough DNA for one complete human
-Assume this hypothetical situation: if you were to take one haploid egg and cause it to duplicate it's DNA to form a diploid cell, (ignoring other factors) that cell could (theoretically) develop into one complete (female) human, no parts missing.
3) Sister Chromatids
*These are the exact same macromolecule
- Same exact DNA molecule (ignoring any mutations). You take the chromosome 6 I got from my dad and duplicate it and the two make sister chromatids.
4) Homologous Chromosomes
*Code for same traits but have different DNA
-For this example we're dealing with 4 chromosomes: the chromosome 6 from my dad duplicated and formed a sister chromatid and the chromosome 6 from my mom did the same so now I have four. Now one of the chromosome 6's from my dad pairs with one of the chromosome 6's from my mom, and the other two pair with each other. Each one of these pairs is a homologous chromosome, they are both chromosome 6's meaning they code for the same traits but they have different DNA.
5) Homologous Chromosome Pair
*Genetically identical pair of homologous chromosomes
- Remember the previous example. Each homologous chromosome contains a chromosome 6 from my mom and a chromosome 6 from my dad and there are two homologous chromosomes. These homologous chromosomes pair up in both prophase of mitosis and prophase 1 of meiosis making a homologous pair of chromosomes.
6) Meiosis
*This is my understanding of the haploid/diploid tracking
-
Diploid (2n)
---Replicates DNA
1 cell (4n)
---Meiosis 1 + Cytokenisis 1
2 cells, each diploid (2n)
---Meiosis 2 + Cytokenisis 2
4 cells, each haploid (1n)
The reason I have this last one is because my study book for the AP Biology test says three times that after Meiosis 1 and Cytokinesis 1 there are 2 haploid cells but I can't see how this is possible.
Please correct me if any of this is wrong!
Thanks,
Mark
Here's the format:
X) Subject
*My Understanding
-Here's Why
As I understand it:
1) Diploid (2n)
*The cell has enough DNA to code for two complete humans
- Notice the word code. I'll use a hypothetical example for this conclusion. Consider 1 trait - eye color: Mom's are blue and dad's are green. I get one chromosome 6 from each parent and the trait that displays is the dominant one, nevertheless I have two chromosomes coding for the same traits.
2) Haploid (1n)
*Cell has enough DNA for one complete human
-Assume this hypothetical situation: if you were to take one haploid egg and cause it to duplicate it's DNA to form a diploid cell, (ignoring other factors) that cell could (theoretically) develop into one complete (female) human, no parts missing.
3) Sister Chromatids
*These are the exact same macromolecule
- Same exact DNA molecule (ignoring any mutations). You take the chromosome 6 I got from my dad and duplicate it and the two make sister chromatids.
4) Homologous Chromosomes
*Code for same traits but have different DNA
-For this example we're dealing with 4 chromosomes: the chromosome 6 from my dad duplicated and formed a sister chromatid and the chromosome 6 from my mom did the same so now I have four. Now one of the chromosome 6's from my dad pairs with one of the chromosome 6's from my mom, and the other two pair with each other. Each one of these pairs is a homologous chromosome, they are both chromosome 6's meaning they code for the same traits but they have different DNA.
5) Homologous Chromosome Pair
*Genetically identical pair of homologous chromosomes
- Remember the previous example. Each homologous chromosome contains a chromosome 6 from my mom and a chromosome 6 from my dad and there are two homologous chromosomes. These homologous chromosomes pair up in both prophase of mitosis and prophase 1 of meiosis making a homologous pair of chromosomes.
6) Meiosis
*This is my understanding of the haploid/diploid tracking
-
Diploid (2n)
---Replicates DNA
1 cell (4n)
---Meiosis 1 + Cytokenisis 1
2 cells, each diploid (2n)
---Meiosis 2 + Cytokenisis 2
4 cells, each haploid (1n)
The reason I have this last one is because my study book for the AP Biology test says three times that after Meiosis 1 and Cytokinesis 1 there are 2 haploid cells but I can't see how this is possible.
Please correct me if any of this is wrong!
Thanks,
Mark