FORM & FUNCTION (Subcellular Organelles)

Question 1

nucleus

Answer 1

-usually one
-some cells have multiple (muscle) or none due to development (RBC)
-basophilic
-euchromatin (EC) and heterochromatin (HC)
-nucleolus
-active cells will have more EC and nucleoli

Question 2

euchromatin

Answer 2

-appears lighter
-less coiled
-DNA more exposed

Question 3

heterochromatin

Answer 3

-appears darker
-more coiled
-DNA less exposed

Question 4

nucleolus

Answer 4

-region where rRNA is made for ribosome synthesis
-darker spots within the nucleus

Question 5

Mitochondria

Answer 5

-primary organelle that produces energy (ATP)
-also metabolizes fatty acids
-visible appearance gives you a clue of it’s function (cristae or tubular projections)

Question 6

mitochondria cristae

Answer 6

-energy producing
-inner folding structure

Question 7

mitochondria tubular projections

Answer 7

-lipid producing (ex. steroids)
-tubular looking

Question 8

endoplasmic reticulum

Answer 8

-extensive network of membranes arranged in flattened sacs
-rough ER: with ribosomes attached
-smooth ER: no ribosomes attached

Question 9

ribosomes

Answer 9

-make proteins (Requires ATP)
-made from rRNA and proteins (basophilic)
-many free ribosomes=polyribosomes

Question 10

2 pathways for protein synthesis depending on their function

Answer 10

1. Proteins that function in the cytosol and have no modification (synthesized by free ribosomes)
2. Proteins that function at specific locations (membrane, organell or outside the cell)
   >synthesized by ribosomes on rER, packaged in vesicles and often modified by Golgi apparatus

Question 11

differential staining of free ribosomes as a diagnostic tool

Answer 11

-mature RBC have no subcellular organelles, filled with Hb=no polyribosomes
-reticulocyte (immature RBC) still contains polyribosomes (normally present in 1% in circulation)
>more basophilic

Question 12

Golgi apparatus structure

Answer 12

1. Stacked membrane
2. Cis face
3. Trans face

Question 13

stacked membrane

Answer 13

-composed of a series of flattened, stacked pouches

Question 14

cis face

Answer 14

-receiving side
-closest to the ER
-receives materials from ER for modification

Question 15

trans face

Answer 15

-shipping side
-oriented toward the PM
-sends modified products to their final destinations

Question 16

Golgi apparatus functions

Answer 16

1. Chemical modification
2. Packing and storage

Question 17

chemical modification (golgi)

Answer 17

-contains enzymes to chemically modify nasent proteins
Ex. glycosylation, sulfation, phosphorylation

Question 18

packing and storage (golgi)

Answer 18

-initiates packing, concentration and storage of secretory products
-prepares them for transportation to specific locations

Question 19

golgi staining

Answer 19

-primarily composed of lipids, making it challenging to visualize
-in a basophilic cytoplasm=Golgi may appear faint or unstained

Question 20

cells that make proteins to be secreted

Answer 20

-many vesicles/granules
1. Pancreatic acinar cells secrete digestive enzymes
2. Fibroblasts secret collagen
3. Plasma cells secret immunoglobulins

Question 21

secretory granules

Answer 21

-can be basophilic or acidophilic
-depends on chemical composition of their contents

Question 22

sER

Answer 22

-continuous rER
-synthesizes cholesterol, steroids, CHO, lipid, phospholipids
-detoxifies drugs or toxin (in liver)
-stores Ca2+ (in skeletal muscle)

Question 23

sER are abundant in cells that

Answer 23

-are important for synthesis of lipids and metabolism of drugs or toxins (hepatocytes)
-produce steroid hormones (adrenocortical cells, testicular and ovarian cells)

Question 24

steroid-secreting cells

Answer 24

-round nuclei
-boxy
-polyhedral shape
-conspicuous and vacuolated cytoplasm
*full of her (white=no dye)

Question 25

lysosome structure

Answer 25

-spherical, range in diameter
-appear uniformly granular and electron-dense
-less electron dense ones=heterolysosomes in which digestion of the content is underway
-typically acidic

Question 26

lysosomes function

Answer 26

1. remove obsolete or non-functional proteins, organelles or membranes (ex. autophagosome-> lipofusion)
2. store hydrolytic enzymes before they are secreted outsided (ex. osteoclasts:remodelling bone)
3. store hydrolytic enzymes to digest invading pathogens (ex. macrophages and neutrophils function to detect, engulf and destroy pathogens)

Question 27

peroxisome structure

Answer 27

-similar to lysosomes
-abundant in liver and proximal convoluted tubules of kidneys
-can appear crytstalline
-contains various enzymes but work at neutral pH

Question 28

peroxisome function

Answer 28

-detoxicication
-beta-oxidation of long chain fatty acids
-removes oxygen species (ex. catalase, oxidases, peroxidases) to prevent oxidative damage

Question 29

lipid droplet structure

Answer 29

-non membrane bound (hydrophobic) droplets are found in adipocytes, steroid producing cells
-stained orange with a special dye

Question 30

lipid droplet function

Answer 30

-lipid storage