FORM & FUNCTION (Subcellular Organelles) Flashcards
nucleus
-usually one
-some cells have multiple (muscle) or none due to development (RBC)
-basophilic
-euchromatin (EC) and heterochromatin (HC)
-nucleolus
-active cells will have more EC and nucleoli
euchromatin
-appears lighter
-less coiled
-DNA more exposed
heterochromatin
-appears darker
-more coiled
-DNA less exposed
nucleolus
-region where rRNA is made for ribosome synthesis
-darker spots within the nucleus
Mitochondria
-primary organelle that produces energy (ATP)
-also metabolizes fatty acids
-visible appearance gives you a clue of it’s function (cristae or tubular projections)
mitochondria cristae
-energy producing
-inner folding structure
mitochondria tubular projections
-lipid producing (ex. steroids)
-tubular looking
endoplasmic reticulum
-extensive network of membranes arranged in flattened sacs
-rough ER: with ribosomes attached
-smooth ER: no ribosomes attached
ribosomes
-make proteins (Requires ATP)
-made from rRNA and proteins (basophilic)
-many free ribosomes=polyribosomes
2 pathways for protein synthesis depending on their function
- Proteins that function in the cytosol and have no modification (synthesized by free ribosomes)
- Proteins that function at specific locations (membrane, organell or outside the cell)
>synthesized by ribosomes on rER, packaged in vesicles and often modified by Golgi apparatus
differential staining of free ribosomes as a diagnostic tool
-mature RBC have no subcellular organelles, filled with Hb=no polyribosomes
-reticulocyte (immature RBC) still contains polyribosomes (normally present in 1% in circulation)
>more basophilic
Golgi apparatus structure
- Stacked membrane
- Cis face
- Trans face
stacked membrane
-composed of a series of flattened, stacked pouches
cis face
-receiving side
-closest to the ER
-receives materials from ER for modification
trans face
-shipping side
-oriented toward the PM
-sends modified products to their final destinations
Golgi apparatus functions
- Chemical modification
- Packing and storage
chemical modification (golgi)
-contains enzymes to chemically modify nasent proteins
Ex. glycosylation, sulfation, phosphorylation
packing and storage (golgi)
-initiates packing, concentration and storage of secretory products
-prepares them for transportation to specific locations
golgi staining
-primarily composed of lipids, making it challenging to visualize
-in a basophilic cytoplasm=Golgi may appear faint or unstained
cells that make proteins to be secreted
-many vesicles/granules
1. Pancreatic acinar cells secrete digestive enzymes
2. Fibroblasts secret collagen
3. Plasma cells secret immunoglobulins
secretory granules
-can be basophilic or acidophilic
-depends on chemical composition of their contents
sER
-continuous rER
-synthesizes cholesterol, steroids, CHO, lipid, phospholipids
-detoxifies drugs or toxin (in liver)
-stores Ca2+ (in skeletal muscle)
sER are abundant in cells that
-are important for synthesis of lipids and metabolism of drugs or toxins (hepatocytes)
-produce steroid hormones (adrenocortical cells, testicular and ovarian cells)
steroid-secreting cells
-round nuclei
-boxy
-polyhedral shape
-conspicuous and vacuolated cytoplasm
*full of her (white=no dye)
lysosome structure
-spherical, range in diameter
-appear uniformly granular and electron-dense
-less electron dense ones=heterolysosomes in which digestion of the content is underway
-typically acidic
lysosomes function
- remove obsolete or non-functional proteins, organelles or membranes (ex. autophagosome-> lipofusion)
- store hydrolytic enzymes before they are secreted outsided (ex. osteoclasts:remodelling bone)
- store hydrolytic enzymes to digest invading pathogens (ex. macrophages and neutrophils function to detect, engulf and destroy pathogens)
peroxisome structure
-similar to lysosomes
-abundant in liver and proximal convoluted tubules of kidneys
-can appear crytstalline
-contains various enzymes but work at neutral pH
peroxisome function
-detoxicication
-beta-oxidation of long chain fatty acids
-removes oxygen species (ex. catalase, oxidases, peroxidases) to prevent oxidative damage
lipid droplet structure
-non membrane bound (hydrophobic) droplets are found in adipocytes, steroid producing cells
-stained orange with a special dye
lipid droplet function
-lipid storage
