1.5 Origin of cells

Question 1

Stem cells

Answer 1

STEM CELLS: undifferentiated cells of a multicellular org. which are capable of dividing many times.

Question 2

Uses of stem cells

Answer 2

1. Therapeutic: replaced degenerated tissue (burns), healing disease (Statgardt’s, type 1 diabetes), replacement of organs
2. Striated muscle - meat for consumption without cattle

Question 3

Sources of stem cells

Answer 3

1. Embryos: totipotent but ethics and might turn into tumor/rejected by organism
2. Umbilical cord: little quantity, must be stored but will not be rejected by organism
3. Adult stem cells: from bone marrow, skin, liver byt painful procedure, not many

Question 4

Extreme example of differentiation (gene expression)

Answer 4

All cells in body have all genes - genes for odorants only expressed in skin of nose - each cells expresses one type of receptor

Question 5

Where stem cells can be found in adult body

Answer 5

1. Bone marrow
2. Skin
3. Liver

Brain, kidney, heart - very limited or no repair at all

Question 6

Treatment of Statgardt’s

Answer 6

1. Genetic disease
2. Memebrane protein for active transport in retina cells malfucntions - photoreceptive cells degenerate
3. Stem cells are injected into eyes to develop into retina cells

Question 7

Treatment of Leukemia

Answer 7

1. Type of cancer - production of too many wbc
2. Fluid removed from bone marrow using large needles - stem cells extracted
3. Chemotherapy - kills dividing cells - alls all wbc - loss of immunity
4. Stem cells injected - restablish and produce rbc and wbc

Question 8

Experiments that confirm that all cells come from pre-existing cells

Answer 8

1. Pasteur’s: spontaneour generations of cells do not occur - boiled nutrient broth kept in sealed - no life, other not sealed - life

Question 9

Evidence for cells theory

Answer 9

1. All cells come from pre-existing cells - Pasteur’s experiment
2. A cell is highly complex structure, no mechanisms can produce it form simpler subunits
3. No example of cell number increase is known without cell division
4. Viruses are not from cells - only produced in host cells (not divide)

Question 10

Theory for the origin of cells

Answer 10

All cells have arisen from non-living matter unless they arrived from somewhere else in the universe

Question 11

Hypotheses for origin of cells

Answer 11

1. Production of C compounds (am. a. and carbohyd):

Miller - Urey: created electrical discahrge in atmosphere like gases - am.a. + C comp. were produced

2. Assembly of C compounds into polymers: in deep-sea vents water gushes with reduced inorg. comp. which supply E
3. Formation fo membranes: phospholipdis naturally form bilayers - vesicles - internal structures, environments
4. Development of mechanism for inheritance: RNA was the first genetic material becasue can store info, is self replicating, acts as a catalyst

Question 12

Endosymbiosis theory

Answer 12

Origin of eukaryotic cell - endosymbosis theory

Prokaryote - evolution of respiration/photosyth - endocytosis of another prokaryote (mutualistic relationship) -> mitoch/chloropl - evolution of plant/animal cell

Question 13

Evidence for endosymbiotic theory

Answer 13

Chloroplasts and mitochondria were separate prokaryotes:

1. Own genes (circular DNA)
2. Own 70S ribosomes
3. Transcribe their DNA
4. Produced by division of pre-exiting organelles