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eukaryotic 9/24 Flashcards

1
Q

what are eukaryotic microorganisms

A
  • Prominent members of ecosystems
  • Useful as model systems and industry
  • Some are major human pathogens
  • two groups

–Protists – protozoa, algae, slime molds

–Fungi

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2
Q

common features of eukaryotic cells

A
  • Unit membrane-delimited nuclei
  • Unit membrane-bound organelles that perform specific functions
  • Intracytoplasmic, unit membrane complex serves as transport system
  • More structurally complex and generally larger than bacterial or archaeal cells
  • Organelle – structure surrounded by one or two unit membranes with 1 or more functions
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3
Q

what is the eukaryotic cell envelope

A

consists of cell membrane and all coverings external to it

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4
Q

what is the eukaryotic cell membrane made of

A

•Cell membrane - lipid bilayer (~ 85%) with proteins (~14 %) and carbohydrates (~1%)

–Lipid bilayer consists of:

–Phospholipid bilayer and other lipids located in hydrophobic interior

•major membrane lipids include phosphoglycerides, sphingolipids, cholesterol and other sterols, all of which contribute to strength of membrane (next slide)

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5
Q

what proteins are found in the eukaryotic cell membrane

A

–transmembrane and integral; many on environmental side of membrane are glycoproteins (have carbohydrate portions attached)

-Functions: similar to prokaryotes but no little or no role in energy metabolism

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6
Q

cell walls in algae, fungi, and protozoa

A

•Algae and fungi have cell walls; protozoa do not have cell walls

–cell walls of photosynthetic algae have cellulose, pectin, or silica as strengthening molecules

–cell walls of fungi have cellulose, chitin, or glucan as strengthening molecules

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7
Q

cytoplasm of eukaryotes

A
  • 90-94 % water with many dissolved solutes; contains cytoskeleton
  • Cytoskeleton

–network of interconnected filaments within the cytoplasmic matrix

–filaments that form the cytoskeleton: microfilaments (actin), microtubules (made of α & β tubulin), intermediate filaments, and motor proteins

–plays role in cell shape, cell movement, mitosis/meiosis, attachment site

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8
Q

what are microfilaments

A
  • Small protein filaments, 4 to 7 nm in diameter
  • Scattered within cytoplasmic matrix or organized into networks and parallel arrays
  • Composed of actin protein
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9
Q

what are intermediate filaments

A
  • Heterogeneous elements of the cytoskeleton, ~10 nm in diameter
  • Keratin and vimentin classes
  • Exact role in cell is unclear

–May play structural role

–some shown to form nuclear lamina

–others may help link cells together to form tissues

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10
Q

what are microtubules

A
  • Thin hollow cylinders ~25 nm in diameter; composed of α - and β-tubulin dimer
  • Functions:

–Helps maintain cell shape

–Involved with microfilaments in cell movements

–Participate in intracellular transport processes

–Plays role in mitosis/meiosis

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11
Q

organelles of the secretory endocytic pathway

A

•Complex of membranous organelles and vesicles that move materials into the cell from outside, from inside to outside, and within the cell

–Endoplasmic reticulum (ER)

–Golgi apparatus

–Lysosomes

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12
Q

what is the er

A

•Irregular network of branching and fusing unit membranous tubules and flattened sacs (cisternae – s., cisterna)

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13
Q

rough ER

A

–ribosomes attached

–Function - synthesis of secreted proteins, cell membrane proteins and those going into organelles by ER-associated ribosomes

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14
Q

smooth ER

A

–devoid of ribosomes

–Function - synthesis of lipids and carbohydrates by ER-associated enzymes

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15
Q

functions of ER

A
  • Transports proteins, lipids, and other materials within cell
  • Major site of cell membrane synthesis
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16
Q

golgi apparatus

A
  • Unit membranous organelle made of cisternae stacked on each other
  • cis and trans faces
  • dictyosomes

–stacks of cisternae

•Function - modification, packaging, and secretion of materials

-cis face starts and materials move away from it

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17
Q

lysosomes

A
  • Unit membrane-bound vesicles found in most eukaryotes
  • Involved in intracellular digestion
  • Contain hydrolases, enzymes which hydrolyze molecules and function best under slightly acidic conditions
  • Maintain an acidic environment by pumping protons into their interior
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18
Q

secretory pathway general

A
  • Moves materials to various sites within the cell, as well as to either the plasma membrane or cell exterior
  • Proteins destined for the cell membrane, endosomes, and lysosomes or secretion are synthesized by ribosomes on rough endoplasmic reticulum (RER)
  • These enter the RER lumen and are released in small budding vesicles from RER
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19
Q

what is intracellular movement of the secretory pathway guided by

A

cytoskeleton

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20
Q

pathway of vesicles/golgi

A

•Released in small vesicles à cis face of Golgi apparatusà trans face of Golgi apparatus

–modification of proteins occurs in Golgi; targets protein for final destination

  • Transport vesicles released from trans face of Golgi
  • After release some vesicles deliver their contents to endosomes and lysosomes
  • Two types of vesicles deliver proteins to cell membrane

–constitutive delivery to membrane

–Secretory vesicles in multicellular eukaryotes store proteins until signal to release

21
Q

what is endocytosis

A

–all eukaryotic cells

–used to bring materials into the cell to big to go through transport proteins

–solutes or particles taken up and enclosed in vesicles pinched from plasma membrane

