CELLS Flashcards
1
Q
What’s a chimera?
A
having parts of different origins
e.g. a eukaryotic cell
2
Q
What’s an endosymbiont?
A
organisms forming symbiotic relationships with another cell/organism
3
Q
2 types of endosymbiont
A
intracellular
extracellular
4
Q
what’s a plastid?
A
membrane-bound organelle
5
Q
How are phylogenetic trees formed?
A
inferred from nucleotide/ amino acid sequence data
6
Q
most common phylogenetic marker
A
small sub-unit ribosomal RNA (SSUrRNA)
7
Q
ARCHEZOA hypothesis
A
eukaryogenesis involving exogenous origins of mitochondrion via phagocytosis of an alphaproteobacterium to form mitochondrion
8
Q
remnant genome of mitochondria
*what does it encode
A
rRNA and protein-coding genes
2 rRNA’s (12S and 16S)
22 tRNA’s
13 essential genes
*encodes sub-units for oxidative phosphorylation enzyme complexes
9
Q
origins of ER
A
Endogenous
10
Q
gram-negative bacteria
A
don’t retain crystal-violet stain
- double membrane systems
11
Q
chloroplast exogenous origin
A
cyano bacteria
12
Q
plasma membrane functions
A
- enclose cell content/ separate from environment
- maintain concentrations of cell substances
- communication w environment/other cells
- barrier
- cell growth/ shape change/ movement/ division
13
Q
cytosol function
A
protein synthesis/ metabolic pathways
14
Q
endoplasmic reticulum
A
lipid synthesis/ protein synthesis
15
Q
golgi apparatus function
A
modification/sorting/packaging of proteins/ lipids
16
Q
endosome function
A
sorting of endocytosed material
17
Q
plasma membrane sub-unit
* polarity of parts
A
phospholipid
- hydrophilic phosphate head
hydrophobic fatty acid tails
* amphiphilic!
18
Q
cholesterol effect on PM
A
decreases membrane permeability to small/ water-soluble molecules
prevent crystallization
19
Q
4 phospholipids in plasma membrane
A
phosphatidylcholine, phosphatidylethanolamine, phosphatidylserine, and sphingomyelin
20
Q
function of glycolipid asymmetry
A
extracellular to intracellular signal conversion
charge differences
binding sites
live and dead cell distuinguishment
sugar group addition
21
Q
self-association of glycolipids
A
H-bonds from sugars / Van der Waals between hydrocarbon chains
22
Q
oligosaccharides charge and function
A
net negative charge
alters electric field and ion concentrations
23
Q
lectins
A
carb binding proteins
bind to sugar groups on other glycolipids/ glycoproteins
24
Q
how is the PM fluid
A
rapid lateral diffusion
flexible hydrocarbon chains
flippases catalyzing movement
cis-double bonds create kinks in fatty acid tail/ shorter tail lengths
25
temp effect on cis bonds
more cis bonds as temp drops
26
types of membrane proteins
integral
peripheral
lipid attached
27
when are integral proteins released?
when detergents dissolve PM
28
where are lipid-attached proteins made?
ER
prior to cleaving and GPI anchor added via vesicle
29
when are peripheral proteins released?
when protein-protein interaction disrupting agents arrive
30
functions of membrane proteins
transporters
linkers
receptors
catalysis
31
how are transmembrane domains identified?
