What is a cell? • The basic unit of structure and function in living things. • They are the “building blocks” of everything that is alive.
How big are cells? • http://learn.genetics.utah.edu/content/cells/scale/
History of Cells • Hans and Zacharias Janssen created the first compound microscope in the 1590’s. • In 1665, Robert Hooke became the first person to see cells. • In 1674, Anton van Leeuwenhoek became the first person to see living cells.
Cell Theory • Over 100 years after cells were discovered, the observations of many scientists led to the development of the cell theory. • The cell theory states that: • All living things are made of one or more cells. • Cells are the basic units of structure in living things. • Cells can only come from other living cells.
Parts of Cells • The cell membrane is a thin structure that surrounds the cell. Its jobs are to protect, support, and allow things into and out of the cell.
Parts of Cells • The cytoplasm is a clear jelly inside of the cell that holds the cell’s structures in place.
Parts of Cells • The nucleus holds the chromosomes (DNA) that control the cell. It is surrounded by a nuclear membrane.
Parts of Cells • The organelles are small structures in the cytoplasm that do special jobs.
Plant Cells • Plant cells have extra structures that allow them to function.
Plant Cells • The cell wall is a firm covering around the PLANT cell membrane, giving the cell extra support and protection.
Plant Cells • The chloroplasts contain chlorophyll and allow the PLANT cell to photosynthesize.
Photosynthesis • Photosynthesis- the process plants use to get energy. http://www.wonderville.ca/asset/photosynthesis
Photosynthesis • During photosynthesis, plants use water, carbon dioxide, and sunlight to make sugar and oxygen. 6H20 + 6CO2 + sunlight ----> C6H12O6 + 6O2 (water) (carbon (UV rays) (glucose) (oxygen) dioxide) REACTANTS PRODUCTS
Respiration • At night, when there is no sunlight, plants perform a process called respiration. • Respiration- the process of breaking down sugar into water, carbon dioxide, and energy. C6H12O6 + 6O2 ----> 6H20 + 6CO2 + energy (glucose) (oxygen) (water) (carbon dioxide) • Plants respire so they can get the energy they need from the sugar they make during photosynthesis.
Photosynthesis & Respiration • http://www-tc.pbs.org/wgbh/nova/assets/swf/1/photosynthesis/photosynthesis.swf • http://www.sumanasinc.com/webcontent/animations/content/cellularrespiration.html
Cell Reproduction - Mitosis • During mitosis, chromosomes duplicate and split, move to opposite sides of the nucleus, the nucleus pinches off, then the cytoplasm pinches off.
Mitosis • Two daughter cells (body cells) are formed, both of which contain the original number of chromosomes. • Mitosis is a form of asexual reproduction because it involves one parent cloning itself (creating a genetically identical offspring).
Meiosis • During meiosis, mitosis happens first, then the chromosome pairs split apart, move to opposite sides of the nucleus, the nucleus splits, and the cytoplasm pinches off.
Meiosis • FOUR daughter cells (gametes) are formed that contain half of the normal number of chromosomes. • Meiosis creates gametes, which are necessary for sexual reproduction (two parents create a genetically different offspring).
Cell Specialization • Blood Cells: • Why do you think blood cells have the shape they do?
Cell Specialization • Bone Cells: • Why do you think bone cells have the shape they do?
Cell Specialization • Nerve Cells (neurons): • Why do you think nerve cells have the shape they do?
Cell Specialization • Sperm Cells: • Why do you think sperm cells have the shape they do?
Cell Specialization • All cells have different shapes. • Their shapes relate to the job they do for the organism (ex: blood cells are round so they can get through blood vessels easily).
Cell Organization • How are cells organized to create living things? • http://www.bbc.co.uk/bitesize/ks3/science/organisms_behaviour_health/cells_systems/activity/