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Bio 130 > Module 9-11 > Flashcards

Module 9-11 Flashcards

(89 cards)

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1
Q

Signalling steps

A

-receptor activation
-signal transduction
-cellular response
-signal termination

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2
Q

Endocrine signalling

A

long distance, signalling molecules travel through blood. Uses hormones produced by endocrine cells

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3
Q

Paracrine signalling

A

neighbouring cells communicate, short distance. signalling molecule moves via diffusion (range 20 cells)

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4
Q

Autocrine signalling

A

cell that secretes signalling molecule is the target cell

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5
Q

Contact-dependent signalling (aka juxtacrine)

A

direct contact between neighbouring cells. transmembrane proteins are signalling molecule/ receptor

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6
Q

intracellular receptor

A

non polar signalling molecule binds to receptor in cytosol or nucleus

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7
Q

cell surface receptors

A

polar. bind to transmembrane proteins and change in conformation activates receptor

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8
Q

groups of cell surface receptors

A

G protein-coupled receptors, receptor kinases, ion channels

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9
Q

G protein-couple receptors

A

associate with G proteins composed of alpha, beta, gamma subunits which join when GDP bind to alpha. Activated when ligand binds, GDP –> GTP and alpha subunit disassociates to bind to target protein.

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10
Q

Epinephrine and heart rate

A

binds to GPCR, GDP–> GTP. alpha subunit with GTP activates adenyl cyclase which converts ATP to signalling cyclic AMP (cAMP). cAMP binds to protein kinase A (PKA) which phosphorylates proteins in heart

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11
Q

GPCR signal amplification

A

small amount of ligand creates a large response

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12
Q

binding affinity

A

how tightly receptor holds onto ligand, which affects amount of time bound

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13
Q

Receptor kinases

A

when ligand binds, receptors associate into dimers (results in phosphorylation which transmits signal)

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14
Q

Wound healing

A

platelets release platelet-derived growth factor. Binds to PDGF receptor kinases which dimerize and become active. Phosphorylated receptors activate Ras in mitogen-activated protein kinase pathway. GTP bound Ras triggers kinase cascade, which enters nucleus to turn on expression of genes for cell division

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15
Q

Kinase cascade

A

sequential protein phosphorylation and activation of cascade parts

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16
Q

Ligand-gated ion channels (three types)

A

change flow of ions across membrane (influx/ efflux). Prevents ion movement when inactive/ close, allows movement when active/ open

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17
Q

ligand-gated

A

respond to binding of signalling molecule

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18
Q

voltage-gated

A

respond to changes of voltage in cell

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19
Q

mechanically-gated

A

respond to force applied to the cell

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20
Q

Tissue types

A

epithelial, connective, muscle, nervous

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21
Q

ECM

A

meshwork of proteins/ polysaccharides outside the cell

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22
Q

Skin composition

A

outer protective barrier (epidermis) and dermis (supports and supplies nutrients)

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23
Q

epithelial tissue

A

covers outside of body and lines internal structures

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24
Q

epidermis composition

A

keratinocytes (protect), melanocytes (pigment)

