Bio MidTerms

• Cell Theory


  A set of ideas, now universally accepted, that living things are made up of cells
• Cell


  The fundamental unit of all living organisms and is also the basic unit for reproduction
• Our understanding of cells has gone through many changes, and this understanding is mediated primarily by the technology available to scientists
• Robert Hooke


  Observed box shaped structures while looking at cork, which he called "cells" as they reminded him of the cells, or rooms, in monasteries
• Modern Cell Theory


  Largely credited to the studies done by Matthias Schleiden and Theodor Schwann in the 19th century
• Matthias Schleiden


  Concluded that all plant tissues are composed of cells and that an embryonic plant arose from a single cell
• Theodor Schwann


  Founded modern histology by defining the cell as the basic unit of animal structure
• Rudolf Virchow


  Described that every cell originates from another existing cell like it
• Postulates of Cell Theory

  • All organisms are made up of one or more cells
  • Cell is the basic unit of life
  • Cells arise from pre-existing cells
• Single celled or unicellular organisms


  Living things made up of one cell
• Multicellular organisms


  Living things made up of more than one cell
• Life takes place because of cells
• The individual organelles that can be found in cells cannot sustain life on their own which is why they are not considered the basic unit of life
• Cells of our body, for example began from a single fertilized egg of our mother, fertilized by a sperm cell of our father
• Additional Postulates of Modern Cell Theory

  • Energy flows happen within cells
  • Heredity information contained in DNA is passed from cell to cell
  • All cells have the same basic chemical composition
• A virus does not meet the third postulate of cell theory, and for that reason it is not considered a living thing
• A virus is neither unicellular nor multicellular
• A virus is not capable of reproducing itself on its own
• A virus is a strand of DNA or RNA with a protective shell made from protein
• A virus's structure is simpler compared with single celled organism
• Bacteria


  Ubiquitous, mostly free-living organism often consisting of one biological cell, constituting a large domain of prokaryotic microorganisms
• Differences between Prokaryotic and Eukaryotic Cells

  • Prokaryotes: Unicellular, No true nucleus, Structures not bound by a membrane, One circular strand of DNA, Smaller (1–10 μm)
  • Eukaryotes: Multicellular, Has nucleus, Organelles enclosed by a membrane, Many DNA strands, Larger (10–100 μm)
• Both prokaryotes and eukaryotes have the following: plasma membrane, cytoplasm, ribosomes, and DNA material
• Deoxyribonucleic Acid (DNA)


  A double-stranded nucleic acid that contains the genetic information for cell growth, division, and function
• One of the often observed phenomena in biology is the tight connection between structure and function
• The structure of an organelle defines its function, and the function of an organelle depends on its structure
• Cell Membrane


  Made from proteins and lipids, controls the movement of materials in and out of cells, maintains the structural integrity of the cell
• Centrosome


  Helps distribute chromosomes to daughter cells during cell reproduction, and initiates formation of cilia
• Chromatin


  Made from protein and DNA molecules, contains genetic information for protein synthesis
• Cytoplasm


  A semifluid substance that constitutes the main body of the cell, it contains many subcellular organelles, many chemical and cellular processes take place in the cytoplasm
• Endoplasmic Reticulum


  A network of interconnected sacs and canals, transports materials within cells, it is the site for protein synthesis
• Golgi Body


  Flattened sacs, they package protein molecules for secretion, it is the origin of lysosomes
• Lysosomes


  Membranous sacs, they contain enzymes that assist in the digestion of substances in the cell
• Microfilaments & Microtubules


  Give support to the cytoplasm, they serve as the cytoskeleton, they also help move materials in the cell
• Mitochondria


  A membranous sac with many internal compartments, it generates the cell's supply of energy, it is the powerhouse of eukaryotic cell
• Nuclear Envelope


  A porous double nuclear membrane which separates the contents of the nucleus from the cytoplasm, it maintains the wholeness of the nucleus and controls the exchange of materials between the nucleus and cytoplasm
• Nucleolus


  A dense small body in the nucleus that contains protein and RNA, involved in the production of ribosomes
• Nucleus


  Large membrane-bound organelle that contains the genetic material in the form of DNA molecules which are organized into structures called chromosomes, it is the "central government of the cell"
• Ribosomes


  Particles composed of protein and RNA, it serves as the site for of protein synthesis
• Vesicles


  Membranous sacs, temporary storage for food and enzymes, involved in metabolism, transport and buoyancy control