Objectives n 1 Describe and explain the three

Objectives n 1. Describe and explain the three parts of the cell theory n 2. Determine why cells are so small n 3. Compare and contrast the structure of Prokaryotic and Eukaryotic Cells n 4. Describe the structure of the cell membrane

Cell Features

Group Challenge n What are 5 characteristics of the cell? n Why are cells so small?

Group Challenge n How are cells made? n What do cells make up? n What protects the cell?

Cell Theory n n Schleiden, Schwann, and Virchow 1. All living things are made of one or more cells 2. Cells are the basic units of structure and function 3. All cells arise from existing cells

Common Features of Cells n n Cell Membrane – encloses the cell and separates the cell interior from outside the cell. Regulates what comes in and out of the cell. Cytoplasm – region of cell within the membrane that includes the fluid, cytoskeleton, and all organelles except the nucleus.

Common Features of Cells n n Cytoskeleton – the cytoplasmic network of protein filaments that play a role in cell movement, shape, and division. Ribosomes – a cell organelle composed of RNA and protein synthesis.

Prokaryotes n n n Smallest and simplest cell Single celled, lacks a nucleus and other internal compartments Therefore can’t carry out many specialized functions • Example Bacteria

Characteristics of Prokaryotes n n n Can Exist in a broad range of environments Enzymes and Ribosomes are free to move around in the cytoplasm. No internal structures to divide the cell Single circular molecule of DNA Have a cell wall that provides structure and support and made of polysaccharides Cell wall can be surrounded by a capsule which enables cell to cling to other objects

Characteristics of Prokaryotes n Many Prokaryotes have a flagella. Flagella – a long threadlike structure that protrude from the cells surface. n What is the function of a flagella n

Prokaryotic Cell

Eukaryotic Cells n n The first cells with compartment Eukaryotic Cells have a nucleus • Nucleus is an internal compartment that houses the cells DNA n n • The Eukaryotic Cell has membrane bound organelles Eukaryotic cell DNA is organized into chromosomes Large Ribosomes

Cytoskeleton n Provides the interior framework of an animal cell

3 Types of Cytoskeleton Fibers n n n Actin Fibers – Play a major role in determining the shape of animal cells by pushing and pulling Microtubules – Act as a highway system for transportation of information from the nucleus to different parts of the cell Intermediate Fibers – Provide a frame on which the ribosomes and enzymes can be confirmed to specific regions of the cell.

The Cell Membrane n Cell membranes are not rigid but fluid Fluidity is caused by lipids which form the foundation Selectively Permeable n Made of Phospholipids n n

Phospholipids n n n Lipid made of a phosphate group and two fatty acids. Polar Head and Two Non-Polar tails Phospholipids arranged in a bi-layer