CH. 3 Cell Cycle

Question 1

Mitosis

Answer 1

• Purpose: Growth and repair/ replacement.
• Occurs in all of the somatic cells of the body (normal body cells like skin, liver, kidney, etc).
• One round of cell division.
• Produces 2 genetically identical daughter cells.
• Each daughter cel has 46 chromosomes.

Question 2

Meiosis

Answer 2

• Purpose: gametogenesis
• Occurs only in the gonads, tested in males and ovaries in females.
• Two rounds of cell division (Meiosis I, Meiosis II).
• Produces 4 daughter cells, each with half the number of chromosomes.
• Each daughter cell has 23 chromosomes.

Question 3

Interphase

Answer 3

(Light Gray)
Phase between cell division
Period of cell growth and normal ongoing metabolic (chemical) activities (when the cell is just being a cell)

G1: metabolic activity and vigorous growth
S: (synthesis): DNA replication
G2: Preparation for division
G0: “resting” cells that cease dividing and exit the cell cycle (May last days, months or even years)

Question 4

Mitosis

Answer 4

Process necessary for cell division into two identical cells (growth and replacement).
Exact and equal division of replicated DNA.

Prophase
Metaphase
Anaphase
Telophase = Cytokinesis

Question 5

Prophase

Answer 5

(Black Dot)
Chromosomes condense.
Nuclear envelope breaks up.
Microtubule spindles form.*

Question 6

Metaphase

Answer 6

(Line)
Spindle microtubules attach to sister chromatids.
Sister chromatids align along metaphase plate.
Get tug-of-war, and with proper tension, move to anaphase.

Question 7

Anaphase

Answer 7

(Pull apart)
Attachments between sister chromatids break.
Sister chromatids migrate to opposite spindle poles.
We now have independent daughter chromosomes.

Question 8

Telophase

Answer 8

(Starting to Split) microtubules 
Chromosomes arrive at opposite spindle poles.
They decondense. 
Microtubules breaks down. 
Nuclear envelope reforms.

Question 9

Cytokinesis

Answer 9

Cleavage furrow and contractile ring form via microfilments.
Cytoplasm splits.
Two new daughter cells (genetically identical to parent cell) are formed.

Question 10

Developmental aspects of Cells
A. Life after mitosis
1. Differentiation- cellular fate

Answer 10

Cellular differentiation-
While all cells originate from one fertilized egg (one cell), they respond to different chemical signals and form the
3 germ layers:
Endoderm, Mesoderm, ectoderm

And then the four major tissue groups:
Epithelial, connective, muscle, nervous tissue

Once a cell has differentiated and the divides, the two new cells should follow their DNA instructions and function as the old cell once did, as a member of a tissue.

Question 11

Developmental aspects of Cells

B. The issue of agin; why cell quit doing their jobs.

Answer 11

Cellular Clock: free a certain amount of time or certain number of cell divisions, cells die, stops dividing.

Programmed cell death (apoptosis).

Free radical detoxification slows as we (our organelles) age, thereby hastening cell death.

Pieces of telomeres, DNA structures on the ends of chromosomes , break off during mitosis and therefore limit the amount of times mitosis can occur in a cell line. Replacement is limited.

Telomeres gets shorter and shorter as cells divide after cell gets old, you only want young ones to divide.

Question 12

Developmental aspects of Cells
C. Understanding Cancer: uncontrolled division and spread of cells in the body.
1. Neoplasm

Answer 12

Neoplasm: abnormal mass of growing cells
-Benign tumor: cells are encapsulated, growing but not spreading.
Often cells functioning correctly in the wrong body area like fat tumors. These contained tumors are often successfully removed by surgery before they pressure other organs.

Question 13

Events of miotic stage

Answer 13

Prophase: black dot
Metaphase: line
Anaphase: pull apart
Telophase/ cytokinesis: starting to split microtubules. 
Interphase: Light gray

Question 14

Mitosis Fact

Answer 14

Some chemotherapy drugs target the stages of mitosis.

A cell caught in the middle of mitosis will die unless allowed to complete the division process.

Question 15

Developmental aspects of Cells
C. Understanding Cancer: uncontrolled division and spread of cells in the body.
1. Neoplasm
B. Malignant cancerous tumor

Answer 15

During mitosis, if a mistake is made, some sections of DNA sense it and halt the replication process, killing the abnormal cell (tumor suppression genes).

If these genes are not present or functioning, cells with improper DNA sequences can survive mitosis. Some will die off, others will begin to die off, others will begin to divide uncontrollably and give rise to cancer.

How do these genes become damaged?
Carcinogens- agents that cause mutations in the DNA. (Ex: radiation Sunday cellphones, mechanical trauma, certain viral infections HPV and many chemicals tobacco tars saccharine.

• Unregulated cell growth- cells no longer respond to normal control mechanism of the cell cycle.
• They No longer heed to normal signals that regulate cell cycle.
• They no longer exhibit density-dependent (contact) inhibition.
• They do not stop dividing when growth factors are depleted.

Cells spread out throughout the body and the term “metastasis” is used.

Cancers kill by displacing and putting pressure on normal tissues, cutting off their blood supply and/ or interrupting organ function.

Tissue haas to repair itself in the S cycle of cell cycle which is DNA synthesis.

Question 16

Developmental aspects of Cells
C. Understanding Cancer: uncontrolled division and spread of cells in the body.
2. Diagnosis and Treatments

Answer 16

Biopsy: Sample of suspect tissue is surgically removed and remixed microscopically for malignant cells.

Surgical removal of the tumor.

X-Ray treatment of surrounding local area to kill metastasized cells.

Chemotherapy to find and destroy cells that have escaped body wide.