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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
cell functions
-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
26
familial hypercholesteremia`
inherited genetic disorder of defects in LDL receptors or proteins -interfere with normal receptor-mediated endocytosis of cholesterol, resulting in elevated cholesterol levels
27
membrane potential
potential energy of charge difference
28
resting membrane potential
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)
29
direct contact cell communication
-immune system cells -sperm & oocyte (egg w unique glycocalyx recognized by sperm) -cellular regrowth after injury (overgrowth of tissue inhibited by direct contact)
30
ligand-receptor cell communication
controls growth, reproduction, & other cellular processes -neurotransmitters & hormones
31
channel-linked receptors
occurs in response to neurotransmitter binding, initiating electrical changes to RMP in muscle & nerve cells
32
enzymatic receptors
protein kinase enzymes that phosphorylate other enzymes, providing mechanism for altering enzymatic activity
33
G-protein coupled receptor
indirectly activate protein kinase enzymes
34
endoplasmic reticulum
extensive interconnected membrane network extending from nuclear envelope to PM -point of attachment for ribosomes
35
rough ER
has ribosomes -synthesize, modify, & store proteins -forms peroxisomes & vesicles
36
smooth ER
no ribosomes -synthesis, transport, & storage of lipids -carbohydrate metabolism -detoxification of drugs & poisions
37
Golgi apparatus
polar structure composed of cisternae (cis=proximal to ER & trans=distal to ER) -protein modification, packaging, & sorting -formation of secretory vesicles
38
lysosomes
small membranous sacs that contain digestive enzymes formed by Golgi -digestion of unneeded substances & contents of endocytosed vesicles
39
Tay-Sachs disease
lack enzyme needed to break down complex membrane lipids, causing lipids to accumulate within nerve cells
40
peroxisomes
membrane-enclosed sacs that are smaller than lysosomes formed from pinched off vesicles from rough ER -chemical digestion -B-oxidation -lipid synthesis
41
mitochondria
oblong shaped organelles w double membrane -engage in aerobic cellular respiration to complete digestion of fuel molecules to synthesize ATP
42
ribosomes
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
centrosome
pair of perpendicularly oriented cylindrical centrioles surrounded by amorphous protein -organize microtubules -cell division
44
proteasomes
large, barrel-shaped protein complexes -degrade cell proteins through ATP-dependent pathway (proteins marked w ubiquitin) -w age, function decreases
45
cytoskeleton
framework of proteins that extend through cell interior
46
microfilaments
smallest component of cytoskeleton composed of actin protein monomers in two twisted filaments -maintain cell shape, internal support, cell division
47
intermediate filaments
more rigid than microfilaments -structural support, cell junctions
48
microtubules
largest component of cytoskeleton composed of tubulin that can be elongated or shortened -maintain shape, cell transport, cell division
49
cilia
hair-like projections that move substances along cell surface
50
flagella
longer & wider than cilia; propels cell
51
microvilli
increase surface are
52
tight junctions
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
desmosomes
composed of different proteins -bind neighboring cells
54
hemidesmosomes
anchor basal layer of cells of epidermis to underlying components
55
gap junctions
form tiny, fluid-filled tunnels -provide direct passageway for substances to travel between cells
56
DNA
molecule composed of deoxyribonucleotides stored in nucleus -three components: five-carbon sugar (deoxyribose), phosphate group, nitrogenous base (purines=A&G, pyrimidines=C&T)
57
chromatin
structure of DNA in nondividing cells
58
chromosome
tightly coiled DNA in dividing cells
59
histones
wrap around DNA to form nucleosome
60
genes
stretches of nucleotides that provide instructions for synthesis of specific proteins -promoter region: start signal -terminator region: stop signal
61
gene expression
process of obtaining RNA or protein products from gene
62
transcription
synthesizing RNA in nucleus
63
required structures of transcription
-DNA (serves as template) -ribonucleotides -RNA polymerase
64
products of transcription
-mRNA -tRNA -rRNA
65
steps of transcription
-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
RNA processing
forms mature mRNA which carries info for protein synthesis
67
splicing
removes introns & splicesomes splice exons, producing larger number of proteins
68
capping
bonding of ribonucleotide containing guanine to lead end of mRNA, preventing destruction of mRNA
69
polyA tail
removal of terminal segments of mRNA & placing adenine nucleotides at tail, creating multiple mRNA transcripts
70
translation
synthesis of protein in ribosomes within cytoplasm
71
required structure of translation
-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
steps of translation
-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
mitosis
cell division in somatic cells producing two cells -necessary for development, tissue growth & repair, replacement of old cells
74
meiosis
cell division in sex cells/gametes
75
cell cycle
interphase (G1, S, G2) & mitotic phase (mitosis & cytokinesis)
76
G1 phase
-growth & production of new organelles -forms structures needed for DNA replication -replication of centrioles
77
S phase (DNA replication)
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
G2 phase
-complete centriole replication -synthesize enzymes for cell division
79
prophase
-chromatin supercoiled into chromosomes -nucleolus broken down -microtubules grow from centrioles -centrioles moved to opposite sides -nuclear envelope broken down
80
metaphase
-spindle fibers extend from centrioles & attach to centromeres -chromosomes aligned at equatorial plate
81
anaphase
-sister chromatids separated by spindle fibers & moved toward opposite poles -each chromatid now chromosome of one DNA double helix w own centromere
82
telophase
-chromosomes uncoil & return to chromatin -nucleolus reforms -mitotic spindle breaks down & disappears -nuclear envelope forms around chromosomes -end of nuclear division
83
cytokinesis
-cytoplasm division -ring of microfilaments pinch mother cell into two separate cells, forming cleavage furrow & two daughter cell
84
cellular aging
-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
cellular death
-killed by harmful agents of mechanical damage -apoptosis
86
apoptosis
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
tumors
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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