cell structure Flashcards
structure RER
-memb organelle
-flattened fluid filled sacs called cisternae.
-interconnected with 80s ribosomes attached to it
-more regular than SER
-continuous with outer nuclear envelope
-extended in almost the entire cytoplasm
structure SER
-memb organelle
-tubular, fluid filled sac
-no ribosomes
-irregular
function SER
-synthesis of lipids, cholesterol and steroids such as sex hormones
-transport steroids to Golgi app
-breaks down toxic substances in liver
function RER
-post translational modification of proteins
-transport proteins to Golgi app
Golgi structure
-memb organelle
-flattened fluid filled sacs called cisternae
-arranged in a stack, parallel to each others swollen at both ends, with Golgi vesicles surrounding them
Golgi function
-processing, chemical modification and glycosylation of proteins
-packaging of protein into secretory vesicles and lysosomes
structure ribosomes
-non memb organelle
-measures 20-25 nm
-made of two subunits a large and small subunit each is made of proteins and rRNA
-large subunit has 2 buildings sites for 2 tRNA
-the small subunit allows mRNA binds to it
function ribosomes
polypeptide snythesis
structure secretory vesicle
-spherical
-memb organelle
-measures 0.5 nm
structure of cilium
-each cilium has 2 central microtubules & a ring of nine microtubule doublets on the side “9+2”
the MTDs structure
the wall of the A-microtubule is a complete ring of 13 protofilaments and B-microtubule attached is an incomplete ring with 10 protofilaments.
each A-microtubule has inner & outer arms made of dynein
function secretory vesicle
-they pinch off Golgi App, move to cell surface memb guided by microtubules “cytoskeleton” using ATP, fuse with it as both are fluid in nature, and release its contents out of cell by exocytosis
lysosomes structure
-spherical
-memb organelle that has hydrolytic enzymes
-it measures 0.5µm
lysosomes function
-stores inactive hydrolytic enzymes
-phagocytosis: moves towards the phagocytic vesicle, fuse with it, as the memb are fluid and release its hydrolytic enzymes as protease to digest cell memb
-autophagy: digest worn out or dead organelles such as mitochondria
-autolysis: digestion of the parent cell by lysosomes
-secretion of enzymes: enzymes in the acrosomes of sperms
beating mech
the inner and outer dynein arms connect with B-microtubules of neighboring MTDs
-MTDs slide past each other using ATP- the sliding motion is converted into bending- beating movement
structure cellulose cell wall
2ry cell wall: founded in most cells not all
importance: rigid layer that supports plant cells
1ry cell wall: between middle lamella and secondary cell wall
importance: provides strength to the cell wall, but its also flexible to allow cell growth
middle lamella: outer layer of cell wall that mainly contains pectin
importance: cell to cell adhesion
prokaryotic flagellum
prokaryotic flagellum is a protein divided into 3 parts: filament, hook & basal body
structure cell sap vacuole
-memb organelle
-surrounded by tonoplast
-filled with sap
function cell vacuole
function:
-support:
concentrated vacuole- low water potential gradient so water enters vacuole by osmosis, increasing pressure in cell keeping plant turgid, so support the stem.
-lysosomal activity:
anthocyanin pigments
alkaloids and tannins
latex
-food reserves:
-as sucrose or mineral salts, protein-storing vacuoles are common in seeds
waste products
structure of centrioles
-made of two hollow cylinders
-each cylinder is made of nine triplets of microtubules
-the 2 cylinders are perpendicular to each other
-measures 0.4 µm
function of centrioles
-organizes microtubules into spindle fibers
microtubules function
-supports cell shape
-direct the movement of the organelles such as secretory vesicle
