Cell Theory

1. All organisms are composed of cells2. Cells are the smallest unit of life

capable of self maintenance, and self replication

3. All living cells are produced by preexisting cells

Types of cells

1. Prokaryotic cells:• No nucleus or internal membranous

organelles• Small cells • In the domains Bacteria and Archaea

Types of cells

2. Eukaryotic cells• Nucleus and complex membranous

organelles• Includes all animal cells, plant cells,

fungi cells, Protozoa

•All eukaryotic cells have generally similar organelles.

•There are a few important differences that are described below.

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Figure 3.14 A typical animal cell.

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Figure 3.14 A typical animal cell.

Copyright © 2009 Pearson Education, Inc.

Figure 3.1a A eukaryotic animal cell.

Plasma (Cell) Membrane

• A boundary between the cell and the environment• Two layers of phospholipids• Selectively permeable

Cell Membrane

Nucleus

• Nucleus – control center of the cell• DNA (genetic material) is located inside

of the nucleus• Nucleoli (inside nucleus) produce

ribosomes

Cytoplasm

• Cytosol-gel like substance• Organelles-carry out specific

functions

Organelles - 1

• Ribosomes – Make proteins. May be attached to RER or floating free in the cytosol

• Rough Endoplasmic Reticulum (RER) -An array of tubules in the cytoplasm. Modifies and transport proteins

Ribosomes and Rough Endoplasmic Reticulum (RER)

Organelles - 2

• Smooth Endoplasmic Reticulum - involved in the synthesis of lipids. Lacks ribosomes

• The Golgi Complex - Array of flattened sacs. Packages proteins in vesicles for transport outside or inside the cell

• Vesicles - transport proteins between compartments

The Golgi Complex

Organelles - 3

• Mitochondria - • Powerhouse of the cell• Site of aerobic cellular respiration, which

releases energy from sugar

Mitochondria

Organelles - 4

• Lysosomes - Vesicles that contain digestive enzymes. Break down old cell parts

• Cytoskeleton - The “skeleton” of the cell. Consists of microtubules and microfilaments

• Vacuoles - Large membranous bubbles which store substances inside the cell

Only in animal cells

Centrioles• Paired structures composed of microtubules• They form the mitotic spindle during cell

division

Only in plant cells

• Cell wall – rigid structure outside the cell membrane, provides support to the cell

• Central vacuole - fluid filled cavity• Chloroplasts – Contains the green pigment

chlorophyll. Convert sunlight into carbohydrates

Plant cell

Aggregations of cells

• Tissue - a group of similar cells working together to perform a specific function

• Organ - two or more tissues cooperating to perform a certain life support function

• Organ System-a group of organs working together to perform a general life support function

• Organism