PCB 3063 Lecture Notes - Lecture 3: Centromere, Microtubule, Meiosis

Daughter cells resulting from meiosis:

(a) have only one member of each homologous pair
(b) have only one member of each pair of alleles
(c) have half as many chromosomes as the parent cell
(d) all of these
(e) none of these.

The centromere is a region in which:

a) chromatids remain attached to one another until anaphase.
b) metaphase chromosomes become aligned at the metaphaseplate.
c) chromosomes are grouped during telophase.
d) the nucleus is located prior to mitosis.
e) new spindle microtubules form at either end.

In the cells of some organisms, mitosis occurs without cytokinesis.This will result in:

a) cells with more than one nucleus.
b) cells that are unusually small.
c) cells lacking nuclei.
d) destruction of chromosomes.
e) cell cycles lacking an S phase.

Which of the following does not occur during mitosis?

a) condensation of the chromosomes
b) replication of the DNA
c) separation of sister chromatids
d) spindle formation
e) separation of the spindle poles.

6. Meiosis and mitosis are both processes that involve nucleardivision. What is the difference between the two?

7. Daughter cells resulting from meiosis:

a) have only one member of each homologus pair
b) have only one member of each pair of alleles
c) have half as many chromosomes as the parentcell
d) all of these
e) none of these.

8. The centromere is a region in which:

a)chromatids remain attached to one another untilanaphase.
b) metaphase chromosomes become aligned at the metaphaseplate.
c) chromosomes are grouped during telophase.
d) the nucleus is located prior to mitosis.
e) new spindle microtubules form at either end.

9. Which of the following does not occur duringmitosis?

a) condensation of the chromosomes
b) replication of the DNA
c) separation of sister chromatids
d) spindle formation
e) separation of the spindle poles.

10. What is the relationship between interphase and celldivision? (Why are they both needed?)

I'll be thankful if someone can help me to do this!

According to this:

Read the following New York Times article and then answer the questions below and then answer the questions New Clues to Sex Anomalies in How Y Chromosomes Are Copied

http://www.nytimes.com/2009/09/15/science/15chrom.html?scp=1&sq=sex%20anomalies&st=cse

This activity contains 5 questions.

5.

You must make 2 reflective, thoughtful, deep, constructive critiques of your class mates posts. as part of a threaded discussion following their initial post. The critiques must not about you, but about science!

Here's the first peson. Needs to reply for some of her answers as it says above.

1. When discarding bad genes, the Y chromosomes recombines with itself.

2. The centromere functions to hold a pair of copied chromosomes together.

3. A person with Turner’s syndrome is born with a single X chromosome.

4. The male-determining gene on the Y chromosome is located close to the end of the left arm.

5. An individual can have some cells with no Y chromosomes and other cells with double Y chromosomes, due to the differing variants present in regards to the genotypes of the cells in a single individual. When the Y chromosome is compared to other chromosomes such as the X chromosome, mutations and deviation in the distance of the centromere are much more prevalent due to the Y chromosome lacking a backup system to promote repairs.¹ (Links to an external site.) Even if a mutation caused a condition such as the XYY syndrome where two Y chromosomes are present, that mutation and genotype would not be present in every single cell of the individual.² (Links to an external site.) The presence of different genotypes offers an tentative explanation to as why a single individual can have some cells with no Y chromosomes while also housing other cells with double Y chromosomes.

Source 1 http://www.nytimes.com/2009/09/15/science/15chrom.html

Source 2 https://www.healthline.com/health/xyy-syndrome

Here's the second person. Needs to do the same as it says above.

1. Itself

2. Centromere

3. A single X chromosome

4. Close to the end of the left arm

5. Briefly explain how an individual can have some cells with no Y chromosome and other cells with a double-Y chromosome.

In some cases, the Y chromosome reaches over to a neighboring counterpart and the two chromosomes fuse. This results in the loss of part of the chromosome. Jacob’s Syndrome is sometimes also called XYY syndrome because the person has two Y chromosomes. Although a person can survive with this genetic mutation, some physical traits may be observed such as taller than average height, weak muscle development or late speech development.

Source 1 https://www.healthline.com/health/xyy-syndrome

Source 2 http://www.isna.org/faq/y_chromosome