bioinformatic analysis 'in silico'
32
glycocalyx components
glycoproteins/ glycolipids
33
glycocalyx function
protect cell chemically, physically, biologically
adhesion
recognition
storage
affect health and disease
34
glycoprotein links
N-linked
O-linked
proteoglycans
35
N-glycans
asparagine-linked
36
O-linked
serine/threonine-linked
37
proteoglycans
glycoproteins w GAGs
polysaccharide chains covalently linked to a protein core> GPI anchor
38
GAG
glycosaminoglycans
39
ruthenium red
stains carbohydrate layer of glycocalyx
40
detergents
small, amphiphilic molecules of variable structure
(more soluble than lipids)
41
detergent behaviour
aggregate to form micelles/ rapidly diffuse in/out
affected by temp, pH and salt conc
displace lipid molecules
affect crystallization/purification
42
tpes of membrane diffusion
rotational
lateral
43
how are PM diffusion rates measured
FRAP
fluorescence recovery after photobleaching
44
FRAP process
1. mark membrane protein w fluorescent group
2. fluoresecnce group bleached w laser beam
3. time for diffusion measured and diffusion coefficient measured
45
disadvantages of FRAP
can't follow individual protein molecules
46
cortical cytoskeleton
spectrin meshwork maintaining integrity and shape of PM
*anaemia doesn't have
47
cell cortex
actin filaments attached to PM
48
cell cortex functions
cell movement
endocytosis
filopedia production
restricts free diffusion of proteins
49
types of active transport
coupled
ATP-driven
light/redox driven
50
membrane-bending protein function
deforms bilayers
(dynamic control of membrane shape)
51
membrane-bending protein mechanisms
insertion of hydrophobic protein domains/ lipid anchors
rigid scaffold formation
clustering of specific membrane lipids
52
selectivity filter
narrowest region of gated ion channel, limiting rate of passage
53
types of gated ion channels
voltage-gated
ligand-gated extracellular
ligand-gated intracellular
mechanically gated
54
Vmax in relation to gated membrane carriers
rate at which carrier can flip between conformational states
55
Km
concentration of solute when rate of transport is half the maximum value
56
location of nuclear localization signal
at N-terminal end and cleaved after synthesis
57
functions of nuclear pores in envelope
small molecule diffusion
dynamic in/out movement
export mRNA/ribosome components
import structural proteins and gene transcription/ regulation proteins
58
SV40 virus nuclear localization signal
mutation means short sequence is lacking (Thre replacing Lys)
59
nuclear localization signal function
responsible for selectivity of active nuclear import processes
60
how is nuclear localization regulated?
regulated by turning signals on/off via phosphorylation of amino acids close to signal sequences
61
transcription regulator mechanisms
bound to cytosolic proteins either anchored via cytoskeleton/ mask nuclear localization signal
gene released by stimuli
62
NF-AT
nuclear factor of activated T-cells
63
what is NF-AT
transcription regulatory protein in cytosol
phosphorylated state
64
what are T-cells activated by in NF-AT?
foreign antigen
calcium ion concentration increase
65
T cell nuclear activation mechanism
Reacting to the increase in calcium ion concentration, protein phosphatase binds to NF-AT, dephosphorylates and exposes nuclear import signals/ blocks export signal
66
what happens to the NF-AT once in the nucleus ?
activates gene txn of genes required for T-cell activation
67
Use of NF-AT pharmaceutically
used in immunosuppressive drugs when inhibited to block T-cell activation
68
How is the NF-AT response stopped?
Ca2+ concentration decreases
NA-FT released from calcineurin
re-phosphorylation inactivates import signals and exposes export
69
3 types of cytoskeleton
actin
microtubules
intermediate filaments
70
actin in plasma membrane
thin, flexible stress fibres
maintains cell shape
aids surface movement
6-8nm
requires ATP to build
regulates binding protein
71
actin in cytoplasm
polar, flexible filaments in cortex, found in bundles
dynamic polymerisation/ depolymerisation
72
microtubules structure/ location/ formation
25nm diameter tubes
made up of tubulins, requiring GTP to build up
grow from centrosome
73
microtubules function
motor proteins
intracellular movement
chr movement in cell division
organelle/vesicle shuttling
breakdown mitotic spindle
74
intermediate filaments structure
10nm diamter
alpha-helical coiled coil
assembly regulated by phosphorylation
staggered tetramer = 1 filament
75
intermediate filament functions
mechanical strength
flexible
excess stress prevention
tensile force distribution
76
actin functions
cell motility
contraction/ adhesion/ mechanosensation
77
actin formation
G-actin monomers added to either end (more rapidly at+)
