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Cells, organisms and systems > 4.2 - The eukaryotic cell > Flashcards

4.2 - The eukaryotic cell Flashcards

1
Q

bacterium cell (4)

A
  1. cell wall
  2. cell membrane
  3. DNA (not in nucleus)
  4. flagellum
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2
Q

animal cell (4)

A
  1. fibroblast (DNA in nucleus)
  2. mitochondria
  3. many organelles
  4. cytoskeleton
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3
Q

plant cell (4)

A
  1. cell wall
  2. vacuole
  3. chloroplasts
  4. rigid
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4
Q

features of eukaryotic nucleus (3)

A
  1. nucleolus within nucleus produces ribosomal RNA
  2. double membrane penetrated by pores (allow transport in/out)
  3. ribosomes stud outer membrane
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5
Q

nuclear pore complex

A

gate through which selected macromolecules and larger complexes can enter/exit

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6
Q

protein nuclear localisation/export signals

A

signals in amino acid sequence, directs proteins to/out of nucleus

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7
Q

which nuclear signal do mRNAs have?

A

nuclear export signal

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8
Q

endoplasmic reticulum structure

A
  1. membranous network
  2. rough ER studded with ribosomes
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9
Q

role of endoplasmic reticulum (rough and smooth)

A

rough - protein synthesis (translation)
smooth - synthesis/ modification of lipids and storage of Ca2+ ions used in intracellular signalling

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10
Q

rough ER role in protein synthesis (3)

A
  1. ribosomes enter lumen of rough ER
  2. modified, re-folded and packaged into vesicles
  3. transported in vesicles to other parts of endomembrane system (often golgi)
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11
Q

golgi apparatus

A

involved in protein sorting and vesicle trafficking

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12
Q

how does the golgi apparatus transport components of the cell?

A

transport vesicles bud from one membrane and fuse with another, carrying membrane components and soluble proteins between compartments of endomembrane system and plasma membrane

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13
Q

endomembrane system

A

network of interconnected membranous organelles in eukaryotic cells

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14
Q

plasma membrane

A

phospholipid bilayer

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15
Q

exocytosis (2)

A
  1. vesicle fuses with plasma membrane
  2. releases content into cell’s surrounding
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16
Q

endocytosis (2)

A
  1. extracellular materials captured by vesicles that bud inward from plasma membrane
  2. carried into cell
    (can be receptor-mediated)
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17
Q

lysosomes

A

contain hydrolytic enzymes (promote hydrolysis)

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18
Q

role of lysosomes (2)

A
  1. each pathway leads to intracellular digestion of materials derived from a different source
  2. phagosomes can fuse with lysosomes to release lysosome enzymes, killing pathogen
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19
Q

vacuoles

A
  1. found in many cells, some prokaryotic many eukaryotic
  2. typically small, membrane bound storage compartments, variety of functions
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20
Q

main purpose of plant cell vacuole (large, central vacuole)

A

maintain turgor pressure within cell (can be adjusted with water uptake/loss)

21
Q

eukaryotic cell: single membrane organelles (4)

A
  1. endoplasmic reticulum
  2. golgi apparatus
  3. lysosome
  4. vesicles
22
Q

eukaryotic cell: double membrane organelles (3)

A
  1. nucleus
  2. mitochondria
  3. chloroplast
23
Q

fluid mosaic model

A
  1. proteins can be embedded/associated with membrane
  2. membrane proteins/phospholipids in outer membrane can be glycosylated (sugars attached)
  3. these carbohydrates protect and lubricate cell (also role in cell recognition and adhesion)
24
Q

role of proteins in phospholipid bilayer

A

mitigate permeability and transfer information

25
Q

why are phospholipid bilayers usually electrically polarised?

A

ion gradients across membrane

26
Q

functions of phospholipid bilayer (5)

A
  1. signalling
  2. import/export
  3. separating reactions
  4. generating proton gradient for ATP synthesis
  5. transmitting nerve signals etc
27
Q

amphipathic

A

phospholipid bilayer - hydrophilic head (phosphate group) and hydrophobic tail (fatty acids joined by glycerol)

28
Q

how do phospholipid bilayers form in aqueous environment?

A
  1. phospholipids spontaneously form bilayers - hydrophobic core and hydrophilic surface/vesicles
  2. nonpolar portions aggregate - fewer water molecules ordered (entropy increases)
  3. hydrophobic effect powers membrane formation
29
Q

what forces stabilise phospholipid bilayer membrane?

A

van der waals between hydrophobic tails

30
Q

phosphatidylcholine (2)

A
  1. major component of most eukaryotic membranes
  2. head of choline + phosphate, 2 fatty acid chains linked by glycerol
    (many prokaryotes can’t synthesise this lipid)
31
Q

what does the presence of C=C bonds introduce in phospholipid bilayers

A

create kinks in fatty acid tails

32
Q

role of cholesterol in phospholipid bilayer membrane (3)

A
  1. can fill spaces between phospholipid molecules generated by kinks
  2. “buffers” membrane fluidity
  3. different effects depending on temperature
33
Q

archaeal membranes

A

better membrane stability by ether linkages and branching structures prevent hydrolysis and oxidation of membranes

34
Q

archaeal membrane composition

A

isoprenoid tetraethers with unique alcohols (differs from glycerol)

35
Q

what determines whether lipid bilayer is gel or fluid phase?

A

composition and temperature

36
Q

phospholipid bilayer gel phase

A

molecules cant move around

37
Q

phospholipid bilayer fluid phase

A

molecules can move around

38
Q

membrane more fluid-like or gel-like under physiological conditions?

A

fluid-like

39
Q

melting point

A

temperature at which membrane transitions from highly ordered to very fluid
(dependant on length of fatty acids in membrane, lipid and degree of cis uncaturation)

40
Q

higher temp membrane requirements

A

need more long, saturated fatty acids

41
Q

lower temp membrane requirements

A

need more unsaturated fatty acids

42
Q

membrane permeability

A

permeable to small nonpolar molecules that can passively diffuse through. impermeable to polar molecules and ions

43
Q

passive diffusion

A

transport of solutes influenced by both concentration gradient and membrane potential

44
Q

where may passive diffusion occur

A

channels or transporters

45
Q

active transport

A

requires energy input to move against concentration gradient

46
Q

where can active transport be performed

A

transporters

47
Q

membrane fusion (2)

A
  1. membranes can fuse without exposure of lipids to aqueous solvent (membrane faces conserved)
  2. spontaneous or protein mediated
48
Q

what allows release of molecules such as neurotransmitters from cell?

A

fusion of internal membranes with plasma membrane

Cells, organisms and systems (26 decks)

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