Transcript Function

Plasma Membrane
• Function – physical barrier for the cell; separates
internal and external environments; selective
• Location – surrounding the cell, outer surface
– Membrane lipids—phospholipids have a polar
phosphate “head” which is hydrophilic (waterloving) and two non-polar fatty-acid “tails” that
are hydrophobic (water-fearing); arranged in a bilayer with the hydrophilic heads facing the inside
and the outside of the cell
– Fluid mosaic model – plasma membrane behaves
more like a fluid than a solid; it is very dynamic;
proteins move within the membrane
– Function – control center of the cell; contains
DNA; filled with a fluid called nucleoplasm
– Nuclear envelope – double-layer membrane
composed of phospholipids; keeps nuclear
contents separate from the rest of the cell;
nuclear pores allow for information to get into and
out of the nucleus when necessary
– Nucleolus – dense area within the nucleus;
produces ribosomal RNA
– Function – site of cellular respiration; the transfer
of energy from organic molecules to ATP
(adenosine triphosphate); double-layered
membrane; number of mitochondria varies
depending on the energy needs of cells – ex:
muscle cells have a lot, fat cells have few
– Mitochondrial DNA – DNA that is separate from
the DNA that is in the nucleus; mitochondria can
only reproduce by the division of pre-existing
• Function – sites of protein synthesis
• Location – in cytoplasm and on
rough endoplasmic reticulum
Endoplasmic Reticulum
– Function – series of membrane bound tubes and
sacs that allow for the transport of substances
throughout the cell
– Rough ER – contains ribosomes; functions in
protein synthesis
– Smooth ER – doesn’t have ribosomes; functions in
lipid synthesis
Golgi Apparatus
• Function – packaging, modifying and
shipping of cellular products
– Lysosomes – membrane-bound sacs that
contain digestive enzymes; break
down/digest bacteria, old or damaged
– Peroxisomes – similar to lysosomes;
produce hydrogen peroxide when they
break down alcohol and engulf bacteria
• Function – Hollow tubes made of protein, hold
organelles in place, maintain cell shape
• Location – Radiate outward from the center
called centrosome near the nucleus
Cilia and Flagella
• Cilia
– Short and present in large numbers
• Flagella
– Long extensions of the cell, usually one
that helps with the cell moving
• Function – Assist in movement
• Location – Outside of the cell
• Function – Two short cylinders of
microtubules that organize cell division
• Location – Near the nuclear envelope
• *Occur only in animal cells