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local regulators:
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~ paracrine: on site release and response of signal molecules
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~ synaptic: neurons use ACH
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~ cell to cell joining
|
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~ long distance regulators: carry communication factor to tissue group far from source
|
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~ endocrine: pituitary gland
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~ animals: hormones / HGH
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~ plants: ethylene CH2 = CH2
|
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~ ex: one bad apple ruins the bunch
|
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Paracrine: target cells lie near the secreting cell
|
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Juxtacrine: a ligand on one cell surface binds to a receptor on the other
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Autocrine: the secreted molecules act on the secreting cell itself
|
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Endocrine: secrete specific hormones into the bloodstream
|
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1) Tyrosine Kinase is separate when inactive
|
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2) Ligand attaches to a receptor
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3) Tyrosine Kinase comes together (dimer)
|
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4) Tyrosine Kinase is phosphorylated with a (P) from ATP
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5) The activated Tyrosine will activate relay proteins
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regulation
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specificity
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|
amplification
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|
termination
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nemotodes
|
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apoptosis occurs when specific proteins that accelerate apoptosis override the proteins that "put the brakes" on apoptosis
|
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needed for proper development:
|
|
~ metamorphosis
|
|
~ removes fetal webbing between fingers / toes
|
|
~ menstruation
|
|
~ synapse formation
|
|
~ eliminates T cells that cause autoimmune
|
|
destroy cells that pose a threat:
|
|
~ infected with virus
|
|
~ DNA damage
|
|
~ cancer cells
|
|
when the phagocytes are overwhelmed:
|
|
~ release a signal to the hypothalamus
|
|
~ body temperature increases
|
|
~ increase in metabolism
|
|
"chemical alarm"
|
|
redness, swelling, heat, pain
|
|
mast cells release histamine:
|
|
~ vasodilation occurs
|
|
~ increase temp = increase in metabolic rate
|
|
~ attracts phagocytes
|
|
life cycle of the cell
|
|
functions: reproduction, growth, repair
|
|
Interphase:
|
|
1) G1: first gap / growth
|
|
2) S: DNA synthesis / DNA is copied
|
|
3) G2: second gap / preparation of cell contents for division
|
|
mitotic division:
|
|
4) the m phase: cell division
|
|
~ prophase
|
|
~ metaphase
|
|
~ anaphase
|
|
~ telophase
|
|
5) cytokinesis: completes division of cytoplasmic contents
|
|
checks for:
|
|
~ cell size
|
|
~ nutrients
|
|
~ growth factors
|
|
~ DNA damage
|
|
CDKs: cyclin dependent kinases (proteins)
|
|
cyclins: regulatory proteins (must be present)
|
|
~ increases as the cell goes through interphase
|
|
MPF: mitosis promoting factors in G2
|
|
~ cyclin + CDK
|
|
APC-Anaphase promoting complex
|
|
~ kinetochore fiber connection
|
|
mutations
|
|
carcinogenic chemicals
|
|
UV light
|
|
viruses
|
|
oncogenes
|
|
p53 genes
|
|
defects in proteins that control the cell cycle
|
|
mutations that knock out key genes
|
|
carcinoma: arises from body's outer coverings and inner linings
|
|
sarcoma: arises from body's supporting structures
|
|
lymphoma: arises from lymph system
|
|
leukemia: arises from red marrow in bone, spleen
|
|
initiate each phase of the cell cycle
|
|
active when conditions are appropriate for growth
|
|
mutations cause growth to occur at all times
|
|
oncogenes promote cancer development
|
|
1) signal reception
|
|
~ a cell detects a signaling molecule
|
|
2) signal transduction
|
|
~ a series of chemical reactions that creates a response
|
|
3) signal response
|
|
~ the signal triggers a cell response
|
|
1) Ligand attaches to receptor
|
|
2) Activates the G-protein
|
|
3) G-protein moves across membrane
