Cell Biology

Cell Biology

www.edumedia-sciences.com/recherche.php?q=Cell

Robert Hooke (1665)English scientist looked at a thin slice of cork through a compound microscope observed tiny, hollow, room like structures called these structures 'cells' because they reminded him of the rooms that monks lived in.He only saw the outer walls (cell walls) because cork cells are not alive ( dead cells)

Anton van Leeuwenhoek Dutch scientist looked at blood, rainwater, scrapings from teeth through a e microscope. Heobserved living cells; called some 'animalcules' some of the small 'animalcules' are now called bacteria

Matthias Schleiden (1838) German botanist viewed plant parts under a microscope discovered that plant parts are made of cells.

Theodor Schwann (1839) German zoologist viewed animal parts under a microscope discovered that animal parts are made of cells

Rudolph Virchow (1855)German physician stated that all living cells come only from other living cells

CELL THEORY        

            1. ALL LIVING THINGS ARE COMPOSED OF CELLS         2. CELLS ARE THE BASIC UNIT OF STRUCTURE AND FUNCTION IN LIVING THINGS         3.ALL CELLS ARE PRODUCED FROM OTHER CELLS.

Theodor SchwannAll animals are made of cells

Matthias Schleiden All plants are made of cells.

SPONTANEOUS GENERATION- an UNTRUE THEORY stating that living things arise from nonliving sources FRANCESCO REDI  in the 1600’S DISPROVED THIS IDEA

Rudolph Virchowall living cells come only from other living cells

NERVE CELLS

Muscle cells

Skin Cells

Why do cells divide. A cell divides so as to maintain a favourable Surface area to volume ratio.

A cell receives food and oxygen and turns out waste materials through it's membrane. A cell membrane of specific area can serve the contents of

a particular volume only.Increase in the volume increases the requirements of the cell and this increases the need for greater

membrane area.Now,the Surface area of a sphere increase as the square of the radius and

the volume of a sphere increases as the cube of the radius or to say, in simpler words,the volume of the cell increase more rapidly then the area

of its membrane.Hence, as a cell grows,it's membrane in due course of time becomes

insufficient to move the required amount of substances in and out. The cell by dividing has a more favourable surface area to volume ratio. Thus, the cell divide so as to maintain it's size such that all it's requirements of

nutrition,respiration and excretion are met. • http://plaza.ufl.edu/alallen/pgl/modules/rio/stingarees/module/why.html

Colonial Organisms

The little stars we can see on the image of the stone are the colonial Tunicates.

Membranipora.

telstar.ote.cmu.edu/.../membranes/index.html

The Structure and Function of the Cell Membrane

http://www.ibiblio.org/virtualcell/textbook/chapter3/chapter3.htm

A Phosphlipid

A lipid bilayer http://telstar.ote.cmu.edu/biology/downloads/membranes/index.html

http://www.wisc-online.com/objects/index_tj.asp?objID=ap1101

http://www.bio.davidson.edu/people/macampbell/111/memb-swf/membranes.swf

http://www.susanahalpine.com/anim/Life/memb.htm

We will group the organelles into three catagories:

Nucleus

cytoplasm

Endoplasmic reticulum

Ribosomes

Golgi apparatus

Mitochondria

Lysosome Cytoskeleton

Vacuoles

Cilia and Flagella

Centrioles

Comparing animal and plant cells

Anatomy of the Plant Cell

Nucleus

cytoplasm

Endoplasmic reticulum

Ribosomes

Golgi apparatus

Mitochondria

Lysosome Cytoskeleton

Vacuoles

Cilia and Flagella

Centrioles

The Cell Wall

Central Vacuole

Plastidschloroplasts

Comparing animal and plant cells

The Nucleus

http://www.ibiblio.org/virtualcell/textbook/chapter3/chapter3.htm

The Cell

One or more per cell - Spherical shape - Denser than surrounding cytoplasm

Chromosomes - Usually in the form of chromatin- Contains genetic information- Composed of DNA- Thicken for cellular division- Set number per species (i.e. 23 pairs for human)

Nuclear membrane - Surrounds nucleus- Composed of two layers- Numerous openings for nuclear traffic

Nucleolus - Spherical shape- Visible when cell is not dividing- Contains RNA for protein manufacture

The Cell

cytoplasm Collective term for cytosol and organelles contained within

Colloidal suspension Cytosol mainly composed of water with free-floating molecules

Viscosity constantly changes We will group the organelles into three categories:

Group 1 - Those organelles involved in protein production Group 2 - Those organelles involved in energy production

Group 3 - Specialty organelles

The Cell

Endoplasmic reticulum                                                                                          - Tubular network fused to nuclear membrane- Goes through cytoplasm onto cell membrane- Stores, separates, and serves as cell's transport system- Smooth type: lacks ribosomes- Rough type (pictured): ribosomes embedded in surface

The Cell

The Cell

The Cell

Ribosomes - Each cell contains thousands- Act as 'protein factories'- Composes 25% of cell's mass- Stationary type(Attached): embedded in rough endoplasmic reticulum, produces proteins to be secreted from the cell. - Mobile type( free): injects proteins directly into cytoplasm, produces proteins to be consumed in the cell.

