Cell Organelles

cell (plasma) membrane

• both prokaryotic and eukaryotic cells have this (animal and plant cells as well)

• separates internal environment from external

• has a hydrophobic interior

• selective permeability

• maintains homeostasis

cell wall

• part of most prokaryotic cells 

• some eukaryotic cells (not animal cells)

• important for cell structure & shape

• offers additional protection

cytoskeleton

• fibrous network in cytoplasm

• contains microtubules and microfilaments

• helps with cell division

nucleus

• houses genetic instructions

• made up of chromatin and chromosomes

• found in eukaryotic cells (plant + animal)

• controls the cell’s activities

nuclear envelope

• membrane that encloses the nucleus

• separates contents from cytoplasm

nucleolus

• ribosome synthesis (rRNA and protein)

smooth endoplasmic reticulum

• synthesizes lipids

• stores calcium

• detoxification of cells

• found in eukaryotic cells (plant + animal)

• has many folds

• helps materials get around the cell

• processes molecules

rough endoplasmic reticulum

• has bound ribosomes

• produces proteins which are distributed by vesicles to membrane or outside of the cell

• found in eukaryotic cells (plant + animal)

• has many folds

• helps materials get around the cell

• processes molecules

vesicles

• a little membrane-bound sac

vacuoles

• found in eukaryotic cells (plant + animal)

• stores materials depending on the cell type (water, proteins, waste)

  • food vacuoles (intracellular digestion)

    • are formed by phagocytosis

    • releases cellular wastes

  • contractile vacuoles

    • pump excess water out of protist cells

• in plant cells: central vacuole

  • holds water and maintains turgor pressure

  • involved in cell growth

• in animal cells: smaller and several vacuoles

• membrane-bound sac

golgi apparatus

• assembled items sent here from ER

• modifies, sorts, and packages materials for delivery

  • correctly folds and chemically modifies newly synthesized cellular products (small molecules) for transport by vesicles

• found in eukaryotic cells (plant + animal)

• consists of flattened membranous sacs

• production of lysosomes

nuclear pore

cytosol/cytoplasm

• found in all cells

• in eukaryotic cells, includes everything in cell except nucleus

• cytosol and cytoskeleton (both part of cytoplasm) support organelles

lysosome

• found in some eukaryotic cells (animal)

• contains enzymes that can break down substances

• membrane-enclosed sac that contains hydrolytic enzymes

  • intracellular digestion

  • recycling of a cell’s organic material

  • programmed cell death (apoptosis)

  • can digest all kinds of macromolecules

centrioles

• found in eukaryotic cells (animal cells only)

• come from the centrosome (two per centrosome)

• involved with cell division

• spindle fibers involved

• made of microtubules

microtubules

• thickest

• tubulin protein

• cilia and flagella, centrioles

chloroplast

• found in some eukaryotic cells (plant cells)

• makes sugars

• involved in photosynthesis

• capture light energy through photosynthesis

  • contains chlorophyll pigment

• double membrane creates a compartmentalized structure

  • increases the surface area

  • contains the internal membrane-bound structures called thylakoids

    • thylakoids have enzymes that help during photosynthesis

mitochondrion (plural: mitochondria)

• found in eukaryotic cells (plant + animal)

• makes ATP; converts food energy

• cellular respiration site (in eukaryotes)

  • inner membrane contains enzymes for ATP production

• enclosed by a double membrane that allows for compartmentalization

• inner membrane is highly convoluted forming folds that increase surface area called cristae

flagellum (flagella)

• locomotion organelles of some bacteria 

• found in prokaryotic cells + eukaryotic cells (animals)

cilia

plasmodesmata

channels through cell walls that connect the cytoplasms of adjacent cells

ribosomes

• found in all cells (eukaryotic + prokaryotic)

• makes (synthesizes) proteins

• non-membrane, sub-cellular structures

  • made of ribosomal RNA (rRNA) + protein

• ribosomes can be either free in cytosol or bound to rough ER

  • free ribosomes make proteins that stay inside the cell

  • bound ribosomes make proteins for secretion out of the cell

peroxisome

• produces hydrogen peroxide and converts it to water

• metabolism of fatty acids; detox of alcohol in liver

• found in eukaryotic cells (plant + animal)

centrosome

• area of the cytosol where microtubules are synthesized

• found in eukaryotic cells (plant + animal)

• centrioles are found inside

central vacuole

• the type of vacuole found in only plant cells

• holds water and maintains turgor pressure

• involved in cell growth