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mcb 244/245 > exam 2- cell biology > Flashcards

exam 2- cell biology Flashcards

1
Q

light microscope

A

passes light through specimen to produce 2D image

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2
Q

electron microscope

A

beams of electrons illuminate specimen, producing greater magnification & resolution than LM

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3
Q

transmission electron microscope

A

directs electron beams through thin-cut sections, producing 2D images

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4
Q

scanning electron microscope

A

directs electron beams across specimen surface, producing 3D images

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5
Q

cell size

A

vary
-erythrocyte = 7-8 um
-human oocyte = 120 um

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6
Q

cell shapes

A

spherical, cube-like, column-like, cylindrical, disc-shaped, irregular

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7
Q

plasma membrane

A

forms outer, limiting barrier separating internal contents from external environment
-modified extensions: cilia, flagella, microvilli
-functions: physical barrier, selectively permeable, electrochemical gradients, communication

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8
Q

lipid components of plasma membrane

A

-phospholipids: polar/hydrophilic head & two nonpolar/hydrophobic tails, forming phospholipid bilayer which ensures cytosol remains inside & interstitial fluid remains outside
-cholesterol: 4-ring molecule scattered within hydrophobic regions, strengthening membrane & stabilizing it at extreme temps
-glycolipids: lipids w/ attached carbs located on outer regions, forming glycocalyx (fuzzy coat of carbs outside of PM that helps in cell identification)

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9
Q

membrane proteins of plasma membrane

A

float & move in fluid bilayer, performing most of membrane’s functions

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10
Q

integral membrane proteins

A

embedded within & extend completely across bilayer
-hydrophobic regions interact w interior & hydrophilic regions interact w outside
-glycoproteins

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11
Q

peripheral membrane proteins

A

not embedded but loosely attached to external or interior surfaces of membrane

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12
Q

transport membrane proteins

A

regulate movement of substance across membrane
-channels, carriers, pumps, symporters, antiporters

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13
Q

cell surface receptors

A

bind ligands
-neurotransmiters bind muscle cells to initiate contraction

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14
Q

identity markers

A

communicate to other cells that they belong in body
-distinguish healthy cells from cells to be destroyed

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15
Q

enzymes

A

catalyze chemical reactions
-attached to internal or external surface of cell

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16
Q

anchoring sites

A

secure cytoskeleton to PM

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17
Q

cell-adhesion proteins

A

perform cell-to-cell attachments

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18
Q

nucleus

A

largest structure in cell, containing DNA & nucleolus
-enclosed by nuclear envelope
-cells = one nucleus except mature RBCs have none & skeletal muscle cells have multiple
-control center

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19
Q

cytoplasm

A

cellular contents between PM & nucleus
-3 components: cytosol, organelles, inclusions

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20
Q

cytosol/intracellular fluid

A

viscous fluid of cytoplasm w high water content & contains dissolved macromolecules & ions

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21
Q

organelles

A

complex, organized structures within cells that have unique shapes & functions

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22
Q

membrane-bound oranelles

A

enclosed by membrane that separates content from cytosol
-ER, Golgi, lysosomes, peroxisomes, mitochondria

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23
Q

non-membrane-bound organelles

A

not enclosed by membrane & composed of protein
-ribosomes, cytoskeleton, centrosome, proteasome

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24
Q

inclusions

A

temporary store of molecules in cytosol that aren’t considered organelles
-pigments, glycogen, triglycerides

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25
Q

cell functions

A

-maintain integrity & shape (depends on PM & internal components)
-obtain nutrients & form chemical building blocks
-harvest energy for survival
-dispose of wastes
-avoid accumulation that could disrupt cellular activities
-cell division
-maintain tissue

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26
Q

familial hypercholesteremia`

A

inherited genetic disorder of defects in LDL receptors or proteins
-interfere with normal receptor-mediated endocytosis of cholesterol, resulting in elevated cholesterol levels

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27
Q

membrane potential

A

potential energy of charge difference

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28
Q

resting membrane potential

A

potential when cell at rest that has two conditions
-unequal distribution of molecules across PM (more K+ in cytoplasm & more Na+ in interstitial fluid)
-unequal relative amounts of positive & negative charges (more positive on outside than inside cell)

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29
Q

direct contact cell communication

A

-immune system cells
-sperm & oocyte (egg w unique glycocalyx recognized by sperm)
-cellular regrowth after injury (overgrowth of tissue inhibited by direct contact)

