Five major types of tissues

1) epithelial

2) muscular

3) connective

4)nervous

5)blood

cell-cell adhesion

cell-matrix adhesion

specialized regions on cell membranes where cell-cell and cell-matrix are joined together by CAMs

-strengthen connections

-facilitate communication among cells and b/w cell and matrix

-transmembrane proteins

-extracellular parts interact with each other

-cytosolic parts of CAMs anchored to adaptor proteins

prevent leakage diffusion between cells

claudins

transmembrane channels constructed form connexin proteins

-permit rapid diffusion of small moolecules between adjacent cells

-collagens

-proteoglycans

-soluble adhesive matrix proteins

major cell adhesion molecule interacting with ECM transmembrane proteins that contain alpha and beta subunits

connect with actin filament by intracellular matrix

can directly bind to specific sequences of collagen or through fibronectin as a linker protein

-provide mechanical support for cells to organize into tissue

-changes in ECM serve as external signals which regulate various cellular activities such as cell proliferation, differentiation and survival

-signal reception

-intracellular signal transduction

-physiological response

1)cell surface receptors-ex.growth factors

2)intracellular receptors-cross cell membrane bind to receptor to intiate intracellular transduction-ex.steroid

1)each cell responds to limited set of signals

2) same signal can induce different responses

3)signals act in various combinations to regulate cells

1)direct contact

2) local signaling

3) long distance signaling

contact between adjacent cells through cell surface proteins

-important during embryogenesis

-quick but limited interference

-face to face contact

ex.gap junctions

like local broadcasting

1)paracrine signaling

2)autocrine signaling

secretion of chemical molecules which travel a short distance and affect activities of nearby cells

ex. growth factors and cytokines

cell can secrete chemical molecules which bind back to own receptors as well as receptors of same cell type

-community effect for synchronized action

global broadcasting

1)endocrine signaling

2)synaptic signaling

depends on hormones that are secreted to bloodstream and carried to essentially all parts of the body

-target cells will have receptors

depends on neurotransmitters as signalling molecules and specialized nervous system

-transmits signal and then relay nervous impulse to next nervous cells or other cells

ex. phone line

limited to hydrophobic hormones that can pass through cell membrane

1)signal reception

2)transduction-receptor signal-signal complex turns on transcription

3) response-synthesis of proteins that promote activities

1) ion channel receptors

2) G-protein linked receptor mediated

3)enzyme linked receptor mediated

ion channel receptors

act as a receptor for signal molecule and channel for specific ion

-convert chemical signal to electric signal (open or close)

-simplest and most direct (neurons)

integral proteins with 7-pass transmembrane domains

-binding signal molecule results in confirmational change resulting in signal transduction

1) G-protein trimeric protein acts as switch (GDP off GTP on)

2) signal molecules activates receptor by replacing GDP with GTP

3)causes dissasociation of alpha and beta subunits and activation

4)activated alpha subunits activate next component in cell pathway

cell surface receptors that have tyrosine kinase activity

1)extracellular ligand binding domain-interacts with signal molecule

2) intracellular tyrosine kinase domain- catalyzes tyrosine phosphorylation transfers P to tyrosine

3)transmembrane domain anchors the receptor to cell membrane

1) binding of signal molecule induces dimerization which stimulates the receptor kinase activity

2) dimerized receptors phosphorylate each other on tyrosine residues

3) recruits and activates the next components of pathway

ex. insulin

mitotic phase:mitosis and cytokinesis

interphase: G1, S, G2

division of cytoplasm after nuclear division

contractile ring made of actin filaments and myosine fibers are responsible for intiation of cytokinesis

G1 checkpoint-allows cell to enter S phase only if external environment is right

S checkpoint-ensures DNA replication is complete and no damage

G2 checkpoint-determines if all duplicated chromosomes are attached to mitotic spindle

cell cycle regulatory proteins whose expression change cycllically during cell cycle

activate CDKs

cyclin dependent kinases

CDKs

1)mitotic spindle

2)cytokinins

3)assembly/disassembly of nuclear envelope

-attachment of a chromsome to spindle microtubules to begin sister chromatid separation

-DNA damage during replication signals for repair

programmed cell death

controlled and prepared

no injury to tissues

DNA degraded

decrease cell volume

cell death due to injury

sudden and unexpected

cell and organelles swell

metabolism collapses

nucleus maintains shape

causes inflammation

-cytokines

-environmental stresses

-internal stimuli

eliminate cells that are defective

degenerative diseases-excessive apoptosis

cancer-insufficient apoptosis

no contact inhibition or anchorage dependent growth

aggregate growth

grow indefinitely

divide excessively

invade and migrate to other tissues

major cause of cancer

-fix mutations by DNA repair

-eliminate cell by immune system

-cell continues to divide and pass mutated genes to next generation

early detection and surgical removal

gene therapy(fix/ replace mutated gene)

chemotherapy(taxol)

-isolated from early stage of embryos (5-7 days old)

-can theoretically differentiate into any type of cell

-great potential in medical application

found in certain tissues

limited # and potential to differentiate

currently more clinical applications but limited

-self renewal- ability to go through numerous cell cycles and maintain undifferentiated-allows stem cells to reproduce

-potency-capacity to differentiate into specialized cells

found in bone marrow

gives rise to all blood cell types

found in connective tisssues

multipotent

high rate of proliferation

can be maintained as undifferentiated cell line

isolated from inner cell mass of blastocyst

cell therapy

cardiomycetes

neurons

pancreatic cells

endothelial cells

-human cloning

-lethal damage to embryos

-understand cell differentiation

-study function of specific genes

-developmental biology

-study genetic diseases

type of pluripotent stem cells artificially derived from an adult somatic cell by force expression of pluripotency marker genes

-patient specific

-reduces ethical problem of embryo