1 cellular Cell cycle phases Rough endoplasmatic reticulum Smooth endoplasmatic reticulum Cell trafficking Peroxisome Protesome

Question 1

List the five main phases of mitosis, in order.

Answer 1

Prophase, prometaphase, metaphase, anaphase, telophase

Question 2

When does mitosis occur in the cell cycle?

Answer 2

Mitosis occurs after G2 and before G1 in the cell cycle

Question 3

When does DNA synthesis occur in the cell cycle?

Answer 3

In S phase, which is after G1 and before G2 in the cell cycle

Question 4

From which phase of the cell cycle can a cell enter G0?

Answer 4

G1, a subset of interphase

Question 5

Which phase of the cell cycle is usually the shortest?

Answer 5

The M phase

Question 6

Which phase of the cell cycle is shortened in rapidly dividing cells?

Answer 6

G1

Question 7

What is the relationship between cyclin-dependent kinases (CDKs) and cyclins?

Answer 7

Cyclins, regulatory proteins that are translated, activate CDKs at appropriate times in the cell cycle

Question 8

Cells such as neurons, red blood cells, and skeletal and cardiac muscle cells remain in what part of the cell cycle?

Answer 8

Permanent cells remain in G0

Question 9

____ (Permanent/Stable/Labile) cells, such as hepatocytes and lymphocytes, enter G1 from G0 when stimulated.

Answer 9

Stable (quiescent)

Question 10

____ (Permanent/Stable/Labile) cells divide rapidly with a short G1 and never go to G0.

Answer 10

Labile

Question 11

A patient undergoing chemotherapy is prone to disturbances of bone marrow, gut epithelium, germ cells, skin, and hair follicles. Why?

Answer 11

These are examples of labile cells, which are affected most heavily by chemotherapy

Question 12

List the three components of interphase.

Answer 12

G1, S phase, and G2

Question 13

Li-Fraumeni patients have unrestrained cell division and are at increased risk of malignancy. What cell cycle stage is uninhibited in them?

Answer 13

These patients are deficient in the p53 tumor suppressor protein, which prohibits G1-to-S-phase progression

Question 14

What are the main functions of the rough endoplasmic reticulum?

Answer 14

The synthesis of secretory (exported) proteins and the addition of N-linked oligosaccharides to proteins

Question 15

A researcher wanting to study rough endoplasmic reticulum (RER) starts taking cells from lab rats. What two cell types would be most useful?

Answer 15

Goblet cells, which secrete mucus, and plasma cells, which secrete antibodies; both are rich in rough ER

Question 16

What is the histologic term for rough endoplasmic reticulum in neurons? What substances are synthesized there?

Answer 16

Nissl bodies; peptide neurotransmitters and enzymes (such as ChAT)

Question 17

____ (Free/Attached) ribosomes synthesize cytosolic and organellar proteins; ____ (free/attached) ribosomes synthesize secretory proteins.

Answer 17

Free; attached

Question 18

List two functions of the smooth endoplasmic reticulum.

Answer 18

Steroid synthesis; detoxification of drugs and poisons

Question 19

A researcher wants to study cells that are rich in smooth endoplasmic reticulum (SER). Name two types of cells that are rich in SER.

Answer 19

Steroid hormone–producing cells of the adrenal cortex and hepatocytes

Question 20

What makes the smooth endoplasmic reticulum so smooth?

Answer 20

It lacks surface ribosomes

Question 21

The Golgi apparatus functions as the distribution center for what?

Answer 21

Proteins and lipids from the endoplasmic reticulum

Question 22

List three places to which the Golgi apparatus sends proteins and lipids.

Answer 22

The plasma membrane, lysosomes, and secretory vesicles

Question 23

Clathrin is a protein that transports vesicles from the trans face of the Golgi apparatus to where?

Answer 23

Clathrin directs from trans-Golgi to lysosomes and from plasma membrane to endosomes

Question 24

• What type of protein-bound saccharides are modified in the Golgi apparatus?

Answer 24

N-oligosaccharides (on asparagine)

Question 25

I-cell disease results in ____ (increased/decreased) phosphorylation of mannose residues on glycoproteins. What enzyme defect contributes?

Answer 25

Decreased; defect in N-acetylglucosaminyl-1-phosphotransferase

Question 26

What clinical signs may be seen if a patient’s proteins are excreted extracellularly instead of being delivered to lysosomes?

Answer 26

This patient has I-cell disease, causing coarse facies, clouded corneas, and restricted joints

Question 27

A child has coarse facies, clouded corneas, restricted joints, and increased plasma lysosomal enzymes. What are the prognosis and diagnosis?

Answer 27

I-cell disease, usually fatal in childhood

Question 28

How are serine and threonine residues modified in the Golgi?

Answer 28

O-oligosaccharides are added

Question 29

What is the role of COPII in vesicular trafficking?

Answer 29

Anterograde transport from rough endoplasmic reticulum to the cis-Golgi

Question 30

Adding which marker to proteins in the Golgi targets them to lysosomes?

Answer 30

Mannose-6-phosphate

Question 31

What is the role of COPI in vesicular trafficking?

Answer 31

Retrograde movement from the Golgi apparatus to the endoplasmic reticulum

Question 32

In which vesicular trafficking protein might a patient with abnormally low LDL receptor levels have a defect?

Answer 32

Clathrin

Question 33

Endosomes are sorting centers for material from outside the cell or from the Golgi. What routes can material take from the endosome?

Answer 33

Back to membrane or Golgi for further use or to lysosomes for degradation

Question 34

Which organelle is involved in the catabolism of amino acids and very long fatty acids? What is this organelle enclosed in?

Answer 34

Peroxisome; it is enclosed in membrane

Question 35

List all substrates that undergo catabolism in the peroxisome.

Answer 35

Very-long-chain fatty acids, branched-chain fatty acids, and amino acids

Question 36

Which barrel-shaped protein complex degrades damaged or unnecessary proteins tagged for destruction?

Answer 36

Proteasome

Question 37

A man with Parkinson disease lacks protein complexes that destroy other proteins. Proteins tagged with what marker fail to be recognized?

Answer 37

Proteins tagged with ubiquitin fail to be recognized by proteasomes, which may be the pathophysiology behind some cases of Parkinson disease