1 cellular Cell cycle phases Rough endoplasmatic reticulum Smooth endoplasmatic reticulum Cell trafficking Peroxisome Protesome Flashcards
List the five main phases of mitosis, in order.
Prophase, prometaphase, metaphase, anaphase, telophase
When does mitosis occur in the cell cycle?
Mitosis occurs after G2 and before G1 in the cell cycle
When does DNA synthesis occur in the cell cycle?
In S phase, which is after G1 and before G2 in the cell cycle
From which phase of the cell cycle can a cell enter G0?
G1, a subset of interphase
Which phase of the cell cycle is usually the shortest?
The M phase
Which phase of the cell cycle is shortened in rapidly dividing cells?
G1
What is the relationship between cyclin-dependent kinases (CDKs) and cyclins?
Cyclins, regulatory proteins that are translated, activate CDKs at appropriate times in the cell cycle
Cells such as neurons, red blood cells, and skeletal and cardiac muscle cells remain in what part of the cell cycle?
Permanent cells remain in G0
____ (Permanent/Stable/Labile) cells, such as hepatocytes and lymphocytes, enter G1 from G0 when stimulated.
Stable (quiescent)
____ (Permanent/Stable/Labile) cells divide rapidly with a short G1 and never go to G0.
Labile
A patient undergoing chemotherapy is prone to disturbances of bone marrow, gut epithelium, germ cells, skin, and hair follicles. Why?
These are examples of labile cells, which are affected most heavily by chemotherapy
List the three components of interphase.
G1, S phase, and G2
Li-Fraumeni patients have unrestrained cell division and are at increased risk of malignancy. What cell cycle stage is uninhibited in them?
These patients are deficient in the p53 tumor suppressor protein, which prohibits G1-to-S-phase progression
What are the main functions of the rough endoplasmic reticulum?
The synthesis of secretory (exported) proteins and the addition of N-linked oligosaccharides to proteins
A researcher wanting to study rough endoplasmic reticulum (RER) starts taking cells from lab rats. What two cell types would be most useful?
Goblet cells, which secrete mucus, and plasma cells, which secrete antibodies; both are rich in rough ER
What is the histologic term for rough endoplasmic reticulum in neurons? What substances are synthesized there?
Nissl bodies; peptide neurotransmitters and enzymes (such as ChAT)
____ (Free/Attached) ribosomes synthesize cytosolic and organellar proteins; ____ (free/attached) ribosomes synthesize secretory proteins.
Free; attached
List two functions of the smooth endoplasmic reticulum.
Steroid synthesis; detoxification of drugs and poisons
A researcher wants to study cells that are rich in smooth endoplasmic reticulum (SER). Name two types of cells that are rich in SER.
Steroid hormone–producing cells of the adrenal cortex and hepatocytes
What makes the smooth endoplasmic reticulum so smooth?
It lacks surface ribosomes
The Golgi apparatus functions as the distribution center for what?
Proteins and lipids from the endoplasmic reticulum
List three places to which the Golgi apparatus sends proteins and lipids.
The plasma membrane, lysosomes, and secretory vesicles
Clathrin is a protein that transports vesicles from the trans face of the Golgi apparatus to where?
Clathrin directs from trans-Golgi to lysosomes and from plasma membrane to endosomes
• What type of protein-bound saccharides are modified in the Golgi apparatus?
N-oligosaccharides (on asparagine)
I-cell disease results in ____ (increased/decreased) phosphorylation of mannose residues on glycoproteins. What enzyme defect contributes?
Decreased; defect in N-acetylglucosaminyl-1-phosphotransferase
What clinical signs may be seen if a patient’s proteins are excreted extracellularly instead of being delivered to lysosomes?
This patient has I-cell disease, causing coarse facies, clouded corneas, and restricted joints
A child has coarse facies, clouded corneas, restricted joints, and increased plasma lysosomal enzymes. What are the prognosis and diagnosis?
I-cell disease, usually fatal in childhood
How are serine and threonine residues modified in the Golgi?
O-oligosaccharides are added
What is the role of COPII in vesicular trafficking?
Anterograde transport from rough endoplasmic reticulum to the cis-Golgi
Adding which marker to proteins in the Golgi targets them to lysosomes?
Mannose-6-phosphate
What is the role of COPI in vesicular trafficking?
Retrograde movement from the Golgi apparatus to the endoplasmic reticulum
In which vesicular trafficking protein might a patient with abnormally low LDL receptor levels have a defect?
Clathrin
Endosomes are sorting centers for material from outside the cell or from the Golgi. What routes can material take from the endosome?
Back to membrane or Golgi for further use or to lysosomes for degradation
Which organelle is involved in the catabolism of amino acids and very long fatty acids? What is this organelle enclosed in?
Peroxisome; it is enclosed in membrane
List all substrates that undergo catabolism in the peroxisome.
Very-long-chain fatty acids, branched-chain fatty acids, and amino acids
Which barrel-shaped protein complex degrades damaged or unnecessary proteins tagged for destruction?
Proteasome
A man with Parkinson disease lacks protein complexes that destroy other proteins. Proteins tagged with what marker fail to be recognized?
Proteins tagged with ubiquitin fail to be recognized by proteasomes, which may be the pathophysiology behind some cases of Parkinson disease
