CELL STRUCTURE L5

Question 1

the cell

Answer 1

• smallest unit that carries out all activities associated with life
• can do everything or be specialized
• all share common features and evolutionary history

Question 2

prokaryotes

Answer 2

• “before nucleus”
• domains: bacteria and archaea
• 4 bya
• 1-10 micrometers

Question 3

eukaryotes

Answer 3

• “true nucleus”
• domain: eukarya
• larger/more complex than prokaryotes
• 1.8 bya
• 10-100 micrometers

Question 4

common features (between pro and eukaryotic cells)

Answer 4

• surrounded by plasma membrane
• distinct internal environment
• store, replicate genetic info
• divide/reproduce
• metabolism
• interact with/respond to external environment
• (generally) limited in size

Question 5

cell size

Answer 5

• most cells are very small

Question 6

limits to cell size

Answer 6

1. plasma membrane
   - all materials must pass to enter cell
   - surface area limits rate
2. advantageous to maximize surface area to volume ratio

Question 7

nucleus

Answer 7

• contains most DNA

- often highly visible

Question 8

nuclear envelope

Answer 8

• double membrane, separates nucleoplasm from cytoplasm
• membranes fused, nuclear pores
• protein complexes
• regulate passage between cytoplasm and nucleus

Question 9

nucleolus

Answer 9

• region of ribosome production within nucleus

- dense in RNA and proteins

Question 10

mitochondria

Answer 10

• aerobic respiration
• present in all eukaryotic lineages: plants and animals
• organelle acquired via endosymbiosis

Question 11

chloroplasts

Answer 11

• photosynthesis
• only found in photosynthetic lineages: mostly plants and algae
• stroma: inside inner membrane
• organelle acquired via endosymbiosis

Question 12

ribosomes

Answer 12

• structures responsible for protein synthesis
• NOT membrane bound therefore not considered organelles
• made of protein and RNA
• found in cytoplasm and associated with endoplasmic reticulum

Question 13

endomembrane system

Answer 13

• internal membrane system
• membrane: lipid bilayer, closed
• divides cell into compartments
• membrane bound organelles

Question 14

membrane communication

Answer 14

• direct continuity
• vesicular transport (transport of membrane segments)
• useful for moving lipids around

Question 15

plasma membrane

Answer 15

• selectively permeable phospholipid bilayer
• not cell wall
• encloses cell contents
• controls flow of materials in and out

Question 16

endoplasmic reticulum

Answer 16

• internal membrane complex
• single contiguous lumen (lumen = internal space)
• connected to outer membrane of nuclear envelope

Question 17

rough ER

Answer 17

• ribosomes attached to outer surface

- proteins made, travel through translocon, into lumen

Question 18

smooth ER

Answer 18

• lipid synthesis metabolism

Question 19

golgi apparatus

Answer 19

• many membranes, modify and transport proteins

- no contiguous lumen

Question 20

vacuoles

Answer 20

• large vesicles derived from endomembrane system
• many functions: food vacuoles, contractile vacuoles, storage in plant cells
• bigger than vesicles

Question 21

lysosomes

Answer 21

• compartments containing hydrolytic or digestive enzymes
• primary lysosome: made in rough ER, processed in golgi, inactive
• secondary lysosome: primary lysosome fuses with vacuole, active, if released in cytoplasm its bad but not too bad