Eukaryotic cell 1 & 2 Flashcards

1
Q

cell consists of 2 main components

A

nucleus and cytoplasm

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2
Q

largest structure

A

nucleus

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3
Q

nucleus contains

A
  • DNA organized in chromosomes
  • nucleoproteins
  • newly synthesized RNA
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4
Q

nucleoproteins involved in

A

DNA and RNA synthesis and folding of DNA

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5
Q

2 forms of DNA in nucleus

A

heterochromatin and euchromatin

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6
Q

heterochromatin

A

dark, clumped peripherally, silenced (not involved in RNA synthesis)

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7
Q

euchromatin

A

light, scattered, actives (involved in RNA synthesis)

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8
Q

nucleus is bound by

A

nuclear envelope

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9
Q

nuclear envelope

A
  • 2 concentric membranes, - continuous with the ER,
  • contains pores to allow movement of substances between nucleus and cytoplasm
  • consist of nucleoporins
  • become leaky w age
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10
Q

nucleolus

A
  • roughly spherical in nucleus
  • involved in ribosomal RNA synthesis and ribosome assembly
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11
Q

nucleolus consists of

A
  • nucleonema; dense, darkly staining, partially assembled ribosomes
  • pars amorpha; DNA coding for rRNA
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12
Q

main organelles in cytoplasm

A
  • ER
  • golgi apparatus
  • ribosomes
  • mitochondria
  • lysosomes
  • centrioles
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13
Q

ER latin

A

rete means net

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14
Q

ER

A

network of membranes, connected to nuclear envelope

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15
Q

2 types of ER

what are each involved in

A

smooth and rough

rough are studded w ribosomes; involved in protein synthesis and modification and packaging of proteins before transport to golgi

smooth; no ribosomes and involved in synthesis and storage of phospholipids, cholesterol, glycerides, glycogen and steroids, also involved in drug detoxification and calcium storage (muscle)

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16
Q

ribosomes are responsible for

A

protein assembly: structural, chemical messengers, enzymes

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17
Q

increased protein production requires more

A

ribosomes

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18
Q

ribosomes consist of

A

rRNA and protein

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19
Q

ribosomes pathway

A

synthesized in nucleus
assembled in nucleolus
transferred to cytoplasm

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20
Q

ribosomes can be

A

free (single unit) or poly-ribosomes

*** listen to lec for this part

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21
Q

golgi apparatus consist of

A

series of membranous sacks called cisternae

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22
Q

golgi apparatus communicates

A

w ER and cell surface via vesicles

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23
Q

major functions of golgi apparatus include (3)

A
  • modification and packaging of secretory products (hormones and enzymes)
  • synthesis of glycoproteins and glycolipids for cell membrane
  • packages enzymes for use within the cell
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24
Q

mitochondria shape

A

sherical to rod-shaped

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25
Q

mitochondria have their own

A

DNA so can self replicate

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26
Q

mitochondria supply

A

cell’s energy, numbers proportional to cell’s metabolic activity

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27
Q

mitochondria membrane

A
  • double; outer and inner
  • inner folded into cristae to increase SA, site of energy production, ATP formed within matrix (oxidative phosphorylation)
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28
Q

mitochondria evolved from

A

bacteria that were engulfed by another single-celled organism

allowed a switch from inefficient process of oxidative phosphorylation

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29
Q

all mitochondrial DNA inherited from your

A

mother

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30
Q

mitochondria also key regulators of

A

apoptosis (cell death)

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31
Q

lysosomes produced by

A

golfi apparatus

round membrane-bound vesicles

32
Q

lysosomes contain around

A

50 types of acid hydrolases (digestive enzymes)

33
Q

lysosomes functions 93)

A
  • degrade defunct organelles
  • digest carbs, lipids, proteins, nucleic acids
  • kill intracellular microorganisms
34
Q

primary lysosomes

A

inactive enzymes

(primary becomes secondary becomes residual body)

35
Q

secondary lysosome

A
  • fused w damaged organelle (autophagy)
  • phagocytosed material (phagocytosis)
  • activated enzymes
36
Q

residual body lysosome

A
  • exhausted lysosome
  • filled w undigested debris
  • extruded from cell or remains as lipofuscin granules (increase w age)
37
Q

centrioles, how many

A

usually 2, near nucleus, in centrosome
aligned at right angles to each other

38
Q

centrioles are

A

cylindrical structures composed of microtubules (9 microtubule triplets)

organizing centres for microtubules; cell division and cytoskeleton of the cell

39
Q

cytoskeleton is

A

framework of several types of proteinaceous filament and tubules within the cell

40
Q

cytoskeleton consist of

A
  • microfilaments (5nm diameter, actin)
  • microtubules (25 nm, tubulin)
  • intermediate filaments (10-12 nm mainly keratins)
41
Q

biological membranes are permeable to

A

lipid soluble molecules, but not to lipid insoluble

42
Q

principle functions of biological membranes

A

protection
absorption and transport
adherence
compartmentalization
providing internal SA
cell to cell communication

