Introduction to Cells

     Cells are the basic structures of life. They are found in every living organism and are the simplest collection of matter that can live and they are self sustained. There are two different types of cells, prokaryotic and eukaryotic. Prokaryotes are less complex than eukaryotes. Prokaryotes generally consist of a plasma membrane, a DNA molecule, ribosomes, cytoplasm, and in most cases, a cell wall.

Basic Structure

Eukaryotic cells are the tiny units of life that make up your entire body, they are composed of

• nucleus: a double membrane-bound control center separating the genetic material DNA (deoxyribonucleic acid), from the rest of the cell
• plasma membrane: it is a phospholipid layer with a double membrane composed of a unique type of lipid. The plasma membrane controls traffic of materials into and out of the cell. It separates the inside from the outside of the cell
• cytoplasm: is the mixture of organic and inorganic materials
• cytoskeleton: protects the cell, enables cell motion, maintains the cell shape
• cilia and flagella: microtubules, and motility achieved by coordinated sliding movements of these microtubules
• ribosomes: make protein under the instruction of DNA. Ribosomes are attached to the rough endoplasmic reticulum
• mitochondria: powerhouses of the cell, where the final and most energy-productive steps of metabolism take place to generate cellular energy (ATP) 
• chloroplasts: organelles containing the pigment chlorophyll. Chloroplasts harness sunlight and turn it into ATP energy

Eukaryotic cells also contain a network of internal membrane-bound structures. These cellular organelles transport materials into, out of, and within the cell, carrying out many of the functions required for the cell to survive, thrive, grow and reproduce.

Animal Cells

     Animal cells are enclosed by a plasma membrane and containing a membrane-bound nucleus and organelles. Unlike plant cell, animal cells do not have a cell wall. Most animal cells are diploid, meaning that their chromosomes exist in homologous pairs. Different chromosomal ploidies are also, however, known to occasionally occur. Cells were discovered in 1665 by British scientist Robert Hooke who first observed them in his crude (by today's standards) seventeenth century optical microscope.

The animal cell contains:

• centrioles: which are self-replicating organelles
• cilia and flagella: are essential for the locomotion of individual organisms
• endoplasmic reticulum: transports chemical compounds for use inside and outside of the cell
• Golgi Bodies:is the distribution and shipping department for the cell's chemical products
• lysosome: The main function of these micro bodies is digestion; Microfilaments: are solid rods made of globular proteins called actin
• mitochondria: are the main power generators, converting oxygen and nutrients into energy
• nucleus: is a highly specialized organelle that serves as the information and administrative center of the cell
• Peroxisome Click Link to Learn More
• plasma membrane: contain and protect their contents; ribosomes: are made of four strands of RNA.

Plant Cells 

     Plant Cells are bounded by a cell wall and the living portion of the cell is within the walls and is divided into two portions: the nucleus, or central control center; and the cytoplasm, a fluid in which membrane bound organelles are found. 

Plant cell organelles include:

endoplasmic reticulum, Golgi bodies, mitochondria, and plastids.

Plant cells also have:

• Chloroplasts: which are used during photosynthesis.
• Vacuoles: are used to store food, water, and waste.

The plant cell has no centrosomes because they are only use during mitosis. The plant gets their green color through chlorophyll (pigment). Chlorophyll also allows the plant to perform photosynthesis.     

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