SEMESTER 1 Flashcards
(227 cards)
1
Q
who created the microscope
A
Robert hooke (1635-1703)
2
Q
how many cells in the body
A
approx. 37 trillion cells
3
Q
what are archaea
A
formerly archaebacteria
many species live in extreme environments
4
Q
components of the cytoskeleton
A
actin filaments
intermediate filaments
microtubules
5
Q
role of the cytoskeleton
A
maintain shape and stability.
adaptation of shape .
cell division.
motility.
movement of particles within cells.
6
Q
how big is a mitochondrion
A
0.5-1um in diameter and 1-2 um in length
7
Q
what is a lysosome
A
single membrane bound organelle that degrade unwanted proteins and particles taken up by the cell, and membranes and organelles that are no longer needed
8
Q
pH of a lysosome
A
4.5-5
9
Q
what are peroxisomes
A
degrade fatty acids and toxic compounds
involved in fatty acid oxidation, produces precursors for biosynthetic pathways. (H202)
10
Q
what catalysed the earliest evolution of life (LUCA)
A
small reactive molecules,
minerals as catalysts,
high temperatures in hydrothermal vents,
RNA world, ribozymes,
DNA more stable,
lipid bilayers spontaneously form vesicles
11
Q
why is bacteria reproduction error prone
A
it is fast
12
Q
endosymbiotic theory
A
eukaryotic cell engulfs bacterium and becomes an organelle
(mitochondria, chloroplasts from photosynthetic bacteria)
13
Q
evidence for endosymbiosis form chloroplasts
A
photosystem I - similar to photosystem in green sulphur bacteria and heliobacteria
photosystem II - similar to photosystem of purple and green filamentous bacteria
14
Q
what are protozoans
A
single celled eukaryotes, motility, predation, not animals, plants, or fungi
15
Q
who discovered cholera is caused by a rod-shaped bacterium (Vibrio cholerae)
A
- Robert Koch (1884):
16
Q
Who discovered penicillin
A
- Alexander Fleming (1928): Nobel Prize for Medicine 1945
17
Q
do archaea cause disease?
A
no, they live in extreme environments
18
Q
properties of viruses
A
outside of host cell,
retroviruses, lentiviruses - integration events can be mutagenic,
dormancy,
very small,
pandoravirus (2,500 genes) can be seen under microscope.
19
Q
function of actin
A
defines shape of cells and sub-cellular structures.
exerts force.
cell movement.
cell division.
20
Q
what is the most abundant protein in eukaryotic cells
A
actin 15%-10%
21
Q
how many amino acids does actin have
A
375 (small)
22
Q
what an actin bind
A
ATP/ADP
23
Q
what causes muscular dystrophy and haemolytic anaemias
A
actin mutations
24
Q
how does actin form a fibre
A
-pointed end (minus)
-barbed end (plus)
growth of fibres is slower at minus end than plus end
25
what regulates microfilament dynamics
approx. 60 actin binding proteins
26
how does actin operate during cell division
contractile actin-myosin ring that squeezes cells apart
27
classes of intermediate filaments
cytoplasmic: keratins (epithelia), vimentin (connective tissue, muscle cells, and glial cells) and vimentin-related, neurofilaments (nerve cells)
nuclear: nuclear lamins (in all animal cells)
28
function of intermediate filaments
structure and support against stretch.
provide support against mechanical stress.
29
what causes epidermolysis bullosa
mutations in Keratin
30
function of nuclear lamins
provide stability to the nucleus
31
what do microtubules do in cell division
push chromosomes to the midline then pull them to the poles
32
what are microtubules composed of
dimers of alpha and beta tubulin
13 parallel protofilaments
polarity: beta tubulin = plus end, polymerises faster
33
where do microtubules originate
MTOCs (microtubule organising centres) such as the centrosome
significant % of cancers have abnormal centrosomes
34
how is microtubule stability regulated
microtubule associated proteins
35
what are motor proteins
fall into 2 category's
kinesins: transport cargo from minus end to plus end (of microtubule)
dyneins: plus to minus
36
what is the role of myosin-I
transport vesicles/organelle along actin fibre.
