Lec 24, 25 Stem cell and nuclear transfer

Question 1

extracellular matrix

Answer 1

complex network of polysaccharides and proteins secreted by cells. A structural component of tissues that also influences their development and physiology

Question 2

tissue

Answer 2

cooperative assembly of cells and matrix woven together to forma distinctive multicellular unit with a specific function

Question 3

importance of the organization of tissues

Answer 3

tissue components have to be properly organized, wtih the right blood vessels, nerves, etc formed inside of them. There has to be functional coordination, many have to be constantly maintained and renewed, and cells have to be replaced in the tight number, and with the right type of cell. disorders in tissue renewal often underlie the development of cancer

Question 4

cell wall

Answer 4

the structure in plants that supports, encloses, protects, and immobilizes the cells. A mechanically strong fibrous layer deposited outside the plasma membrane. (also present in bacteria, algae, and fungi

Question 5

cellulose microfibrils

Answer 5

give plant cell walls their strength, these are long, thin polysaccharide fibers. They resist stretching, so their orientation governs the direction in which a growing cell can enlarger, which can control the direction the entire plant is able to grow in.

It is is synthesized on the outside of the cell by enzyme complexes in the plasma membrane. microtubules within the cell controls the shape and modelling of the cellulose fibers

Question 6

Animal connective tissues

Answer 6

tissues such as bone, tendon, and the dermis. In connective tissues the extracellular matrix is abundant and carries the mechanical load

Question 7

four types of tissues in animal cells

Answer 7

connective, epithelial, nervous, muscle

Question 8

collagens

Answer 8

a family of fibrous proteins hat is a major component of the extracellular matrix and connective tissues. They provide tensile strength in animal connective tissues

Question 9

fibroblasts

Answer 9

cell type that produces the collagen-rich extracellular matrix in connective tissues such as the skin and tendons

Question 10

integrins

Answer 10

transmembrane proteins that enable cells to make and break attachments to the extracellular matrix, helping them crawl through a tissue

Question 11

Answer 11

orientation of microtubules on the cytoplasmic side of the plasma membrane

Question 12

Answer 12

connective

Question 13

epithelium

Answer 13

sheet of cells covering an external surface or lining an internal body cavity

Different varieties: act as a protective layer, secrete substances, absorb nutrients, detect signals (like light or sound)

Question 14

types of epithelial cells:

Answer 14

Question 15

organization of epithelial cells

Answer 15

they are polarized (apical and basal surface) and rest on a basal lamina

Question 16

Epithelial cell junctions

Answer 16

1) Tight junctions: seal neighboring cells together so that water soluble molecules can’t pass between them, also help preserve the polarity of the cell
2) Cytoskeleton-linked junctions that hold the epithelium together:
a) Adherens and desmosomes bind one epithelial cell to another
b) hemidesmosomes bind epithelial cells to the basal lamina
3) gap junctions: create small water-filled channels across between two membranes

Question 17

plasmodesmata

Answer 17

cell to cell junction that connects one plant cell to another

Question 18

Answer 18

tight junctions

Question 19

totipotency

Answer 19

the ability to produce a fully formed, complex, multicellular organism–resides within a fertilized egg cell

Question 20

Factors that contribute to the stability of tissue organization:

Answer 20

1) cell communication: each cell monitors signals from its neighbors and adjusts behavior accordingly. This helps make sure that new cells are produced and survive only when they are required
2) selective cell adhesion: different cells types have different binding proteins, so they tend to only stick to cells of the same type, or other things that they have a selective attachment to.
3) cell memory: some types of gene expression are passed on from cell to cell

Question 21

differentiated cell

Answer 21

cell that has undergone a coordinated change in gene expression, enabling it to perform a specialized function

Question 22

terminally differentiated cells

Answer 22

many differentiated cell types (ie red blood cells) are no longer able to divide, so they need a steady supply or replacement cells

Question 23

precursor cells

Answer 23

a stock of proliferating cells that replace terminally differentiated cells

Question 24

stem cells

Answer 24

relatively undifferentiated, self-renewing cells that produce daughter cells that can either differentiate into more specialized cell types or can retain the developmental potential of the parent cell.

Question 25

how stem cells become differentiated cells

Answer 25

Answer 26

The host immune system would destroy such cells

Question 27

Cancer cells

Answer 27

1) proliferate in defiance of normal constraints
2) invade and colonize territories normally reserved for other cells

Question 28

types of mutations in cancer cells

Answer 28

passenger mutations: ones that just happen to be in the cancer cell, and don’t cause disease

cancer-critical, or driver mutations: mutations that actively promote cancer development. They often don’t act alone and, need more than one of these mutations to actually develop cancer

Question 29

Things can can contribute to genetic instability

Answer 29

Question 30

General list of characteristics that can distinguish cancer cells from normal cells

Answer 30

1) reduce dependence on signals from other cells for their survival, growth, and division. (ex Ras gene mutation)
2) can survival levels of stress and internal derangement that would cause apoptosis in most cells. (ex p53 mutation)
3) cancer cells can often proliferate indefinitely, unlike most normal human cells (that lose the ability to produce telomerase)
4) most cancer cells are genetically unstable, with a gratly increased rate of mutations and an abnormal number of chromosomes
5) abnormally invasive, in part because they lack the normal adherins that would hold them in place
6) consume a lot of glucose, and can generate large amounts of ATP
7) survival and proliferate in unusual places: they don’t need normal intracellular signalling to survival
8) secrete signals that influence the behavior of cells in surrounding connective tissues, and modify the cancer cell’s extracellular environment.

Question 31

Two major classes of gene that are important for cancer:

Answer 31

oncogenes: a gene that when activated can make a cell cancerous. Usually a mutant form of a normal gene (a proto-oncogene) involved in the control of cell growth or division

tumor suppressor genes: a gene that normally inhibits cancerous behavior

Question 32

Answer 32

tumor suppressor genes: affected individuals typically inherit one normal copy and one mutant copy of the gene

Question 33

Differentiated cells vs stem cells

Answer 33

Question 34

Nuclear transplantation

Answer 34

Question 35

Induced pluripotent stem cells

Answer 35

Turns adult tissue back into stem cells by over-expressing the right transcription factors

Question 36

Embryonic stem cells vs adult stem cells

Answer 36