Chapter 3

 Encloses the cell and forms a boundary  Separates the interior of the cell from its surroundings  Interior is filled with cytoplasm  Regulates the gases, nutrients, and wastes that enter and leave the cell

 Regulates cellular activities and enables the cells to reproduce  Carries the instructions for making proteins

 Cellular structure where proteins are made

 “before the nucleus”  Smallest and simplest cells  Single-celled organisms (bacteria)  Lack a true nucleus  Lack cell organelles

 DNA is not enclosed in a nucleus A single loop located near the center

 Contain a cell wall that surrounds the cell membrane Offers support and structure  May contain a capsule that surrounds the cell wall  Many have a flagella that help to propel the cell

 Contain a true nucleus  Contain organelles  Some have flagella and some have cilia

 Cytoplasm includes everything inside the cell membrane but outside the nucleus  Vesicles and channels move proteins between organelles  Nucleus houses the DNA  Cytosol is the fluid surrounding the inside of the cell  Cytoskeleton provides internal framework

 Holds the cell together and helps to keep its shape  Functions in cell movement  Transports materials within the cell  Aids in cell division

 Contains three types of fibers Actin fibers (microfilaments)- determine shape by contracting and expanding Microtubules- act as a highway system for transportation of information from the nucleus to different parts of the cell Intermediate fibers- a frame to confine ribosomes and enzymes to a certain region of the cell

 Is selective permeable Due to how the phospholipids interact with water  Fluid Due to the lipids that form the foundation of the membranes Lipids are the barrier between the inside and outside of the cell

 A phospholipid is a lipid that is made up of a phosphate group and two fatty acids The polar head contains the phosphate group and is attracted to water (hydrophilic) The two nonpolar tails are the fatty acids and are repelled by water (hydrophobic)  Phospholipids are arranged in a double layer called a lipid bilayer

 Contains proteins that are embedded in the bilayer Appear to float within the lipid (fluid)  Proteins carry out most of the functions of the membranes  Attractions to polar and nonpolar ends hold the proteins in place

 Marker proteins- attach to carbohydrates and advertise the cell type  Receptor proteins- bind certain substances that trigger cell activities  Enzymes- involved in biochemical reactions  Transport proteins- aid substances into and out of the cell