37
what is the basement membrane/basal lamina
2D sheet on which epithelial cells reside
38
fibrillar matrix
3D matrix composed of various fibres, in which cells such as fibroblasts are buried
39
what are the two types of extracellular matrix
basement membrane and fibrillar matrix
40
where do you find basement membrane
epithelium, muscle, kidney glomerulus
41
main components of fibrillar matrix
colagen I
fibronectin
elastin
proteoglycans
42
what is an occluding junction
seals different compartments away from each other ~(tight junction)
43
what is a cell-cell anchoring junctions
junctions that anchor cells to each other adherens junctions and desmosomes
44
what are cell matrix anchoring junctions
junctions that anchor cells to extracellular matrix (focal adhesion and hemidesmosome)
45
what is the difference between adherens junction and desmosome
both are cell cell anchoring junctions but desmosomes anchor to intermediate filaments and adherens junctions anchor to the actin filaments
46
what is the difference between focal adhesion and hemidesmosome
both are cell-matrix anchoring junctions but the hemidemmosome anchors to then intermediate filaments and focal adhesion anchors to actin filaments in the cell.
47
what are channel forming junctions
form connection between the cytoplasm of adjacent cells (gap junctions).
48
what do tight junctions do
turn epithelia into barriers
49
where are adherent junctions found on epithelial cells
in close proximity of tight junctions
50
how do adherens junctions help conduct morphological changes of tissues
contracting junction complexes in groups of cells (important in embryonic development)
51
function of lamellipodium
drive cell movement
52
how do cells move along basement membrane
actin filaments attach to different focal adhesions and pull the rest of the cell behind them in a crawling motion
53
what are cadherins
calcium dependent adhesion molecules
54
what are selectins
adhere white blood cells in vessels (leukocyte rolling)
55
how is cell adhesion involved in metastasis
tumour cells use specific mechanisms to undermine the tight sealing of epithelium and move through the blood stream to a another location and form a secondary tumour (metastasis)
56
what is a nissil body
clusters of neuronal endoplasmic reticulum (within the cell body (soma))
57
what are the dendrites of a neurone
antenna for information
58
what is an axon hillock
meeting point between cell body and axon where the action potential is generated
59
what is the axolemma
axon membrane
60
what is the unidirectional flow of the neutron
AP always travels from dendrites to cell body to axon
61
why are our brains poor in regenerating
neurones are post mitotic so can’t divide and our brains have limited active stem cells
62
what is the make up of the neuronal cytoskeleton and what are their functions?
microtubule: transport
neurofilaments: structural
microfilaments: structural + movement
63
what is the minus end and plus end of a neurone
cell body is the minus end and nerve endings are the plus ends
64
dynein in axonal transport
move towards minus end (cell body)
move 50-250mm/day
transport mitochondria, endocytotic vesicles
65
kinesin in axonal transport
move towards plus end (pre synaptic nerve endings)
move 100-400mm/day
transport mitochondria, neurotransmitter vesicles
66
how are axons myelinated by glial cells
glial cell sits on axon and extends membrane and wraps the membrane around many times
67
what's multiple sclerosis
auto-immune disease where neurones undergo de-myelination
68
what are the coverings for nerve fibres
endoneurium - surround axon
perineurium - surround groups of axons called fascicles
epineurium - surround groups of fascicles
69
what is nissl staining
stains cell body, ER
70
what is a multipolar neurone
send out dendrites from the cell body in many directions
71
what are glial cells
non neuronal cells that are part of the nervous system
72
73
what are the major classes of glial cells
CNS:
ependymal cells
oligodendrocytes
astrocytes
microglia
PNS:
satellite cells
Schwann cells
74
what are astrocytes
most abundant glial cells in brain tissue
provide structural support
regulate extracellular electrolyte homeostasis
energy storage
75
what do oligodendrocytes do
myelinate axons in the CNS (multiple at once)
inhibit axon regeneration in the CNS
76
what do microglia do
provide immune defence in the brain
induce a pro-inflammatory reaction
can be activated and become phagocytitic
77
what are ependymal cells
line the fluid filled spaces in the brain
secrete , monitor and aid in the circulation of cerebrospinal fluid
cilia and micro villi
78
what is choroid plexus epithelium
