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Part 2: Eukaryotic Cell Structures

Cytoplasm• Location / Structure: The region of a cell

between the cell membrane and the nucleus; made of a jelly-like watery fluid called the cytosol

• Function: “cushions” the organelles

Cell MembraneLocation / Structure:•Also called the plasma membrane•A barrier that surrounds the cytoplasm •Separates the inside of cells from the outside environment Function: •Regulates passage of materials into and out of the cell

NucleusLocation / Structure:

• Found at the center of the cell

• Contains DNA

• Surrounded by a double-membrane with holes (aka pores) to allow passage of materials (not DNA) into and out of the nucleus

Function: Controls the activities of the cell

Nucleolus

Location / Structure:

• A spherical structure found at the center of the nucleus

Function: Creates (synthesizes) ribosomes… see next slide for a description of ribosomes

Ribosomes

Location / Structure:• Found floating in the cytoplasm and

attached to the rough ER• Very small• Made of RNA and protein

Function:• Make proteins

Rough Endoplasmic Reticulum

Location / Structure:

•Tubes and sacs made of membrane

•Has ribosomes on its surface

Function:

•Make proteins (due to ribosomes)

•Transport materials (like proteins) around the cell… it is the highway of the cell!

Smooth Endoplasmic Reticulum

Location / Structure:

•Tubes and sacs made of membrane

•Does not have ribosomes on its surface

•Attached to the Rough ER, farther out from the nucleus

Function:

•Makes lipids

•Breaks down toxins

Golgi ApparatusLocation / Structure:•Another system of tubes and sacs made of membrane close to the cell membrane

Function: •Vesicles (spheres of membrane) carry materials (ex: proteins from the Rough ER) to the Golgi and from the Golgi to release materials at the membrane•Called the “post office” because it repackages materials and sends them out of the cell

LysosomesLocation /Structure: •small, spherical organelles that contain enzymes•float in the cytoplasm

Function: •enzymes can digest carbs, lipids, DNA, RNA, old organelles, viruses, bacteria•Only found in animal cells

Mitochondria

Location / Structure: Has a double membrane, inner membrane is folded

Function: powerhouse of the cell; produces energy!

Question: In what types of cells would mitochondria be the most numerous?

ChloroplastsLocation / Structure:•only found in plant cells•double membrane•stacks of “disks” inside inner membrane•green due to pigment “chlorophyll”

Function: •Sunlight energy is captured by chlorophyll and converted to energy stored in sugars like glucose during photosynthesis

Vacuole

Location / Structure•Floating in the cytoplasm, sphere of membrane surrounding fluid•Found in plants and animals, but large and in the middle of the cell in plants

Function: Stores waste, water, food, etc.

Cell Wall

Location / Structure:

•Outer barrier on plant cells

•Made of cellulose, a tough polysaccharide

Function: supports and protects the cell

Cytoskeleton• Location / Structure: a

“mesh” of three types of long protein strands located in the cytoplasm

• Function: a structure to maintain the shape and size of cells (like our skeletons!)

Cilia / FlagellaLocation / Structure: •hair-like organelles that extend from the surface of the cell•cilia are shorter and more numerous•flagella are longer and less numerous

Function: •Movement

CentriolesLocation / Structure: •Made of the same types of proteins found in the cytoskeleton arranged in cylinders (look like “churros”)•Found only in animal cells

Function: •Assist with cell division