What is a cell? A cell is the smallest unit of life. The cell theory states: ● All living things are made up of cells ● Cells are the basic units of structure and function in living things ● New cells are produced from existing cells

CELL THEORY 1. The basic unit of life is the cell. (Hooke) In 1665, an English scientist named Robert Hooke made an improved microscope and viewed thin slices of cork viewing plant cell walls Hooke named what he saw "cells"

CELL THEORY 2. All living things are made of 1 or more cells. Matthias Schleiden (botanist studying plants) Theodore Schwann (zoologist studying animals) stated that all living things were made of cells Schleiden Schwann

CELL THEORY 3. All cells divide & come from old cells. (Virchow) Virchow

The different shapes of cells reflect their different functions. The long extensions that reach out in various directions from the nerve cell allows the cell to send and receive nerve impulses(messages) The flat, plate-like shape of skin cells suits their function of covering and protecting the surface of the body.

What limits cell size? Small cells can exchange substances(oxygen, nutrients, and carbon dioxide) more readily than larger cells because small objects have a higher surface area to volume ratio. So, the cells divide!

There are 2 kinds of cells: Eukaryotes – Have a nucleus Examples of eukaryotes are plants, animals, fungus, and protists More complicated Prokaryotes – Do NOT have a nucleus Examples of prokaryotes are bacteria Smaller than eukaryotes Less complicated

Prokaryotic Cells No ______________ No _________________________ Examples: Bacteria Prokaryotic cells include the following features: –Smaller in size –DNA in a nucleoid region –Cell membrane –Ribosomes –Cell wall of peptidoglycan

Eukaryotic Cells Have _____________________ Have _______________ Larger than Prokaryotic Cells Examples: –animal cells, –plant cells, –fungi cells and –protist cells

Cells have specialized structures to carry out functions. These are called organelles.

Cell Organelles: Nucleus – command center of the cell. Contains the cell’s genetic material in the form of DNA. ONLY FOUND IN EUKARYOTES Cytoplasm – the “gel” material inside the cell membrane but not in the nucleus. The organelles live inside the cytoplasm.

Cell Organelles: Endoplasmic Recticulum (ER) – makes lipids, proteins and other materials that are exported (taken out) of the cell. Rough ER – part of the ER that makes proteins. -Called “rough” because ribosomes are attached to the surface and makes it look bumpy. Smooth ER – part of the ER that makes lipids and contains enzymes. Also plays a role in the detoxification of drugs. Ex.) Liver cells play a key role in detoxifying drugs, so they contain large amounts of Smooth ER. -Called “smooth” because ribosomes are not attached to the surface.

Cell Organelles: Ribosomes – small particles of RNA and protein found throughout the cytoplasm. They produce proteins by following instructions that come from the nucleus.

Cell Organelles: Golgi Apparatus– modifies, sorts and packages the proteins that come from the Rough ER and either stores them or ships them out of the cell. Lysosome – removes waste from the cell.

Cell Organelles Vacuoles – saclike structures used to store materials such as water, salts, proteins, and carbohydrates.

Cell Organelles Mitochondria – converts food into energy that the cell can use. They are the power centers of the cell. Cytoskeleton – supports the cell and helps to maintain the shape.

Cell Organelles Cell membrane – regulates what enters and leaves the cell and also provides protection and support. Centriole-located near the nucleus and helps organize cell division. Not found in plant cells.

Cell Organelles Nuclear membrane- surrounds the nucleus and allows material to move in and out of the nucleus. Nucleolus- within the nucleus, where the assembly (making) of ribosomes begin.

Cell Organelles: Chloroplasts – ONLY FOUND IN PLANT CELLS - captures energy from sunlight and converts it into chemical energy in plant cells. Cell Wall – ONLY FOUND IN PLANT CELLS - provides support and protection for the plant cell.

Peroxisomes—absorb nutrients, digest fatty acids, and alcohol -breakdown toxic hydrogen peroxide to water