L16: Cell Cycle & Mitotic Cell Division

Question 1

Does cell division produce genetically identical or genetically unique daughter cells?

Answer 1

mitosis makes genetically identical cells

Question 2

During mitosis how do the daughter cells compare to the parent cell in regards to the number of sets of genes/chromosomes?

Answer 2

they contain the same number of chromosomes as their parent cell

Question 3

How many daughter cells are produced? Are they diploid or haploid? What do the terms diploid and haploid mean?

Answer 3

one diploid cell divides into two diploid daughter
cells

Haploid cells contain only one set of Chromosomes (n). Diploid, as the name indicates, contains two sets of chromosomes (2n) (maternal and paternal set)

Question 4

Which roles in your body does mitosis serve? Which role in your body does meiosis serve?

Answer 4

cells must divid to proliferate their kind. many roles like:
- asexual reproduction

mitosis:
- development of a zygote into adult
- proliferate immune cells to wage n immune response
- repair/regenerate damaged tissue (ex: wound)
- replace short-lived tissues (ex: epidermis, RBCs)
- form ephemeral tissues (ex: placenta)

meiosis:
- make gametes for sexual reproduction

Question 5

Do you recall the animal life cycle?

Answer 5

germ cells divide by meiosis to produce gametes.

gametes, egg and sperm, produce a zygote.

zygote divides by mitosis to produce all somatic and germ cells for offspring

Question 6

Where are germ cells located? Are germ cells are diploid or haploid?

Answer 6

ovaries & testes

diploid

Question 7

Do germ cells divide by mitosis or meiosis? What are their daughter cells called? Are they diploid or haploid?

Answer 7

germ cells divide by meiosis to produce gametes

ovary germ cell —-> egg (haploid)
teste germ cell —-> sperm (haploid)

Gametes do NOT divide

Question 8

Which cell is formed when an egg is fertilized by a sperm? Is it diploid or haploid? Which form of cell division does it use to divide into daughter cells. Are these daughter cells diploid or haploid? What do these daughter cells become in the offspring?

Answer 8

A sperm fertilizes an egg producing a zygote (diploid)

zygote divides by mitosis to produce all somatic cells and germ cells for the offspring (all cells are diploid excluding your gametes)

Question 9

What happens during M phase of the cell cycle?

Answer 9

Mitotic (M) Phase includes mitosis and cytokinesis

During M phase a cell divides a parent nucleus (with replicated chromosomes) into two daughter nuclei that are partitioned into two daughter cells during cytokinesis.

Question 10

What happens during Interphase of the cell cycle?

Answer 10

G1, S, and, G2, cell grows

Question 11

What occurs during the S phase of Interphase? Why is this important?

Answer 11

Cells replicate chromatin during S phase.

Question 12

What is cytokinesis? When during the cell cycle does cytokinesis occur?

Answer 12

The cell divides into two identical daughter cells. This occurs at the end of the cell cycle

Question 13

M phase is subdivided into other phases that begin with the following letters: P, PM, M, A, and T. What are the complete names of these phases?

Answer 13

1. prophase
2. prometaphase
3. metaphase
4. anaphase
5. telophase

Question 14

During Interphase two important activities necessary for M phase occur, what are they?

Answer 14

a cell must replicate its centrioles and its DNA

Question 15

During what state is DNA replicated: chromatin or chromosome?

Answer 15

chromatin because it’s easier to read

Question 16

What is a centromere?

Answer 16

the region of a chromosome to which the microtubules of the spindle attach, via the kinetochore, during cell division.

Question 17

Which two activities occur during Prophase?

Answer 17

chromatin is coiled into replicated chromosomes and centrioles begin migrating to cell poles and begin growing microtubules

Question 18

What are sister chromatids?

Answer 18

Chromatin replicates and each replicate is attached to its ‘sister’ via a central connection called a centromere

Question 19

What do centrioles (centrosomes) grow during this phase? Centrioles begin to move during this phase. Where are they going? (prophase)

Answer 19

Centrioles begin migrating to cell poles and begin growing microtubules

Question 20

What happens during Prometaphase?

Answer 20

the nuclear envelope is disorganized and form small vesicles as opposed yo forming a contiguous envelope around the nucleus

Question 21

Why must plant and animal cells disassemble their nuclear envelope during this phase? (prometaphase)

Answer 21

because it’s replicated chromosomes are inside the nucleus but the centrioles and microtubules that organize/separate sister chromatids are in the cytoplasm

Question 22

What are kinetochores and what do they do?

Answer 22

form at the centromeres of each replicated chromosomes and begin growing microtubules

Kinetochore and centriole microtubules
connect and are collectively called
spindle fibers. They help move/organize
the replicated chromosomes

Question 23

What are spindle fibers?

Answer 23

Kinetochore and centriole microtubules
connect and are collectively called
spindle fibers. They help move/organize
the replicated chromosomes

Question 24

What happens during Metaphase?

Answer 24

Centrioles reach cell poles at the start of metaphase.
Spindle fibers organize replicated
chromosomes on the cell equator so
sister chromatids face cell poles.

Question 25

Where would you expect to find replicated chromosomes and centrioles during this phase?

Answer 25

on the cell equator so sister chromatids face cell poles

Question 26

How should sister chromatids be oriented during Metaphase? Why is this important?

Answer 26

sister chromatids are facing towards opposite cell poles on the cell equator.

It’s important because the cell is in a structure known as mitotic spindle which is a step it needs to complete to divide into two identical cells

Question 27

What happens during Anaphase?

Answer 27

each pair of sister chromatids separate into identical daughter chromosomes.

Microtubules elongate cell and spindle fibers move daughter chromosomes toward cell poles forming two identical
groups of chromosomes.

Question 28

What must break when sister chromatids are pulled apart?

Answer 28

must break apart at the centromere

Question 29

Where are the chromatids (now just called chromosomes) going during this phase? (anaphase)

Answer 29

to opposite cell poles

Question 30

What happens during Telophase?

Answer 30

Telophase is the final phase of mitosis; division of nucleus.

Cell re-assembles nuclear envelopes around each group of separated chromatids, now called chromosomes, forming daughter nuclei.

Chromosomes begin to uncoil back to chromatin (easier to read to make proteins).

Question 31

How many daughter nuclei form during this phase? Are these nuclei diploid or haploid? (telophase)

Answer 31

2 diploid

Question 32

What happens during cytokinesis?

Answer 32

The cell pinches in between the two daughter nuclei and splits into two daughter cells

Question 33

Plant cells do not undergo cytokinesis as animal cells do. Why not? What do they do instead?

Answer 33

they build a cell plate that is converted into a cell wall

Question 34

Can you recognize the various phases of mitosis in diagrams of animal cells or photomicrographs of plant cells such as those depicted in the lecture slides or comparable images?

Answer 34

maybe

Question 35

Are prokaryotes diploid or haploid? Describe the number and shape of their chromosome(s).

Answer 35

haploid and they only have one single chromosomes

Question 36

How do prokaryotes divide: mitosis, meiosis, or binary fission?

Answer 36

binary fission

Question 37

How does binary fission work? Is there a nucleus to contend with? Is there a mitotic spindle? How then do prokaryotes separate their replicated chromosome?

Answer 37

no nucleus an process is much easier and quicker

1. Bacteria first replicate their DNA including the origin.
2. The two origins become attached at opposite ends of the cell.
3. The cell elongates and as it does, the
   two circular chromosomes stay near
   the end to which they are attached.
4. Cell divides and partitions one chromosome into each daughter cell.