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DIT > 1C Foundations 3 - Organelles > Flashcards

1C Foundations 3 - Organelles Flashcards

1
Q

Embryologic origin of the tissue just proximal to the pectinate line?

A

Endoderm

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2
Q

The origin of the tissue just distal to the anal canal?

A

Surface ectoderm

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3
Q

What is the general amino acid sequence of Nuclear Localization Signals?

A

4-8 amino acids

Rich in Lysine, Arginine and Proline

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4
Q

What are Nuclear Localization Signals a part of?

A

Essential component of proteins bound for or residing in the nucleus (e.g. histones)

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5
Q

How are Nuclear Localization Signals transported to the nucleus?

A

Through recognition by nuclear pores and by ATPase

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6
Q

What happens if there is a single amino acid mutation in Nuclear Localization Signals?

A

It may prevent nuclear transport of the protein

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7
Q

What regulates the cell cycle?

A

Tumor suppressor proteins
Cyclins
Cyclin-dependent kinases

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8
Q

Tumor suppressor proteins between G1 and S phase?

A

Rb

p53

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9
Q

Cancers associated with mutations in the Rb gene?

A

Retinoblastoma

Osteosarcoma

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10
Q

Tumor suppressor gene and gene product that regulates G2 to M phase?

A

p53

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11
Q

Cyclin-dependent kinases’ properties?

A

Constitutive (use ATP to phosphorylase things)

Inactive (must be activated)

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12
Q

Cyclins properties?

A

Regulatory proteins that control cell cycle events

They activate CDKs and are phase specific?

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13
Q

Cyclins + cyclin-dependent kinases –>?

A

phosphorylate target proteins to drive the cell cycle

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14
Q

What are cyclins degraded by when their cell-cycle specific job is complete?

A

Ubiquitin protein ligase

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15
Q

What is ubiquitin?

A

A protein that marks other proteins for destruction by ubiquitin protein ligase

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16
Q

Ubiquitin is important because?

A

It degrades cyclins and hence regulate the cell cycle

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17
Q

What does the tumor suppressor p21, p27 and p57 have in common?

A

They bind to and inactivate cyclin-CDK complexes

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18
Q

Who controls the activation of p21?

A

p53

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19
Q

Molecular process in which cell moves from G1 to S phase?

A

Cyclin D binds and activates CDK4. Then CDK4 phosphorylates the Rb protein –> release of Rb protein from transcription factor E2F. With E2F unbound cell is now free to transcribe and synthesize proteins needed for progression through the S phase. Next: Cyclin E binds to CDK2. After this the cell is allowed to move into S phase.

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20
Q

What proteins are needed through S phase?

i.e. they are needed to synthesize DNA

A

DNA polymerase
Thymidine kinase
Dihydrofolate reductase
Cyclin E

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21
Q

What happens when moving from G2–>M

A

Cyclin A - CDK2 complex –> mitotic prophase. Also: Cyclin B - CDK1 complex activated by cdc25 –> breakdown of nuclear envelope (specifically nuclear lamin breakdown) and initiation of mitosis.

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22
Q

What is the nuclear lamin?

A

Like a skeleton framework inside the nucleus.
Type of intermediate filament.
Has to be broken down in order for the nucleus to be able to break down –> division of cell

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23
Q

Rough Endoplasmic Reticulum (RER) is rough because?

A

It has a lot of ribosomes on it.

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24
Q

What is produced in the RER?

A

Secretory (exported) proteins

N-linked oligosaccharide addition to many proteins also happen here

25
Q

Where are cytosolic and organellar proteins synthesized?

A

Free ribosomes

26
Q

What are Nissl bodies?

A

RER of neurons

27
Q

What does Nissl bodies produce?

A

Enzymes (e.g. Choline acetyltransferase (ChAT))
ACh
Peptide neurotransmitters

28
Q

Where in the neuron can you find Nissl bodies?

A

Dendrite. Not axon

29
Q

What does Smooth Endoplasmic Reticulum produce?

It has another function as well?

A

Synthesizes Steroids and detoxifies drugs and poisons

30
Q

Where do you find a lot of smooth ER?

A

Liver hepatocytes

Steroid producing cells of the adrenal cortex

31
Q

Where do you find a lot of RER?

