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Bio 130 > Module 9-11 > Flashcards

Module 9-11 Flashcards

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Biology 101 flashcards
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
Q

basal lamina

A

ECM between epidermis and dermis

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26
Q

dermis composition

A

mostly connective tissue (fibroblast cells that produce ECM), contains nerves/ blood vessels)

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27
Q

microtubule composition

A

polymers of protein dimers, each dimer has an alpha tubulin and beta tubulin. Form at centrosome and radiate toward cell periphery

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28
Q

microtubule function

A

maintains cell shape (withstands compression), secures organelles

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29
Q

microfilaments composition

A

polymers of actin monomers arranged into a helix, short and branched just beneath membrane

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30
Q

microfilaments function

A

reinforces membrane and organizes associated proteins. Can also help to transport materials, contract muscles, separate daughter cells

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31
Q

how are microtubles/ microfilaments dynamic?

A

change by adding/ losing subunits. Plus end (projecting out) grows faster than minus end (at centrosome)

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32
Q

Dynamic instability

A

microtubules undergo random depolymerization (rapid shrinkage) and polymerization (slower growth)

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33
Q

microtubule catastrophe

A

rapid shrinkage/ depolymerization. can re-organize and explore cell

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34
Q

accessory motor proteins

A

Kinesin (cargo toward +) and dynein (cargo toward -) associate with microtubule tracks, driven by conformational changes powered by ATP

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35
Q

Flagella and cilia

A

microtubules help to propel cells and propel surrounding substances

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36
Q

Intermediate filaments

A

In animal cells, provide mechanical strength by forming strong cable-like polymers of proteins

37
Q

types of intermediate filaments

A

keratins (epithelial), vimentins (fibroblasts), lamins (nucleus), and neurofilaments (neurons)

38
Q

polarity

A

cells exhibit spatial differences in shape, structure, function

39
Q

Cadherins

A

integral transmembrane glycoproteins for cell-cell

40
Q

Integrins

A

integral transmembrane glycoproteins for cell-ECM

41
Q

Adherens junction

A

belt-like complex of cadherins that goes around circumference attaching to adjacent cells cadherins. Intracellularly attach to actin microfilaments

42
Q

desmosomes

A

button-like points of adhesion, strengthened by cadherins. Intracellularly linked to intermediate filaments

43
Q

Hemidesmosomes

A

anchors epithelial cells to basal lamina (IF –> integrins –> BL)

44
Q

Tight junctions

A

prevents movement of materials by sealing extracellular space (needs cellular transport mechanism)

45
Q

Gap junctions

A

cell-cell comunication. small connexon channels span gap, allows cytoplasmic continuity for adjacent cells

46
Q

plasmodesmata

A

version of gap junctions in plants, much larger to send signals

47
Q

Plant ECM

A

middle lamella, primary cell wall, secondary cell wall

48
Q

middle lamella

A

carbs, how plants cells adhere

49
Q

Primary cell wall

A

cellulose, pectin, etc. thin and flexible

50
Q

Secondary cell wall

A

cellulose, lignin. rigid and water resistant because of lignin.

51
Q

Animal ECM

A

large fibrous proteins (collagen, elastin, laminin) and secreted polysaccharides

52
Q

Collagen

A

1/4 of protein in body, more than 20 forms. Type 1 is in dermis for support. Polypeptide triple helix –> fibril –> fiber

53
Q

basal lamina

A

present beneath all epithelial tissues. provides structural foundation, flexible support, scaffold for other proteins.

54
Q

cell classes in multicellular organism

A

stem cells (undifferentiated), somatic (most common), germ (reproductive)

55
Q

Interphase

A

G1 - increase cell size
S - replication of DNA
G2 - preparing for M
G0 - no active preparation

56
Q

helicase

A

unwinds helix at replication fork

57
Q

single-stranded binding protein

A

prevents parental strands from coming back together

58
Q

topoisomerase

A

upstream of fork, relieves stress by changing supercoiled state

59
Q

DNA polymerase

A

adds bases, requires deoxyribonucleotides, DNA template, RNA primer with 3’-OH. Can correct mistakes

60
Q

RNA primase

A

synthesizes short piece of RNA for DNA polymerase to add DNA bases

61
Q

leading strand

A

3’ end toward fork, synthesized continuously

62
Q

lagging strand

A

3’ end away from fork, synthesized in okazaki fragments. Add RNA primer, let DNA pol extend, then replace primer with bases

63
Q

DNA ligase

A

joins fragments to complete backbone

64
Q

Proofreading

A

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
Q

prokaryotic replication

A

origin of replication, then proceeds in both directions until forks meet and fuse

66
Q

eukaryotic replication

A

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
Q

telomeres

A

repeated sequence (5’-TTAGG-3’ in humans)

68
Q

telomerase

A

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
Q

Hayflick limit

A

division around 50 times before telomeres too short

70
Q

Eukaryotic DNA packaging

A

DNA+histones–>chromatin –> chromosomes

71
Q

prophase

A

appearance of visible chromosomes, assembles mitotic spindle

72
Q

prometaphase

A

nuclear membrane breaks down, microtubules attach to centromeres (kinetochores attachment sites)

73
Q

metaphase

A

spindle microtubules lengthen/shorten, pulls chromatids toward oppposite poles

74
Q

telophase

A

microtubules break down, nuclear envelopes re-form around each set, chromosomes decondcense

75
Q

cytokinesis in animal cells

A

ring of actin filaments form at equator (contractile ring). ring contracts and pinches cytoplasm to divide

76
Q

cytokinesis in plant cells

A

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
Q

Prophase 1

A

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
Q

Meiosis 2

A

no DNA synthesis, sister chromatids separate to form gametes

79
Q

Female gametes

A

unequal division results in oocyte (egg) and 3 polar bodies

80
Q

male gametes

A

equal cytoplasmic division

81
Q

cyclins

A

regulatory proteins subunits of specific protein kinases, levels rise/fall with cell cycle

82
Q

CDKs

A

kinases that phosphorylate proteins to progress cell cycle. Always present, active when bound to appropriate cyclin

83
Q

cyclin-CDK complexes

A

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
Q

Cell cycle checkpoints

A

-DNA damage checkpoint before S
-DNA replication checkpoint before mitosis
-Spindle assembly checkpoing before mitosis progresses

85
Q

Radiation damage

A

activates protein kinase to phosphorylate p53 which blocks G1/S transition

86
Q

p53

A

stimulates transcription of Bax gene and represses transcription of Bcl-2 gene, resulting in Bax/bax dimers

87
Q

apoptosis

A

activated by bax/bax dimers. Controlled disintegration

88
Q

apoptosis advantages

A

remodelling tissues in embryo. In adult, maintains tissue size, eliminates specific cells or genetically damaged cells

89
Q

Cancer

A

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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