specialised epithelium in all ventricles; secretes cerebro-spino fluid
79
what are Schwann cells
myelinate pns axons
remove myelin debris by phagocytosis
promote axon regeneration
80
what are satellite cells
PNS glial cells that provide structural and metabolic support
81
what is extracellular recording of electrical potential
electrode outside cell (group of cells)
82
what is intracellular recording of electrical potential
electrode inside cell (one cell)
83
what is patch clamping
electrode sealed to cell surface (single cell)
84
what is the equilibrium potential of an ion
the membrane voltage required to prevent movement of an ion down its concentration gradient
85
how do you measure the amount of work done at the membrane
Nernst equation:
E= 58(mV) x log [c]out / [c]in
86
how do you calculate concentration gradient
[c]out/ [c]in for +ve ions
[c]in / [c]out for -ve ions
87
membrane potential difference for K and Na
E(k) = -90mV (if above K will leave)
E(Na) = +50mV (if below Na will enter)
88
what can move across the lipid bilayer
small uncharged or hydrophobic molecules can freely transverse by simple diffusion
charged polar molecules require specialist proteins
89
what is secondary active transport across a membrane
requires an electrochemical gradient
e.g Na+/Glucose transporter (intestine)
90
what is the octane/water
partition coefficient
(Kow) ratio of how soluble a solute is in water compared to octanol
higher = more lipid soluble
91
components of K+ channel
ion filter
gate
92
example of mechanical gated channel
auditory receptors
93
what is the Jmax in a rate of uptake against external membrane concentration graphs
max rate of uptake of molecule
94
what is the Km in membrane transport
transporter affinity for substrate
lower Km higher affinity
95
where does the brain get all its energy
sugar
96
structure of GLUT1 glucose transporter
central cavity (aqueous cavity)
intracellular domains (latch)
97
what is SGLT1
sodium glucose symporters
intestinal epithelial cells for the absorption of dietary glucose
98
SGLT2: sodium-glucose symporters
sodium-glucose symporters
epithelial cells in proximal tubules of the kidney for reabsorption of glucose from the primary urine
99
how would you treat cholera with Na+/ glucose cotransporter
replacement therapy includes a high concentration of glucose , which drives Na+ back into the intestine through the Na+/glucose symporter, SGLT1
100
where does GLUT1 act
highly expressed in blood brain barrier, erythrocytes
101
where does GLUT2 act
liver, kidney, intestinal epithelium, pancreatic beta cells
102
where does GLUT 3 act
neurones
103
where does GLUT4 act
muscle, adipocytes
104
why are gap junctions important in neurones
smooth activation across cells
105
what is the width of a synapse
0.5 um
106
how are neurotransmitters removed from synapse
taken up by astrocytes and taken back up by presynaptic terminal
enzymes breakdown the molecule and taken into bloodstream or back to nerve
107
inotropic receptor
allows ions in
108
what is a graded potential
can be excitatory or inhibitory
gradual shift in charge following excitation
degrades over time and may not be strong enough to trigger AP along axon
109
temporal summation
one graded potential after another
second one adds to the first and threshold is reached
110
EPSP
excitatory postsynaptic potential
111
IPSP
inhibitory postsynaptic potential
112
metabotrapic receptors
combined to a G-protein
generates along-lasting more varied response
slower acting
113
spatial summation
addition of multiple graded potentials at once
114
somatic nervous system
motor fibres (general somatic efferens)
sensory fibres (general somatic afferens)
115
visceral (autonomic) nervous system
sympathetic = fight or flight
parasympathetic = rest and digest
motor fibres (general visceral efferens)
sensory fibres (general visceral afferens)
116
effect of parasympathetic nerves
constrict pupils
stimulate saliva
slow heart
constrict airways
stimulate activity of stomach
inhibit release of glucose; stimulate gallbladder
stimulate activity of intestines
contract bladder
project erection of genitals
117
effects of sympathetic nerves
dilate pupils
inhibit salivation
increase heartbeat
relax airways
inhibit activity of stomach
stimulate release of glucose; inhibit gall bladder
inhibit activity of intestines
secrete epinephrine and noradrenaline
relax bladder
promote ejaculation and vaginal contraction
118
anatomical directions
ventral forward (belly side)
dorsal back (back)
(rostral) anterior up (head)
(caudal) posterior down (feet)
119
planes of section
horizontal (flat)
coronal (crown)
sagital (middle part)
120
names for surfaces of the cerebrum
gyrus = ridges
sulcus = grooves
fissures = deep grooves
121
