Presentation on theme: "A CELL is the smallest unit that can carry on all the PROCESSES of life. Every LIVING thing is made up of ONE or more cells."— Presentation transcript:
A CELL is the smallest unit that can carry on all the PROCESSES of life. Every LIVING thing is made up of ONE or more cells.
A living thing that is made up of ONE cell is called UNICELLULAR. A living thing that is made up of MORE than one cell is a MULTICELLULAR organism.
How many cells are there in a human body? Between 50 to 100 trillion depending on a person’s size!
How many bacterial cells are there in and on a human body? 182 species of bacteria colonize the average person's skin There are about 1,000,000 bacteria per square inch on human skin Saliva may contain up to 1,000,000,000 bacteria per milliliter We have more bacteria living in and on us than cells in our bodies! Only about 10% of the cells in our bodies are Human!
Cells were first discovered in 1665 by the English scientist ROBERT HOOKE.
Hooke cut a piece of CORK and observed it with a microscope.
He sectioned other specimens and saw that they were all made up of ”LITTLE BOXES,” or cells, which reminded him of the little rooms MONKS of that time lived in.
The first person to view LIVING cells was Anton VAN LEEUWENHOEK In 1675 I’m Anton
It took another 150 years for scientists to take the work of HOOKE and VAN LEEUWENHOEK, And devise a unified theory of cells.
In 1838 a GERMAN botanist, Matthias SCHLEIDEN concluded that all plants were COMPOSED of cells.
In 1855 a German PHYSICIAN, Rudolph VIRCHOW determined that cells only come from other CELLS.
The observations of these three scientists are known as CELL THEORY
1. All living things are COMPOSED of one or more CELLS. 2. Cells are organisms BASIC UNITS of structure and function. 3. Cells come only from OTHER cells.
Cells vary greatly in SIZE, SHAPE, and internal ORGANIZATION.
Size Cells must maintain a SMALL size or else their surface area becomes too SMALL to maintain all life functions.
Shape Most cells are SPHERICAL or CUBOIDAL. They can also be FLAT like skin cells, have long extensions like NERVE cells, or may have the ability to change SHAPE like white BLOOD cells.
Internal Organization Cells differ in their internal organization. Cells that contain a NUCLEUS and membrane bound ORGANELLES are called EUKARYOTES. Examples: PLANT & ANIMAL cells
Cells that lack a NUCLEUS and membrane BOUND organelles are called PROKARYOTES. Example: BACTERIA CELLS
Cell Membrane Is the structure that SEPARATES the cell from its external environment.
Cell Membrane Allows some molecules to PERMEATE, or pass through it, and acts as a barrier to keep some MOLECULESout of the cell. For this reason it is called a SEMIPERMEABLE membrane.
The Fluid MOSAIC Model of cell membranes reveals that they are made up of a LIPID bilayer.
It is like a fluid lipid sandwich with the Hydrophilic heads pointing OUTWARD and the hydrophobic tails pointing inward. The cell membrane also has proteins embedded in it that can move around.
Is the JELLYLIKE material found inside the cell membrane and is made up of WATER, salts, and organic molecules.
It is in constant motion called CYTOPLASMIC streaming. The cytoplasm surrounds “little organs” or ORGANELLES which each have a specific job.
Are the organelles where PROTEINS are made and are the most NUMEROUS of the organelles.
(ER) is a membrane system of folded SACS and tunnels. There are two kinds of ER.
(rER) is studded with RIBOSOMES. Is abundant in cells that export a lot of proteins or ENZYMES like the pancreas.
(sER) has no RIBOSOMES And is like a highway for molecules to move around the cell and as a STORAGE area.
Is the processing, PACKAGING, and secreting organelle of the cell. It is like a factory where a product is ASSEMBLED at one end, packaged, then put into a mail bag for delivery at the other end.
Are the POWERHOUSES of the cell that process and release ENERGY from the nutrients that enter the cell.
They have CRISTAE which make more surface area for cellular respiration to take place, and ATP is formed here. Cells that use a lot of energy like muscle cells have many mitochondria. Mitochondria have their own DNA.
Are the garbage men of the cell and contain DIGESTIVE enzymes that break down wastes.
Provide a frame for the cell called the CYTOSKELETON. They also help move things around in the cell.
Are used in MOVEMENT and extend out from the surface of the cell. Cilia are short and hairlike. They beat in WAVES. Flagella are long and whiplike, occur SINGLY or in pairs.
Directs the ACTIVITIES of the cell. It is surrounded by a NUCLEAR membrane that has holes in it where molecules can enter and EXIT.
The nucleus contains CHROMATIN, strands of DNA and proteins. When it condenses, it forms CHROMOSOMES, the genetic information of the cell. The NUCLEOLUS is a spherical body in the nucleus where ribosomes are made.
Plant cells differ from ANIMAL cells because they have a cell WALL that surrounds the cell MEMBRANE. This helps support and protect the cell. They also have sacs called VACUOLES and plastids which store food or pigments.
Contain a green pigment called CHLOROPHYLL that is used in photosynthesis.
Contain pigments like orange CAROTENES, and yellow XANTHOPHYLLS, and red pigments. They give plants their distinctive colors.
Store food such as STARCHES, proteins, and lipids. They are storage organs in potato TUBERS.