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Cells > organelles > Flashcards

organelles Flashcards

1
Q

cytosol organelle dfn

A
  • cellular fluid which bathes biologically active structures

- biologically active structures found within a cell ( little organs )

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2
Q

list organelles

A 
ribosome
endoplasmic reticulum
Golgi body
peroxisomes
proteasome
lysosomes
mitochondria
secretory granules
inclusions
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3
Q

ribosome structure and function and location

A
  • small non-membrane bound structres with subunits
  • site of amino acids from tRNA assemble into polypeptides following sequence on mRNA
  • found in cytosol or bound to rER
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4
Q

structure of ribosomes subunit

A
  • small subunit - rRNA core and 30 peripheral proteins

- large - 3 rRNA and 50 peripheral

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5
Q

function of rRNA in ribosome

A
  • makes up core of subunit
  • provide structural support
  • catalyze protein synthesis
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6
Q

formation of ribosomes

A

-ribosomal proteins made in cytoplasm, move to nucleus becomes associated with rRNA in nucleolus ( becomes assembled ) and move out of nucleus

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7
Q

polyribosomes and fate of protein made depending on site

A
  • multi functional ribosomes on the same strand of mRNA
  • if made in cytosol the proteins are for cytoskeleton or organelles

-if made in rER then sent to Golgi body
1 secretion
2 lysosome formation
3 incorporate into membrane

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8
Q

staining nature of ribosomes and prominent in what type of cells

A
  • basophilic

- in secretory cells eg pancreatic cells

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9
Q

Endoplasmic reticulum structure and location

A

membrane network contiouns with outer memebrane of nucleus ( found near nucleus ) folded up enclosing channels called cisternae

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10
Q

rER structure, function, location and characteristics

A

-prominent In secretory cells
-flattened parallel membranes enclosing cisternae
-has bound polysomes
-makes membrane proteins, secretory proteins and lysosmal proteins
-stores newly synthised molecules
-transport of molecules through cisternae sequerested from cytoplasm
-posttranslational modification of proteins
-ensures proper folding of proteins via chaperones
-

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11
Q

sER structure, function, haracteristics and location

A
  • continuous with rER
  • no bound polysomes ( not basophilic )
  • enzymes in sER make phospholipids and steroids
  • detoxify harmful substances via hydroxylation ( adding OH to drug making it more water soluble, prominent in liver )
  • stores and release Ca2+ ions vital in muscles contraction ( called sacroplamsic reticulum )
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12
Q

how do phospholipids move away from sER

A

1 lateral diffusion
2 lipid carrier molecules
3 vesicles from sER

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13
Q

How a protein is segregated into rER

A
  • protein synthesis begins in cytosol and if a peptide is to be rER segregated 5 end of mRNA encodes signal sequence ( 15-40 aas hydrophobic region )
  • signal peptide is bound by signal recognition particle ( SRP ) wc binds to SRP receptor on ER.
  • Ribosome receptor on ER membrane firmly holds ribosomes in place.
  • SRP released and peptide translocates into rER via translocon ( protein translocator complex pore )
  • signal peptide removed by signal peptidase and peptide grows and continually segregated into ER by translocation pore and chaperones pulling on it
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14
Q

What does SRP do

A

Inhibits further peptide elongation

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15
Q

Golgi body structure, functiona and location

A
  • smooth membranes sacs enclosing cistane. Not connected
  • near nucleus
  • site of post translational modifications of rER proteins and sorting and packing and synthesis of lysosomes
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16
Q

In rER of protein synthesis

A
  • new peptides translocate to Cisternae of rER
  • Proteins folded ( guides by chaperone )
  • disulfide bonds formed between cysteine last
  • preassembled ohliosaccharide added to asparagine ( N linked )
17
Q

In cis Golgi network

A
  • mannose-6-phosphate added to future lysosome hydrolase

- N linked ogliosaccharide trimmed and other sugars added

18
Q

Transport proteins between Golgi and rER

A
  • COP 2 towards Golgi

- COP 1 retrograde

19
Q

Medial Golgi network

A
  • n linked ogliosaccharides modified
  • glycoproteins and glycolipids sorted into specific vesicles
  • glycosylation of serine and threonine
20
Q

Trans Golgi body

A
  • specific vesicles sorted and separated
  • sialic acid added as terminal sugar to certain ogliosaccharides
  • sulfation of tyrosine
  • vesicles sent to membrane for incorporating or secretion
  • lysosomal proteins packed into vesicle which is released as lysosome
21
Q

Secretory granules function and structure

A
  • made in Golgi body
  • granules surrounded by membrane
  • store Golgi products until release signaled ( regulated secretion eg via hormones )
22
Q

Zymogen granules

A

-secretory granules with dense content of digestive enzymes

23
Q

Lysosome function and structure and were prominent and were made

A
  • spherical membrane bound sites of intracellular digestion
  • prominent in phagocytotic cells
  • synthesis in rER and packed then release by Golgi
24
Q

Marker for lysosomes

A

-mannose-6-phosphate added to n liked ogliosaccharides of hydrolases made by rER

25
Q

Fate of lysosome

A

1 contents exocytized eg in osteoclasts

2 fuse with autophagosome, endosome, phagosome or pinocytotic vesicles forming secondary lysosome. Content degraded releasing nutrient and residual body formed

26
Q

Residual body

A

Contained indigestible material

-accumulate overtime forming lipofuscin

27
Q

Autophagy

A
  • it is when old or excess organelles are degraded by lysosomes
  • membrane from sER enclosed organelle forming autophagosome which fuses with lysosomes
28
Q

Proteasome function, structure

A

-non-membrane bound 4 ring stacked cylindrical protein structures size of small ribosome subunit which function to degrade denatured, non-functional and poorly folded proteins

29
Q

How do proteasomes work

A
  • at end of 4 ring stack is particle with ATP and can recognize ubiquitin.
  • ubiquitinated proteins are recognized and opened up via ATP hydrolysis
  • translocated into core of cylinder and degraded by endopeptodases
  • ubiquitin recycled
30
Q

What happens to misfolded proteins

A

-chaperones in rER recognizes them add ubiquitin and release them into cytosol

31
Q

Peroxisomes structure function and mode of replication

A
  • spherical, one membrane bound structure which produce enzymes oxidase which degraded H2O2
  • form via fission or budding of precursor vesicles from Golgi
32
Q

Inclusion and types

A

-contain accumulated metabolites but they themselves show no metabolic activity
Include
1 lipid droplets
2 glycogen granules - store glucose
3 lipofuscin - accumulating of residual lysosomes
4 melanin - dark brown granules which protect the body against UV
5 Hemosiderin - brown aggregate of denatured ferritin proteins with many atoms bonded to iron ; prominent in liver due to phagocytosis of RBC

33
Q

Mitochondria structure and function formation and prominence

A
  • Elongated structure with outer membrane and inner membrane folding into Kristy and closing matrix
  • Has enzymes specialized for aerobic respiration and ATP synthesis
  • powerhouse of cells some energy formed not trapped in ATP but released as heat
  • prominent in Muscle cells highenergy need
  • has transmembrane proteins forming channel called aquaporin to allow exchange between organelle and cytoplasm
  • cristae increase surface area
  • releases cytochrome c to initiate cell death via apoptosis
  • new from fission of pre-existing
  • shows activity of protein synthesis

Cells (11 decks)

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