A2.2

• Cell theory

  1. All organisms are composed of one or more cells
  2. Cells are the smallest unit of life
  3. All cells come from pre-existing cells
• Image size = Magnification x actual size
• 1mm = 1000 picometers
• Flouroscent stains

  Substances bind to a chemical, gives bright images
• Immunoflouresence staining

  Stains antibodies to target proteins within a cell, can be tracked
• Freeze Facture

  Requires freezing a cell and fracturing at a weak point under EM
• Cyrogenic electron microscopy

  Transmission electron microscopy to determine the structure near atomic level
• Plasma membrane, cytoplasm, DNA and ribosomes are present in eukaryotes and prokaryotes
• Plasma membrane

  Seperates interior from exterior allowing for seperate chemical reactions to take place
• Cytoplasm

  Cytosol is the liquid part of the cytoplasm

  Contains many salts, fatty acids, sugars, aminoacids which carry out metabolic processes
• DNA

  All living organisms contain DNA as genetic material
• Ribosomes

  Catalyzes the synthesis of polypeptides

  Prokaryotes have 70S ribosomes

  Eukaryotes have 80S ribosomes
• Pilli

  Enables the cell to attach to the surface
• Capsule body

  helps keep the cell from dehydration and adheres to surfaces
• Flagellum

  Long extensions used in cell locomotion
• Cell Wall

  Provides turgidity in order to hold the shape
• Prokaryotic cell DNA contains

  Nucleoid

  Plasmid
• Nucleoid

  contains the main DNA of the cell

  DNA is a single loop

  DNA is not wrapped around histones (naked)
• Plasmid

  circular and naked DNA

  smaller than nucleoid
• Nucleus (eukaryotic)

  Contains DNA and nucleolus where ribosomes are made

  Double membrane with pores to seperate activities
• Ribosomes

  Catalyze the synthesis of polypeptides

  Composed of two subunits (free or bound)
• Rough Endoplasmic Reticulum

  Series of flattened sacs that play a role on synthesis and transport of polypeptides

  Has membrane bound ribosomes
• Smooth Endoplasmic reticulum

  Series of flattened sacs that play a role on the synthesis of phospholipids and cholesterol for membranes

  no bound membranes present
• Golgi Apparatus

  Flattened sacs called cisternae

  Modifies polypeptides

  Sorts, packs proteins into vesicles (either within cell, plasma membrane, outside the cell)
• Vesicles

  Membrane bound sacs containing and transports within cells
• Lysosome

  Contains enzymes that work in oxygen poor areas

  are internal digestive centers

  Involved in the break down of molecules brought in by phagocytosis
• Mitochondria

  Adapted for ATP production

  Double membrane

  Endosymbiosis
• Chloroplasts

  Adapted for photosynthesis

  Endosymbiosis
• Vacuoles

  Mature plant cells and occupies 30-90% of volume in cell

  to maintain turgor pressure
• Cytoskeleton

  Helps maintain the shape and organizes cell

  Works together with microtubles, actin filaments.
• Microtubles

  Polymer of protein(tubi
• Microtubles

  Polymer of protein (tubilin) and forms cytoskeleton

  Responsible for intracellular transport
• Centrioles

  Cylindrical shaped organelle composed of 9 rows of 3 microtubles

  Arrangement of mitotic spindle during cell division

  Serves as anchor points for microtubles in cytoplasms and for cillia/flagella
• In unicellular organisms

  Metabolism --> Mitochondria

  Growth --> Ribosomes

  Response to stimuli --> Flagellum
• In plant cells;

  The cell wall is composed of cellulose

  Chloroplasts store carbohydrates

  Large central vacuole is for the carbohydrate storage

  Stores carbs as starch

  No cillia/flagella

  Angular cell wall shape

  Centrosomes but no centrioles
• Basal bodies relate to the centrosome of the base of cillia/flagella.
• Animal cells do not have cell walls or chloroplasts

  small and numerous vacuoles

  stores carb as glycogen

  flagella/cillia is present with basalbodies

  flexible round shape

  both centrosomes + centrioles
• Fungal cells

  cell walls are composed of chitin

  no chloroplast

  small and numerous vacuoles

  stores carbs as glycogen

  no basal bodies but cillia and flagella are present

  varying cell shape

  centrosomes no centrioles
• Erythrocytes

  No nucleus or mitochondria

  For efficient gas exchange, and has ability to move through narrow vessels

  Increase in surface area to volume

  Concave surface for extra surface area
• Aseptate Fungal Hyphae

  Not a single celled organism, but multiple nuclei together causing tubular projections of multicellular fungi