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BL1011- Fundamentals of Biosciences > Cell Structure > Flashcards

Cell Structure Flashcards

1
Q

what are the 3 fundamentals of cell theory?

A
  1. cells are the structural and organisational unit of life
  2. all living organisms are composed of cells
  3. all cells come from pre-existing cells
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2
Q

how do prokaryotes and eukaryotes differ?

A

eukaryotes- nucleus, larger, introns, histones, linear DNA, membrane-bound organelles, 80S ribosomes, mitosis/meiosis
prokaryotes- no nucleus, smaller, no introns, no histones, circular DNA, no membrane-bound organelles, 70S organelles, binary fission

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3
Q

what are the types of animal cells

A

muscle tissue
nervous tissue
epithelial tissue
connective tissue

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4
Q

what are the types of myocytes?

A

skeletal
cardiac (highly contractive)
smooth (involuntary movement)

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5
Q

what types of neural cells are there?

A

neurons
neuroglia (maintain axon health/structure)
dendrites
axon

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6
Q

what types of connective cells are there? what do they do?

A

adipose tissue
blood
bone
protect organs
make ligaments/tendons
interacts with other cells

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7
Q

what types of epithelial cells are there?

A

simple (monolayer)
stratified (multiple layers)
pseudostratified (disorganised monolayer)
squamous (oval)
cuboidal (square)
columnar (rectangular)

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8
Q

how does the small intestine increase its surface area?

A

plicae extensions-> villi-> microvilli
so more interactions with the lumen

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9
Q

how does a brightfield microscope work?

A

focusses light through a lens onto slide

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10
Q

what are the advantages to a brightfield microscope?

A

cheap
Can use living cells

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11
Q

what are the disadvantages of a brightfield microscope

A

stains have a lack of contrast
low resolution
staining takes time

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12
Q

how does the process of cell fractionation work?

A

a strong rotational centrifugation force separates materials according to their mass
cell is homogenated to break cells open
mixture is strained to remove connective tissue/unopened cells
centrifuge at low speed to get pellet of less dense organelles (600G)
centrifuge at higher speed to gain pellet of more dense organelles (15,000G)

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13
Q

what does the plasma membrane do?

A

maintains cell integrity/signalling
transports substances as selectively permeable
separates living cells from surrounding

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14
Q

what is the structure of phospholipids?

A

negatively charged, hydrophilic phosphate head
non-polar, hydrophilic fatty acid tail
1 glycerol, 2 fatty acids, 1 phosphate group

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15
Q

what is the structure of the phospholipid bilayer?

A

hydrophilic head pointing outside to keep water out of cell
hydrophobic tail pointing inside
asymmetrical on each side so the cell can bend into different shapes

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16
Q

what are the two major phospholipids on the outer leaflet?

A

phosphatidylcholine
sphingomyelin

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17
Q

what are the two major phospholipids on the inner leaflet?

A

phosphatidylethanolamine
phosphatidylserine

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18
Q

how do the presence of unsaturated fatty acids increase fluidity?

A

double C=C bond prevents tight packing of phospholipids

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19
Q

how does temperature affect fluidity?

A

high temperatures- more fluid as interactions are overcome
low temperatures- more interactions (van der Waals) so less fluid

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20
Q

what is the structure of micelles?

A

all the hydrophilic heads on the outside
forms a sphere
makes up liposome

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21
Q

what is the structure of micelles?

A

all the hydrophilic heads on the outside
forms a sphere
makes up liposome

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22
Q

what is the structure of cholesterol?

A

intercalated into lipid bilayer
has fatty acid tail

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23
Q

what is the function of cholesterol?

A

makes bilayer less deformable so less permeable
prevents phase shifts
stops phospholipids packing too tightly at low temperatures
holds phospholipids together at high temperatures

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24
Q

what property are both the phospholipid bilayer, micelles, and cholesterol?

