Chapter 18/20: Cell Communities(Tissues, Stem Cells, and Cancer

Question 1

Describe trigger of Apoptosis

Answer 1

• Bax and Bak can trigger apoptosis by releasing cytochrome c from the mitochondria
• cytochrome c activates multiple adaptor proteins, enough to assemble an apoptosome
• the apoptosome recruits procaspase-9 molecules/proteins
• proteins assemble with apoptosome
• activation of apoptosome with procaspase-9 occurs, initiates to start breaking apart substances, cascade to apoptosis

Question 2

Tissues

Answer 2

cooperative assembly of cells and matrix woven together to form a distinctive multicellualr unit with a specific function

examples: nervous, muscular, epithelial, connective

Question 3

extracellular matrix

Answer 3

• complex network of polysaccharides(such as cellulose) and proteins(such as collagen) secreted by cells
• structural component of tissues that also influences their development and physiology

Question 4

Cancer

Answer 4

disease caused by abnormal and uncontrolled cell proliferation, followed by invasion and colonization of body sites normally reserved for other cells

Question 5

Metastases

Answer 5

• the spread of cancer cells from the initial site of the tumor to form secondary tumors at the other sites in the body

Question 6

Describe Metastasis

Answer 6

• cells of primary tumor in an epithelium must typically cross the protective barrier provided by the basal lamina, migrate through connective tissue, and get into either blood or lymphatic vessels
• then they have to exit from bloodstream or lymph to settle, survive, and proliferate in new location

Question 7

What do cancer cells lose by mutation in their genes?

Answer 7

• contact inhibition, the ability to come into contact with other cells and they stop dividing

Question 8

What common gene is mutated in cancer?

Answer 8

cadherin

Question 9

Cadherin

Answer 9

• allows cells to stick together on surfaces
• common gene that is mutated

Question 10

Genetic instability

Answer 10

• increased rate of mutation often caused by defects in the systems that govern the accurate replication and maintenance of the genome
• resulting mutations sometimes drive evolution to cancer
• highly abnormal chromosomes reflect this, multicolored chromosomes instead of one color in fluorescent stains

Question 11

Describe the advantage of cancer cells

Answer 11

• initial population grows and evolves, new chance mutations occur that could be favored by natural selection since they enchance cell proliferation and survival

Question 12

Ras mutation

Answer 12

• GTP always on Ras, connected in motgen pathway instead

Question 13

Examples of genetic instability

Answer 13

• defects in DNA replication and/or repair
• defects in cell-cycle checkpoint mechanisms
• mistakes in mitosis

Question 14

Two main types of genes mutated in cancer

Answer 14

dominant mutation and recessive mutation

Question 15

dominant mutation

Answer 15

• mutation in one copy of proto-oncogene creates oncogene
• excessive cell survival, proliferation, or both
  (hyperactive oncogene)

Question 16

proto-oncogene

Answer 16

• gene that when mutated or over expressed can help transform a normal cell into a cancerous one

Question 17

oncogene

Answer 17

• a gene that, when activated, can potentially make a cell cancerous
• typically a mutant form of normal gene (proto-oncogene) involved in the control of cell growth or division

Question 18

recessive mutation

Answer 18

• mutation inactivates one copy of tumor supressor gene, then second mutation inactivates second gene copy
• no effect in mutation in one gene copy, but complete loss of tumor suppressor gene activity

Question 19

tumor suppressor gene

Answer 19

• a gene that in a normal tissue cell inhibits cancerous behavior
• loss or inactivation of both copies of such a gene from a diploid cell can cause it to behave as a cancer cell

Question 20

Explain differences between dominant mutation and recessive mutation

Answer 20

• dominant mutation is a gain of function and only needs one mutation in one copy of gene (not in both)
• recessive mutation is a loss of function and needs one mutation in BOTH copies of genes (not just one)