Cell Division and Death 1

Question 1

define neoplasm

Answer 1

• “New growth”
• abnormal mass of cells

Question 2

describe the 2 main groups of neoplasms

Answer 2

1. Benign neoplasms
   
   1. Grow slowly and remain localized to site of origin
2. Malignant neoplasms = cancer
   
   1. Grow rapidly and may spread
   2. Abnormal growth of tissue
   3. Rapid cell proliferation ignoring normal restraints on cell division

Question 3

define carcinoma

Answer 3

• Malignant tumor growing from epithelial tissue
• Many carcinomas affect glands that are involved with secretion

Question 4

define sarcoma

Answer 4

• Malignant tumor growing from connective tissues
  
  • Cartilage, fat, muscle, tendons and bones
  • Ex: osteosarcoma (bone) and chondrosarcoma (cartilage)

Question 5

define leukemia

Answer 5

Cancer of the blood or bone marrow

Question 6

define melanoma

Answer 6

Malignant tumor of melanocytes

Question 7

contrast behavior between benign and malignant tumors

Answer 7

• Benign
  
  • Expansile growth only; grows locally
  • Often encapsulated
• Malignant
  
  • Expansile and invasive growth; may metastasize
  • Not encapsulated

Question 8

contrast histology between benign and malignant tumors

Answer 8

• Benign
  
  • Resembles cell of origin (well differetiated)
  • Few mitoses
  • Normal or slight increase in ratio of nucleus to cytoplasm
  • Cells are uniform throughout the tumor
• Malignant
  
  • May show failure of cellular differentiation
  • Many mitoses, some of which are abnormal forms
  • High nuclear to cytoplasmic ratio
  • Cells vary in shapre and size and/or nuclei vary in shapre and size

Question 9

define and describe 2 kinds of metastasis

Answer 9

• Malignant
  
  • Locally invasive
    
    • Tumor invades the tissues surrounding it by sending out “fingers” of cancerous cells into the normal tissue
  • Metastatic
    
    • Distant spread of the tumor cells into other tissues of the body
      
      • Vascular
      • Lymphatic
      • Transcoelomic

Question 10

the majority of cancers are _____

Answer 10

• 90% of human cancers are carcinomas
  
  • Most of the cell proliferation in the body occurs in epithelia
  • Epithelial tissues frequently exposed to physical and chemical damage

Question 11

describe cancer growth (origin, size, doubling time)

Answer 11

• Origins can usually be traced to a single primary tumor
• Derived by cell division of a single cell
• Typical tumor can contain more than a billion cells before first detection
• Doubling time of a typical breast tumor is ~100 days

Question 12

describe the theories of tumor formation

Answer 12

1. Clonal evolution
   
   1. Develops through repeated rounds of mutation and proliferation
   2. Cells acquire a selective growth advantage over neighbors cells
2. Stem cells
   
   1. Tumors contain cancer stem cells
   2. Indefinite proliferative potential
   3. Linked initially to leukemias

Question 13

explain tumor progression

Answer 13

• Most human cancer cells are geneticall unstable
  
  • Defective repair of DNA damage or replication errors
  • Loss of chromosome integrity
    
    • Abnormal karyotype

Question 14

describe a karyotype

Answer 14

• Chromosomes sorted by size, shape and fluorescent colors

Question 15

compare and contrast the 2 types of cell death

Answer 15

• Necrosis
  
  • Pathological
  • Acute cell injury
  • Cell unable to maintain homeostasis
  • Cell swelling
  • Loss of plasma membrane integrity
  • Cell contents released
  • Surrounding tissue damage
  • Inflammation
• Apoptosis
  
  • Physiological
  • Genetic
  • Programmed cell death
  • Cell shrinking
  • DNA aggregation
  • Maintains PM integrity
  • No surrounding tissue damage
  • No inflammation

Question 16

list the cellular changes during apoptosis

Answer 16

1. Membrane PS moves from inner to outer leaflet
2. Membrane bleb
3. Condensed chromatin is found in nucleus
4. Cytochrome c is released from mitochondria

Question 17

describe the removal of the apoptotic ell

Answer 17

1. PS is exposed on the outer leaflet of PM
2. The apoptotic cell is engulfed or phagocytosed by a macrophage
3. The engulfed apoptotic cell is internalized then degraded within the macrophage
4. The macrophage releases cytokines IL-10 and TGF-B to inhibit inflammation

Question 18

list when apoptosis is used by body cells

Answer 18

• Normal embryological development
  
  • Developing digits (fingers); apoptosis sculpts
• Normal tissue homeostasis
  
  • Billions fo cells undergo apoptosis daily
  • Replaced by renewing cell populations
• Abnormal tissue homeostasis
  
  • Loss of cells due to apoptosis
  • Irreplaceable due to non-renewing cell populations

Question 19

Describe the extrinsice apoptosis pathways

Answer 19

• Binding of ligand to death receptor
• Recruitment of death domain adaptor proteins
• Death inducing signaling complex
• Caspase cascade
  
  • Activation of initiator caspases
    
    • Caspase 8
  • Activation of effector caspases
    
    • Caspase 3
• Caspases
  
  • Protein family of cysteine-aspartic proteases
  • Target nuclear and cytoplasmic proteins

Question 20

list the intrinsic apoptosis pathway

Answer 20

1. Death signal
   
   1. ex: DNA damage
2. Proapoptotic proteins upregulated
   
   1. Bax
3. Release of cytochrome c from mitochondria and activates Apaf-1
4. Apoptosome formation
   
   1. Procaspase 9
5. Caspase cascade
   
   1. Activation of initiator caspase 9
   2. Activation of effector caspases
      
      1. ex: Caspase 3

Question 21

explain the function of Bax

Answer 21

1. Bax, a pro-apoptotic protein is inserted into the mitochondrial membrane
2. Cytochrome c is released into the cytoplasm and activates Apaf-1
3. The caspase proteolytic cascade is activated to cleave cellular proteins and DNA
4. An apoptotic cell shows blebbing of its PM