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Cell Bio Final material
Cell Bio last chapters
71
Biology
Undergraduate 3
05/11/2011

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Term

Five major types of tissues

 

Definition

1) epithelial

2) muscular

3) connective

4)nervous

5)blood

Term
cells integrate into different tissues
Definition

cell-cell adhesion

cell-matrix adhesion

Term
cell junctions
Definition

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

Term
cell adhesion molecules
Definition

-transmembrane proteins

-extracellular parts interact with each other

-cytosolic parts of CAMs anchored to adaptor proteins

 

Term
tight junctions
Definition

prevent leakage diffusion between cells

claudins

Term
adherens junctions
Definition
formed by interaction of cadherins which interact with linker proteins that connect with actin filaments
Term
desmosomes
Definition
button like structures formed by desmosomal cadherins which interact with intermediate filaments
Term
hemidesmosomes
Definition
structurally similar to half of a desmosome fix cells to matrix through integrins
Term
gap junctions
Definition

transmembrane channels constructed form connexin proteins

-permit rapid diffusion of small moolecules between adjacent cells

Term
extracellular matrix
Definition
insoluble network consisting of fibrous proteins, polysaccharides and adhesive proteins secreted by animal cells
Term
structure of ECMs
Definition

-collagens

-proteoglycans

-soluble adhesive matrix proteins

Term
collagens
Definition
insoluble fiber-like proteins that provide mechanical strength
Term
proteoglycans
Definition
highly viscous glycoprotein molecules that provide cushion materials
Term
soluble adhesive matrix proteins
Definition
various proteins that cross link the ECM components and CAMs
Term
integrins
Definition

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

Term
function of ECM
Definition

-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

Term
3 types of cell signaling
Definition

-signal reception

-intracellular signal transduction

-physiological response

Term
signal reception
Definition
detection of signals by receptors in target cells
Term
intracellular signal transduction
Definition
interaction of a signal molecule with its receptor leads to a series of chemical reactions which translate initial signal to cell responses
Term
cell response
Definition
reaction of cell to initial signal, such as changes in metabolism, gene expression and motility
Term
2 ways signals are detected by specific receptors
Definition

1)cell surface receptors-ex.growth factors

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

Term
Solution to the fact that cells are exposed to variety of signals
Definition

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

Term
3 forms of cell signaling
Definition

1)direct contact

2) local signaling

3) long distance signaling

Term
Direct contact signaling
Definition

contact between adjacent cells through cell surface proteins

-important during embryogenesis

-quick but limited interference

-face to face contact

ex.gap junctions

Term
local signaling
Definition

like local broadcasting

1)paracrine signaling

2)autocrine signaling

Term
paracrine signaling
Definition

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

ex. growth factors and cytokines

Term
autocrine signaling
Definition

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

-community effect for synchronized action

Term
long distance signaling
Definition

global broadcasting

1)endocrine signaling

2)synaptic signaling

Term
endocrine signaling
Definition

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

-target cells will have receptors

Term
synaptic signaling
Definition

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

Term
Cell signaling through intracellular receptors
Definition

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

Term
cell signaling through cell surface receptors
Definition

1) ion channel receptors

2) G-protein linked receptor mediated

3)enzyme linked receptor mediated

Term

ion channel receptors

 

Definition

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)

Term
G-protein linked receptor mediated
Definition

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

Term
parts of enzyme linked receptor mediated
Definition

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

Term
steps of enzyme linked receptor mediated
Definition

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

Term
2 stages of mitosis
Definition

mitotic phase:mitosis and cytokinesis

interphase: G1, S, G2

Term
cytokinesis
Definition

division of cytoplasm after nuclear division

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

Term
G1 phase
Definition
determine if internal/external conditions are suitable for cell division
Term
S phase
Definition
DNA synthesis and chromosome replication
Term
G2 phase
Definition
protein synthesis and duplication of cytoplasmic content and organelles
Term
cell cycle checkpoint
Definition
a critical checkpoint that determines whether or not cell cycle proceeds to next phase of cell division
Term
3 major checkpoints
Definition

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

Term
cyclins
Definition

cell cycle regulatory proteins whose expression change cycllically during cell cycle

activate CDKs

Term

cyclin dependent kinases

CDKs

 

Definition
protein kinases that control cell cycle progression
Term
Role of cytoskeleton in mitosis
Definition

1)mitotic spindle

2)cytokinins

3)assembly/disassembly of nuclear envelope

Term
internal signals that regulate cell cycle
Definition

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

-DNA damage during replication signals for repair

Term
external signals that regulate cell cycle
Definition
growth factors bind to specific receptors @cell surface and signal cell to synthesize signals for cell division
Term
apoptosis
Definition

programmed cell death

controlled and prepared

no injury to tissues

DNA degraded

decrease cell volume

Term
necrosis
Definition

cell death due to injury

sudden and unexpected

cell and organelles swell

metabolism collapses

nucleus maintains shape

causes inflammation

Term
apoptosis signals
Definition

-cytokines

-environmental stresses

-internal stimuli

Term
capsase cascade
Definition
a series of proteases that eventually execute the apoptotic cell death by hydrolyzing cell proteins
Term
apoptosis in adults
Definition
mechanism for removal of aged, malfunctioning and damaged cells
Term
apoptosis in diseases
Definition

eliminate cells that are defective

degenerative diseases-excessive apoptosis

cancer-insufficient apoptosis

Term
cancer cells
Definition

no contact inhibition or anchorage dependent growth

aggregate growth

grow indefinitely

divide excessively

invade and migrate to other tissues

Term

major cause of cancer

 

Definition
mutation of proto-oncogenes(Ras) and tumor suppression genes (p53)
Term
proto-oncogenes
Definition
normal genes encoding proteins that are critical for cell cycle control
Term
oncogenes
Definition
mutated proto-oncogenes
Term
tumor suppresor genes
Definition
encodes proteins that inhibit abnormal cell division
Term
Body's fight against cancer
Definition

-fix mutations by DNA repair

-eliminate cell by immune system

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

Term
cancer treatment
Definition

early detection and surgical removal

gene therapy(fix/ replace mutated gene)

chemotherapy(taxol)

Term
embryonic stem cells
Definition

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

-can theoretically differentiate into any type of cell

-great potential in medical application

Term
adult stem cells
Definition

found in certain tissues

limited # and potential to differentiate

currently more clinical applications but limited

Term
Major stem cell properties
Definition

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

-potency-capacity to differentiate into specialized cells

Term
hematopoietic stem cells
Definition

found in bone marrow

gives rise to all blood cell types

Term
mesenchymal stem cells
Definition

found in connective tisssues

multipotent

Term
Major properties of ES cells
Definition

high rate of proliferation

can be maintained as undifferentiated cell line

isolated from inner cell mass of blastocyst

Term
Med applications of ES cells
Definition

cell therapy

cardiomycetes

neurons

pancreatic cells

endothelial cells

Term
social and ethical probs with ES cells
Definition

-human cloning

-lethal damage to embryos

Term
Basic research knowledge of ES cells
Definition

-understand cell differentiation

-study function of specific genes

-developmental biology

-study genetic diseases

Term
induced pluripotent stem cells
Definition

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

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