Chapter 2Chapter 2

Cells– The Units of LifeCells– The Units of Life

Section 1- The World of CellsSection 1- The World of Cells

A.A. Cells help living creatures with activities of Cells help living creatures with activities of life such as movement, growth, and life such as movement, growth, and reproductionreproduction

1.1. The cell theory developed after Robert Hooke The cell theory developed after Robert Hooke invented the microscope in 1865invented the microscope in 1865

a.a. All living things are made of one or more cellsAll living things are made of one or more cells

b.b. The cell is the basic unit of lifeThe cell is the basic unit of life

c.c. All cells come from cells that already exist.All cells come from cells that already exist.

2.2. Bacteria are one-celled organisms; larger Bacteria are one-celled organisms; larger organisms are made of many cells, sometimes organisms are made of many cells, sometimes trillions of cells.trillions of cells.

3.3. The term cell came from Robert Hooke in 1865The term cell came from Robert Hooke in 18651.1. Looked at a thin slice of corkLooked at a thin slice of cork

2.2. The word ‘cells’ comes from the Latin word Cella, The word ‘cells’ comes from the Latin word Cella, meaning a small room.meaning a small room.

3.3. Hooke was the 1Hooke was the 1stst scientist to recogonize that living scientist to recogonize that living matter was built from basic units.matter was built from basic units.

B.B. Cells are composed of parts that do specific Cells are composed of parts that do specific jobs.jobs.

1.1. The flexible cell membrane is the boundary of The flexible cell membrane is the boundary of the cell and helps control what enters and exits the cell and helps control what enters and exits the cell; some plant cells have a cell wall that the cell; some plant cells have a cell wall that helps support and protect the cell.helps support and protect the cell.

2.2. CytoplasmaCytoplasma- is a gelatin like substance - is a gelatin like substance containing may chemicals the cell needs.containing may chemicals the cell needs.

3.3. Specialized cell parts called Specialized cell parts called organellesorganelles do do various jobs within a cell.various jobs within a cell.

4.4. The The nucleusnucleus contains the hereditary material contains the hereditary material called chromosomes.called chromosomes.

5.5. VacuolesVacuoles are storage organelles for food, water, are storage organelles for food, water, and wastes.and wastes.

Cytoplasm

Nucleus

Vacuoles

Cytoplasm

C.C. Inside the Inside the mitochondriamitochondria, cellular respiration , cellular respiration uses oxygen to convert food energy into a uses oxygen to convert food energy into a form the cell can use.form the cell can use.

1.1. Waste Waste products of cellular respiration are carbon products of cellular respiration are carbon dioxide and water.dioxide and water.

2.2. Leaf cell in plants contain Leaf cell in plants contain chloroplastschloroplasts that help that help the cell make its own food through the cell make its own food through photosynthesis.photosynthesis.

MitochondriaChloroplasts

Section 2 Section 2 The Different Jobs of CellsThe Different Jobs of Cells

A.A. The cells in many-celled organisms are specialized The cells in many-celled organisms are specialized in shape and size for their function.in shape and size for their function.

1.1. Human specialized cells include fat cells, bone cells, Human specialized cells include fat cells, bone cells, bone nerves, nerve cells, and muscle cells.bone nerves, nerve cells, and muscle cells.

a.a. FatFat cells store so much fat that the nucleus is pressed against the cells store so much fat that the nucleus is pressed against the cell membrane.cell membrane.

b.b. A hard calcium and phosphorus material surrounds A hard calcium and phosphorus material surrounds bone bone cellscells

c.c. NerveNerve cells have many long branches to send and receive cells have many long branches to send and receive messages.messages.

d.d. MuscleMuscle cells have fibers that can contract and relax. cells have fibers that can contract and relax.

2.2. Plants cells in leaves, stems, and roots are specialized to Plants cells in leaves, stems, and roots are specialized to move food and water or to support the plant.move food and water or to support the plant.

Fat cellsFat cellsFat Cell

Nucleus

Animal CellPlant cell

Cell Wall

Chloroplasts

Permenant Vacoule