A

Mucus-secreting goblet cells of the small intestine

Antibody-secreting plasma cells

32
Q

Where does post-translational modifications take place?

A

Golgi apparatus

33
Q

What is the role of Coat protein 2 (COP2) proteins?

A

Anterograde trafficking.

From ER to cis-Golgi

34
Q

What is the role of Coat protein 1 (COP1) proteins?

A

Retrograde trafficking.

From Golgi to ER

35
Q

What is the role of Clathrin?

A

Helps transport hydrolase enzymes from trans-Golgi –> lysosomes.
Also: helps in transport from the plasma membrane –> endosomes (in receptor mediated endocytosis)

36
Q

Golgi Apparatus. Function?

A

Distribution center of protein and lipids from ER to plasma membrane, lysosomes and secretory vesicles
Post-translational modification of proteins and proteoglycans

37
Q

What kind of tissue are proteoglycans important in?

A

Connective tissue

38
Q

Glycosylation process is where and how?

A

Golgi.

Core proteins + (e.g. chondroiton sulphate, Heparin suplphate)

39
Q

Golgi can modify what on asparagine?

A

N-oligosaccharides

40
Q

The Golgi apparatus can add what to Serine and Threonine?

A

O-oligosaccharides

41
Q

Golgi can can add what to sugars, proteoglycans and tyrosine?

A

Sulfate groups (“sulfation”)

42
Q

Golgi can add what to lysosomal enzymes?

A

mannose-6-phosphate

43
Q

I-cell Disease

A

Deficiency in mannose phophorylation.
No mannose-6-phosphate to target lysosomal proteins –> secretion out of cell instead of into lysosomes – > High levels of lysosomal enzymes in plasma.
Death by age 8-
Corneal clouding, coarse facies, Hepatosplenomegaly (HSM), skeletal abnormalities, restricted joint movementm +/- intellectual disability

Similar to Mucoplysaccharidosis like (Hurler or Hunter syndromes)

44
Q

Function of Chaperones in the ER and Golgi?

A

Assist in proper folding and transport of polypeptides

45
Q

Some chaperones are synthesized constantly and are involved in?

A

Normal intracellular protein trafficking

46
Q

What is the function of heat shock proteins (also a kind of chaperone). Mention two.

A

“Rescue” shock-stressed proteins from misfolding (They are sent for degradation).
hsp70 and hsp90

47
Q

If a protein is unable to be rescued (it’s abnormally folded) what happens?

A

The heat shock proteins will attach ubiquitin (also a heat shock protein) to them –> degradation

48
Q

Mention the different types of proteolysis

A
  1. Lysosomal degredation (Lysosomal enzymes).
  2. Proteasomal degradation (Ubiquitin-tagged protein is recognized by ubiquitin-protein-ligase which is a part of the proteosome complex –> destruction of protein).
  3. Calcium-dependent enzymes
49
Q

Function of sarcoplasmic reticulum?

A

Store calcium and help manipulate Ca2+ balance to regulate muscle contraction

50
Q

Where do you find sarcoplasmic reticulum?

A

Striated muscle and smooth muscle cells

51
Q

What does Ca2? trigger?

A

Muscle contraction and exocytosis of neurotransmitters and hormones

52
Q

ATP production happens in which organelle?

A

Mitochondria

53
Q

ATP happens in which processes?

A

TCA cycle and Electron transport chain

54
Q

Mitochondria self-replicate. Why?

A

They have their own DNA

55
Q

Mitochondrial DNA comes from mother or father?

A

Mother

56
Q

How does the mitochondria relate to Ca2+

A

It can absorb Ca+ if excess exist in the cytoplasm

57
Q

Function of the membrane-enclosed organelle peroxisomes?

A

Beta-oxidation of very long chain fatty acids and branched fatty acids and amino acids.
Synthesis of plasmalogens.
Oxidases and catalase for meatabolizing ethanol and other toxic substances.

58
Q

What are plasmalogens?

A

Important phospholipid found in myelin

59
Q

What is the proteasome?

A

Barrel-shaped protein complex that degrades damaged and unnecessary proteins tagged for destruction with ubiquitin.

DIT (11 decks)

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