Chapter 7 CELLS

History of Cells It all begins with CORK in 1665.

 10 years later, Anton van Leeuwenhoek viewed pond water under a microscope and discovered many tiny, living creatures which he called “animalcules.” History of Cells

 Today, we know that they were not animals, but single- celled organisms. History of Cells

The Cell Theory Three scientists, Schleiden, Schwann, and Virchow put together what we know today as the cell theory.

Cells, Cells, Cells 1. All living things are made of one or more cells. 2. Cells are the basic unit of structure and function in living things. 3. All cells arise from existing cells.

2 Major Categories of Cells  PROKARYOTES –The smallest and simplest cells are prokaryotes. –They are single-celled organisms that lack a nucleus and other internal compartments.

2 Major Categories of Cells  EUKARYOTES –The first cells with internal compartments. –Evolved about 2.5 billion years ago. –Eukaryotes include plants and animals and have a nucleus and other membrane bound organelles.

PROKARYOTES  Without separate compartments (organelles), prokaryotes cannot carry out many specialized functions.

PROKARYOTES  They are very simple and very small.

PROKARYOTES  The familiar prokaryotes that cause infection and food to spoil belong to a class commonly called bacteria.

PROKARYOTES  They can live in a range of environments: some do not even need oxygen to survive, some make their own food, some live in extreme hot or extreme cold.

PROKARYOTES  They can grow and divide very rapidly.

PROKARYOTES  There are no internal organelles, so the cell’s enzymes and ribosomes are free to move around in the cytoplasm.

Prokaryote Structures  Genetic material (DNA or RNA) is a single circular molecule. This loop is located near the center of the cell.

Prokaryote Structures  Cell Membrane (Cytoplasmic Membrane) that allows certain materials in/out of the cell.

Prokaryote Structures  There is a cell wall that surrounds the cell membrane, providing structure and support.

Prokaryote Structures  They lack the internal supporting skeleton, so they depend on a strong cell wall to give the cell shape.

Prokaryote Structures  Some have flagella, long threadlike structures that protrude from the cell’s surface and enable movement.

Prokaryote Structures  Some may have cilia for movement.

Prokaryote Structures  Ribosomes to make proteins.

Prokaryotes things to remember  Prokaryotes are BACTERIA.  Prokaryotes have NO nucleus. PRO rhymes with NO….NO NUCLEUS!  Prokaryotes have CELL WALLS.

EUKARYOTES  EUKARYOTE – an organism whose cells have a nucleus and membrane bound organelles.

EUKARYOTES  Eukaryotes include Plants and Animals.

EUKARYOTES  EU rhymes with Do….Eukaryotes DO HAVE A NUCLEUS!

Eukaryote Organelles  Cell wall – only in plants. Composed of proteins and carbohydrates, including cellulose, it helps support and maintain the shape of the cell, protects it from damage, and connects it with adjacent cells.

Eukaryote Organelles  Chloroplast – only in plants. Organelles that use light energy to make carbohydrate s from CO 2 and HO.  Chloroplast – only in plants. Organelles that use light energy to make carbohydrate s from CO 2 and H 2 O.

Eukaryote Organelles  Central Vacuole – only in plants. Stores water. When the central vacuole is full, it makes the cell rigid, which enables the plant to stand upright.

EUKARYOTES  Cytoplasm – includes everything inside the cell membrane, but outside the nucleus.

EUKARYOTES  Flagella and Cilia – only in some animal cells. Both are used for movement. Flagella is like a long tail. Cilia are short, hair like structures.

EUKARYOTES  Cytoskeleton – provides the interior framework of an animal cell, much like a human skeleton.

EUKARYOTES  Cell Membrane – it is fluid, like a soap bubble. It separates the inside from the outside of the cell. This barrier allows only certain substances into the cell and out of the cell.

EUKARYOTES  Nucleus – houses DNA. It is like the brain of the cell and regulates the cells functions.

EUKARYOTES  Nucleolus – small dense region in the center of the nucleus that puts together ribosomes.

EUKARYOTES  Ribosomes – make proteins.

EUKARYOTES  Endoplasmic Reticulum – the highways system of the cell that transports proteins. If it has ribosomes stuck to it, its known as rough E.R. If it does not have ribosomes stuck to it, it is known as smooth E.R.

EUKARYOTES  Golgi Apparatus – packaging and distribution center of the cell.

EUKARYOTES  Lysosomes – digestion center of the cell.

EUKARYOTES  Mitochondria – The powerhouse of the cell. By breaking down big molecules, the mitochondria makes ATP for the cell. ATP is energy!