Biochem - Cellular (Cell Cycle, Cell Trafficking, & Select organelles) Flashcards Preview

FA - Biochemistry > Biochem - Cellular (Cell Cycle, Cell Trafficking, & Select organelles) > Flashcards

Flashcards in Biochem - Cellular (Cell Cycle, Cell Trafficking, & Select organelles) Deck (41):
1

In general, what controls transitions between phases of cell cycle? What are 3 factors/substances that regulate this process?

Checkpoints control transitions between phases of cell cycle; This process is regulated by cyclins, cyclin-dependent kinases (CDKs), and tumor suppressors

2

What is the shortest phase of the cell cycle? What is included in this phase?

Mitosis (shortest phase of cell cycle) includes prophase, metaphase, anaphase, and telphase

3

Describe the duration of G1 and G0 cell cycle phases.

G1 and G0 are of variable duration

4

What 2 words describe the normal functionality of CDKs?

Constitutive and inactive

5

What are Cyclins, and how do they function?

Regulatory proteins that control cell cycle events; Phase specific; Activate CDKs

6

What must happen to Cyclin-CDK complexes in order for cell cycle to progress?

Must be both activated and inactivated for cell cycle to progress

7

What are 2 examples of tumor suppressors that function in the cell cycle? What function do they have?

p53 and hypophosphorylated Rb normally inhibit G1-to-S progression

8

What results from mutations in tumor suppressor genes? Give an example.

Mutations in these genes result in unrestrained cell division (e.g., Li-Fraumeni syndrome)

9

What defines the permanent cell type?

Remain in G0, regenerate from stem cells

10

What are 4 examples of permanent cells?

(1) Neurons (2) skeletal and (3) cardiac muscle (4) RBCs

11

What defines the stable (quiescent) cell type?

Enter G1 from G0, when stimulated

12

What are 2 examples of stable (quiescent) cells?

(1) Hepatocytes (2) Lymphocytes

13

What defines the labile cell type?

Never go to G0, divide rapidly with a short G1.

14

What are 5 examples of labile cells?

(1) Bone marrow (2) Gut epithelium (3) Skin (4) Hair follicles (5) Germ cells

15

Which cell type is most affected by chemotherapy?

Labile cell type

16

What are 2 events that occur at/in the rough endoplasmic reticulum?

Site of synthesis of secretory (exported) proteins and of N-linked oligosaccharide addition to many proteins

17

What are Nissl bodies? What function do they serve?

Nissl bodies (RER in neurons) - synthesize peptide neurotransmitters for secretion

18

What defines free ribosomes? What function do they serve?

Free ribosomes - unattached to any membrane; site of synthesis of cytosolic and organellar proteins

19

Give 2 examples of cells that are rich in RER.

Mucus-secreting goblet cells of the small intestine and antibody-secreting plasma cells are rich in RER

20

What is the function of smooth endoplasmic reticulum?

Site of steroid synthesis and detoxification of drugs and poisons

21

How does smooth endoplasmic reticulum differ from rough endoplasmic reticulum in its appearance?

Lacks surface ribosome

22

Give 2 examples of cells that rich in SER.

Liver hepatocytes and steroid hormone-producing cells of the adrenal cortex and gonad are rich in SER.

23

What function does the golgi serve?

Golgi is the distribution center for proteins and lipids from the ER to the vesicles and plasma membrane

24

How does the golgi modify asparagine?

Modifies N-oligosaccharides on asparagine

25

How does the golgi modify serine? What other amino acid is modified by the golgi in the same way?

Modifies O-oligosaccharides on serine and threonine

26

How does the golgi modify certain proteins, and for what reason?

Adds mannose-6-phosphate to proteins for trafficking to lysosomes

27

What are endosomes, and what function do they serve?

Endosomes are sorting centers for material from outside the cell or from the Golgi, sending it to lysosomes for destruction or back to the membrane/Golgi for further use

28

What does the I in I-cell disease stand for? What kind of disorder is it?

I-cell disease (inclusion cell disease) - inherited lysosomal storage disorder

29

What is the defect in I-cell disease, and what cellular effect(s) does it have?

Defect in phosphotransferase => Failure of the Golgi to phosphorylate mannose residues (i.e., decreased mannose-6-phosphate) on glycoproteins => Proteins are secreted extracellularly rather than delivered to lysosomes

30

What are 4 signs/symptoms that result from I-cell disease?

Results in coarse facial features, clouded corneas, restricted joint movement, and high plasma levels of lysosomal enzymes

31

What is often the prognosis/outcome of I-cell disease?

Often fatal in childhood

32

What is SRP? What function does it serve?

Signal recognition peptide (SRP); Abundant, cytosolic ribonucleoprotein that traffics protein from the ribosome to the RER.

33

What happens in the event of an absent or dysfunctional SRP?

Absent or dysfunctional SRP => proteins accumulate in the cytosol

34

Name 3 vesicular trafficking proteins.

(1) COPI (2) COPII (3) Clathrin

35

What is the function of COPI?

Vesicular trafficking protein; COPI: Golgi => Golgi (retrograde); Golgi => ER

36

What is the function of COPII?

Vesicular trafficking protein; COPII: Golgi => Golgi (anterograde); ER => Golgi

37

What is the function of Clathrin?

Vesicular trafficking protein; Clathrin: trans-Golgi => lysosomes; Plasma membrane => endosomes (receptor-mediated endocytosis) [e.g., LDL receptor activity]

38

Which vesicular trafficking protein is involved in receptor-mediated endocytosis? Give an example of receptor-mediated endocytosis.

Clathrin: trans-Golgi => lysosomes; Plasma membrane => endosomes (receptor-mediated endocytosis) [e.g., LDL receptor activity]

39

What is the peroxisome, and what function does it serve?

Membrane-enclosed organelle involved in catabolism of very-long-chain fatty acids, branched-chain fatty acids, and amino acids

40

What is the proteasome, and what function does it serve?

Barrel-shaped protein complex that degrades damaged or ubiquitin-tagged proteins

41

In what important disease have defects in ubiquitin-proteasome system been implicated?

Defects in the ubiquitin-proteasome system have been implicated in some cases of Parkinson's disease

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