–in most cases materials are then delivered to lysosome and destroyed

22
Q

what is phagocytosis

A

•– only in cells without walls

–use of cell surface protrusions (pseudopods) to surround and engulf particles

–fuse with lysosomes and resulting vesicles called phagosomes

23
Q

what is clathrin dependent endocytosis

A

–involves membrane regions coated on cytoplasmic side with the protein clathrin (coated pits)

–coated pits have external receptors that specifically bind macromolecules

–pinching off of coated pits forms coated vesicles

–Type of receptor-mediated endocytosis

24
Q

caveolae dependent endocytosis

A

–enriched in cholesterol and the membrane protein caveolin

–when caveolae pinch off membrane are called caveolar-coated vesicles

–do not deliver their contents to lysosomes

–may play role in signal transduction, transport of small as well as macromolecules

25
what is autophagy
* Delivery of materials to be digested by route that does not involve endocytosis * Macroautophagy involves digestion and recycling of cytoplasmic components * Double membrane surrounds cell component forming an autophagosome * Autophagosome fuses with a lysosome
26
what are lysosomes
* Digestion occurs without release of lysosome enzymes into cytoplasmic matrix * As contents are digested, products leave lysosome and can be used as nutrients * Resulting lysosome called a residual body which can release contents to cell exterior by process called lysosome secretion
27
what organelles are involved in genetic control of cell
nucleus and ribosome
28
what is the nucleus
* Double unit membrane-bound spherical structure containing genetic material * Contains dense fibrous material called chromatin –complex of DNA, histones, and other proteins –five types of histones form nucleosomes •H1, H2A, H2B, H3, and H4 –chromatin condenses into chromosomes during division
29
what is the nuclear envelope of the nucleus
•Nuclear envelope –double membrane structure that delimits nucleus –continuous with ER –penetrated by nuclear pores * associated proteins make up the nuclear pore complex * pores allow materials to be transported into or out of nucleus
30
what is the nuclear envelope
–double unit membrane structure that delimits nucleus –continuous with ER –penetrated by nuclear pores * associated proteins make up the nuclear pore complex * pores regulate what materials are to be transported into or out of nucleus
31
what is the nucleolus
* 1 or more nucleolus/nucleus * Organelle but not membrane enclosed * Important in ribosome synthesis –directs synthesis and processing of rRNA –directs assembly of rRNA to form partial ribosomal subunits –ribosomes mature in cytoplasm
32
size and attachment of eukaryotic ribosomes
* Larger than the 70S bacterial and archaeal ribosomes * 80S in size –60S + 40S subunits * Some attached to ER; others attached to cytoskeleton * 60S is bound subunit to ER
33
Proteins made on ribosomes of RER are
•secreted out from cell, or inserted into cell membrane, or transported into organelles
34
what do ribosomes attached to the cytoskeleton do
•synthesize nonsecretory and nonmembrane proteins –some proteins are inserted into organelles
35
what organelles are involved in energy conservation
Mitochondria Hydrogenosomes Chloroplasts
36
what are mitochondria
•Involved in energy metabolism –Site of most of aerobic cellular respiration –Most ATP made here * About the same size as bacterial cells * Reproduce by binary fission as do bacterial cells * Variable number per cell
37
what are the outer and inner membranes of the mitochondria
•Outer membrane –contains transport porins similar to the outer membrane of gram-negative bacteria •Inner membrane –highly folded to form cristae (s., crista) –location of enzymes and electron carriers for electron transport and oxidative phosphorylation
38
what is the mitochondrial matrix
•Matrix enclosed by inner membrane –contains ribosomes (same size as bacterial), mitochondrial DNA (may be closed circular like bacterial DNA), and large calcium phosphate granules –contains enzymes of the tricarboxylic acid cycle and enzymes involved in catabolism of fatty acids
39
what are hydrogenosomes
* Small energy conservation organelles in some anaerobic protists * Descended from common mitochondrial ancestor –double membrane, no cristae, usually lack DNA –ATP is generated by fermentation process rather than respiration –CO2, H2, and acetate are products
40
what is a chloroplast
•Type of plastid –pigment-containing organelles observed in plants and algae * Site of photosynthetic reactions * Surrounded by double unit membrane
41
what is the stroma
•chloroplast Stroma (a matrix) is within inner membrane –contains DNA, ribosomes, lipid droplets, starch granules, and thylakoids •thylakoids –flattened, membrane-delimited sacs –grana (s., granum) – stacks of thylakoids –site of light reactions (trapping of light energy to generate ATP, NADPH, and oxygen) •Stroma is site of dark reactions of photosynthesis (formation of carbohydrates from water and carbon dioxide)
42
Algal chloroplasts many contain
•a pyrenoid –participates in polysaccharide synthesis
43
what is part of the external cell covering
Cilia Flagella Pseudopods
44
how long is the cilia and how does it work
•(s., cilium) –5-20 μm long –beat with two phases, working like oars
45
what is the length and movement of the flagella
•(s., flagellum) –100-200 μm long –move in undulating fashion * tinsel – tip pulls cell along * whiplash – naked flagellum
46
what is the ultrastructure of flagella and cilia
* Unit membrane-bound cylinders ~2 μm in diameter * Axoneme –set of microtubules in a 9 + 2 arrangement •Basal body –at base of flagellum or cilium –directs synthesis of flagella and cilia
47
what are pseudopods
* cytoplasmic extensions surrounded by cell membrane with structure maintained by cytoskeleton, mainly microfilaments * Found in some protozoa
48
differences in euk cells
–eukaryotic nucleus –larger, more complex –meiosis, mitosis –complex processes
49
•Molecular unity basic to all three cells
–biochemical processes, metabolic pathways –genetic code

microbiology (11 decks)

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