Life ScienceChapter 3

Spring 06’

Cells are the building blocks of life

All living things begin life as a single cell

Those cells reproduce and become organisms containing trillions of cells

Think of your body as a brick wall-each brick is a cell with a job to do

Discovery of the cell

1665 Robert Hooke placed a piece of dead corkwood under a microscope. He noticed many different tiny openings in the cork. They looked like rooms-he called them cells. What he saw was dead. Scientists can now look at living cells and see the organelles inside doing their jobs

Cell Theory

1800’s Scientists had developed more powerful microscopes. They could see some structures inside the cell. They also could see some of the activities going on with those structures

Cell Theory says: All living things are

made of one or more cells

Cells carry out all life functions

New cells only come from other living cells

Cell Parts

Cell membrane- a thin flexible covering that controls what goes in and what goes out of the cell.

Cytoplasm- a clear jellylike substance within the cell. Activities between the different structures is regulated by the cytoplasm. The structures are called organelles

Organelles

Nucleus- surrounded by the nuclear membrane the nucleus is the control center for the cell. Genes store information and are found in the nucleus.

Mitochondria- the “powerhouse” of the cell. Bean shaped structure that controls the “power” in the cell. They breakdown molecules of food and release the energy.

Organelles

Vacuole- The storeroom of the cell. Food and water are stored here as well as waste

Ribosome- Small structures that make protein for the cell

Organelles

Endoplasmic Reticulum, ER- Network of tubes inside the cell that works as a highway moving molecules from place to place

Golgi Bodies- flattened, folded sacs that package and move materials (the Fed-Ex of celldom) through the cell.

Organelles

Lysosome- round packets that contain chemicals to break down molecules in the cell. They also breakdown the dead parts of the cell.

Plant cells are different from animal cells

Plant cells have chloroplasts which are structures that help plants make food using light (photosynthesis)

Plant cells also have a cell wall which is rigid and helps the plant stand up.

Plant cells have fewer vacuoles than animal cells. The one or two vacuoles are larger due to the water needs of the plant.

Tissues

OrgansOrgan Systems

Cells

More building

Tissue-groups of cells that work together to do a certain job

Muscle tissue

Covering tissue-skin

Connective tissue-bone

Nerve tissue

4 Types of tissue

Groups of tissue then work together to do certain jobs. These groups of tissue

are called organs.

Your heart is an organ that has

several different types of tissue.

Muscle tissue make your heart pump,

nerve tissue tells it when to pump, and connective tissue

holds it all together.

Plants have organs too.

Plants have cells and tissue just like animals. Plants also have organs. Plant organs would include-FlowersLeaves StemsRoots

Cell Reproduction

Cells reproduce by dividing the nucleus and forming two new cells. This process is called mitosis. The new cells are called daughter cells.

Daughter cells have the same traits as the parent cell.

Cell reproduction

Before mitosis the chemical in the nucleus makes a replica of itself. The chemical then forms strands called chromosomes. Chromosomes are thick strands of nuclear material that passes on traits from the parent cell to the daughter cells during mitosis.

Stages of Mitosis

Prophase-The nuclear membrane disappears, the chromosomes can be seen under a microscope

Metaphase- The chromosomes line up in the center of the cell

Stages of Mitosis

Anaphase- The chromosomes split and separate. Each set goes to an end of the cell

Telophase – The middle of the cell begins to pinch apart. A nuclear membrane forms around each set of chromosomes. In plant cells a new cell wall also forms.

www.cellsalive.com/cells/animcell.htm

Review

Cells are the basic building blocks of life. Some parts of the cell include the cell membrane, the nucleus, cytoplasm, mitochondria, vacuoles, ribosome, endoplasmic reticulum, Golgi bodies, and Lysosome.

Cells can reproduce by dividing in two. This process is called mitosis.

Review

Plant cells differ from animal cells in three important ways-plant cells have chloroplasts. Plant cells have a cell wall. Plant cells have fewer but larger vacuoles

A group of cells that work together to do a certain job is called a tissue. A group of tissues that work together to do a certain job is called an organ.

Review

Meiosis is a type of cellular reproduction that produces sex cells