Cell Theory

Discovery of Cells Cells are the basic units of structure and function in living things The microscope made it possible to observe cells. We use compound light microscopes that have more than one lens Robert Hooke- used a compound microscope to observe cells in a slice of cork Anton van Leuwenhoek- used a simple microscope to observe lake water and scraping from teeth and gums. He called them “animalcules”

The Cell Theory Developed by three German scientists along with others in the field 1. All organisms are composed of one or more cells. 2. The cell is the basic unit of structure and function in living things. 3. All cells are produced from other cells.

Light and Electron Microscopes Magnification is the ability to make things look larger than they are. The lenses of a light microscope make an object look larger by bending the light that passes through them. In a convex lens, the center of the lens is thicker than the edges.

Microscopes Resolution is the ability to clearly distinguish the individual parts of an object; also called sharpness A microscope that uses a beam of electrons to examine a specimen is called an electron microscope. –This has better resolution and can see smaller parts

Microscopes In order to find the total magnification of a compound light microscope, you must multiply the magnification of the two lenses (ocular and objective) together.

Looking inside cells Organelles are tiny cell structures inside a cell that carry out specific functions within the cell Looking from the outside the first organelle of some cells will be the cell wall. –The rigid layer of nonliving material that surrounds plant cells –Made of cellulose –Protects and supports the cell

Inside the cell As you move into the cell past the cell wall, you will reach the cell membrane If there is not cell wall the cell membrane is the outside boundary that separates the cell from its environment. The main job of the cell membrane is to control what comes into and out of a cell.

The Nucleus The nucleus is known as the control center of the cell Materials pass in and out of the nucleus through pores in the nuclear envelope Chromatin (chromosomes/DNA) contains the instructions that direct the functions of the cell Ribosomes are made in the nucleolus which is found inside the nucleus

Cytoplasm The area between the cell membrane and the nucleus is known as the cytoplasm Cytoplasm aids in transportation and is where the first part of respiration takes place

Cellular Organization In many-celled organisms, cells are specialized to perform different functions. Cells – Smallest functional and structural unit of all living organisms. Tissues – A group of cells working together to perform a specific job. Organ – A structure that is made up of two or more tissues working together to perform a specific function. Organ System – A group of organs working together to perform a particular function.

Cellular Organization in Living Things Example: Circulation Cells  Tissue  Organ  Organ System

Cellular Chemicals

Elements and Compounds An element is any substance that cannot be broken down into simpler substances. Its smallest unit is the atom. When two or more elements combine chemically, they form a compound. Its smallest unit is usually called a molecule. Most chemical reactions within cells could not take place without water.

Elements and Compounds Organic Compounds –Contain carbon –These include: Carbohydrates Proteins Lipids Nucleic acids Inorganic Compounds –Do not contain carbon ex: water and table salt

Carbohydrates Contain the elements –Carbon, hydrogen, and oxygen Sugars and Starches –Potatoes, noodles, rice, and beans have starch Used for –Energy –Making up cell parts

Lipids Fats, oils, and waxes Similar to carbohydrates because both are energy-rich and made up of the elements –Carbon, hydrogen, and oxygen Used for storage of energy

Proteins Form parts of cell membranes and many of the cell’s organelles Proteins are made up of amino acids, Some are enzymes that speed up chemical reactions Made of the elements carbon, hydrogen, oxygen, nitrogen, and in some cases sulfur. Foods high in protein include meat, eggs, fish, nuts, and beans

Nucleic Acids Very long organic molecules that contain instructions that cells need to function Contain the instructions that cells need to carry out all functions of life Made of the elements –Carbon, oxygen, hydrogen, nitrogen, and phosphorus Two kinds of nucleic acids are DNA and RNA

Inorganic Compounds Made from elements other than Carbon (C) They are the sources for many elements needed by living things

Water Water is important to us because –It makes up most of the blood –Most chemical reactions occur in water