Chapter 5

Question 1

Common features of eukaryotic cells

Answer 1

-unit membrane delimited nuclei. unit membrane bound organelles that perform specific functions. Intracytoplasmic, unit membrane complex serves as transport system. Structurally complex, generally larger than bacterial or archaeal cells. Organelle= structure surrounded by one or two unit membranes with 1 or more function.

Question 2

Eukaryotic cell membrane

Answer 2

Cell membrane is a 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

Question 3

Eukaryotic Cell membrane proteins

Answer 3

transmembrane and integral; many on environmental side of membrane are glycoproteins (have carbohydrate portions attached)
Functions:similar to prokaryotes but little or no role in energy metabolism

Question 4

Eukaryotic cell envelope

Answer 4

algae and fungi have cell walls, protozoa do not have cell walls. Cell walls of photosynthetic algae have cellulose, pectin, and silica as their strengthening molecules. Cell walls of fungi have cellulose, chitin, or glucan as their strengthening molecules.

Question 5

Cytoplasm of eukaryotes

Answer 5

consists of 90-94% water with many dissolved solutes, contains cytoskeleton.

Question 6

cytoskeleton

Answer 6

vast network of interconnected filaments within the cytoplasmic matrix, filaments that form the cytoskeleton (microfilaments(actin), microtubules (made of alpha and beta tubulin) intermediate filaments, and motor proteins. Plays role in cell shape, cell movement, mitosis, meiosis, attachment site.

Question 7

Microfilaments

Answer 7

Small protein filaments 4-7 nm in diameter. Scattered within cytoplasmic matrix or organized into networks and parallel arrays, composed of actin protein.

Question 8

Intermediate Filaments

Answer 8

Heterogeneous elements of the cytockeleton (10nm 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 cels together to forms tissues.

Question 9

Microtubules

Answer 9

shaped like thin cylinders (25um in diameter of alpha and beta tubulin).
Functions= help maintain cell shape, involved with microfilaments in cell movements. Participate in intracellular transport processes. Plays role in mitosis/ meiosis.

Question 10

Organelles of the secretory endocytic pathway

Answer 10

Intricate complex of membranous organelles and vesicles that move materials into the cell from outside, from inside to outside, and within the cell. Endoplasmic reticulum, Golgi apparatus, lysosomes.

Question 11

Endoplasmic reticulum

Answer 11

Irregular network of branching and fusing unit membranous tubules and flattened sacs (cisternae). Other functions= transports proteins, lipids, and other materials within cell. Major site of cell membrane synthesis.

Question 12

Rough ER

Answer 12

ribosomes attached. function= synthesis of secreted proteins, cell membrane proteins and those going into organelles by ER associated ribosomes.

Question 13

Smooth ER

Answer 13

devoid of ribosomes. Function= synthesis of lipids and carbohydrates by ER associated enzymes.

Question 14

Golgi Apparatus

Answer 14

Unit membranous organelle made of cisternae stacked on eachother. Cis and Trans faces. Dictyosomes-stacks of cisternae. Function- modification, packaging, and secretion or materials.

Question 15

lysosomes

Answer 15

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 env by pumping protons into their interior.

Question 16

Secretory Pathway

Answer 16

Used to move 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 ER. These enter the RER lumen and are released in small budding vesicles from RER. Intracellular movement guided by ctoskeleton

Question 17

Secrettory Pathway 2

Answer 17

released in small vesicles> cis face of Golgi.trans face of Golgi apparatus.
Modification of proteins occurs in Golgi, targets protein for final destination. Transport vesicles released from trans face of Golgi.

Question 18

Secretory Pathway 3

Answer 18

After release some vesicles deliver their contents to endosomes and lysosomes. Two types of vesicles deliver proteins to cell membranes (delivary to membrane)

Question 19

Secretory Pathway 4

Answer 19

Quality assurance mechanism unfolded or misfolded proteins are secreted into cytosol, targeted for destruction by ubiquitin.

Question 20

Endocytosis

Answer 20

All eukaryotic cells, used to bring materials into the cell too 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.

