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Cells molecules and genes > Cytology 3-4 mitochrondria and lecture 3(cytoskeleton) and 4(nucleus) > Flashcards

Cytology 3-4 mitochrondria and lecture 3(cytoskeleton) and 4(nucleus) Flashcards

0
Q

Which stain used to detect mitochondria and which colour is positive?

A

Mitotracker - pink

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1
Q

Importance of granules in mitochrondria

A

Maintain low levels of Calcium and Mg ions.

Store these ions

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2
Q

What makes mitochondria semi-independent? (5)

A 
Replicate by fission or fusion with other mitochondria - form larger mitochrondria 
MtRNA, DNA - protein synthesis
Mito-ribosomes
Mt DNA - circular similar to plasmids
RNA polymerase
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3
Q

Composition of outer mitochondrial membrane? (4)

A

50% lipids - main phosphotidylcholine
Porins - channel proteins
Similar to ER membrane
Enzymes - (lipid synthesis, fatty acid metabolism)

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4
Q

Inner membrane composition?

A

20% lipids
Cristae or tubular (in cells specialised for steroid hormone synthesis)
3 transport proteins
Enzymes for ETC and ATP synthase

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5
Q

Where are tubular inner membrane mito found?

A

Cells syn of steroid hormones. Eg adrenal glands, gonads.

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6
Q

What is an inclusion?

A

Not metabolically active cytoplasmic component.

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7
Q

Give 5 examples of inclusions

A

Glycogen - hydrolysed to glucose.
Lipid droplets of fat - triglycerides - energy store, insulation, protection.
Cholesterol - component in lipid and steroid hormone synthesis.
Lipofuscins - dead residual body from lysosomal digestion. Increase with age. Common in stationary cells. E.g. Cardiac, skeletal, neurons.
Plectin - adhesion of 3 structural proteins. Micro, intermediate filaments and microtubules. Found at cell to cell junctions.

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8
Q

Actin and microtubules tread-milling req.

A

Actin - atp, mg2+, k+

Microtubules - gtp, mg2+

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9
Q

How are mito proteins formed in the cytosol?

A

Specific Terminus C AA sequence.
Followed by heat shock protein 70.
Translocation into mitochondria via TOM - ITM
Heat shock protein 70 cleaves AA positive terminus C sequence,

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10
Q

At what inclination does actin bind to myosin?

A

45 degrees

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11
Q

Function of actin binding protein?

A

Accelerate/decelerate polymerisation of actin filaments.

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12
Q

What type of myosin do non muscle cells contain?

A

Myosin I

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13
Q

Nucleus quick points (4)

A

DNA, Double bilayer membrane, nucleolus (protein synthesis), continuous with ER

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14
Q

Nucleus irregular in….

A

Leukocytes, plasma cells, spermatozoa

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15
Q

Observing nucleus…..(4)

A

Display different shapes,
Not present in all cells eg rbs, platelets
Not present during whole cell cycle (nucleolus)
Multiple nucleus present eg syncytia, plasmodia, dome cells

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16
Q

Ratio of nucleus to cytosol

A

Vn / Vcytoplasm - Vn

= k

If k not constant - pathology

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17
Q

Nucleolus

A 
No membrane, basophilic, granular and fibrillar layer.
Breakdown during pro-metaphase. 
rRNA transcription
Synthesis of ribosomal sub units. 
Surrounded by nuclear chromatin
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18
Q

Inner nuclear membrane?

A

Unique proteins - nuclear lamina - filaments -> lamin proteins A B C

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19
Q

2 types of chromatin in NUCLEUS

A

Euchromatin - dark, active

Heterochromatin - compacted, not active, electron dense

20
Q

Nuclear lamina size

A

25nm

21
Q

Cell cycle, lamin phosphorylation

A

Prophase, lamin phosphorylation, breakdown NE

Telophase, lamin dephosphorylation, reform NE

22
Q

Nuclear lamina (4)

A

Intermediate filaments beneath NE,
Provides shape and stability, link between DNA + envelop.
Regulates chromatin compartment - therefore gene expresson reg.

Therefore mutation of proteins effects gene expression

23
Q

3 laminopathy

A

Muscular laminopathy - muscle weaken, die - skeletal muscle, heart, conduction of heart
Lipodystrophies - loss of fat from facial area. Decrease in leptin ( hormone which regulates satiety - controls lipid met)
Progeria laminopathy (premature ageing) - patients die within 20 years of birth. Due to abnormal lamin A - accumulation into nucleus therefore effect lamina formation - therefore effect gene expression

24
Q

What is a npc?

