Chap 4 PT 4

Question 1

(ER) Endoplasmic Reticulum

Answer 1

Extensive interconnected membrane network

Extends from nuclear envelope outward
Varies in shape, but one continuous lumen (“lumen”=internal tubing)

Composes about 50% of membrane within cell!
With ribosomes—rough ER
Without ribosomes—smooth ER

Question 2

Rough ER 1:

Answer 2

Ribosomes produce proteins

Question 3

Rough ER (2)

Answer 3

Proteins transported out in enclosed membrane sacs
(Transport vesicles)

Question 4

Smooth ER

Answer 4

metabolic processes vary by cell
Synthesis, transport, and storage of lipids
Carbohydrate metabolism
Ion storage
Detoxification of drugs and poisons
Abundant in
Liver, testes

Question 5

Golgi Apparatus

Answer 5

Composed of cisternae, elongated saclike membranous structures Modification, packaging, and sorting of proteins

Formation of secretory vesicles
Some vesicles become part of plasma membrane
Others release contents outside cell (secretions)

Question 6

Lysosomes

Answer 6

Small, membranous sacs formed by Golgi
Contain digestive enzymes
For removal of unneeded substances
For digesting contents of endocytosed vesicles (phagocytosis

Question 7

Peroxisomes

Answer 7

Membrane-enclosed sacs, smaller than lysosomes, formed from rough ER
Role in chemical digestion
Beta oxidation
Lipid synthesis

Question 8

Endomembrane System

Answer 8

Extensive array of membrane-bound structures
Includes Smooth and Rough ER, Golgi apparatus, vesicles, lysosomes, peroxisomes
Includes plasma membrane and nuclear envelope
Connected directly or through vesicles moving between them
Provides means of producing and transporting substances within cells

Question 9

Mitochondria

Answer 9

Oblong organelles with double membrane
Aerobic cellular respiration
Complete digestion of fuel molecules to synthesize ATP
“Powerhouses” of cell

Question 10

Ribosomes produce proteins

Answer 10

Protein and RNA arranged into large and small subunit
Made within nucleolus and assembled in cytoplasm

Question 11

Bound ribosomes

Answer 11

attached to outside of Rough ER
synthesize proteins for export, to become part of plasma membrane, or serve as enzymes in lysosomes

Question 12

Free ribosomes

Answer 12

suspended within cytosol
All other proteins within cell synthesized here

Question 13

Cytoskeleton

Answer 13

Plays roles in
Intracellular support
Organization of organelles
Cell division
Movement of materials
Extends throughout interior of cell
Includes microfilaments, intermediate filaments, microtubules

Question 14

Microfilaments

Answer 14

Smallest components of cytoskeleton
Form interlacing network on cytoplasmic side of membrane to
Help maintain cell shape
Form internal support of cell membrane and extensions called microvilli
Separate two cells during cytokinesis

Question 15

Microtubules

Answer 15

Largest components of cytoskeleton
May be elongated or shortened as needed
Maintain cell shape
Organize and move organelles
Form components of cilia and flagella
Participate in transport of vesicles (endocytosis, exocytosis)
Move and separate chromosomes during cell division

Question 15

Intermediate filaments

Answer 15

Intermediate-sized components of cytoskeleton
More rigid than microfilaments
Support cells structurally, Stabilize cell junctions

Question 16

Centrosome

Answer 16

Pair of centrioles
Surrounded by protein
Primary function: organizes microtubules within cytoskeleton
Functions in cellular division

Question 17

Proteasomes

Answer 17

Protein-digesting organelles

Proteins that are damaged, misfolded, or no-longer-needed are marked with ubiquitin tag for disposal

Question 18

Cilia

Answer 18

Contain both microtubule proteins and cytoplasm
Enclosed in plasma membrane
Usually found on exposed surfaces of specific cells
Beating moves fluid across cell surface, creates current

Question 19

Flagella

Answer 19

Similar to cilia in structure, but longer
Propels cell. In humans, only example is sperm cell

Question 20

Microvilli

Answer 20

Microscopic extensions of plasma membrane. (Absorption)
Smaller than cilia
More densely packed, lack powered movement
Supported by microfilaments

Question 21

Tight junctions

Answer 21

Prevent substances from passing between cells
Requires materials to move through, rather than between cells

Question 22

Desmosomes

Answer 22

Provides integrity to cells exposed to stress
Mechanical reinforcement
E.g., external layer of skin

Question 23

Gap junctions

Answer 23

Form tiny, fluid-filled tunnels between cells
direct passageway for substances to travel between cells
E.g., flow of ions between cells in cardiac muscle