Plant and Animal Cells 1 Unit 2: Biology- Tissues, Organs, and Systems of Living Things September 22nd, 2010

The Discovery of the Cell The microscope was invented in the mid 1600’s Before this time scientists could not look at cells Robert Hooke was the first to describe cells in 1663 He thought that the cells were the passages for fluids in a plant.

Cell Theory: All cells are similar to each other, but not identical. Every living organism is made of cells New cells are created by old cells dividing into two. A cell contains everything that it needs to live and grow. Cells take nutrients from its environment and release waste products into the environment.

Using Technology to Study the Cell Early light microscopes only allowed scientists to see and study the external structure of the cell. Advances in technology, such as the development of the electron microscope have allowed biologists to learn detailed information about different cell parts and their functions. the electron microscope can produce images that are 1000 times more detailed than the light microscope

Cell Parts and Their Functions All living things are made of cells. Our bodies are made up of between 10 trillion (1013) and 100 trillion (1014) cells. A cell is the basic unit of life.

Cell Parts and Their Functions Each cell contains smaller parts called organelles. These organelles have special functions that maintain all the life processes of the cell, including: intake of nutrients exchange of gases movement waste removal Growth Reproduction response to stimuli

Structures and Organelles in Cells There are two types of cells: plant cells and animal cells A cell contains structures and organelles that carry out various functions. Some structures and organelles are the same in both plant and animal cells while other structures and organelles differ between plant and animal cells.

Cell Membrane Protective barrier around the cell (hold everything in) Regulate the exchange of substances and communicate with other cells Cell membranes

Cell Membrane The membrane is made up of two layers known as the phospholipid bilayer. The outsides of the membrane are said to be hydrophilic. This means that they love water. The inside of the membrane is said to be hydrophobic. This means that it hates water.

Process for moving substances across a cell membrane Diffusion Particles will move from an area of high concentration to an area of low concentration until equilibrium is met.

Cytoplasm Jelly-like substance that fills the cell and surrounds the organelles Cytoplasm contains the nutrients required by the cell The organelles are suspended in the cytoplasm. Allows the nutrients and organelles to move within the cell.

Nucleus Control centre organelle of the cell It controls all the activities in a cell, including growth and reproduction.   Surrounded by the nuclear envelope, which contains pores to allow the transport of materials.

Nucleus Most nuclei also contain a small dense area called the nucleolus. The nucleus contains nearly all of the cell’s DNA. Deoxyribonucleic acid Contains the coded information for making proteins and other molecules.

Nucleus Granular substance that contains protein and DNA Chromatin In cell division the chromatin condenses to form chromosomes.