ATP hydrolysis fuels polymerisation
actin-binding proteins regulate assembly
78
villi
non-motile actin filaments increasing SA for absorption
79
microtubule assembly
dimers of alpha (-) and beta (+) tubulin formed up of 13 protofilaments via GTP
80
kinesins
motor proteins w head/tail regions
globular
bind ATP
tails bind cargo
81
dyneins
drive cilia/ flagella
9+2 microtubule arrangement
bends structure via microtubule sliding
82
cilia
motile
numerous/ short
aid locomotion
microtubules
83
flagella
few/ long
aid cell locomotion
microtubules
84
intermediate filaments in the nucleus
nuclear lamins (inner membrane meshwork) act as chr/nuclear pore anchorage sites
strong > coiled fibrillar protein-packing
85
cytoplasmic intermediate filaments
keratins in epithelia
vimentin/ vimentin-related tissue
neurofilaments
N-/C- terminal domains vary in size
86
examples of vimentin
connective tissue, muscle cells, neuroglial cells
87
nuclear lamins
LMNA/LMNB/LMNC
fibrous meshwork of inner nuclear envelope
provide structural support
cell division breakdown
88
keratin
structural/ mechanical strength in cytoplasm
indirect connection via desmosomes
89
myosin I
all cells
head/tail
intracellular organization
moves cargo along actin
90
myosin II
muscle cells
dimer
filaments
contractile
91
spectrin
inner plasma membrane
provides mech strength/ stability/ shape
link membranes
motor proteins / filament systems
RBC membranes
92
interphase
normal functions
DNA replication for 2 identical chromatids
S phase
93
G1
cells produce RNA, enzymes and growth proteins
main growth
checkpoint
94
G2
cell growth
errors corrected
tubulin increase
checkpoint
95
early prophase
centrosomes replicated prior
chromatin coils
96
late prophase
centrosomes to opposite nuclear ends
nucleolus dissapears
2 chromatids appear
97
metaphase
centrosome reaches pole
spindles appear
chromosomes line along equator via centromeres
98
anaphase
chromosomes to opposite poles
99
telophase
nuclear envelope/ nucleolus reformation
spindle breakdown
cytokinesis
chromosomes uncoil
100
Meiosis 1 middle prophase I
synapsis to form bivalents
centrosomes to opp nuclear ends
101
Meiosis 1 late prophase I
nuclear envelope breakdown
crossing over
nucleolus disappears
102
Meiosis I metaphase 1
bivalent alignment
spindle forms
103
Meiosis 1 anaphase 1
whole chr movement to poles
104
Meiosis I telophase I
nuclear envelope/ nucleolus reformation
cytokinesis
105
meiosis II
mitosis behaviour
106
somatic
non-reproductive cells
107
2 phases of prokaryotic division
replication
division (binary fission)
108
4 phases of eukaryotic division
M
G1
G2
S
109
G1 checkpoint
assesses size
environment favorability
DNA damage
space availability
110
G2 checkpoint
assesses DNA replication
correct DNA
cell size
environment availability
111
M checkpoint
assesses whether spindles are attached to centromeres
112
CdK
cyclin dependent kinases
113
cyclin-dependent kinases
require cyclins to activate
add phosphate from ATP to amino acid in protein
differ and destroyed at different checkpoints
114
quiescent state
G0/pause
maintenance period
reversible/ irreversible depending on cell type
115
PDGF
platelet-derived growth factor
116
FGF
Fibroblast growth factor
117
EGF
epidermal growth factor
118
growth factor concentration
10^-10 M
119
where are growth factors found/ recognised
found in serum
receptors in PM
120
apoptosis
cell shrinks
nuclear fragmentation
apoptotic bodies digested/ recycled
121
necrosis
accidental cell death due to physical/chemical injury
122
necrosis process
cell/ nucleus swells leading to leakage
cell lysis
triggers inflammatory response
123
2 types of apoptosis triggers
physiological
pathogenic
124
physiological activation of apoptosis
used in embryonic development, removing/remodelling tissues
homeostasis maintenance
cell number control
125
pathogenic activation
viral infection
heat shock
toxins
cytotoxic T cells
stressed/damaged cell removal
126
apoptosis activators
hormonal signals
cell signalling
127
apoptosis suppressors
survival factors
extracellular matrix contact
128
consequences of apoptosis
P53 activation
mitochondria leak
caspase activation
129
caspase
enzyme, when activated, cleaving nuclear lamins, activating DNAase, cleaving cytoskeleton
leaves apoptotic bodies
130
what happens when the cytoskeleton is cleaved?
cells detach from neighbours and lose contact with ECM
131
p53 weight
53KDa
132
p53
transcription factor acting as tumour suppressor
133
DNA damage mechanism
1. damage activates p53
2. p53 blocks progression of cell cycle at G1 checkpoint
3. mitochondrial membrane rupture > cytochrome C leaks between inner/outer membrane
4. cytochrome C in cytosol activates caspases which activate DNAase to cleave lamins and cytoskeletons
5. apoptosis
