Cytoplasmic Organelles

Question 1

What is the cytoplasm?

Answer 1

Located between the plasma membrane and nucleus

Question 2

What is the cytosol?

Answer 2

Clear viscous watery colloid

Question 3

What are the membranous cytoplasmic organelles?

Answer 3

• Mitochondria
• Peroxisomes
• Lysosomes
• Endoplasmic reticulum
• Golgi apparatus

Question 4

What are the nonmembranous organelles?

Answer 4

• Cytoskeleton
• Centrioles
• Ribosomes

Question 5

Describe the Mitochondria

Answer 5

• Double membrane structure with inner membrane folds called cristae
• Provides most of the cells ATP
• Contains its own DNA and RNA

Question 6

Describe the Ribosomes

Answer 6

• Granules of protein and rRNA
• Site of protein synthesis
• Can be membrane bound or free
• Membrane bound ribosomes synthesize proteins to be incorporated into membranes or exported from the cell
• Free ribosomes synthesize soluble proteins

Question 7

Describe the Endoplasmic Reticulum (ER)

Answer 7

• Continuous with nuclear membrane
• Rough or smooth

Question 8

Describe the Rough ER

Answer 8

• External surface is covered with ribosomes
• Manufactures all secreted proteins
• Synthesizes integral proteins and phospholipids

Question 9

Describe the Smooth ER

Answer 9

Synthesis of phospholipids, cholesterol, steroid hormones, glycerides, glycogen, and calcium
No role in protein synthesis

Question 10

Describe the Golgi Apparatus

Answer 10

• Receives newly synthesized proteins from the Rough ER and synthesizes them into packages:
• Plasma membrane renewal
• Secretions to be discharged from the cell
• Enzymes for the cytosol contained in lysosomes

Question 11

Describe Lysosomes

Answer 11

• The “demolition crew”
• Membraneous bags containing digestive enzymes
• Digests macromolecules, microorganisms, and damaged organelles

Question 12

Describe Peroxisomes

Answer 12

• Similar to lysosomes but contain different enzymes
• Oxidize organic molecules
• Detoxify harmful/toxic substances
• Catabolizes fats

Question 13

Describe the Cytoskeleton

Answer 13

• Composes of microfilaments, intermediate microfilaments, and microtubules
• Adds strength and flexibility to the cell

Question 14

Microfilaments

Answer 14

• Made of actin
• Concentrated in a fibrous mat called the terminal web
• Provides physical support

Question 15

Intermediate microfilaments

Answer 15

• Give the cell shape
• Resist stress
• Form junctions that attach cells to their neighbors
• Anchor organelles

Question 16

Microtubules

Answer 16

• Made of 13 parallel strands called protofilaments
• Each prootofilament is a long chain of globular proteins called tubulin
• Radiate from the centrosome
• Hold organelle in place
• Maintain cell shape and rigidity
• Form mitotic spindle during cell division

Question 17

Motor Proteins

Answer 17

Attach to receptors on vesicles or organelles and “walk” the organelles along the microtubules of the cytoskeleton

Question 18

Describe the Centrosome

Answer 18

• Near the nucleus
• Generates microtubules
• Organizes mitotic spindle
• Contain centrioles (set of three microtubules)

Question 19

Describe the Nucleus

Answer 19

• “Genetic Control center”
• Responds to signals, dictates kinds and amounts of proteins to be synthesized

Question 20

Describe the Nucleoli

Answer 20

Involved in rRNA synthesis and ribosome assembly

Question 21

Describe Nucleosomes

Answer 21

Contains chromatin (threadlike strands of DNA)

Question 22

What are some forms of cellular extensions?

Answer 22

• Cilia: Move substances across cells
• Flagella: Propel whole cells
• Microvilli: Extensions of the plasma membrane that increase the surface area for absorption