A

amphipathic

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25
what is the function of glycolipids/glycoproteins?
help with cell-cell recognition help cell sorting to form tissues help with migration help with foreign cell detection used as identification marker
26
what are the three types of membrane proteins?
integral transmembrane peripheral
27
what do integral membrane proteins look like?
partially embedded in plasma membrane
28
what do transmembrane proteins look like?
fully across all of the bilayer
29
what do peripheral membrane proteins look like?
not touching the membrane, but on other proteins associated with the membrane
30
what are the 4 types of transporter membrane proteins?
anchor transporters receptors enzymes
31
what are the functions of transporter proteins?
allow water soluble molecules to go through membrane release chemicals e.g. neurotransmitters
32
what are the functions of anchor proteins?
linked to cytoskeleton
33
what are the functions of receptors?
involved in cell signalling collects information from the outside to send to the inside
34
what are the functions of enzymes
transform to make energy activated by inner/outer substrate
35
what are the two types of transporter proteins?
antiporter symporter
36
what is the function of antiporters? what example can we use?
two channels one entering one exiting used for K+/Na+ for depolarisation
37
what is the function of symporters? what example can we use?
two channels both entering cell glucose/Na2+ for cotransport
38
what is the cytoskeleton?
network of filament proteins that extend from the cell nucleus to the membrane provide structure of the cell provides transport for organelles
39
what 3 filaments is the cytoskeleton made of?
intermediate filaments actin filaments microtubules
40
what is the structure of intermediate filaments?
strong, rope-like extends throughout the cytoplasm and nucleus anchored to desmosomes (cell-cell junctions) and hemidesmosomes (cell-matric junctions) central rod-like domain with c-terms (carboxyl group) and n-term (amine group)
41
what is the function of intermediate filaments?
protect cell from mechanical stress helps with stretching keratins (strengthens epithelia) vimentin (strengthens connective tissue, muscle cells, glia) neurofilaments (strengthens nerve cells) lamins (strengthens nucleus)
42
what is the structure of microtubules?
long, hollow tubes stiff extend from centrosome pair composed of a-tubulin (-ve) and b-tubulin (+ve) dimers that stack to form protofilaments 13 parallel protofilaments form hollow tubule
43
what is the function of microtubules?
movement of vesicles, organelles, other cell components migration of chromosomes cell movement (flagella/cilia) organelle structure) exo/endocytosis provides direction
44
what is a centrosome?
also known as microtubule organising centre (MTOC) anchors microtubule network enriched in y-tubulin rings
45
what is dynamic instability?
microtubules stop growing and shrink
46
how do cancer treatments cause dynamic instability?
taxol blocks activity at positive end of microtubule so prevents polymerisation vincristine binds to tubulin at the negative end so no polymerisation, only depolymerisation
47
what is the structure of actin?
what is the structure of actin?
48
what is the function of actin?
rapidly polymerises/depolymerises forms permanent structures (microvilli) related to motor protein myosin for muscle contraction
49
what is the extracellular matrix? what makes it up?
part of support tissue for organs collagen elastic fibres (elastin) proteoglycan glycosaminoglycan glycoproteins growth factors linked to connective and epithelial cells
50
what are the five types of cell junctions/adhesions?
tight junctions adherend junctions gap junctions focal adhesions hemidesmosomes desmosomes
51
what are the functions of tight junctions?
ensure cell-cell cohesion at the apical membrane prevent protein diffusion between basal and apical side
52
what is the basal side of epithelial cells?
faces tissue
53
what is the lateral side of epithelial cells?
faces adjacent cell
54
what is the apical side of epithelial cells?
faces lumen
55
what are the functions of adherend junctions/desmosomes?
attachment via cytoplasmic plaque cell belt maintains cell shape stud-like structure adherend=actin filament desmosome=intermediate filament
56
what is the function of gap junctions?
channels for cell-cell communication channels open/close
57
what is the function of focal adhesion matrix?
cell anchorage stress fibre
58
what is the function of hemidesmosomes?
attachment to extracellular matrix
59
what is the endomembrane?
series of membrane-bound organelles evolved from the plasma membrane by invagination
60
how do plant and animal cells differ?
plant- rectangular, chloroplasts, singular large vacuole, cell wall animal- round/irregular, lysosomes, cilia, multiple small vacuoles, only cell membrane
61
what makes up the secretory pathway?
endoplasmic reticulum Golgi body vesicles
62
what is the secretory pathway?
what is the secretory pathway?
63
what is the structure of the endoplasmic reticulum?
series of hollow tubules, vesicles, cisternae in contact with nuclear envelope phospholipid bilayer
64
what is the structure of the rough endoplasmic reticulum?
studded with ribosomes for protein synthesis
65
what is the structure of the smooth endoplasmic reticulum?
no ribosomes tubular periphery of the cell
66
what is the function of the smooth endoplasmic reticulum?
lipid synthesis calcium homeostasis liver detoxification
67
what is the sarcoplasmic reticulum?
specialised smooth endoplasmic reticulum stores and releases Ca2+ for muscle contraction
68
what happens when proteins leave the endoplasmic reticulum?
