Unit 1 Biology Thingy Ma Bob

• Organisms


  Made up of cells, which are like tiny building blocks
• Cells


  • Can be eukaryotic or prokaryotic
  • Eukaryotic cells are complex, and include all animal and plant cells
  • Prokaryotic cells are smaller and simpler, e.g. bacteria
• Organelles


  Tiny structures within cells, can only be seen using a powerful microscope
• Typical animal cell


  • Nucleus: contains genetic material that controls cell activities, surrounded by membrane
  • Cytoplasm: gel-like substance where most chemical reactions happen, contains enzymes
  • Ribosomes: where proteins are made
  • Cell membrane: controls substances going in and out
  • Mitochondria: where aerobic respiration reactions take place, transfers energy the cell needs
• Typical plant cell


  • Chloroplasts: where photosynthesis happens, contain chlorophyll
  • Vacuole: large organelle containing cell sap, helps support the cell
  • Cell wall: rigid structure made of cellulose, surrounds cell membrane and supports/strengthens the cell
• There's quite a bit to learn in biology-but that's life, I guess...
• A good way to check that you know what all the bits and pieces are is to copy out the diagrams and see if you can remember all the labels
• Stem cells


  Undifferentiated cells that can divide to produce more undifferentiated cells and differentiate into different cell types
• Embryonic stem cells


  • Can turn into any type of cell
  • Found in early human embryos
  • Have the potential to turn into any kind of cell
• Adult stem cells


  • Only found in certain places like bone marrow
  • Can only turn into certain cell types, such as blood cells
• Cell differentiation


  1. Cell changes to become specialised for its job

  2. Cells develop different organelles

  3. Cells turn into different types of cells
• Stem cells from embryos and bone marrow can be grown in a lab to produce clones and made to differentiate into specialised cells to use in medicine or research
• Stem cells may be able to cure many diseases

  • Medicine already uses adult stem cells to cure disease
  • Embryonic stem cells could be used to replace faulty cells in sick people
• There are risks involved in using stem cells in medicine, such as stem cells grown in the lab becoming contaminated
• Arguments against stem cell research

  • Human embryos shouldn't be used for experiments as each one is a potential human life
  • Curing existing patients who are suffering is more important than the rights of embryos
  • Scientists should concentrate more on finding and developing other sources of stem cells
• Plants, animals and fungi are eukaryotic organisms
• Features of plants


  • Multicellular
  • Have chloroplasts which means they can photosynthesise
  • Have cell walls made of cellulose
  • Store carbohydrates as sucrose or starch
• Features of animals


  • Multicellular
  • Don't have chloroplasts and can't photosynthesise
  • Cells don't have cell walls
  • Have some kind of nervous coordination
  • Can usually move around
  • Store carbohydrates as glycogen
• Features of fungi


  • Some are single-celled, others have a body called a mycelium made up of hyphae
  • Can't photosynthesise
  • Have cell walls made of chitin
  • Feed by saprotrophic nutrition, secreting extracellular enzymes to dissolve their food
• Eukaryotic cells


  Complex cells that include all animal and plant cells
• Prokaryotic cells


  Smaller and simpler cells, e.g. bacteria
• Organelles are tiny structures within cells that can only be seen using a powerful microscope
• Organelles in a typical animal cell

  • Nucleus
  • Cell membrane
  • Cytoplasm
  • Ribosomes
  • Mitochondria
• Additional organelles in a typical plant cell

  • Chloroplasts
  • Vacuole
  • Cell wall
• Cells are specialised to carry out particular functions, so their structures can vary
• Tissue


  A group of similar cells that work together to carry out a particular function
• A tissue can contain more than one cell type
• Organ


  A group of different tissues that work together to perform a function
• Organ system


  Organs that work together to do a different job
• Examples of protoctists


  • Chlorella (plant-cell-like)
  • Amoeba (animal-cell-like)
• Examples of bacteria


  • Lactobacillus bulgaricus
  • Pneumococcus
• Examples of viruses


  • Influenza virus
  • Tobacco mosaic virus
  • HIV
• Protoctists


  Single-celled and microscopic eukaryotic organisms, some similar to plant cells and others to animal cells
• Bacteria


  Single-celled and microscopic prokaryotic organisms without a nucleus
• Viruses


  Particles rather than cells, smaller than bacteria, that can only reproduce inside living cells
• Pathogens are organisms that cause disease, including some fungi, protoctists, bacteria, and viruses