Cells

• The centromere is the point where sister chromatids are attached to spindle fibers during cell division.
• A karyotype is an image that shows all the chromosomes from a single individual arranged by size and shape.
• Chromosomes have two arms, one short arm labeled p and one long arm labeled q
• Each chromosome has a specific number of bands that can be used as reference points when describing its structure.
• Jesus D. Villafranca, RMT MSc DPAMET

  2012
• Cell


  The fundamental unit of any living organism
• Cell


  Obtains food (nutrients) from the environment to produce energy for metabolism and other activities
• Metabolism


  All the chemical reactions that occur within a cell
• Eucaryotic Cell Structure


  Cell membranes have selective permeability, allowing only certain substances to pass through them
• Nucleus


  A “true nucleus” consists of nucleoplasm, chromosomes, and a nuclear membrane. It controls the functions of the entire cell and can be thought of as the “command center” of the cell
• Components of Nucleus


  1. Nucleoplasm is the gelatinous matrix or base material of the nucleus

  2. Chromosomes are embedded or suspended in the nucleoplasm

  3. Nuclear Membrane serves as a “skin” around the nucleus; it contains holes (nuclear pores) through which large molecules can enter and exit the nucleus
• An organism’s complete collection of genes is referred to as its genotype or genome
• Genes are located along the DNA molecules
• Each gene contains the genetic information that enables the cell to produce one or more gene products
• Gene products


  • Proteins
  • Ribosomal ribonucleic acid (rRNA)
  • Transfer ribonucleic acid (tRNA)
• Cytoplasm


  A semifluid, gelatinous, nutrient matrix within the cell, containing insoluble storage granules and various cytoplasmic organelles
• Endoplasmic Reticulum


  A highly convoluted system of membranes forming a transport network of tubules and flattened sacs within the cytoplasm
• Endoplasmic Reticulum


  1. Rough Endoplasmic Reticulum (RER) is caused by the many ribosomes attached to the outer surface of the membranes

  2. Smooth Endoplasmic Reticulum (SER) does not have attached ribosomes
• Ribosomes


  The sites of protein synthesis in a cell
• Clusters of ribosomes held together by a molecule of messenger RNA (mRNA) are sometimes observed by electron microscopy
• Golgi Complex


  Also known as a Golgi apparatus or Golgi body, it connects or communicates with the endoplasmic reticulum and can be considered “packaging plants”
• Lysosomes


  Small vesicles that contain lysozyme and other digestive enzymes to break down foreign material taken into the cell by phagocytosis
• Lysosomes also aid in breaking down worn-out parts of the cell and may destroy the entire cell by a process called autolysis if the cell is damaged or deteriorating
• Phagocytes


  The engulfing of large particles by amebas and certain types of white blood cells
• Peroxisomes


  Membrane-bound vesicles in which hydrogen peroxide is both generated and broken down. They contain the enzyme catalase, which speeds up the breakdown of hydrogen peroxide into water and oxygen
• Peroxisomes are found in most eucaryotic cells, but are especially prominent in mammalian liver cells
• Peroxisomes


  Membrane-bound vesicles in which hydrogen peroxide is both generated and broken down
• Peroxisomes


  Contain the enzyme catalase, which catalyzes the breakdown of hydrogen peroxide into water and oxygen
• Characteristics of Peroxisomes


  • Found in most eukaryotic cells
  • Especially prominent in mammalian liver cells
• Mitochondria


  • Can be considered "power plants" or "energy factories"
  • About 0.5 to 1 µm in diameter and up to 7 µm in length
  • ATP molecules are the major energy carrying or energy storing molecules within cells
• Plastids


  • Membrane-bound structures containing various photosynthetic pigments
  • The sites of photosynthesis
• Chloroplasts


  • One type of plastid, contain a green, photosynthetic pigment called chlorophyll
  • Found in plant cells and algae
• Photosynthesis


  1. The process by which light energy is used to convert carbon dioxide and water into carbohydrates and oxygen

  2. The conversion of light energy into chemical energy
• Cytoskeleton


  • System of fibers throughout the cytoplasm
  • Includes Microtubules, Microfilaments (Actin Filaments), Intermediate filaments
• Cell Wall


  • External structures that provide rigidity, shape, and protection
  • Simple structure in eukaryotic cells
  • The cell walls of algae contain a polysaccharide cellulose that is not found in the cell walls of any other microorganism
• Flagella


  • Motile eukaryotic cells possess either flagella or cilia
  • Relatively long, thin structures
  • Organelles of locomotion (cell movement)
  • E.g. spermatozoa and certain types of protozoa and algae
• Cilia


  • Organelles of locomotion
  • Tend to be shorter, thinner, and more numerous than flagella
  • Found on some species of protozoa and certain types of cells in our bodies
  • Tend to beat with a coordinated, rhythmic movement
• Procaryotic cells are about 10 times smaller than eukaryotic cells
• Procaryotes are very simple cells compared with eukaryotic cells, yet they are able to perform the necessary processes of life
• Reproduction of procaryotic cells

  By binary fission, the simple division of one cell into two cells after DNA replication and the formation of a separating membrane and cell wall