tissue 2

cell proliferation/division

increase in # of cells as a result of cell growth & cell division

cell differentition

process by which a less specialized cell develops or matures to possess a ore distinct form & function

cell migration

process by which cells move from one location to another by adopting different motility modes

cell death

terminal failure of a cell to maintain essential life functions

cell apoptosis

programmed sequence of events leads to the elimination of cells without releasing harmful substances into surrounding areas

what are challenges in cell growth?

do they look like they’re supposed to?

are cells exposed to proper environment?

are cells growing as needed?

do cells look like they’re supposed to?

cell bio, histology, microscopy

sre cells exposed to proper environment conditions?

nutrition, hormone, CO2/O2 gas levels

are cells growing as needed?

need models & assays for cell growth

cell proliferation is a _____________ regulated by important classes of proteins

highly ordered, evolutionarily conserved process

what is cell division characterized by?

cell cycle

cell cycle

1. M - mitosis

2. G1 - Gap 1

3. S - DNA synthesis

4. G2 - Gap 2

duration of cell cycle

1. M - constant

2. G1 - variable length

3. S - constant

4. G2 - constant

how is the success of DNA replication assessed?

during G2 phase

what is the result of DNA replication?

exact duplication & segregation of DNA into 2 daughter cells

what is G0?

quiescent state; cell that is not “in cycle”

(6) characteristics of cell cycle:

1. turns each event on at a specific time

2. initiating events in correct order

3. each event is triggered once

4. binary switches

5. backup mechanisms

6. adaptable to environment

what are the 3 cell cycle checkpoints?

1. G1

2. G2

3. M1

usually operated by negative signals

G1 checkpoint (3)

1. is environment favorable?

2. is DNA damaged?

3. is cell big enough?

go ahead → complete CC & divide

G2 checkpoint (2)

1. is all DNA replicated?

2. is cell big enough?

prepare for cell division

M1 checkpoint (1)

1. are all chromosomes attached to spindle?

cell cycle control

cyclin-dependent kinases complex w/ cyclins

CdK activity

oscillates & phosphorylates lots of intracellular proteins

types of CdK complexes w/ cyclins (3)

1. G1/S-cyclins

2. S-cyclins

3. M-cyclins

activating/inactivating CdKs controlled by: (3)

1. phosphorylation state of kinase sub-unit

2. cyclin availability, controlled by degradation & synthesis

3. specific proteins that bind that affect activity by inhibiting phosphor/protecting from degrad

cancer has: (2)

1. too much cyclin D

2. defective P53

cyclin D

required to pass the restriction point

but once passes, do not require anymore to enter S phase

cell growth in vitro (2)

1. isolation of cells

2. culturing of cells & cell lines

how do cells grow (2)?

1. in suspension

2. anchorage dependent

cell growth in suspension

cancer, hematopoietic, & transformed cells

anchorage dependent cell growth

most mammalian cells

assays for cell proliferation (6)

1. cell counting

2. metabolic activity

3. DNA based assay

4. protein content

5. fluorescence based assay

6. relative/absolute

DNA based assay (2)

1. 3H thymidine

2. bromodeoxyuridine incorp

modeling cell proliferation

cells divide at a rate that is proportional to # of cells that are in cycle at a given point in time

dX/dt = uX

contact inhibition

arresting cell growth when 2 of more cells come into contact with each other

used to distinguish b/n normal & cancer cells (cancer cells don’t arrest aka stop growing)

monod model of cell growth

phases of cell growth (4):

1. lag phase

2. phase II

3. phase III

4. phase IV

lag phase (4)

1. adjusting to new environment

2. synthesizing machinery for division

3. transporting molecules

4. utilizing substances

phase II

growth rate is proportional to concentration of cells - max growth rates

phase III

stationary due to depletion of essential nutrients & accumulation of wastes

phase IV

cell death occurs due to nutrient depletion or toxic substances

cell senescence (ageing) (3)

1. terminally differentiated state

2. absences of growth promoting signals - CdK inhibition of G1

3. disassemble control mech from cell cycle & exit from cell cycle entering G0

cell apoptosis failure

part of tumor formation

greek word meaning “dropping off” of petals/leaves from a plant/tree

3 phases of apoptosis:

1. induction

2. effector

3. degradation

induction phase

depends on specific death-inducing signals

effector phase

“central executioner” is activated & the cell commits suicide

degradation phase

biochem & morphological changes occur

induction of apoptosis (4)

1. murder - extrinsic pathway

2. survival signals

3. stress-induced - intrinsic pathway

4. caspase is activated, leading to activation of endogenous endonucleases & fragmentation of genomic DNA

murder - extrinsic pathway

signaling through Fas receptor

survival signals

regulation by Bcl-2 family of proteins

block translocation of Cyt-C from mitochondria to cytosol

stress-induced - intrinsic pathway

damaged mitochondria

release of cytochrome C

what does differentiation begin with?

lineage commitment followed by coordinated gene expression

what changes occur in differentiated cells? (3)

1. cell structure

2. cell function

3. cell metabolism

how can u tell the differentiation state of a cell?