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25
basal lamina
ECM between epidermis and dermis
26
dermis composition
mostly connective tissue (fibroblast cells that produce ECM), contains nerves/ blood vessels)
27
microtubule composition
polymers of protein dimers, each dimer has an alpha tubulin and beta tubulin. Form at centrosome and radiate toward cell periphery
28
microtubule function
maintains cell shape (withstands compression), secures organelles
29
microfilaments composition
polymers of actin monomers arranged into a helix, short and branched just beneath membrane
30
microfilaments function
reinforces membrane and organizes associated proteins. Can also help to transport materials, contract muscles, separate daughter cells
31
how are microtubles/ microfilaments dynamic?
change by adding/ losing subunits. Plus end (projecting out) grows faster than minus end (at centrosome)
32
Dynamic instability
microtubules undergo random depolymerization (rapid shrinkage) and polymerization (slower growth)
33
microtubule catastrophe
rapid shrinkage/ depolymerization. can re-organize and explore cell
34
accessory motor proteins
Kinesin (cargo toward +) and dynein (cargo toward -) associate with microtubule tracks, driven by conformational changes powered by ATP
35
Flagella and cilia
microtubules help to propel cells and propel surrounding substances
36
Intermediate filaments
In animal cells, provide mechanical strength by forming strong cable-like polymers of proteins
37
types of intermediate filaments
keratins (epithelial), vimentins (fibroblasts), lamins (nucleus), and neurofilaments (neurons)
38
polarity
cells exhibit spatial differences in shape, structure, function
39
Cadherins
integral transmembrane glycoproteins for cell-cell
40
Integrins
integral transmembrane glycoproteins for cell-ECM
41
Adherens junction
belt-like complex of cadherins that goes around circumference attaching to adjacent cells cadherins. Intracellularly attach to actin microfilaments
42
desmosomes
button-like points of adhesion, strengthened by cadherins. Intracellularly linked to intermediate filaments
43
Hemidesmosomes
anchors epithelial cells to basal lamina (IF --> integrins --> BL)
44
Tight junctions
prevents movement of materials by sealing extracellular space (needs cellular transport mechanism)
45
Gap junctions
cell-cell comunication. small connexon channels span gap, allows cytoplasmic continuity for adjacent cells
46
plasmodesmata
version of gap junctions in plants, much larger to send signals
47
Plant ECM
middle lamella, primary cell wall, secondary cell wall
48
middle lamella
carbs, how plants cells adhere
49
Primary cell wall
cellulose, pectin, etc. thin and flexible
50
Secondary cell wall
cellulose, lignin. rigid and water resistant because of lignin.
51
Animal ECM
large fibrous proteins (collagen, elastin, laminin) and secreted polysaccharides
52
Collagen
1/4 of protein in body, more than 20 forms. Type 1 is in dermis for support. Polypeptide triple helix --> fibril --> fiber
53
basal lamina
present beneath all epithelial tissues. provides structural foundation, flexible support, scaffold for other proteins.
54
cell classes in multicellular organism
stem cells (undifferentiated), somatic (most common), germ (reproductive)
55
Interphase
G1 - increase cell size S - replication of DNA G2 - preparing for M G0 - no active preparation
56
helicase
unwinds helix at replication fork
57
single-stranded binding protein
prevents parental strands from coming back together
58
topoisomerase
upstream of fork, relieves stress by changing supercoiled state
59
DNA polymerase
adds bases, requires deoxyribonucleotides, DNA template, RNA primer with 3'-OH. Can correct mistakes
60
RNA primase
synthesizes short piece of RNA for DNA polymerase to add DNA bases
61
leading strand
3' end toward fork, synthesized continuously
62
lagging strand
3' end away from fork, synthesized in okazaki fragments. Add RNA primer, let DNA pol extend, then replace primer with bases
63
DNA ligase
joins fragments to complete backbone
64
Proofreading
DNA polymerases correct their own errors, checked when H-bonds hold new nucleotide +base across and DNA pol detects mispairing of H-bond and activates cleavage function
65
prokaryotic replication
origin of replication, then proceeds in both directions until forks meet and fuse
66
eukaryotic replication
multiple origins = multiple replication forks which each proceed bidirectionally. When 2 bubbles meets, ligase seal gap. When final primer of lagging strand removed, section remains unreplicated which would lead to severe shortening
67
telomeres
repeated sequence (5'-TTAGG-3' in humans)
68
telomerase
extends end of chromosome to address shortening. Ribonucleoprotein w/ its own primer, has reverse transcriptase activity. Adds nucleotides to 3'-OH end of lagging strand template
69
Hayflick limit
division around 50 times before telomeres too short
70
Eukaryotic DNA packaging
DNA+histones-->chromatin --> chromosomes
71
prophase
appearance of visible chromosomes, assembles mitotic spindle
72
prometaphase
nuclear membrane breaks down, microtubules attach to centromeres (kinetochores attachment sites)
73
metaphase
spindle microtubules lengthen/shorten, pulls chromatids toward oppposite poles
74
telophase
microtubules break down, nuclear envelopes re-form around each set, chromosomes decondcense
75
cytokinesis in animal cells
ring of actin filaments form at equator (contractile ring). ring contracts and pinches cytoplasm to divide
76
cytokinesis in plant cells
form phragmoplast (overlapping microtubules) during telophase. Guides vesicles w/ cell wall components, fuse to form cell plate. Cell plate fuses with original cell wall to complete
77
Prophase 1
homologous chromosomes pair, become connected (synapsis). Four-stranded structure called bivalent. Crossing over when bivalent has formed chiasma --> random exchange of DNA segments. Homologous chromosomes separated
78
Meiosis 2
no DNA synthesis, sister chromatids separate to form gametes
79
Female gametes
unequal division results in oocyte (egg) and 3 polar bodies
80
male gametes
equal cytoplasmic division
81
cyclins
regulatory proteins subunits of specific protein kinases, levels rise/fall with cell cycle
82
CDKs
kinases that phosphorylate proteins to progress cell cycle. Always present, active when bound to appropriate cyclin
83
cyclin-CDK complexes
G1-cyclin D and E rise to prepare for S S-cyclin A rises to initiate DNA synthesis G2-cyclin B rises to initiate nucleus breakdown, formation of mitotic spindle
84
Cell cycle checkpoints
-DNA damage checkpoint before S -DNA replication checkpoint before mitosis -Spindle assembly checkpoing before mitosis progresses
85
Radiation damage
activates protein kinase to phosphorylate p53 which blocks G1/S transition
86
p53
stimulates transcription of Bax gene and represses transcription of Bcl-2 gene, resulting in Bax/bax dimers
87
apoptosis
activated by bax/bax dimers. Controlled disintegration
88
apoptosis advantages
remodelling tissues in embryo. In adult, maintains tissue size, eliminates specific cells or genetically damaged cells
89
Cancer
uncontrolled cell division cause by oncogenes. cell division regulated by proto-oncogenes and tumour suppression genes in balance. In cancer cells can divide on their own with no growth signals, resist inhibitory signals, invade tissues (metastasis), promote blood vessel formation (angiogenesis)

Bio 130 (1 decks)

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