proteins fuse together part of membrane wraps around and buds off leave in COP-coated vesicles that contain some of the secretary proteins and transmembrane fuses with Golgi, transported by microtubules
69
what is the structure of the Golgi body?
cisternae= series of flattened sacs cis Golgi= side of Golgi facing endoplasmic reticulum medial Golgi= middle of Golgi Trans Golgi= side of Golgi facing cell membrane
70
what is the function of the Golgi body?
post-translation/carbohydrate modification sorts proteins into vesicles for transport to membrane, endosomes or lysosomes
71
how does the protein travel through the Golgi? How does the Golgi change?
cis turns into medial into trans Golgi as protein moves through trans Golgi buds off into vesicle vesicle goes to new location
72
what are the two types of secretion?
constitutive secretion regulated secretion
73
what is constitutive secretion?
continuous secretion uncontrolled serum proteins (albumin) extracellular matrix proteins (collagen)
74
what is regulated secretion?
proteins are packaged into dense secretory granules granules stored in cytoplasm released upon stimulation (hormones, depolarisation)
75
what is the endocytic pathway?
part of the endomembrane system internalisation recycling degradation of transmembrane proteins/extracellular materials
76
what is involved in the endocytic pathway?
endocytic vesicles endosomes lysosomes
77
how do extracellular materials get into the cell?
large, polar molecules can't pass through cell membrane pit formation on cell membrane inward budding neck closure vesicle formation
78
what is phagocytosis?
bigger molecules (250nm) uses specialised cells (e.g. macrophages destroy pathogens pathogens are engulfed
79
what is pinocytosis?
small, fluid vesicles are engulfed
80
what are early endosomes?
just beneath plasma membrane protein sorting site returns useful cargo to plasma membrane/Golgi sends cargo for destruction to lysosome
81
what are late endosomes?
closer to nucleus early endosomes matured fuse with lysosome mediates final sorting and preparation for cargo destruction
82
what happens to the pH of the endosomal pathway as you go down
endosomes are acidic as pump H+ into membrane endosomal pathway gains a lower pH
83
what are lysosomes
contain hydrolytic enzymes low pH useful molecules transported out of lysosome and to cytosol very glycosylated for protection
84
what is receptor mediated endocytosis
uses receptors that bind to protein ensures the cell is getting what they want uses clathrin coated vesicles
85
what is autophagy?
cell destroys its own organelles and components vesicle creates autophagosome fuses with lysosome degradation
86
what are the 5 key structures of the mitochondria?
cristae outer membrane inner membrane matrix intermembrane space
87
what are the 4 key structures of the chloroplast?
thylakoid (grana) stroma (matrix) inner membrane outer membrane
88
what are the key features of mitochondria?
number and position depend on type of cell e.g. sperm can form chains can change shape if under stress can move out of the cell contain their own circular DNA contain RNA and transcription/translation machinery
89
what is the function of the mitochondria's outer membrane?
contains larger porins (transmembrane channel-forming proteins) porous
90
what is the function of the mitochondria's inner membrane
folded into cristae contains proteins that carry out oxidative reactions of the electron transport chain not porous
91
what is the function of the mitochondria's matrix
concentrated mixture of enzymes enzymes for pyruvate oxidation enzymes in citric acid cycle aerobic respiration contains circular DNA for protein synthesis
92
what is the function of the mitochondria's intermembrane space?
contains enzymes that use ATP passing out of the matrix to phosphorylate nucleotides
93
what is the function of the chloroplast's inner membrane?
site of photosynthesis
94
what is the function of the thylakoids
stacked into granum harness light energy to produce ATP and NADPH to power sugar production from oxyge
95
what is the function of the chloroplast's stromal matrix
houses the enzymes for trapping carbon dioxide
96
what are peroxisomes?
rich in enzymes break down fatty acids, amino acids, toxins, producing hydrogen peroxide contain catalase to break this down site of cholesterol synthesis produce bile acids in liver cells
97
what are proteosomes
not membrane bound large macromolecular complex degrades unwanted proteins in the cytosol q
98
what is a ribosome?
not membrane bound site of translation contains rRNAs made of small and large unit small unit- 30 proteins, 1 rRNA large unit- 40 proteins, 3 rRNA
99
what is the nucleus?
contains and protects DNA co-ordinates cell activity all DNA in one place so can ensure right genes are transcribed at the right time
100
what is the nucleolus?
non membrane contains gene encoding for rRNA sit of rRNA synthesis and assembly of ribosomes
101
what is chromatin?
DNA and specialised packaging proteins (histones) visible as chromosomes during cell division
102
what do histones do?
organises DNA double helix to form chromatin allows DNA to be unwrapped at specific places for transcription of specific genes
103
what is the nuclear envelope?
prevent nuclear damage inner membrane provides anchoring for nuclear lamina- contains network of lamins continuous with endoplasmic reticulum
104
what is the nuclear pore complex?
made of proteins that allow substances in/out octagonal 8 filaments project into cytoplasm 8 filaments project into nucleoplasm join to form nuclear basket

BL1011- Fundamentals of Biosciences (5 decks)

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