1.1 Introduction to cells

1.1 Introduction to cells

1. Cell theory

   • Cells are the smallest unit of life
   • All living things consist of cells
   • Cells come from pre-existing cells

2. Function of life

   • Homeostasis
     • Organism's metabolic activities are in a state of balance
       • Ex : Body temperature
   • Nutrition
     • process- living things take in materials from its environment for growth and repair
   • Growth
     • Increase in cell size and volume
   • Reproduction
     • living things produce offsrping
       • 2 types
         • asexual reproduction--one parent and the offspring are identical to the parent
         • sexual reproduction--two parents and the offspring is a combination of both parents
   • Response
     • Action or movement- application of a stimulus.
   • Metabolism
     • chemical reactions involved in maintaining the living state of the cells and the organism
   • Excretion
     • Removal of waste products

3. Surface area : volume ratio

   • Smaller the cells
     • High surface area to volume ratio
   • Limit cell size
   • High ratio
     • Function of life - better

4. Differentiation

   • A less specialized cell develops or matures to become more distinct in form and function.
   • Stem cells
     • Produce cells- pluripotent
       • Affecting cells, organs or tissues.
     • The capacity of stem cells to divide and differentiate along different pathways is necessary in embryonic development and also makes stem cells suitable for therapeutic uses.
       • Therapeutic use of stem cells from specially created embryos, from the umbilical cord blood of a new-born baby and from an adult’s own tissues.

5. multicellular organisms show emergent properties

   • Example: cells form tissues, tissues form organs, organs form organ systems and organ systems form multicellular organisms. Greater than the composition of its parts.
     • For example your lungs are made of cells. Not much use. Many cells working as a unit that allow the lungs to perform their function.

6. Calculation

   • Magnification
     • Size of drawing / size of specimen
   • Actual size

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