1. cell surface markers

2. cell morphology

   1. cell functions

what factors affect growth vs. differentiation? (5)

intrinsic & extrinsic:

1. transcription factors

2. ECM

3. cell shape/cell-cell contact

4. EC growth factors

5. EC metabolites

why is differentiation important in tissue engineering?

cell growth of one or more cell types followed y differentiation of those cells

and/or

cell growth of a differentiated cell population

modeling cell dkifferentiation

compartmental model

clonal succession

0 stem cell daughters

deterministic

1 stem cell daughter

stochastic

0,1, or 2 stem cell daughters

telomerase

reverse transcriptase enzyme that carries its own RNA molecule

autophagy

degrading & recycling cell components

significance of autophagy research (8)

1. can rapidly provide fuel for energy & building blocks for renewal of cell

2. after infection, can eliminate invading intracell bacteria & viruses

3. contributes to embryo development & differentiation

4. to eliminate damaged proteins & organelles, quality control mechanism

5. disrupted has been linked to parkinsons, type 2, etc.

6. mutations can cause genetic disease

7. disturbances in machinery have been linked to cancer

8. develop drugs that can target it

basic properties of cells (9)

1. highly complex & organized

2. possess a genetic program & the means to use it

3. capable of producing more of themselves

4. acquire & utilize energy

5. carry out a variety of chemical reactions

6. engage in mechanical activities

7. are able to respond to stimuli

8. are capable of self-regulation

9. evolve

cells are highly complex & organized (4)

1. can grow & reproduce in culture for extended periods

2. HeLa cells are cultured tumor cells isolated from cancer patient

3. highly regulated

4. different species share similar structures, comp, metabolic

cells possess a genetic program & the means to use it (2)

1. info for building is encoded in genes

2. can be haploid or diploid

cells are capable of producing more of themselves

divide, mother cell → 2 daughter cells

cells acquire & utilize energy (2)

1. animals get energy from products of photosynthesis (sugar)

2. store sugar bond energy in ATP

cells carry out a variety of chem rxns (4)

1. like miniaturized chem plants

2. bacterial cell is capable of 100s of diff. chem rxns

3. all chem changes that take place in cells require enzymes to increase rate

4. sum total of the chem rxns in a cell represents that cell’s metabolism

cells engage in mechanical activities

cells are very active which is based on dynamic, mechanical changes within cells initiated by changes in the shape of motor proteins

cells are able to respond to stimuli (4)

1. single-celled protest can move away from an object in path or toward nutrients

2. cells in plants/animals are covered with receptors that interact with substances in environment

3. hormones, growth factors, ECM, etc. on surface interact

4. respond by altering metabolism, moving, committing suicide

cells are capable of self-regulation (5)

1. cells are protected from dangerous fluctuations in comp & behavior

2. feedback circuits

3. constant regulation

4. info in nucleic acids

5. each step must occur spontaneously so that the next step is automatically triggered

cells evolve (2)

1. common genetic code, plasma membrane, & ribosomes

2. LUCA - last universal common ancestor

what are the 4 basic cell processes

1. proliferation

2. differentiation

3. migration

4. senescence (aging) & apoptosis

the adept tissue engineer needs an in depth & mechanistic understanding of: (6)

1. how many diff. types of cells & tissues

2. what cells compose each tissue

3. how those cells can be isolated cultured

4. how diff. properties of cell can be controlled/manipulated to elicit cell function

5. understand quantitative aspects of cell growth

6. think creatively to solve problems

cells commonly measured in

micrometers, nanometers

cell size is limited by: (3)

1. volume of cytoplasm supported by genes in nucleus

2. volume of cytoplasm supported by exchange of nutrients

3. distance over which substances can travel via diffusion

cell organelles (9)

1. nucleus

2. mitochondria

3. endoplasmic reticulum

4. golgi apparatus

5. lysosomes

6. peroxisomes

7. cytosol

8. cytoskeleton

9. vesicles

nucleus (3)

1. nuclear envelope

2. chromatin & DNA

3. nucleolus

mitochondria (3)

1. double membrane

2. mitochondrial DNA

3. power house of the cell - ATP

endoplasmic reticulum (2)

1. where membrane & exported materials are made

2. ribosomes (rough) - make proteins

golgi apparatus (2)

1. receives & modifies

2. directs new material

lysosomes (3)

1. intracell digestion

2. releases nutrients

3. breakdown of waste

peroxisomes

hydrogen peroxide generated & degraded

cytosol (2)

1. water based gel

2. chem rxns

cytoskeleton (3)

1. filaments (actin, intermed, microtub)

2. movement of organelles

3. structure/strengthen cell

vesicles (2)

1. material transport

2. membrane, ER, golgi

org molecules of cells (4)

1. proteins

2. carbs

3. lipids

4. nucleic acids

proteins (2)

1. structure, function, & info

2. linearly arranged AA residues - folded up w/ active regions

types of proteins (9)

1. enzymes

2. structural

3. motility

4. regulatory

5. storage

6. hormonal

7. receptors

8. transport

9. special purpose

enzymes

catalyzes covalent bond breakage or formation, trypsin, DNA polymerase

structural

collagen, elastin, keratin

motility

actin, myosin, tubulin

regulatory

bind to DNA to switch genes on or off

storage

ovalbumin, casein

hormonal

insulin, nerve growth factor

receptors

hormone & neurotransmitter receptors

transport

carries small molecules or irons

special purpose

green fluorescent protein

4 types of tissues

1. epithelial

2. connective

3. muscular

4. nervous