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30
Q

ligand-receptor cell communication

A

controls growth, reproduction, & other cellular processes
-neurotransmitters & hormones

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31
Q

channel-linked receptors

A

occurs in response to neurotransmitter binding, initiating electrical changes to RMP in muscle & nerve cells

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32
Q

enzymatic receptors

A

protein kinase enzymes that phosphorylate other enzymes, providing mechanism for altering enzymatic activity

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33
Q

G-protein coupled receptor

A

indirectly activate protein kinase enzymes

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34
Q

endoplasmic reticulum

A

extensive interconnected membrane network extending from nuclear envelope to PM
-point of attachment for ribosomes

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35
Q

rough ER

A

has ribosomes
-synthesize, modify, & store proteins
-forms peroxisomes & vesicles

36
Q

smooth ER

A

no ribosomes
-synthesis, transport, & storage of lipids
-carbohydrate metabolism
-detoxification of drugs & poisions

37
Q

Golgi apparatus

A

polar structure composed of cisternae (cis=proximal to ER & trans=distal to ER)
-protein modification, packaging, & sorting
-formation of secretory vesicles

38
Q

lysosomes

A

small membranous sacs that contain digestive enzymes formed by Golgi
-digestion of unneeded substances & contents of endocytosed vesicles

39
Q

Tay-Sachs disease

A

lack enzyme needed to break down complex membrane lipids, causing lipids to accumulate within nerve cells

40
Q

peroxisomes

A

membrane-enclosed sacs that are smaller than lysosomes formed from pinched off vesicles from rough ER
-chemical digestion
-B-oxidation
-lipid synthesis

41
Q

mitochondria

A

oblong shaped organelles w double membrane
-engage in aerobic cellular respiration to complete digestion of fuel molecules to synthesize ATP

42
Q

ribosomes

A

contain protein & RNA arranged into large (A,P,E sites) & small subunit
-made within nucleolus & assembled in cytoplasm
-bound: attached to external surface of ER & synthesizes proteins for export, that become part of PM, or that serves a lysosomal enzymes
-free: suspended within cytosol & synthesize all other proteins

43
Q

centrosome

A

pair of perpendicularly oriented cylindrical centrioles surrounded by amorphous protein
-organize microtubules
-cell division

44
Q

proteasomes

A

large, barrel-shaped protein complexes
-degrade cell proteins through ATP-dependent pathway (proteins marked w ubiquitin)
-w age, function decreases

45
Q

cytoskeleton

A

framework of proteins that extend through cell interior

46
Q

microfilaments

A

smallest component of cytoskeleton composed of actin protein monomers in two twisted filaments
-maintain cell shape, internal support, cell division

47
Q

intermediate filaments

A

more rigid than microfilaments
-structural support, cell junctions

48
Q

microtubules

A

largest component of cytoskeleton composed of tubulin that can be elongated or shortened
-maintain shape, cell transport, cell division

49
Q

cilia

A

hair-like projections that move substances along cell surface

50
Q

flagella

A

longer & wider than cilia; propels cell

51
Q

microvilli

A

increase surface are

52
Q

tight junctions

A

strands/rows of protein-linking cells
-prevent materials from passing between cells (materials must move through rather than between cells)
-maintain polarity of epithelia

53
Q

desmosomes

A

composed of different proteins
-bind neighboring cells

54
Q

hemidesmosomes

A

anchor basal layer of cells of epidermis to underlying components

55
Q

gap junctions

A

form tiny, fluid-filled tunnels
-provide direct passageway for substances to travel between cells

56
Q

DNA

A

molecule composed of deoxyribonucleotides stored in nucleus
-three components: five-carbon sugar (deoxyribose), phosphate group, nitrogenous base (purines=A&G, pyrimidines=C&T)

57
Q

chromatin

A

structure of DNA in nondividing cells

58
Q

chromosome

A

tightly coiled DNA in dividing cells

59
Q

histones

A

wrap around DNA to form nucleosome

60
Q

genes

A

stretches of nucleotides that provide instructions for synthesis of specific proteins
-promoter region: start signal
-terminator region: stop signal

