Cytology 3-4 mitochrondria and lecture 3(cytoskeleton) and 4(nucleus) Flashcards
(48 cards)
Which stain used to detect mitochondria and which colour is positive?
Mitotracker - pink
Importance of granules in mitochrondria
Maintain low levels of Calcium and Mg ions.
Store these ions
What makes mitochondria semi-independent? (5)
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
Composition of outer mitochondrial membrane? (4)
50% lipids - main phosphotidylcholine
Porins - channel proteins
Similar to ER membrane
Enzymes - (lipid synthesis, fatty acid metabolism)
Inner membrane composition?
20% lipids
Cristae or tubular (in cells specialised for steroid hormone synthesis)
3 transport proteins
Enzymes for ETC and ATP synthase
Where are tubular inner membrane mito found?
Cells syn of steroid hormones. Eg adrenal glands, gonads.
What is an inclusion?
Not metabolically active cytoplasmic component.
Give 5 examples of inclusions
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.
Actin and microtubules tread-milling req.
Actin - atp, mg2+, k+
Microtubules - gtp, mg2+
How are mito proteins formed in the cytosol?
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,
At what inclination does actin bind to myosin?
45 degrees
Function of actin binding protein?
Accelerate/decelerate polymerisation of actin filaments.
What type of myosin do non muscle cells contain?
Myosin I
Nucleus quick points (4)
DNA, Double bilayer membrane, nucleolus (protein synthesis), continuous with ER
Nucleus irregular in….
Leukocytes, plasma cells, spermatozoa
Observing nucleus…..(4)
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
Ratio of nucleus to cytosol
Vn / Vcytoplasm - Vn
= k
If k not constant - pathology
Nucleolus
No membrane, basophilic, granular and fibrillar layer. Breakdown during pro-metaphase. rRNA transcription Synthesis of ribosomal sub units. Surrounded by nuclear chromatin
Inner nuclear membrane?
Unique proteins - nuclear lamina - filaments -> lamin proteins A B C
2 types of chromatin in NUCLEUS
Euchromatin - dark, active
Heterochromatin - compacted, not active, electron dense
Nuclear lamina size
25nm
Cell cycle, lamin phosphorylation
Prophase, lamin phosphorylation, breakdown NE
Telophase, lamin dephosphorylation, reform NE
Nuclear lamina (4)
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
3 laminopathy
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
