Chapter 18/20: Cell Communities(Tissues, Stem Cells, and Cancer Flashcards
Describe trigger of Apoptosis
- 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
Tissues
cooperative assembly of cells and matrix woven together to form a distinctive multicellualr unit with a specific function
examples: nervous, muscular, epithelial, connective
extracellular matrix
- 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
Cancer
disease caused by abnormal and uncontrolled cell proliferation, followed by invasion and colonization of body sites normally reserved for other cells
Metastases
- the spread of cancer cells from the initial site of the tumor to form secondary tumors at the other sites in the body
Describe Metastasis
- 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
What do cancer cells lose by mutation in their genes?
- contact inhibition, the ability to come into contact with other cells and they stop dividing
What common gene is mutated in cancer?
cadherin
Cadherin
- allows cells to stick together on surfaces
- common gene that is mutated
Genetic instability
- 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
Describe the advantage of cancer cells
- initial population grows and evolves, new chance mutations occur that could be favored by natural selection since they enchance cell proliferation and survival
Ras mutation
- GTP always on Ras, connected in motgen pathway instead
Examples of genetic instability
- defects in DNA replication and/or repair
- defects in cell-cycle checkpoint mechanisms
- mistakes in mitosis
Two main types of genes mutated in cancer
dominant mutation and recessive mutation
dominant mutation
- mutation in one copy of proto-oncogene creates oncogene
- excessive cell survival, proliferation, or both
(hyperactive oncogene)
proto-oncogene
- gene that when mutated or over expressed can help transform a normal cell into a cancerous one
oncogene
- 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
recessive mutation
- 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
tumor suppressor gene
- 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
Explain differences between dominant mutation and recessive mutation
- 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)
