Cellular Biology II

Question 1

What causes wrinkles of aging?

Answer 1

Reduced production of collagen and elastin (p.79)

Question 2

Cellular Biochemistry Questions

Answer 2

Answers + First Aid Page Number

Question 3

What regulates checkpoints between phases of the cell cycle?

Answer 3

Cyclins, CDKs, tumor suppressors (p.74)

Question 4

What is the shortest phase of the cell cycle and what phases are of variable duration?

Answer 4

Mitosis is shortest; G0 and G1 are of variable duration (p.74)

Question 5

What is the order of subphases in Mitosis?

Answer 5

Prophase, Metaphase, Anaphase, Telophase (p.74)

Question 6

What phases of the cell cycle compose Interphase?

Answer 6

G1, S, G2 (p.74)

Question 7

Compare CDKs to Cyclins.

Answer 7

CDKs (cyclin dependent kinases) are constitutive and inactive; Cyclins are regulatory proteins that control cell cycle events, are phase specific and activate CDKs; In Cyclin-CDK complexes, both must be either active or inactivated for the cell cycle to progress (p.74)

Question 8

Name 2 Tumor Suppressors.

Answer 8

1.) p53; 2.) hypophosphorylated Rb. Both normally inhibit progression from G1 –> S (p.74)

Question 9

What is the function of the Rough Endoplasmic Reticulum?

Answer 9

Site of synthesis of secretory (exported) proteins and of N-linked oligosaccharide addition to many proteins. Contains free ribosomes where synthesis of cytosolic and organellar proteins occurs (p.74)

Question 10

What is Rough ER in neurons called and what is its function?

Answer 10

Nissl bodies- synthesize enzymes ChAT, Ach, and peptide NTs (p.74)

Question 11

Name two cell types that are rich in Rough ER.

Answer 11

1.) Mucus secreting goblet cells of the small intestine; 2.) Antibody secreting plasma cells (p.74)

Question 12

What is the function of the Smooth Endoplasmic Reticulum?

Answer 12

Site of steroid synthesis and detoxification of drugs and poisons (p.74)

Question 13

Name two cell types that are rich in smooth ER.

Answer 13

1.) Liver hepatocytes; 2.) Steroid hormone producing cells of the adrenal cortex (p.74)

Question 14

Where does cell trafficking occur?

Answer 14

Golgi apparatus is the distribution center for proteins and lipids from the ER to the vesicles and plasma membrane (p.75)

Question 15

What modification are made in the Golgi apparatus for cell trafficking?

Answer 15

1.) Modification of N-oligosaccharides on asparagine; 2.) Addition of O- oligosaccharides on serine and threonine; 3.) Addition of Mannose 6- phosphate to proteins for trafficking to lysosomes (p.75)

Question 16

What is the function of endosomes in cell trafficking?

Answer 16

Sorting centres for material from outside the cell or from the Golgi; sends material to lysosomes for destruction or back to the golgi/ membrane for further use (p.75)

Question 17

What is the pathology of I-Cell Disease?

Answer 17

Inherited lysosomal storage disorder. Failure of addition of mannose-6-phosphate to lysosome proteins causes enzymes to be secreted outside the cell instead of targeted to the lysosome (p.75)

Question 18

What is the clinical Presentation of I-Cell Disease?

Answer 18

Coarse facial features, clouded corneas, restricted joint movement, high plasma levels of lysosomal enzymes; often fatal in childhood (p.75)

Question 19

Name the three vesicular trafficking proteins and their direction of trafficking.

Answer 19

1.) COPI: Golgi –> Golgi (retrograde) OR Golgi –> Endoplasmic Reticulum; 2.) COPII: Golgi –> Golgi (anterograde) OR ER –> Golgi; 3.) Clathrin: trans-Golgi –> lysosomes OR plasma membrane –> endosomes (receptor mediated endocytosis) (p.75)

Question 20

What is a peroxisome?

Answer 20

A membrane enclosed organelle involved in catabolism of very long fatty acids and amino acids (p.75)

Question 21

What is a proteosome?

Answer 21

A barrel shaped complex that degrades damaged or unnecessary proteins tagged for destruction with ubiquitin (p.75)

Question 22

Describe the structure of a microtubule?

Answer 22

Cylindrical structures composed of a helical array of polymerized dimers of a and b-tubulin. Each dimer has 2 GTP bound. Microtubules grow slowly and collapse quickly (p.76)

Question 23

What structures/ functions involve microtubules?

Answer 23

They are incorporated into flagella, cilia, mitotic spindles, and are also involved in slow axoplasmic transport in neurons (p.76)

Question 24

Name 2 molecular motor proteins and their direction of transport.

Answer 24

1.) Dynein –> retrograde to microtubule (+ –> -); 2.) Kinesin –> anterograde to microtubule (- –> +) (p.76)

Question 25

What is the function of molecular motor proteins?

Answer 25

To transport cellular cargo towards opposite ends of microtubule tracks (p.76)