B2.2 Organelles and Compartmentalization

Question 1

cell components not considered to be organelles

Answer 1

cell wall, cytoplasm, cytoskeleton

Question 2

steps to ultracentrifugation

Answer 2

1. fractionation
2. solution spun at low speeds, densest organelles forms pellet
3. pellet removed, process repeated at faster speed
4. 2nd-densest forms pellet, and so on

Question 3

steps to fractionation

Answer 3

1. homogenization: blending in cold, isotonic, buffered solution
2. filtration

Question 4

advantages of nucleus compartmentalization

Answer 4

DNA protected from outside reactions, transcription inside nucleus separated from translation outside (mRNA modified before entering cytoplasm), maintains conditions for transcription, membrane breaks down for cell division then fuses back together

Question 5

epigenetic change

Answer 5

changes in chromatin resulting in different gene expression

Question 6

disadvantage of no nucleus compartmentalization

Answer 6

prokaryotes have no nucleus; as mRNA transcribed, ribosomes attach and begin translation, no separation results in increased errors

Question 7

advantages of lysosome compartmentalization

Answer 7

only releases enzymes when cell damaged

Question 8

phagocytosis

Answer 8

material like food or bacteria engulfed, forming phagocytic vacuole, which fuses with lysosome, becoming phagosome, which digests bacteria

Question 9

what is the function of acinar cells and what special organelle features do they have for this function?

Answer 9

secrete digestive enzymes in pancreas; have bigger ER, golgi, granule storage compartments

Question 10

adaptations of mitochondria for efficient ATP production

Answer 10

• outer membrane with channels for pyruvate to enter, impermeable to protons to allow for build-up in intramembrane space
• inner membrane has proteins of electron transport chain and ATP synthase, allows chemiosmosis
• matrix has enzymes for link reaction and Krebs cycle
• cristae increase surface area for reactions during oxidative phosphorylation

Question 11

ATP synthase

Answer 11

conversion of ADP and P to ATP

Question 12

chemiosmosis

Answer 12

diffusion of ions across membrane (protons across mitochondria membrane during respiration/chloroplast during photosynthesis)

Question 13

draw and label a mitochondria

Answer 13

porins, ribosomes, matrix, outer/inner membrane, intramembrane space, cristae, DNA, granule

Question 14

equation for respiration

Answer 14

C6H12O6 + 6 O2 = 6 CO2 + 6 H2O + energy

Question 15

catabolic vs anabolic

Answer 15

breaks down larger molecules to smaller pieces vs smaller form larger

Question 16

stages of cellular respiration

Answer 16

1. Krebs cycle
2. oxidative phosphorylation
3. electron transport chain

Question 17

adaptations of chloroplasts for efficient glucose production

Answer 17

• thylakoid membrane contains chlorophyll, facilitates electron transport chain and ATP synthase, increases surface area
• stroma: has enzymes for light-independent reactions (Calvin cycle)
• space in thylakoid (lumen) allows rapid proton build-up

Question 18

equation for photosynthesis

Answer 18

6 CO2 + 12 H2O + energy = C6H12O6 + 6 H2O + 6 O2

Question 19

organism that performs photosynthesis, makes own food

Answer 19

autotroph

Question 20

draw and label a chloroplast

Answer 20

thylakoid, grana, lipids, lumen, stroma, DNA, ribosomes, outer/inner membrane

Question 21

structure of ribosomes

Answer 21

one large and one small subunit, each composed of proteins and rRNA

Question 22

function of free-floating ribosomes vs attached to ER

Answer 22

synthesizes proteins for use in cell vs for out of cell/production of lysosome enzymes

Question 23

receptor-mediated endocytosis

Answer 23

1. clathrins line coated pits on cell exterior that anchor receptors that bind to molecules
2. molecules cause pit to deepen and clathrins polymerize to form cage, forcing membrane into rounded bud
3. coated vesicle formed inside cell, cage removed

Question 24

clathrin

Answer 24

triskelion-shape protein associated with receptor-mediated endocytosis