Biology chapter 10

Homologous chromosome & Duplicated chromosome- In homologous chromosomes are chromosomes that pair of the same length and staining pattern, with genes for the same characteristics at corresponding loci. We human, receives 23 chromosomes from mother, and 23 chromosomes from father. They pair up during meiosis in synapse, which starts cell division. After the synapse, there will be 23 more duplicated chromosomes from the homologues chromosomes. We need to have homologous chromosome to achieve duplicated chromosome.
Kinetochore and MTOC- Kinetochore and MTOC- During mitosis, two identical sister chromatids are held together each with its own kinetochore which face opposite directions and attach to opposite poles of the mitotic spindle. The main function of the MTOC is to separate the chromosomes during cell division. So, as MTOC separates the chromosomes during cell division, the Kinetochore will attach to the opposite poles as well.
Haploid and Somatic- Haploid cell can be defined as containing one set of chromosomes. Somatic cells are diploid containing two copies of each chromosome, whereas the germ cells are haploid as they only contain one copy of each chromosome.

Nucleosome and Dehydration reaction-

Outline the sorting of chromosomes that takes place during meiosis.
A. Prophase 1
a. As prophase 1 begins, each pairs of chromosomes pairs with their homologue and usually swaps segments with it. Microtubules are forming a bipolar spindle. If the centroles are present, one pair will move to the opposite side of the nuclear envelop, which it will start to break up.
B. Metaphase 1
b. Microtubules from one spindle pole have tethered one of each type of chromosome, and microtubules from the other pole have tethered its homologue. They align all chromosomes midway between the poles.
C. Anaphase 1
c. Then, Microtubules attach to each of the chromosome and move it toward a spindle pole. Other microtubules, which extend from the poles and overlap at the spindle equator, ratchet past each other and push the two poles farther apart.
D. Telophase 1
d. One of each type of chromosome arrives at the spindle poles, and forms two haploid cells. All chromosomes are duplicated.
E. Prophase 2
e. The new bipolar spindle forms in each haploid cell. One chromatid of each chromosome becomes tethered to one spindle pole, and its sister chromatid becomes tethered to the opposite pole.
F. Metaphase 2
f. All chromosomes are positioned midway between the poles.
G. Anaphase 2
g. The attachment between sister chromatid of each chromosome breaks and moves it over to the spindle pole. Several of unduplicated chromosomes end up near each pole.
H. Telophase 2
h. Four nuclei forms as a new nuclear envelop encloses each cluster of chromosomes. Each of the daughter cells has a haploid number of chromosomes. \
Briefly outline section 10.4 on how meiosis generates genetic variation.
A. Crossing over in prophase 1
a. crossing over- a molecule interaction between a chromatid of one chromosome and a chromatid of the homologous partner.
b. The random tethering and subsequent positioning of each pair of maternal and paternal chromosomes at metaphase 1 lead to different combinations of maternal and paternal traits in each new generation.

Consult section 10.6 to formulate a list of similarities and differences between mitosis and meiosis, beginning with how the overall
For Meiosis, it only occurs in reproductive organs only; it has 4 haploid cells; Involves 2 rounds of division; propose of division is for reproduction; resulting cells each have 23 chromosomes. For mitosis, it occurs in all somatic; results in 2 diploid cells; involves one round of division; resulting of each have 46 chromosomes.