cells

• cells are building blocks of life, they have all the characteristics of life
• we can use light and electron microscope to see cells and their parts
• cameras can be fitted to the microscope to take pictures called micrographs
• longitudinal, cutting along the cell
• transverse, cutting across the cell
• each living cell consists of living materials called protoplasm, jelly like substance, contains protein, carbohydrates and fats
• protoplasm contains, nucleus, cell surface membrane and cytoplasm
• • cell surface membrane aka plasma membrane, partially permeable, controls substances entering or leaving the cell
• • cytoplasm most cell activities occur here, contains structures called organelles
• • nucleus contains nuclear envelope, nucleoplasm, nucleolus, chromatin
• nucleus controls the activities of the cell, essential for cell division
• nucleus may contain one or more nucleoli
• chromatin, is a network of threadlike structures that control cell activities aka cell division, made up of deoxyribonucleic or DNA
• • animal cell has cell surface membrane, cytoplasm, nucleus
• cell wall is made up of cellulose, protects the cell from injuries, fully permeable
• chromatin threads condense into chromosomes when the cell is actively dividing
• • mitochondria performs aerobic respiration, oxidises glucose to release energy
• • ribosome they are needed to synthesis protein for the cell
• chloroplast


  contains chlorophyll
• • vacuole store substances within cell, animal cell have many vacuoles containing water and food substances
• • vacuole

  store substances within cell, plant cell have large central vacuole containing cell sap, made up of sugars, mineral salts and amino acids
• large vacuole is surrounded by a tonoplast, it keeps vacuole acidic by bringing in protein
• • difference between plant cell and animal cell

  1. cell wall is present in plant cell, cell wall is absent in animal cell
  2. chloroplast is present in plant cell, chloroplast is absent in animal cell
  3. centrioles is absent in plant cell, centrioles is present in animal cell
  4. large central vacuole in plant cell, vacuoles small and many in animal cell
• centrioles serve as cells skeleton system