Cell Structure & Function

Cell Theory  All living things are made up of cells.  Cells are the smallest working units of all living things.  All cells come from preexisting cells through cell division.

Examples of Cells Amoeba Proteus Plant Stem Red Blood Cell Nerve Cell Bacteria

Two Types of Cells  Prokaryotic  Eukaryotic

Prokaryotic  Do not have structures surrounded by membranes  Few internal structures  One-celled organisms, Bacteria

 1—No nucleus.  2—DNA in bacteria are one long, circular molecule that is shaped like a rubber band.  3—Bacterial cells contain a cell wall and a cell membrane.  4—First type of cell on Earth probably 3.5 billion years ago.

Eukaryotic  Contain organelles surrounded by membranes  Most living organisms PlantAnimal

 1—10 times larger than prokaryotes.  2—All living things that are not bacteria are made of one or more eukaryotic cells.  3—Contain more DNA than prokaryotic cell and DNA is formed in lines (linear).  4—Some have both cell walls and cell membranes.

Prokaryotic CellsEukaryotic Cells No nucleus No membrane- covered organelles Circular DNA Bacteria Nucleus Membrane covered organelles Linear DNA All other cells Differences Between Prokaryotic and Eukaryotic Cells

Organelles:  A--Inside the cell are tiny structures that carry out the specific function of the cell called organelles.  B--Types of organelles are the cell wall, cell membrane, and nucleus. It is made of cellulose.

 The organelles function to produce, energy, build and transport needed materials, and store and recycle wastes.

“Typical” Animal Cell /~ acarpi/NSC/images/cell.gif

“Typical” Plant Cell”

Cell Parts Organelles

Cell Membrane  Outer membrane of cell that controls movement in and out of the cell  Double layer  Tiny openings, called pores, in the cell membrane control the materials that enter or leave the cell. This is the main function of the cell membrane.

Cell Wall  Most commonly found in plant cells & bacteria  Supports & protects cells

Inside the Cell

Nucleus  Directs cell activities  Separated from cytoplasm by nuclear membrane  Contains genetic material – DNA  “brain” of the cell.

Nuclear Membrane  Surrounds nucleus  Made of two layers  Openings allow material to enter and leave nucleus

Nucleolus  Inside nucleus  Contains RNA to build proteins  The nucleolus is where ribosomes are made.

Cytoplasm  Gel-like mixture  Surrounded by cell membrane  Contains hereditary material  The area between the cell membrane and the nucleus

Endoplasmic Reticulum  Moves materials around in cell  Smooth type: lacks ribosomes  Rough type (pictured): ribosomes embedded in surface  “Cell’s Delivery or Transport System”

Ribosomes—only organelle common to all cells.  Each cell contains thousands  Make proteins— protein factories  Found on ribosomes & floating throughout the cell

Mitochondria  Produces energy through chemical reactions – breaking down fats & carbohydrates  Controls level of water and other materials in cell  Recycles and decomposes proteins, fats, and carbohydrates  “Power Plant”

Golgi Bodies  Protein packaging plant'  Move materials within the cell  Move materials out of the cell  “Cell’s Packaging Center”

Lysosome  Digestive 'plant' for proteins, fats, and carbohydrates  Transports undigested material to cell membrane for removal  Cell breaks down if lysosome explodes  “Waste Disposal— Garbage Men”

Vacuoles  Membrane-bound sacs for storage, digestion, and waste removal  Contains water solution  Help plants maintain shape  “Storage Center of Plant Cell”

Chloroplast  Usually found in plant cells  Contains green chlorophyll  Where photosynthesis takes place

 Plant cells have organelles that animal cells do not: a cell wall, chloroplasts and a large vacuole (animal cells have a small one).

DOL Investigation 4 Part 2  In this activity you will study the lives of cells more closely.