organelles

Question 1

cytosol organelle dfn

Answer 1

• cellular fluid which bathes biologically active structures

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

Question 2

list organelles

Answer 2

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

Question 3

ribosome structure and function and location

Answer 3

• 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

Question 4

structure of ribosomes subunit

Answer 4

• small subunit - rRNA core and 30 peripheral proteins

- large - 3 rRNA and 50 peripheral

Question 5

function of rRNA in ribosome

Answer 5

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

Question 6

formation of ribosomes

Answer 6

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

Question 7

polyribosomes and fate of protein made depending on site

Answer 7

• 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

Question 8

staining nature of ribosomes and prominent in what type of cells

Answer 8

• basophilic

- in secretory cells eg pancreatic cells

Question 9

Endoplasmic reticulum structure and location

Answer 9

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

Question 10

rER structure, function, location and characteristics

Answer 10

-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
-

Question 11

sER structure, function, haracteristics and location

Answer 11

• 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 )

Question 12

how do phospholipids move away from sER

Answer 12

1 lateral diffusion
2 lipid carrier molecules
3 vesicles from sER

Question 13

How a protein is segregated into rER

Answer 13

• 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

Question 14

What does SRP do

Answer 14

Inhibits further peptide elongation

Question 15

Golgi body structure, functiona and location

Answer 15

• 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

Question 16

In rER of protein synthesis

Answer 16

• 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 )

Question 17

In cis Golgi network

Answer 17

• mannose-6-phosphate added to future lysosome hydrolase

- N linked ogliosaccharide trimmed and other sugars added

Question 18

Transport proteins between Golgi and rER

Answer 18

• COP 2 towards Golgi

- COP 1 retrograde

Question 19

Medial Golgi network

Answer 19

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

Question 20

Trans Golgi body

Answer 20

• 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

Question 21

Secretory granules function and structure

Answer 21

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

Question 22

Zymogen granules

Answer 22

-secretory granules with dense content of digestive enzymes

Question 23

Lysosome function and structure and were prominent and were made

Answer 23

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

Question 24

Marker for lysosomes

Answer 24

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

Question 25

Fate of lysosome

Answer 25

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

Question 26

Residual body

Answer 26

Contained indigestible material | -accumulate overtime forming lipofuscin

Question 27

Autophagy

Answer 27

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

Question 28

Proteasome function, structure

Answer 28

-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

Question 29

How do proteasomes work

Answer 29

- 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

Question 30

What happens to misfolded proteins

Answer 30

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

Question 31

Peroxisomes structure function and mode of replication

Answer 31

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

Question 32

Inclusion and types

Answer 32

-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

Question 33

Mitochondria structure and function formation and prominence

Answer 33

- 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