major subdivisions of the brain
forebrain
midbrain
hindbrain (pons, cerebellum, medulla)
spinal chord
122
4 lobes of brain
frontal lobe
parietal lobe
occipital lobe (vision)
temporal lobe (memory language)
123
how many pairs of spinal nerves
31
124
why is spinal chord shorter than vertebral column
spinal nerves hang down and leave at an angle
harder to damage
125
why is brain fluid filled
make brain less heavy
cushions entire brain
remove waste product
contains growth factors
126
how much cerebrospinal fluid do we produce each day
500ml normally reabsorbed into blood stream
if this pathway blocked = hydrocephalus
127
meningeal layers of CNS (protective)
pia mater (inner) tightly adhered
arachnoid mater (intermediate)
dura mater (outer)
CSF released between layers 1&2 the sub arachnoid space
128
how is cerebrospinal fluid recycled into the blood
via arachnoid granulations into venous blood
129
purpose of the cell cycle
copy genome and partition the copies equally between the daughter cells
enable a multicellular organism to grow to adult size
maintain total cell number of an adult organism
replace lost or damaged cells
130
prokaryote cell division
binary fission
DNA attached to cytoplasmic membrane (nucleoid)
cell enlarges and DNA duplicates
septum forms
cell divides in two
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131
replication of DNA in prokaryotes
- circular chromosome has one origin of replication
-two replication forks form at the origin (bidirectional replication
-two identical copies of the circular chromosome
132
cytokinesis of prokaryote
-FtsZ distributed within cell
-FtsZ ring forms and contracts
-cell spits
133
how is the DNA replication speed brought up to the cytokinesis speed
-multiform replication
-replication of DNA initiated before completion of previous round
134
what is G1
growth phase, doubling the mass of organelles and protein, including synthesis of enzymes that will drive DNA replication
135
what is S phase
DNA synthesis phase. chromosome duplification
136
during the cell cycle how is premature chromosome separation prevented
after replication, sister chromatids are held together by cohesin
137
what is cohesin made up of
SMC3 and SMC1 and kleisin
138
what is G2
preparation for mitosis. the beginning of mitosis is marked by two events:
-chromosome condensation
-formation of mitotic spindle
139
what drives condensation of the chromosomes
condensin
140
how does condensin condense chromosomes
condensin encircles loops of DNA and compresses the sister chromatids to give a compact structure
141
what does the mitotic spindle bind to
kinetochore
-complex of proteins attached to the centromere
142
how is cohesin removed from sister chromatids
kleisin subunit of cohesin is cleaved by a protease
143
how do mitotic spindle have access to the chromosomes
during G2 the nuclear membrane breaks down and mitotic spindle can enter
144
what is the phragmoplast
guides synthesis of new cell wall in plant cell division
contains microtubules derived from the mitotic spindle
145
when is the cell cycle the shortest and why
early embryonic stages
division without growth
146
cell cycle time in liver
1 year
147
why do unicellular organism carry out closed mitosis
nuclear envelope remains intact throughout
spindle pole body is imbedded within the membrane
148
during mitosis what is distributed symetrically and symmetrically
DNA distributed symmetrically
cell fate determinants distributed asymmetrically
149
polarity in stem cell division
one cell is attached to niche cell and fated to retain its identity as a stem cell
and another cell is free to dissociate
150
what is contact inhibition
once cells contact each other they stop growing. inactivated in cancer cells
151
what does cyclin dependent kinase do
drive the phases of the cell cycle. it is the activity (not the levels) of the kinase that activate the phases of the cycle
152
what controls the activity of kinases
cyclin.
undergo cycles of synthesis and degradation so levels rise and fall
different CDKs and cyclins activate different phases
153
which cyclin activates G1/S CDK
cyclin E
154
what phase of cell cycle does G1/S CDK drive?
transition from G1 to S phase.
commits cell to the cycle
155
what cyclin does MCDK bind
cyclin B
156
what does M CDK do in the cell cycle?
promotes entry into mitosis.
activates condensin
induces nuclear membrane breakdown
157
how is the activity of M CDK diminished after mitosis
cyclin B degradation
158
G1 checkpoint
R (restriction point)
positive signal from the outside will instruct the cell to divide
159
G2/M checkpoint
is dna synthesis complete?
cell cycle is suspended if not
160
M checkpoint
is each chromosome attached to spindle?
