MODULE 1 GENBIO: THE CELL AND THE CELL THEORY

• Animal’s cells have lysosomes, but plant cells do not.
• Mature plant cells may have only one large vacuole.
• In the 1600’s, Dutch lens maker, Zacharias Jansen, invented one of the microscope’s first prototypes.
• Robert Hooke reported some first clear drawings of the plant cells he had observed in thin cells of cork in 1665.
• Anton van Leeuwenhoek discovered blood cells, sperm cells, and a lively world of “animalcules” which were later found to be bacteria and protozoans in 1673.
• Robert Brown discovered the nucleus as a constant part of the plant cell in 1833.
• Felix Dujardin, a French Biologist, first recognized the living substance within the cell which he termed as sarcode in 1835.
• Matthias Schleiden and Theodore Schwann concluded that cells are the elementary particles of both plants and animals in 1838.
• Rudolf Virchow concluded that cell is the basic and structural unit of life and that every cell is formed from a preexisting cell in 1858.
• The nucleus is a large structure surrounded by a double membrane and stores genetic information, synthesizes DNA and RNA.
• The nucleolus is a granular body within the nucleus, consists of RNA protein, and is the site for ribosomal RNA synthesis and ribosome subunit assembly.
• Chromosomes are composed of a complex of DNA and protein known as chromatin, condense during cell division, becoming visible as rod-like chromosomes, and contain genes that govern the structure and activity of the cell.
• The cell wall contains cellulose fibrils, found in plants, prokaryotes, fungi, and some protists, for protection, maintains cell shape, prevents excessive uptake of water, and is the site of cell-to-cell signaling.
• The plasma membrane is the membrane boundary of the cell, encloses cellular contents, regulates movement of materials in and out of the cell, helps maintain cell shapes, and communicates with other cells.
• The Endoplasmic Reticulum (ER) is a network of internal membranes extending through the cytoplasm, synthesizes lipids and modifies many proteins, and is the origin of intracellular transport vesicles that carry proteins.
• The smooth ER lacks ribosomes on the outer surface and is involved in lipid biosynthesis.
• The rough ER has ribosomes studded on the outer surface and is involved in the manufacture of many proteins destined for secretion or for incorporation into membranes.
• Ribosomes are granules composed of RNA and protein, some attached to the ER, some free in the cytosol, and synthesize polypeptides in both prokaryotes and eukaryotes.
• The modern Cell Theory includes the following three principles: All organisms are composed of one or more cells, Cells are the basic unit of organization of all organisms, and Cells arise only by division of a previously existing cell.
• Animal cells use mitochondria for energy production; plants primarily use chloroplasts to produce energy.
• Microtubules are hollow tubes made of subunits of tubulin protein that provide structural support; have role in cell and organelle movement and cell division; components of cilia, flagella, centrioles, basal bodies.
• Golgi complex consists of stacks of flattened membrane sacs that modify proteins, package secreted proteins, and sort other organelles.
• A few large animal cells have more than one nucleus, but plant cells always have just one.
• Plant cells have cell walls that provide structure; animal cells do not have cell walls.
• Lysosomes are membranous sacs (in animals) that contain enzymes to breakdown ingested materials, secretions, wastes.
• Peroxisomes are membranous sacs containing a variety of enzymes and are the site of many diverse metabolic reactions.
• Both have a nucleus where DNA is stored.
• Cellular locomotion by sperm cells and some unicellular eukaryotes.
• Both have ribosomes, protein builders of cells.
• Plastids are the site of photosynthesis; chlorophyll captures light energy; ATP and other energy-rich compounds are formed and then used to convert CO2 to glucose.
• Both have Golgi bodies to distribute proteins outside of the cell.
• Mitochondria are sacs consisting of two membranes; the inner membrane is folded to form cristae and encloses matrix.
• Plant cells have chloroplasts for photosynthesis; animal cells do not.
• Mitochondria are the site of most reactions of cellular respiration; the transformation of energy originating from glucose or lipids into ATP energy.
• Plastids, such as chloroplasts, are double membrane structures enclosing material thylakoid membranes; chloroplasts contain chlorophyll in thylakoid membranes.
• Both have endoplasmic reticulum, where a system of tubes transports proteins.
• Both plant and animal cells have mitochondria that use oxygen to breakdown food and release energy.
• Both are filled with cytoplasm, a gel-like substance containing chemicals needed by the cell.
• Intermediate filaments are tough fibers made of protein that help strengthen cytoskeleton; stabilize cell.
• Cilia are relatively short projections extending from surface of cell; covered by plasma membrane; made of two central and nine pairs of peripheral microtubules (9+2 structure).