61
Q

gene expression

A

process of obtaining RNA or protein products from gene

62
Q

transcription

A

synthesizing RNA in nucleus

63
Q

required structures of transcription

A

-DNA (serves as template)
-ribonucleotides
-RNA polymerase

64
Q

products of transcription

A

-mRNA
-tRNA
-rRNA

65
Q

steps of transcription

A

-initiation: DNA unwound by enzymes; RNA polymerase attaches to promoter region; template strand transcribed
-elongation: free ribonucleotides base-paired w exposed DNA bases via H-bonds (A-U=2 bonds & C-G=3 bonds); phosphodiester bonds connect ribonucleotides; RNA polymerase moves down
-termination: RNA polymerase released at terminator region; H-bonds broken between DNA & mRNA; DNA resumes double helix structure

66
Q

RNA processing

A

forms mature mRNA which carries info for protein synthesis

67
Q

splicing

A

removes introns & splicesomes splice exons, producing larger number of proteins

68
Q

capping

A

bonding of ribonucleotide containing guanine to lead end of mRNA, preventing destruction of mRNA

69
Q

polyA tail

A

removal of terminal segments of mRNA & placing adenine nucleotides at tail, creating multiple mRNA transcripts

70
Q

translation

A

synthesis of protein in ribosomes within cytoplasm

71
Q

required structure of translation

A

-ribosomes
-rRNA (serves as catalysts during AA assembly)
-mRNA (carries instructions for protein synthesis)
-tRNA (brings AA to mRNA codon)
-amino acids (monomeric units of protein connected by peptide bonds- carboxylic group bonds w amino group; differentiated by R group)

72
Q

steps of translation

A

-initiation: complex formed between ribosomal subunits, mRNA, & tRNA; base-pairing between tRNA & start codon located in P site
-elongation: charged tRNA base pairs w codon in A site; peptide bond formed between AA in P & A sites; ribosome moves down one codon
-termination: release factor binds stop codon in A site; ribosome subunits separate; new protein released

73
Q

mitosis

A

cell division in somatic cells producing two cells
-necessary for development, tissue growth & repair, replacement of old cells

74
Q

meiosis

A

cell division in sex cells/gametes

75
Q

cell cycle

A

interphase (G1, S, G2) & mitotic phase (mitosis & cytokinesis)

76
Q

G1 phase

A

-growth & production of new organelles
-forms structures needed for DNA replication
-replication of centrioles

77
Q

S phase (DNA replication)

A

in nucleoplasm using deoxyribonucleotides & DNA polymerase, creating sister chromatids attached at centromere
-unwind DNA
-break parent DNA strands
-synthesis & assembly of new DNA strands
-restoration of DNA double helix

78
Q

G2 phase

A

-complete centriole replication
-synthesize enzymes for cell division

79
Q

prophase

A

-chromatin supercoiled into chromosomes
-nucleolus broken down
-microtubules grow from centrioles
-centrioles moved to opposite sides
-nuclear envelope broken down

80
Q

metaphase

A

-spindle fibers extend from centrioles & attach to centromeres
-chromosomes aligned at equatorial plate

81
Q

anaphase

A

-sister chromatids separated by spindle fibers & moved toward opposite poles
-each chromatid now chromosome of one DNA double helix w own centromere

82
Q

telophase

A

-chromosomes uncoil & return to chromatin
-nucleolus reforms
-mitotic spindle breaks down & disappears
-nuclear envelope forms around chromosomes
-end of nuclear division

83
Q

cytokinesis

A

-cytoplasm division
-ring of microfilaments pinch mother cell into two separate cells, forming cleavage furrow & two daughter cell

84
Q

cellular aging

A

-not obvious at molecular level
-reduced metabolic function = reduced ability to maintain homeostasis
-lower number of normally functioning cells
-some abnormal function of remaining cells
-alteration in structure or number of organelles
-changes in structure of chromatin & chromosomes

85
Q

cellular death

A

-killed by harmful agents of mechanical damage
-apoptosis

86
Q

apoptosis

A

programmed cell death
-initiated by ligand-receptor signaling
-actions initiated by enzymes: destruction of DNA polymerase; DNA & cytoskeleton digestion; condensation of cytosol & destruction of organelles; bleb formation; initiation of other signals to stimulate destruction
-occurs to promote proper development & remove harmful cells

87
Q

tumors

A

disrupted regulated cell signaling results in tumors which interfere w function of normal cells & may enter blood or lymph & metastasize to other areas

mcb 244/245 (8 decks)

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