43
Q

structure of biological membranes

A
  • semi-fluid phospholipid bilayer
  • hydrophilic heads on the surfaces
  • hydrophobic tails in between
44
Q

integral proteins

A

embedded in the bilayer

some span entire width of membrane: transmembrane proteins

45
Q

peripheral proteins

A

bound to membrane surface

46
Q

plasma membrane PROTEIN functions

A

anchoring
cell recognition
enzymes
carriers
channels

47
Q

carrier vs channel

A
  • carrier; move substances across membrane
  • channel; movement of water and ions across the membrane (like a pore)
48
Q

cholesterol molecules are embedded within the _____ region of the bilayer

A

hydrophobic

49
Q

on the extracellular surface of the membrane there are

A

glycoproteins and glycolipids

the carb chains extend into extracellular environment and form the glycocalyx

50
Q

glycocalyx functions

A
  • cell recognition
  • adhesion
  • adsorption of molecules
  • mechanical and chemical protection
51
Q

specializations of plasma membrane: tight junctions aka occluding junctions

A
  • located beneath apical surface of cell
  • partial fusion of lipids of adjacent cells’ membranes
    block the passage of solutes into intercellular spaces
  • each tight junction forms a band around apical portion of cell; zonula occludens
52
Q

desmosomes

A
  • adhering or anchoring junctions
  • membrane proteins or proteoglycans bind the adjacent cell
  • linked to cytoskeleton
  • strong
53
Q

zonula adherens (belt desmosome)

A

continous band just below the tight junctions

54
Q

macula adherens (spot desmosome)

A

spots arranged circumferentially

55
Q

hemidesmosomes

A

between basal protion of cell and basement membrane in epithelial cells

56
Q

zonula occludens + zonula adherens + macula adherens=

A

junctional complex

57
Q

gap junctions (communication junctions)

A

2 cells locked together by membrane proteins (connexins)
form channels for movement of molecules such as ions, nutrients and signalling chemicals (large organelles such as mitochondria cannot pass)

58
Q

luminal surface specializations: microvilli

A

short finger like projections of plasma membrane
increase SA fro absorption
brush border
epithelial cells

59
Q

luminal surface specializations; sterocilia

A
  • NOT CILIA
  • long microvilli; branch and anastomose
  • increase SA for absorptions
60
Q

luminal surface specializations; cilia

A
  • long
  • wavelike, synchronous motility –> propels fluid, mucus
  • 9 microtubule doublets are a central pair (9+2)
  • at their base is a basal body, v similar to a centriole
61
Q

passive diffusion

A
  • lipids, lipid soluble molecules (alcohol, steroids)
  • hydrophilic molecules and ions pass at transmembrane protein channels
  • down a concentration gradients
  • no energy expended
62
Q

facilitated diffusion

A
  • larger hydrophilic molecules; too big for membrane channels, bind to carrier proteins
  • rate of transport is determined by number of carrier proteins
  • down a concentration gradient
  • no energy expended
63
Q

active transport

A
  • transport molecule across membrane irrespective of concentration gradient
  • ATP required
64
Q

endoxytosis

A
  • inward bulk transport
  • extracellular material is packaged into a vesicle at the cell’s surface
  • cell membrane bulges inwards forming pseudopodia and pinches off to form vesicle
  • vesicles fuse with lysosomes
65
Q

endocytosis; pinocytosis

A

extracellular fluid

66
Q

endocytosis; phagocytosis

A

extracellular solid material including bacteria

67
Q

receptor-mediated endocytosis

A

receptors within a clathrin -coated pit on cell surface bind specific molecules
form a clathrin-coated vesicle

68
Q

exocytosis

A
  • outward bulk transport
  • expelled material may be waste or secretory products (proteins, steroid, lipids)
69
Q

exocytosis; proteins released form cell one of 2 ways:

A
  • constitutive secretion; continuoulsy in coated vesicles
  • regulated secretion; stored in vesicles until signalled for release
70
Q

exocytosis; steroid and lipids leave the cell by

A

passive diffusion or are stored until bulk release

71
Q

apoptosis

A
  • genetically programmed cell death
  • common in embryonic tissue
  • response to genetic errors
  • absent in tumour cells
72
Q

2 pathways of apoptosis

A
  • intrinsic; stress, UV radiation, DNA damage, activates signalling cascade within mitochondria
  • extrinsic; initiated via death ligands, soluble, bound to cytotoxic T cells
73
Q

necrosis

A
  • cells exposed to conditions that they cannot tolerate and die
  • uncontrolled cell death
  • lysis of cells
  • inflammatory response
74
Q

which of the following statements about eukaryotic cells is incorrect

the nucleolus contain heterochromatin and euchromatin, both responsible for ribosomal RNA synthesis

The Golgi apparatus is involved in the synthesis of the glycoproteins and glycolipids that form the cell membrane

Nuclear morphology is distinct for different cell types and can be used to identify cells that are abnormal, including those that are neoplastic

The smooth endoplasmic reticulum synthesises phospholipids and steroid hormones, and in muscle cells is an important store of calcium ions

A

the nucleolus contain heterochromatin and euchromatin, both responsible for ribosomal RNA synthesis

75
Q

Which of the following statements about eukaryotic cells is INCORRECT?

Transmembrane integral proteins can function as channels and carrier proteins to move ions and compounds across the plasma membrane

Characteristics of the glycocalyx on the surface of red blood cells determines blood type (i.e., A, B, O, and AB)

Gap junctions consist of connexin proteins that form channels between cells for the movement of ions, nutrients, and signalling molecules

Desmosomes are located immediately below the apical surface of the cell, where they form a tight band to block the passage of solutes into the intercellular space

A

Desmosomes are located immediately below the apical surface of the cell, where they form a tight band to block the passage of solutes into the intercellular space

76
Q

Which of the following statements about eukaryotic cells is INCORRECT?

Mitochondria produce ATP within their matrix and the number within a cell reflects the cell’s metabolic activity; they are also key regulators of apoptosis

Characteristics of the glycocalyx on the surface of red blood cells determines blood type (i.e., A, B, O, and AB)

Gap junctions consist of connexin proteins that form channels between cells for the movement of ions, nutrients, and large molecules (i.e., glucose)

Lysosomes are vesicles that contain acid hydrolases that digest phagocytosed material and degrade defunct organelles

A

Gap junctions consist of connexin proteins that form channels between cells for the movement of ions, nutrients, and large molecules (i.e., glucose)