ap organelles & subcellular organization

Organelles & Subcellular Organization

Nucleus

• Nuclear envelope– Double memb enclosing the nucleus– Perforated by pores– Continuous w/ER

• Nucleolus– Non-mbo involved in prod’n of ribosomes– 1 or more/nucleus

• Chromatin– Material consisting of DNA & proteins– Visible as indiv chromosomes in a dividing cell

Plasma Membrane

• Memb enclosing cell

Ribosomes

• Non-mbo that make proteins• Found free in cytoplas,• Found bound to ER or nuclear envelope

Golgi Apparatus

• Active in synthesis, modification, sorting & secreting cell products

• Cis & trans face

Lysosome

• Digestive orgll where macromols are hydrolyzed

Peroxisome

• Orgll w/var sp’d metabolic functiosn• Prods H2O2

• Contains enz that transf H to O prod-ing H2O2 which is toxic

• Also contains enz that ∆s H2O2 H2O• Glyoxysome – sp’ed peroxysome– Fat storing tissue of seeds

Microvilli

• Projections that ↑ SA

Centrosome

• Region where cell microtubules are initiated– Animals: contain pr of centrosomes• Function unknown

– Plants : lack centrosomes

Cell Wall

• Outer layer • Maintains shape• Protects cell from mechanical damage• Made of cellulose, other polysaccharides &

proteins

Plasmodesmata

• Channels thru CWs that connect the cytoplasm of adj cells

Chloroplast

• PS-ic orgll• Converts nrg of sun to chem’l nrg stored in

sugar mol

ENDOMEMBRANE SYSTEM (EMS)

ER

• Network of membranous sacs & tubes• Active in membrane synthesis & other

synthetic & metabolic processes• Has rough & smooth regions

Smooth ER

• Synthesis of lipids• Metabolism of carbs• Detoxification of drugs & poisons• Cells rich in sER– Testes & ovaries (make & secrete sex hormones)– Liver cells (detox)– Muscle cells

Rough ER

• Secrete prot prod by ribosomes on rER• Memb factory of cell• Pacreas – secretes (prot) insulin

Vacuoles

• Food vacuoles – formed by phagocytosis• Contractile vacuole – pumps fw out• Central vacuole - plant

Central Vacuole

• Prominent orgll in older plant cells• Funct incl:– Storage– Breakdown of waste prods– Hydrolysis of mmols– Enlargement of vac is maj mech of plant growth

Tonoplast

• Memb around central vac

MITOCHONDRIA & CHLOROPLAST

•DNA•Ribosomes•Grow & reproduce inside of cell

Mitochondria

• Orgll where CR occurs & most ATP is generated • Outer memb• Intermemb space• Inner memb• Cristae – infolding of inner memb

• Mitochondrial matrix – Inside inner memb– Contains ribosomes & mRNA

Chloroplast

• Thylakoid – flattened sacs• Granum – stacks of thylakoids• Stroma – fluid outside thylakoid

Cytoskeleton

• Network of fibers extending thru cytoplasm• Plays maj role in organizing structures &

activities of cell

Roles of Cytoskeleton

• Mechanical support: maintains cell shape (dynamic ∆s)

• Motility– Flagella & cilia– Muscle cell contraction– Vesicles that bud off ER to Golgi travel tracks of

cytoskeleton elements– Cytoplasmic streaming– Regulation of biochem’l activities of cell

Components of cytoskeleton

• made of protein– Microfilaments– Intermediate filaments– Microtubules

Flagellum

• Locomotion orgll• Composed of membrane enclosed

microtubules• Move by gripping microtubules w/in those

orglls & propelling them past each other