Biology p1 p2

• Cells


  Tiny building blocks that make up all living things
• Types of cells


  • Prokaryotic
  • Eukaryotic
• Prokaryotic cells


  • Simple and small
  • Genetic material is not enclosed in a nucleus
  • Do not have membrane-bound organelles
• Prokaryotic cells


  • Bacteria
  • Archaea
• Eukaryotic cells


  • Complex and larger
  • Genetic material is inside a nucleus
  • Have membrane-bound organelles for specific functions
• Eukaryotic cells


  • Plants
  • Animals
  • Fungi
  • Protists
• Prokaryotic cells are simpler and lack organelles, while eukaryotic cells are more complex and have organelles that help with different tasks
• Understanding the differences between prokaryotic and eukaryotic cells helps us learn more about living things
• Animal cell


  • Does not have a cell wall
  • Does not have chloroplasts
  • Does not have large central vacuoles
• Plant cell


  • Has a cell wall made of cellulose
  • Has chloroplasts that contain chlorophyll
  • Has large central vacuoles
• Animal cells


  Do not have a cell wall, chloroplasts, or large central vacuoles
• Plant cells


  Have a cell wall, chloroplasts, and large central vacuoles
• Organisms


  can be Prokaryotes or Eukaryotes
• Prokaryotic


  single-celled organien
• Plant and Animal Cells have Similarities and Differences
• Plant cells usually have all the bits that animal cells have, plus a few extra things that animal cells don't have

  • Rigid cell wall-made of cellulose. It supports the cell and strengthens it.
  • Permanent vacuole - contains cell sap. {a week solution of sugar and salts}. cell sap is a very strong substance which helps keep the cell turgid.
  • Chloroplasts- these are where photosynthesis occurs, which makes food for the plant (see page 57). They contain a green substance called chlorophyll, which absorbs the light needed for photosynthesis.
• Bacterial Cells Are Much Smaller
• Bacterial cell structure


  • Cell membrane
  • Cell wall
  • Cytoplasm
• Bacteria don't have chloroplasts or mitochondria.
• Bacterial cells don't have a 'true' nucleus-instead they have single circular strand of DNA that floats freely in the cytoplasm. They may also contain one or more small rings of DNA called plasmids
• Cell Differentiation


  The process by which a cell changes to become specialised for its job
• Cell Specialisation


  As cells change, they devote and fum into different tubes of o
• In meet acinal cell, fe abdly to differentiate is than out at an early stage, offer they become specialised
• However, lots of plant cells dan ever one this city.
• The calls fal diflorendale in betania are mainly used forming and mack, wh as akin or blood cells.
• Stem cells


  Undifferentiated cells that can divide to produce lots more undifferentiated cells and differentiate into different types of cell
• Examples of Specialised Cells


  • SPERM CELLS are specialood for REPRODUCTION
  • NERVE CELLS are specialized for RAPID SIGNALLING
  • MUSCLE CELLS are specialised for CONTRACTION
  • ROOT HAIR CELLS are specialised for absorbing WATER and MINERALS
  • PHLOEM and XYLEM CELLS are specialised for TRANSPORTING SUBSTANCES
• Chromosomes


  Coiled up lengths of DNA molecules that contain genetic information
• Body cells normally have two copies of each ohromosome-one from the organism's 'mother', and one from its father'.
• The Cell Cycle


  1. Growth & DNA Replication

  2. Mitosis
• Multicellular organisme use mitosis to grow or replace cells that have been damaged.
• The end of the cell cycle results in two new cells identical to the original cell, with the same number of chromosomes.
• Embryonic Stem Cells


  Can turn into ANY Type of Cell
• Adult Stem Cells


  Can only turn into certain cell types, not any cell type
• Stem cells from embryos and bone marrow can be grown in a lab to produce clones (enefically identical cals) and made to differentials into specialised calls to use in medicine or research.
• Potential uses of Stem Cells

  • Replace faulty blood cells
  • Replace insulin-producing cells for diabetes
  • Replace nerve cells for spinal injuries
• Arguments against Stem Cell Research

  • Embryos are potential human lives and shouldn't be used for experiments
  • Curing existing patients is more important than rights of embryos
  • Scientists should focus on developing other sources of stem cells instead
• In some countries stem cell research is banned. It's allowed in the UK as long as it follows strict guidelines.
• Plant Stem Cells


  Found in the meristems (parts of the plant where growth occurs) and can differentiate into any plant cell type
• Stem cells can be used to grow more plants of rare species and to grow crops of identical plants with desired features