bio

• Three aspects of the cell theory

  • All cells come from pre-existing cells through the process of cellular division
  • All living things are made up of one or more cells
  • Cells are the smallest unit of life (in other words, are the building blocks of life)
• 7 characteristics of life

  • Movement
  • Respiration
  • Sensitivity
  • Growth
  • Reproduction
  • Excretion
  • Nutrition
• Movement refers to the ability the organism has to relocate from one place to another
• Respiration is the ability to break down glucose to release energy
• Sensitivity is the ability to respond to changes in the environment
• Growth is the way in which an organism can achieve a permanent change in size
• Reproduction is the ability to produce offspring
• Excretion is the ability to get rid of waste products that have been produced by chemical reaction in the cells
• Nutrition refers to the ability an organism possesses to obtain crucial nutrients from the food it consumes
• Viruses do not conform to any of the biological kingdoms of life, furthermore, require a living host cell to be able to synthesize products of metabolism to reproduce. Due to this, it is unquestionable that viruses fail to follow all seven characteristics of what is deemed necessary for 'living' organisms, therefore, cannot be classified as one
• Pasteur's experiment


  1. Two sterile broth-filled flasks were set up

  2. One had the swan-neck snapped off, whereas the other remained intact to prevent the entry of unwanted microbes

  3. The flask that did not have the swan-neck turned cloudy as a result of microbial growth, whereas the other flask (the one with the swan-neck) remained clear

  4. This was for the reason that the microbes are not able to appear spontaneously without the presence of prior microbes
• Pasteur deduced from his experiment that all cells come from pre-existing cells through the process of cell division
• Plasma membrane


  • A semipermeable membrane which regulates which molecules enter and exit the cell (water, oxygen, and carbon dioxide can pass freely)
  • Composed of a phospholipid bilayer and provides support to the cell
• Mitochondria


  • The site at which cellular respiration takes place
  • Converts sugar, fat, and proteins from food to useable energy which is then released
• Nucleus


  • Often referred to as the 'control center of the cell'
  • Contains the majority of the cell's genetic material which is organized as DNA molecules with proteins to form chromosomes
• Nucleolus


  The area in which ribosomes are made
• Cell wall


  Made up of cellulose which provides the cell with structural support as well as protection
• Ribosomes


  • Made up of RNA and protein
  • Make and synthesize proteins using amino acids which are then used to repair the cell's damage
• Chloroplasts


  • The site where photosynthesis takes place
  • Store the chlorophyll (the green pigment in plants)
• Rough endoplasmic reticulum (RER)


  Plays a central role in the synthesis of proteins and glycoproteins
• Lysosomes


  Organelles that contain digestive enzymes to digest excess or worn out organelles, food particles, as well as engulfed viruses or bacteria
• Golgi apparatus


  Made up of membrane-bound sacs to process and bundle macromolecules (proteins and lipids)
• Centriole


  Helps form the spindle fibres which are then used in cellular division
• Prokaryotic cells


  Cells that lack a 'true' nucleus
• Prokaryotic cell


  • Bacteria
• Pili


  • The pilus allows the bacteria to attach to other cells or surfaces
• Flagella


  • The flagellum is a whip-like structure that enables the cell to move
• Nucleoid


  • The nucleoid region is an irregularly-shaped section of the cell which contains the DNA
• Cytoplasm


  • The cytoplasm is a jelly-like fluid that fills the cell
• Differences between Prokaryotes and Eukaryotes

  • Prokaryotic cells lack various membrane-bound organelles (such as the nuclei, mitochondria, or chloroplasts)
  • Eukaryotic cells have membrane-bound organelles (such as the nuclei, mitochondria, and chloroplasts)
  • Prokaryotic cells lack a 'true' nucleus
  • Eukaryotic cells have a 'true' nucleus
  • All prokaryotes are placed in the kingdom 'Monera' (eg. Bacteria)
  • The protista, fungi, plants, and animals are all eukaryotic
• All living things can be classified as either prokaryotic or eukaryotic
• Organ system


  A group of different organs that operate together to carry out a definite task
• Organ systems in humans

  • Gas exchange
  • Breaking down food
  • Hormones
  • Transport of nutrients
  • Reacting to stimuli
  • Urine and water/salt balance
  • Protection and movement
  • Protection from injury and pathogen entry
• Levels of organization


  1. Atom

  2. Molecule or compound

  3. Organelle

  4. Cell

  5. Tissue

  6. Organ

  7. Organ system

  8. Organism
• Tissue


  A collection of cells that operate together
• Organ


  A collection of tissues that operate with one another
• Organ system


  A collection of organs that operate together
• Red blood cell


  • Large surface area and concave shape to transport oxygen
  • Adapted to increase oxygen uptake
• Nerve cell


  • Elongated (up to 2 meters) to carry nerve impulses
• Muscle cell


  • Elongate and contract to enable movement