|
|
4) G-protein interacts with another protein in the cell membrane
|
|
1) the ion channel is closed
|
|
2) ligand attaches to a receptor
|
|
3) the ion channel opens
|
|
4) ions pass through
|
|
regulation of activities or transcription initiation = signals sent to turn on a gene
|
|
ex: testosterone enters directly into the cell
|
|
elaborate pathways amplify and specify responses to signals
|
|
caspases are the main proteases (enzymes that cut up proteins) that carry out apoptosis
|
|
apoptosis can be triggered by external or internal factors
|
|
examples:
|
|
~ an extracellular death-signaling ligand
|
|
~ DNA damage in the nucleus
|
|
~ protein misfolding in the ER
|
|
homeostasis: maintaining stable internal conditions
|
|
negative feedback:
|
|
~ shuts off original stimulus
|
|
~ ex: thermostat
|
|
positive feedback:
|
|
~ speeds up the original stimulus
|
|
~ ex: gossip
|
|
neutrophils:
|
|
~ engulf a pathogen and self-destruct
|
|
macrophages:
|
|
~ grabs pathogens with cytoplasmic extensions
|
|
~ engulfs pathogen
|
|
~ digests pathogen
|
|
~ removes pathogen through exocytosis
|
|
natural killer cells:
|
|
~ kills cells infected with a class 1 MHC protein
|
|
when a cell is infected:
|
|
~ the cell stops making MHC
|
|
~ NK cells poke the infected cell with enzymes
|
|
~ triggers apoptosis
|
|
Interphase: 46 chromosomes
|
|
Prophase: 92 chromosomes
|
|
Prometaphase: nucleus dissolves and microtubules attach to centromeres
|
|
Metaphase: chromosomes align in the middle of the cell
|
|
Anaphase: separated chromosomes pulled apart by spindle fibers
|
|
Telophase: microtubules disappear and cell division begins
|
|
Cytokinesis: two daughter cells formed
|
|
centrosome
|
|
kinetichore fibers:
|
|
~ attach to chromosomes
|
|
~ movements
|
|
nonkinetichore fibers:
|
|
~ attach pole to pole
|
|
~ support
|
|
checks for:
|
|
~ DNA damage
|
|
~ DNA replication completeness
|
|
the spindle checkpoint
|
|
checks for:
|
|
~ chromosome attachment to spindle at metaphase plate
|
|
~ 92 spindle fibers
|
|
~ 46 chromosomes
|
|
chemical factors:
|
|
~ nutrients
|
|
~ PDGF
|
|
physical factors:
|
|
~ density dependent
|
|
~ anchorage
|
|
genes that stop or slow the cell cycle
|
|
~ ex: tumor suppressor genes
|
|
genes that trigger cell growth and division by initiating different stages of the cell cycle
|
|
~ ex: proto-oncogenes
|
|
epinephrine (adrenaline) is released
|
|
hormone / neurotransmitter
|
|
endocrine / nervous system
|
|
initiates a flight or fight response
|
|
triggered by stressors
|
|
secreted from adrenal gland
|
|
small molecules and ions are key signaling components
|
|
cyclic AMP /adenyl cyclase / phosphodiesterase
|
|
calcium ion and inosital triphosphates IP3
|
|
programmed cell death
|
|
"cell suicide"
|
|
evolved early
|
|
injury:
|
~ mechanical damage
|
|
~ toxic chemicals
|
|
|
suicide:
|
~ shrink, bleb, fragment
|
|
~ chromatin degrades
|
|
|
~ mitochondria breaks down
|
|
|
~ "find me" / "engulf me" signal
|
|
physical and chemical barriers that protect the body
|
|
1st line of defense:
|
|
~ skin (physical barrier)
|
|
~ mucous membranes (chemical and physical barrier; enzymes and defensins)
|
|
2nd line of defense:
|
|
~ fever
|
|
~ chemical signals
|
|
~ inflammation
|
|
identification of specific antigens in body fluid
|
|
antigen:
|
|
~ bacteria
|
|
~ virus
|
|
~ fungus
|
|
~ toxin
|
|
~ diseased cell
|
|
protein receptors on the surface of B cells
|
|
some antibodies travel freely
|
|
antibodies connect with a complementary antigen
|
|
animal cells: cleavage furrow
|
|
~ contractile ring of actin involved
|
|
plant cells: cell plate
|
|
cells should only divide when needed
|
|
internal and external controls
|
|
cell cycle control systems (internal control):
|
|
~ series of checkpoints
|
|
~ must pass all checkpoints to divide
|
|
example: cellular inspection station
|
|
checks for:
|
|
~ DNA damage
|
|
~ prevents reduplication of DNA
|
|
definitions of cancer:
|
|
~ neoplasm of proliferating cells (new tissue growing out of control)
|
|
~ cell division out of control
|
|
~ cells produced are useless
|
|
~ compete with healthy cells for nutrients and oxygen
|
|
benigns (not moving) versus malignant (moving)
|
|
~ benign is a sedentary mass of cancerous cells
|
|
~ malignant is a moving mass of cancerous cells - metastasis
|
|
p53 (guardian of the genome)
|
|
~ p53 protein increases in cells exposed to UV radiation
|
|
p53 mode of action"
|
|
1) DNA damage
|
|
2) p53 increases
|
|
3) p53 bind to DNA (not at damage site)
|
|
4) transcription of genes that stop cell cycle or lead to cell death
|
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