161
what are anuploidies and trisomies
A: chromosome numbers other than 46
T: 3 copies of a chromosome
162
4 main types of intercellular communication
endocrine
paracrine
neuronal
contact dependent
163
what is autocrine signalling
special type of paracrine signalling where the secreting cell contains receptors for the secretory molecule
164
examples of signalling faces in cell signalling
hormones
growth factors
metabolic regulators
neurotransmitters
migratory cues
cell death factors
developmental patterning factors
165
intracellular receptors
either in the cytoplasm or in the nucleus
166
major membrane receptor families
ion channels
G-protein couples receptors
enzymes
167
G-protein couples receptors (GPCRs) structure
7 transmembrane domains
amino terminus in the exterior
carboxy terminus in the cytosol
168
functionality of GPCR
G protein is heterotrimeric which means it has 3 different subunits (alpha, beta and gamma)
A subunit is bound to GTP at rest, when signal binds GDP exchanges for GTP
G(alpha)-GTP activates effector enzyme adenyl cyclase which produces second messenger (cAMP)
169
what does cAMP do
activates protein kinase A PKA
170
what does protein kinase A do
phosphorylate proteins to make them functional active
has 2 subunits (regulatory and catalytic)
catalytic group phosphorylates proteins
atp phosphate donor
serine threonine kinase
171
what is a protein phosphatase
remove phosphate group from a protein and makes it inactive
172
what is protein kinase C
activated by adrenaline
(alpha 1 adrenergic receptor)
activated by ca ions and diacylglycerol
173
how is adrenaline able do have different effects
different receptors types for same ligand
174
effect of adrenaline on beta GPCR
2nd messenger:cAMP
causes glucose metabolism
175
effect of adrenaline on alpha 1 GPCR
2nd messenger DAG, IP3, Ca2+
causes contraction of smooth muscle
176
what is endocytosis
uptake of outside material(fluids and macromolecules) by invagination of the plasma membrane followed by pinching off and intracellular vesicle formation
177
mechanism of phagocytosis
-receptors that bind bacteria activated
-activation of F-actin polymerisation
-membrane protrudes and zippers around particle and phagosome sealed off
-F-actin disassembles
-fuses with lysosomes = phagolysosomes
degradation of content
178
function of macropinocytosis
uptake of fluid for feeding and removal of large number of growth factor receptors from plasma membrane
179
types of endocytosis
Cathrin mediated:
dynamin dependent - constitutive receptor-mediated, ligand induced receptor mediated
non-clathrin mediated:
dynamin-dependent- cave-in-mediated
dynamin-independent
180
Clathrin-mediated endocytosis function
receptor-mediated endocytosis allows the cell to take up specific macromolecules which are not abundant in the extracellular fluid via more than 25 different receptors
181
Cathrin mediated endocytosis: mechanism
egf receptor bings egf
adoption binds the inside of the receptor
bud formation
dynamin pinches off the vesicle (actin can contribute)
uncoating
182
what is dynamin
large protein that oligomerise into spirals
required for fission of vesicles
183
what is the functional unit of Cathrin
tryschelium
184
what mediates Cathrin cade disassembly
HSC70
auxilin
185
cytoplasmic pathway of a protein
-ribosome
-protein completed and released in folded form into cytoplasm (nucleus, peroxisome,cytoplasmic protein)
un folded protein transported to mitochondria where it is folded
186
where do endoplasmic reticulum pathway proteins get transported to
lysosomes, peroxisomes,new cytoplasmic membrane
secretory vesicles
187
what determines the pathway of proteins
endoplasmic reticulum signal sequence
188
what binds ER signal sequence to ER membrane
signal recognition particle SRP
189
destinations of ER pathway
-ER lumen
-further vesicular compartments
-secreted from cell
-embedded in membrane
190
what docks transport vesicle to plasma membrane
v-snare on vesicle and t-snare on target (membrane)
191
what are glycosyltranferases
enzymes in Golgi that add sugars to proteins
192
what three alleles of glycosyltransferases glycosylate the proteins on red blood cells
O, A, B
193
necrosis
traumatic cell death from acute injury
194
apoptosis
activation of a death programme
195
what causes apoptosis
-withdrawal of growth factors
-chemotherapy
-contact with cytotoxic T cells
-following a developmental programme
196
characteristics of necrosis
-membrane damage
-chromatin flocculation
-energy levels rapidly depleted
-leaking of cellular contents
-elicits an inflammatory response
197
apoptosis pathway
-chromatin condensation and membrane blebbing
-cell fragmentation (into apoptotic bodies)
-apoptopic bodies engulfed by phagocytes
198
why do apoptoses?
