cells - booklet 1

• The nucleus is the control center of the cell, containing the genetic material (DNA).
• Cells are the fundamental unit of living things
• Cell biology is the study of cells in bio
• the nucleus is the control centre of the cell
• ribosomes are where proteins are made
• Prokaryotes lack nuclei and the DNA lies free in the cytoplasm (eg. bacterial cells)
• Eukaryotes possess a nuclei and DNA is enclosed in a nucleus (eg. fungi, animals, plants, protists)
• Viruses do not have cell structure, non-living, considered to be parasitic
• Cell models - a model is a representation of something that is too big or too small to be easily seen
• Plant cells

  cell wall, big vacuole, no centriole, chloroplast, more structure
• Animal cells

  no cell wall, small vacuole, centriole, no chloroplast, less structure
• Cytoplasm

  • most of cell is made up of it
  • soluble molecules of various substances are dissolved in the water of it (eg. minerals like iron and calcium; organic compounds like amino acids; and carbohydrates like glucose)
  • the cytoplasm also contains many small parts called organelles that have special functions (eg. chloroplasts in plant cells)
  • the cytoplasm moves constantly around the cell (called cyclosis) and in the process it changes in consistency from a firm, jelly-like substance to a watery substance
• Organic molecules are large molecules containing carbon. Proteins, carbohydrates
• Inorganic molecules are small, don't contain carbon (except CO2). Water, minerals
• 6 functions of water:

  • Solvent (Sally)
  • Chemical reaction (Caught)
  • Transport (The)
  • Reproduction (Rabbit)
  • Body shape (By)
  • Temperature regulation (Tail)
• 5 minerals:

  • Calcium (Cath)
  • Magnesium (Made)
  • Sodium (Soup)
  • Iron (In)
  • Iodine (India)
• Cell wall:

  • Only found in plant cells
  • Outermost boundary of plant cells
  • Firm and rigid structure that gives the cell support
  • Permeable (most substances can move through it)
  • Strands of the cell wall are made up of cellulose (a carbohydrate)
  • Cellulose makes the wall firm and rigid as the strands are very tough
  • Cellulose is very difficult to digest, forming fibre essential in our diets
• In older, taller plants, the cell wall needs extra support supplied by lignin (a substance):

  • Lignin is made in the cytoplasm then deposited between the cellulose strands
  • Lignin is waterproof so the cell contents, eventually die but still supporting the plant (how wood forms)
• Plant cells are linked to neighbouring cells by fine strands of cytoplasm called plasmodesmata (singular plasmodesma):

  • Plasmodesmata pass through pore-like structures in their walls
• Nucleus

  • each cell has one nucleus surrounded by a double membrane called the nuclear membrane or nuclear envelope
  • the nucleolus, nucleoplasm and chromatin material are all found in the nucleus
  • the nucleoplasm is the same as cytoplasm and is linked to it by tiny holes in the nuclear membrane called nuclear pores
  • the chromatin material (deeply stained material in nucleus) is made of chromosomes (which are large molecules of DNA that carry genes of the organism - these genes determine all characteristics of the organism)
  • the chromosomes contain info for each cell to make its own proteins
• Plastids are only found in plant cells (3 types) and are very similar and can change from one type to another
• Plastid 1 - Leucoplasts

  • store starch, have no colour (pinkish)
  • if exposed to light may turn green and become chloroplasts
• Plastid 2 - Chromoplasts

  • contain red or orange pigments that give colour to fruit or flowers
• Plastid 3 - Chloroplasts

  • contain green pigment, chlorophyll which traps light energy from the sun and uses it to produce glucose during PSN
  • found mainly in leaves of plants
• Mitochondria

  • found in all living cells
  • 'powerhouse' of the cell because they change the energy from food (glucose) into a form of energy that cells can use called ATP (adenosine triphosphate), during the process of aerobic respiration
  • oxygen is used in the process and carbon dioxide and water are waste products of the reaction
• Endoplasmic reticulum (ER) is a series of interconnected tubules running through the cytoplasm from the nuclear membrane to the cell membrane

  • the ER allows substances to pass between the cell membrane and the nucleus
• Rough ER has ribosomes on the surface and is the site where amino acids are joined to make proteins during protein syntheses. Proteins are then folded into a particular shape in the ER
• Smooth ER has no ribosomes and is the area of detoxification of toxic chemical compounds as well as lipid and steroid synthesis. In some plant cells extensions of ER called plasmodesmata run from one plant cell to the next though gaps/pores in the adjacent cell walls
• DIFFERENCE BETWEEN MITOCHONDRION AND CHLOROPLAST

  Process in the organelle:

  Chloroplast - Photosynthesis

  Mitochondrion - Respiration

  Type of cell:

  Chloroplast - Plant cell

  Mitochondrion - Animal and plant cell

  Membrane arrangement:

  Chloroplast - Standard double membrane

  Mitochondrion - Folded double membrane

  Liquid found inside:

  Chloroplast - Stroma

  Mitochondrion - Matrix

  Other:

  Chloroplast - Produces glucose via PSN

  Mitochondrion - Produces ATP via respiration
• Gogli body

  • stack of cup-shaped tubules with SWELLINGS at the ends which process and package macromolecules (large molecules) such as proteins and lipids
  • swelling break off and form vesicles (tiny little sacs containing chemicals)
  • proteins are 'packaged' in this way into secretions (liquids eg. saliva)
  • vesicles containing the secretions move to the cell membrane and are released by exocytosis
• Lysosomes

  • made by Golgi body apparatus
  • they are spherical vesicles that are not exported but remain in the cytoplasm for use inside the cell
  • they mostly contain digestive enzymes that are to used to digest or dissolve things (eg. food particles, unwanted (old) organelles)
  • in white blood cells lysosomes are used to digest bacteria