The Cell

The Cell

Mitochondria- Second largest organelle with unique genetic structure- Double-layered outer membrane with inner folds called cristae- Produce Energy in the form of ATP through chemical reactions take place on cristae through a process called oxidative phosphorylation. This process uses oxygen and simple sugars to create adenosine triphosphate (ATP), the cell’s main energy source. - Controls level of water and other materials in cell- Recycles and decomposes proteins, fats, and carbohydrates, and forms urea- Although most DNA is packaged in chromosomes within the nucleus, mitochondria also have a small amount of their own DNA. This genetic material is known as mitochondrial DNA or mtDNA. mitochondria originate only from other mitochondria.- for the origin of mitochondria (and chloroplasts) suggests that mitochondria are descended from specialized bacteria that became part of the cytoplasm of another cell. The ability of symbiont bacteria to conduct cellular respiration in host cells that relied on glycosis and fermentation would have provided a considerable evolutionary advantage. Similarly, host cells with symbiont bacteria capable of photosynthesis would also have an advantage. In both cases, the number of environments in which the cells could survive would have been greatly expanded.

The Cell

Golgi apparatus - Protein 'packaging plant'- A membrane structure found near nucleus- Composed of numerous layers forming a sachttp://bcs.whfreeman.com/thelifewire/content/chp04/0402002.html

The Cell

Lysosome- originating in part from the Golgi apparatus - contain digestive enzymes- sites for the breakdown of food and foreign objects taken up by the cell. - Digestive 'plant' for proteins, lipids, and carbohydrates- Transports undigested material to cell membrane for removal- Vary in shape depending on process being carried out- Cell breaks down if lysosome explodes

The Cell

Peroxisomes function to rid the cell of toxic substances, in particular, hydrogen peroxide -- a common byproduct of cellular metabolism. These organelles contain enzymes that convert the hydrogen peroxide to water, rendering the potentially toxic substance safe for release back into the cell. Some types of peroxisomes, such as those in liver cells, detoxify alcohol and other harmful compounds by transferring hydrogen from the poisons to molecules of oxygen.

Glyoxysomes They are small bodies usually located near the mitochondria.They help to convert stored lipids (oils) into energy for the developing plant embryo.

The Cell

Vacuoles- Membrane-bound sacs for storage, digestion, and waste removal- Contains water solution- Contractile vacuoles for water removal (in unicellular organisms)

The Cell

Cytoskeleton- The cytoplasm contains a fine network of fibrous protein elements that form a framework for supporting the extensively branched membranes found in the relatively fluid cytoplasmic matrix. - Supports cell and provides shape.- composed of three types of organelles microtubules, microfilaments and microbodies. - Aids movement of materials in and out of cells.

The Cell

The Cell

Cilia and Flagella-Whiplike appendages extend from the surface of many types of eukaryotic cells.- If there are many of them, they are called cilia; if only one, or a few, they are flagella.- Flagella also tend to be longer than cilia but are otherwise similar in construction.- Cilia and flagella move liquid past the surface of the cell. For single cells, such as sperm, this enables them to swim. -For cells anchored in a tissue, like the epithelial cells lining our air passages, this moves liquid over the surface of the cell (e.g., driving particle-laden mucus toward the throat).-Structure of Cilia and Flagella

The Cell

Structure of Cilia and FlagellaBoth cilia and flagella consist of: •a cylindrical of 9 pair of microtubules and a pair of single microtubules running up through the center of the bundle,. •The entire assembly is sheathed in a membrane that is an extension of the plasma membrane.

Cilia and Flagella

Cilia and Flagella

Cilia and Flagella

trachea

Cilia and Flagella

Cilia and Flagella

Cilia and Flagella

Centrioles are cylindrical structures that are composed of groupings of microtubules arranged in a 9 + 3 pattern. The pattern is so named because a ring of nine microtubule "triplets" are arranged at right angles to one another. Centrioles are found in animal cells and play a role in cell division.

The Cell

The Cell Wall The rigid cell wall of plants is made of fibrils of cellulose embedded in a matrix of several other kinds of polymers such as pectin and lignin.

Primary cell walls. Although each plant cell is encased in a boxlike cell wall, it turns out that communication between cells is just as easy, if not easier, than between animal cells. Fine strands of cytoplasm, called plasmodesmata, extend through pores in the cell wall connecting the cytoplasm of each cell with that of its neighbors.

Plant Cell

Vacuoles are membrane-bound sacs within the cytoplasm of a cell that function in several different ways. In mature plant cells, vacuoles tend to be very large and are extremely important in providing structural support, as well as serving functions such as storage, waste disposal, protection, and growth. Many plant cells have a large, single central vacuole that typically takes up most of the room in the cell (80 percent or more). Vacuoles in animal cells, however, tend to be much smaller, and are more commonly used to temporarily store materials or to transport substances.

Plant Cell

http://www.cellsalive.com/cells/vacuole.htm

The structure of the secondary cell wall, built up of a series of layers of cellulose

Plant Cell

Plastids- large organelles found on plants and some protists but not in animals.-Chloroplasts represent one group of plastids.-Chloroplasts are the organelles in which photosynthesis takes place. - - Photosynthesis is an important process by which autotrophic cells manufacture their own food. Chloroplasts contain the green pigment chlorophyll (this is why plant leaves are green) which absorbs light to provide the energy necessary to complete photosynthesis-

Plant Cell

Group 1 - Those organelles involved in protein production

The endoplasmic reticulum

Ribosomes The golgi apparatus

Lysosomes cytoplasm

Group 2 - Those organelles involved in energy production

MitochondriaPlant & Animal cells

ChloroplastsPlant Cell

cytoplasm

Group 3: Specialty Structures

This last group of cell structures described here and only grouped together for convienence. While the other structures we have talked about are found in all cells these structures are usually found only in certain kinds of cells.

Animal cells generally contain centrioles.Plant cells generally contain storage vacuoles, cell walls, and plastids.Cilia and flagella are found in many different life forms.

Be aware that there are many other kinds of living things besides plants and animals.

cytoplasm

Comparing Plant and Animal CellsPlant Animal