CELLS

What is a Cell?• Cells are small compartments that

hold all of the biological equipment necessary to keep an organism alive and successful on Earth.

Types of Cells

• Eukaryotic– Cells with a

nucleus.– Animal and Plant

• Prokaryotic– Cells without a

nucleus.– Bacteria

An Overview of Cells

• All living things are made of cells.

• Cells are the basic units of structure and function in living things.

• Cells form the parts of an organism and carry out all of an organism’s processes, or functions.

Cell Structure

• All living organisms on Earth are divided in pieces called cells.

• The structures of living things are determined by the variety of ways in which cells are put together.– There are smaller pieces to cells that

include proteins and organelles.– There are also larger pieces called tissues and systems.

Cell Function

• An organism’s functions are the processes that enable it to stay alive and reproduce.– obtaining oxygen– getting rid of wastes– obtaining food– growing

• A main purpose of a cell is to organize.– Cells hold a variety of pieces and each cell has

a different set of functions.

Cell Size• The invention of the

microscope made it possible for people to discover and learn about cells.

• Unicellular – made up of a single cell.– bacteria & protists

• Multicellular – made up of two or more cells.– fungi, plants and animals

Multicellular Organisms

• When multicellular organisms grow in size, it is because their cells multiply in number.

• When cells reach a certain size, they will go through the process of cell division (mitosis).

Animal Cells

• Animal cells are the cells found in animals.

• You are made up of trillions of animal cells.

• An animal cell is a very complicated system.– Animal cells have three

main parts; cell membrane, cytoplasm and nucleus.

– Animal cells have many organelles that carry out life processes.

Plant Cells

• Plant cells are cells that are in plants.

• Plant cells are like animal cells, but they have a cell wall and chloroplasts.

• A very special process that takes place inside of the chloroplasts in plant cells is called photosynthesis.

Bacterial Cells• Prokaryotes

– lacking well-defined nuclei and membrane-bound organelles

• They come in many shapes and sizes.– spheres, cylinders, spiral threads,

flagellated rods, and chains • They are found practically

everywhere on Earth and live in some of the most unusual and seemingly inhospitable places.

• They are essential to human life and life on planet Earth.

• Although they are notorious for their role in causing human diseases, from tooth decay to the Black Plague, there are beneficial species that are essential to good health.

Common Cell Structure

• Cell Membrane– Works like a screen. – It lets the good things in

like nutrients and lets the bad things out like waste.

• Cytoplasm – The jelly-like part of the

cell where the action takes place.

– It is where the nutrients are used.

• Nucleus/DNA – The brain of the cell.