Question 21

Phagocytosis

Answer 21

Only in cells without walls. Use of cell surface protrusions (pseudopods) to surround and engulf particles. Fuse with lysosomes and resulting vesicles called phagosomes.

Question 22

Clathrin dependent endocytosis

Answer 22

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. Called receptor mediated endocytosis.

Question 23

Caveole dependent endocytosis

Answer 23

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 wall as macromolecules.

Question 24

Autophagy

Answer 24

Delivery of materials to be digested by route that does not involved endocytosis. Macroautophagy involves digestion and recycling of cytoplasmic components. Double membrane surrounds cell component forming an autophagosome. Autophagosome fuses with a lysosome.

Question 25

Nucleus

Answer 25

double unit membrane bound spherical structure that houses genetic material of eukaryotic cell. Contains dense fibrous material called chromatin. Complex of DNA, histones, and other proteins. Five types of histone (H1 H2A H2B H3 and H4). Chromatin condenses into chromosomes during division.

Question 26

Nuclear envelope

Answer 26

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.

Question 27

Nucleolus

Answer 27

> 1 nucleolus per nucleus.Importants in ribosome synthesis- directs synthesis of rRNA and ribosomal proteins to form partially completed ribosomal subunits. Ribosomes mature in cytoplasm.

Question 28

Eukaryotic Ribosomes

Answer 28

Larger than the 70s bacterial and archaeal ribosome. 80S in size. 60S and 40S subunits. Some attached to ER, others attached to cytoskeleton. 60S is bound subunit to Er.

Question 29

Endosymbiotic Hypothesis

Answer 29

Mitochondria, hydrogenosomes, and chloroplasts are all thought to have evolved from bacterial cells that invaded or were ingested by early ancestors of eukaryotic cells. Mitochondria and chloroplasts are very similar to extant bacteria and cyanobacteria

Question 30

Mitochondria

Answer 30

Site of tricarboxlic acid cycle activity. Site where ATP is generated by ETC and oxidative phosphorylation. About the same size as bacterial cells. Reproduce by binary fission as do bacterial cells.

Question 31

Mitochondria Outer membrane

Answer 31

contains transport porins similar to the outer membrane of gram negative bacteria

Question 32

Mitochondria Inner membrane

Answer 32

highly folded to form cristae. location of enzymes and electron carriers for electron transport and oxidative phosphorylation.

Question 33

Mitochondrial structure

Answer 33

matrix enclosed by inner membrane. Contains ribosome, mitochondrial DNA and large calcium phosphate granules. Contains enzymes of the tricarboxylic acid cycle and enzymes involved in catabolism of fatty acids.

Question 34

Hydrogenosomes

Answer 34

Small energy conservation organelles in some anaerobic protists. Descended from common mitochondrial ancestor. Double membrane, no cristae, usually lack dna

Question 35

Chloroplasts

Answer 35

type of plastid- pigment containging organelles observed in plants and algae. Site of photosynthetic reactions. Surrounded by double unit membrane.

Question 36

Chloroplast structure

Answer 36

Stroma is within inner membrane. Contains DNA, ribosomes, lipid droplets, starch granules, and thylakoids.stroma is site of dark reactions of photosynthesis (formation of carbs from water and co2). algal chloroplasts may contain a pyrenoid-participates in polysaccharide synthesis

Question 37

Thylakoids

Answer 37

flattened, membrane delimited sacs. Grana-stacks of thylakoids. Site of light reactions

Question 38

Cilia

Answer 38

5-20um long. Beat with two phases, working like oars

Question 39

Flagella

Answer 39

100-200 um long. Move undulating fashion, tinsel-tip pulls cell along. whiplash-naked flagellum

Question 40

Ultrastructure of Flagella and Cilia

Answer 40

Unit membrane bound cylinders 2um in diameter. Axoneme set of microtubules in 9+2 arrangement. Basal body- at base of flagellum or cilium. directs synthesis of flagella and cilia.

Question 41

Pseudopods

Answer 41

Pseudopods-cytoplasmic extensions surrounded by cell membrane with structure maintained by cytoskeleton, mainly microfilaments. Found in some protozoa.