Biology
3.2 Organelle notes
Cytoskeleton
Function: supports and shapes the cell
Shape: long threads, or fibers, made of protein
3 main types of fibers:
Microtubules- long hollow tubes that act as “tracks” for movement of
organelles; gives cell its shape
Intermediate filaments – smaller than microtubules; gives cell strength
Microfilaments – smallest fiber; enable cells to move and divide
Cytoplasm
Function: organizes organelles and gives cell strength
Shape/location: jelly-like substance that fills space btwn the nucleus and cell membrane
Other info: fluid portion is called cytosol (mainly water); cytoplasm contains the organelles
Vacuole
Function: storage
Shape/location: fluid filled sac
Other info: central vacuole in plant cells takes up most of cell space; aids in support of cell
Golgi apparatus
Function: modifies, packages, and transports proteins
Shape/location: close to ER; closely layered stacks of membrane enclosed spaces
Other info: proteins move from the ER to this organelle
Endoplasmic Reticulum (ER)
Function: aids in production of proteins and lipids
Shape/location: interconnected network of folded membranes; takes up a large part of the
Cytoplasm. Lumen is the interior of the ER.
Rough ER: covered with ribosomes; as proteins are made by ribosomes they enter
the lumen and may be modified.
Smooth ER: not covered with ribosomes; makes lipids
Ribosomes
Function: link amino acids together to form proteins; site of protein synthesis
Shape/location: very small; found on Rough ER and suspended in cytoplasm
Other info: made in nucleolus; made of proteins and RNA
Nucleus
Function: store and protect DNA
Shape/location: large, sphere shaped organelle. Has double membrane called the nuclear
envelope
Nucleolus
Function: assembles ribosomes
Shape/location: found inside the nucleus
Vesicles
Function: isolate and transport specific molecules
Shape/location: small, membrane bound sacs; short lived
Other info: After a protein is made, part of the ER forms a vesicle around the protein to
protect it on its way to the golgi apparatus.
Mitochondria
Function: generate energy for the cell
Shape/location: bean shaped; have an inner and outer membrane
Other info: have their own ribosomes and DNA which suggests that they were originally
free living prokaryotes.
Lysosomes
Function: digest and recycle foreign materials or worn-out parts
Shape/location: membrane bound; contains enzymes
Other info: found in animal cells; presence in plant cells is still questioned
Defends cells from invading bacteria and viruses
Centrosome
Small region of cytoplasm that produces microtubules (including spindle fibers present during cell division.
Centrioles
Function: help divide DNA during cell division; also organize microtubules to form
Cilia (hairs) and flagella (tail)
Shape/location: cylinder shaped; made of short microtubules arranged in a circle
Found in animal cells
Cell Wall
Function: shape and support of cell and organism
Shape/location: found in plants, algae, fungi and bacteria. Surrounds cell membrane
Other info: plant and algae cell walls are made of cellulose
Chloroplast
Function: carry out photosynthesis (convert solar energy into chemical energy)
Shape/location: have an outer and inner membrane. Inside chloroplast are stacks of
Thylakoids, disc shaped sacs, that contain the green pigment chlorophyll.
Other info: have their own ribosomes and DNA which suggests that they were originally
free living prokaryotes.
Plants have chloroplasts and mitochondria