Bio 240 Cell Organelles

characteristics that all cells share

plasma membrane, cytosol, chromosomes, ribosomes

location of DNA in eukaryotes

nucleus

location of DNA in prokaryotes

nucleoid

fimbriae

attachment structures on the surface of some prokaryotes

nucleoid

region where the cell’s DNA is located (not enclosed by a membrane)

ribosomes

complexes that synthesize proteins according to the instructions from the genes through use of a mRNA strand as a template to make a polypeptide chain; they perform dehydration synthesis reactions to join amino acids together; function in cytosol and rough er

cytosol

the semifluid portion of cytoplasm in which sub cellular components are suspended; not an organelle

plasma membrane

membrane enclosing the cytoplasm; acts as a selective barrier regulating the cells chemical composition

cell wall

rigid structure outside the plasma membrane (plants and prokaryotes)

glycocalyx

outer coating of many prokaryotes consisting of a capsule or a slime layer

flagella

locomotion organelles of some prokaryotes

microvilli

long thin projections of a cell which increase surface area with out an appreciable increase in volume

endoplasmic reticulum

network of membraneous sacs and tubes; active in membrane synthesis and other synthetic and metabolic processes(approximately 1)

nuclear envelope

double membrane enclosing the nucleus, perforated by pores and continuous with er

nucleolus

nonmembraneous structure involved in production of ribosomes; a nucleus has one or more nucleoli

chromatin

material consisting of DNA and proteins; visible in a dividing cell as individual condensed chromosomes

Golgi apparatus

organelle active in synthesis, modification, sorting, and secretion of cell products (1 per cell); consists of stacks of flattened sacs aka cristernae; lies between rough er and cell surface; modifies proteins by adding oligosaccharides and trimming those sugars \, small vesicles move proteins between organelles and sacs of Golgi

lysosome

digestive organelle where macromolecules are hydrolyzed (approximately 300 per cell); in animal cells; contain digestive enzymes that perform hydrolysis reactions on ingested materials; participate in phagocytosis and autophagy

mitochondrion

organelle where cellular respiration occurs and most ATP is generated (approximately 1700 per cell)

peroxisome

organelle with various specialized and metabolic functions; produces hydrogen peroxide as a by-product and then converts it to water (appro 400 per cell); break down molecules by oxidation rather than by hydrolysis reactions

cytoskeleton

reinforces cell shape; functions in cell movement; components are made of protein; includes: microfilaments, intermediate filaments, and microtubules

centrosome

region where the cells microtubules are initiated; contains a pair of centrioles

flagellum

motility structure present in some animal cells composed of a cluster of microtubules within an extension of the plasma membrane

cell wall

outer layer that maintains cells shape and protects cell from mechanical damage; made of cellulose, other polysaccharides and protein

plasmodesmata

cytoplasmic channels through cell walls that connect the cytoplasms of adjacent cell

chloroplasts

photosynthetic organelle; converts energy of sunlight to chemical energy stored in sugar molecules

central vacuole

prominent organelle in older plant cells; functions include storage, breakdown of waste products, and hydrolysis of macromolecules; enlargement of the vacuole is a major mechanism of plant growth; perform function of lysosomes in plant cells and store water to provide turgor pressure to support plant stems

why do eukaryotes tend to be larger than prokaryotes

due to the existence of membrane bound organelles

what happens to organelle volumes as cell size increases

the number of molecules and organelles must increase to maintain the same concentrations as in the smaller cells

molecules that increase with cell size

proteins, mRNA, nucleus, nucleolus, mitochondria, vacuole, mitotic spindle, and centrosome

molecules that are size independent

genomic DNA and size independent proteins

how do the membrane bound organelles compartmentalize and increase the efficiency of various intracellular functions and activities

localizing processes to small areas increase reaction rates (synthesis of various molecules and breakdown of various molecules), increased transport efficiency (moving molecules in vesicles rather than diffusion), and storage of molecules (ex for later use as energy source)

endosomes

type of vesicle that sorts endocytose material (approximately 200 per cell)

nuclear lamina

a netlike array of proteins filament that lines the inner surface

nucleus

surrounded by double membrane called nuclear envelope; contains most of cells genetic material

rough er

appears rough due to ribosomes on surface; consists of connected flattened sacs called cristernae; where some proteins are synthesized including those that are secreted by the cell and those that remain on the cell membrane. the proteins are made by ribosomes and inserted into rough er; phospholipids are also made here

smooth er

appears smooth because no ribosomes; mostly connected tubes; where lipids are made and broken down, detoxification of organic (carbon based) molecules like ethanol and some drugs and toxins,a dn stores calcium

vesicles

move materials between organelles and the cell surface; some store materials until directed to release them outside of cell; they bud from and fuse with other membranes; involved in endocytosis and exocytosis

exocytosis

proteins and polysaccharides made by er and Golgi are secreted by the cell via this

endocytosis

materials taken up by cell and ends up in lysosomes

phagocytosis

lysosome digesting food or foreign materials from food vacuolea

autophagy

lysosome and peroxisome breaking down damaged organelles

vacuoles in protists

assist in maintaining water balance and may be involved in digesting food taken in by phagocytosis

vacuoles in animal cells

used mostly for storage and not for transport; also assist in the killing and destruction of ingested material by phagocytic cells of the immune system system; phagosome

proteosomes

degrade misfiled, damaged, old and unnecessary proteins into small peptides; hydrolysis reactions take place within proteasome to digest proteins and there are peptidase enzymes in the sore