-during metamorphosis
-elimination of cells that have served their purpose
-cells infected by viruses
-cancer cells
-cells bearing excessive DNA damage
-promote self tolerance. auto reactive lymphocytes undergo apoptosis before they fully develop
199
where is DNA cut during apoptosis
DNA cleaved in linker regions between nucleosomes
200
how do we detect new free ends of DNA after apoptosis
TUNNEL assay
201
how does annexin V detect apoptosis cells
phosphotidile serine in plasma membrane flips and can be detected
202
why do phosphotidile serene lipids expose the the surface during apoptosis
this is a signal for phagocytes to bind and engulf the cell
203
what enzymes drive apoptosis in eukaryotes
capsases
204
what do caspases target
lamins
gelsolin (regulator of actin filament assembly/disassembly)
205
example of excess apoptosis
-heart attack
-type I diabetes Miletus
206
excitotoxicity
if excess glutamate is transported to a neurone it can cause unwanted cell death
207
how germ cells form in development
-primordial germ cells first seen in proximal epiblast pre-gastrulation.
-migrate to posterior during gastrulation
-migrate to gonads
-differentiate into egg or sperm
208
how meiosis ensures the gametes have the correct amount of genetic material
two cell divisions with DNA replication only taking place before the first division
209
how fertilisation occurs in mammals
-fusion between sperm and egg in the fallopian tube
-divides and forms a blastocyst which is then implanted into uterine wall
-sperm binds and penetrates zona pellucida
- plasma membrane of sperm fuses with egg plasma membrane
210
describe asexual reproduction in hydra
-little region buddy of the side of the embryo
-buds off and becomes its own organism
211
what is parthenogenesis
development of an embryo from an unfertilised egg cell
(haploid diploid bees)
212
cortical granule exocytosis
due to high Ca2+ granule membrane fuses with egg membrane
contents of granules released into space between cell membrane and vitelline envelope.
enzymes from cortical granules harden
213
innate immunity
non specific, rapid, response to infections, response to altered self
214
adaptive immunity
-specific
-slower to develop
-response to infections
-response to altered self
-can be humoural or cell mediated
-has memory
215
B vs T cells
Both arise from bone marrow and activated in secondary lymphoid organs and have a capacity to produce memory cells
B - mature in bone marrow, secrete antibodies
T - mature in thymus, induce a cell mediated response
216
antigen presenting cells
e.g dendritic cells
217
secondary lymphoid tissues
sites where immune responses are carried out
218
mesenchymal cells
connective tissue, bone, cartilage, fat
219
220
2 things stem cells must be able to do
self renew and differentiate
221
ensuring cultured cells are embryonic stem cells
-karyotyping
-expression of pluripotent markers
-differentiate
-transplant
222
reproductive cloning
enucleated egg + nucleus from somatic cell = egg with transplanted nucleus which develops into a clone of the nucleus donor
223
what are yamanaka factors
OCT4
SOX2
KLF4
C-MYC
The original set of reprogramming factors
224
antigen recognition
immunoglobin (secreted antibody and BCR) recognise whole antigen
TCR recognises processed antigen fragments presented by MHC
225
antibody segments
variable regions of the antibody are made up of two or three gene segments - VJ (kappa or lambda light chain) or VDJ (heavy chain)
226