A

Nuclear pore comples

25
Q

Function of NPC

A

Channel which Regulates movement of proteins/rna in/out of nucleus

26
Q

Nuclear pre example no.

A

Somatic - 10-20/um^2
Ooctye 40-50/um^2

Active cell - greater no. of pores

27
Q

6 structural features of a NPC

A 
Luminal anchor,
Luminal ring,
Basket,
Ring,
Filament,
Scaffold
28
Q

Trafficking thru nuclear pores?

A

Importins - specific proteins - contain Nuclear localisation sequence(NLS)
Exportination - less common - nuclear exp. sequence (NES)

29
Q

Active transport of proteins into nucleus and give example.

A

Receptor for import.
Bind to nucleus.
Moved thru pore via cytosol fibrils.
Passage requires : GTP

EXAMPLE: ribosome subunits. Proteins syn in cytoplasm. Contain NLS. Into nucleus-nucleolus. Synthesis of ribosomal subunits. Back into cytoplasm

30
Q

Nucleoplasm and nucleocytoskeleton

A

80-90% proteins, 10% Nucleic acids, 1% lipids

Nucleocytoskeleton : fibrous lamina, fibrillary network

31
Q

3 structural areas of nucleolus

A

Fibrillar centre - light stain - 5 chromosome - contain rRNA gene
Dark straining region
Pars fibrillosa - processing + precursor of rRNA
Pars granulosa - assembling of ribosome subunits - completed jn cytoplasm

32
Q

Time taken for a eukaryotic cell to divide

A

2hr-3days

33
Q

Interphase 3 subphases

A

G1 protein syn, organelle replication
S dna replication
G2 atp syn, cytoplasmic element doubling, form mitotic spindle

34
Q

Which staining to see mitosis and nucleus in detail?

A

Feulgen staining - fluorescent strain - red:chromosomes. Green : filaments.

35
Q

3 types of MT In mitotic spindle

A

Free - located at radial MTOC
Kinetochore - shorten, contract - depolymerisation
Polar - lengthen at positive end and slide

36
Q

Dephosphorylation of lamins causes?

A 
Telephase - NE To reform
Then cytokenesis ( division of cytoplasm ) - contraction of contractile ring (containing actin and myosin)
37
Q

Time taken for MITOSIS

A

G1 8++ hr
S - 7-10hr
G2 - 2-5hr
Ipmat - 2 hour

38
Q

What is the G0 phase

A

Resting phase. No replication.

Eg neurons and cardiac muscle. Permanently in resting phase

39
Q

Cell renewal (3)

A

Static - resting phase - eg neurons, cardiac muscle.
Stable - quiescent - eg remove portion of hepatocytes stimulated to replicate.
Continuos - renewing - epidermis

40
Q

Cell no. Maintainence

A

Proliferation, differentiation, apopsis (programmed cell death)

41
Q

Cell differentiation - 3 types of genes

A

House keeper - constitutive genes
Conditional ( on/off )
Specialised ( expressed in certain types of tissue, function and time specific)

42
Q

Apoptosis definition

A

Programmed cell death. Condensed chromatin therefore inactive therefore no rRNA syn therefore no ribosomes therefore no protein synthesis.

43
Q

Morphological changes in apoptosis

A

Cell shrinkage - modification of PM ( phosphotidylserine translocated from PM to EC face). Mitochrondria destruction -> cytochrome C released - activates enzymes (Caspases) - digest cell substrates -nuclear changes (dna fragmentation).

44
Q

Necrosis

A

Cell death after injury
1 cell swell
2 cell lysis
3 tissue inflammation ( apoptosis no inflammation )

45
Q

CASPASES

A

Activate Dnase -> dna fragmentation

46
Q

Gel electrophoresis of apoptotic cells

A

Normal cell - high molecular weight
Apoptotic cells - dna ladder formed
Necrotic cells - low weight

47
Q

5 types of actin binding protein

A

Actin binding protein - fibrin, fascin (eg microvilli) cross link actin filaments into parallel strands
Actin filament severing - cut into short fragments (eg gelsolin - high ca2+ conc - severing)
Acting capping - tropomodulin - prevent polymerisation
Actin cross linking - cross link actin filaments ( spectrin, actin, protein 4.1, 4.3
Actin motor proteins - hydrolysis of atp - recock myosin head

Cells molecules and genes (5 decks)

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