detailed notes to flashcards - cell bio section 1

• Eukaryotes

  Cells that have a nucleus and membrane-bound organelles
• Prokaryotes

  Cells that lack a nucleus and membrane-bound organelles
• Components of animal and plant cells

  • Cell membrane
  • Cytoplasm
  • Nucleus containing DNA
• Components of bacterial cells

  • Cell wall
  • Cell membrane
  • Cytoplasm
  • Single circular strand of DNA and plasmids
• Orders of magnitude

  Used to understand how much bigger or smaller one object is from another
• Prefixes to show multiples of units

  • Centi (0.01)
  • Milli (0.001)
  • Micro (0.000,001)
  • Nano (0.000,000,001)
• Structures in animal and plant cells

  • Nucleus
  • Cytoplasm
  • Cell membrane
  • Mitochondria
  • Ribosomes
• Additional structures in plant cells

  • Chloroplasts
  • Permanent vacuole
  • Cell wall
• Structures in bacterial cells

  • Cytoplasm
  • Cell membrane
  • Cell wall
  • Single circular strand of DNA
  • Plasmids
• Cell specialisation

  The process where cells gain new sub-cellular structures to be suited to their role
• Specialised animal cells

  • Sperm cells
  • Nerve cells
  • Muscle cells
• Specialised plant cells

  • Root hair cells
  • Xylem cells
  • Phloem cells
• Cell differentiation


  The process where stem cells switch on/off genes to produce different proteins and acquire different sub-cellular structures
• In animals, most cells differentiate early and lose ability to differentiate, but some like red blood cells are replaced by adult stem cells
• In plants, many cell types retain ability to differentiate throughout life
• Light microscope

  Has two lenses (objective and eyepiece), illuminated from underneath, max magnification x2000, resolving power 200nm
• Electron microscope

  Uses electrons instead of light, two types (scanning and transmission), max magnification x2,000,000, resolving power 10nm (SEM) and 0.2nm (TEM)
• Calculating magnification of light microscope

  Magnification of eyepiece lens x magnification of objective lens
• Calculating size of object

  Size of image / magnification = size of object
• Standard form

  Used to represent very large or small numbers by multiplying a number between 1 and 10 by a power of 10
• Culture medium

  Contains carbohydrates, minerals, proteins and vitamins to grow microorganisms
• Growing microorganisms in nutrient broth solution

  Make suspension of bacteria, mix with sterile nutrient broth, stopper with cotton wool, shake regularly
• Standard form

  Multiplying a certain number by a power of 10 to make it bigger or smaller, with the 'number' being between 1 and 10
• Standard form examples

  • 1.5 x 10^-5 = 0.000015
  • 3.4 x 10^3 = 3400
• Culturing microorganisms

  • Microorganisms are very small, so scientists need to grow many of them in the lab using nutrients
• Components of culture medium

  • Carbohydrates for energy
  • Minerals
  • Proteins
  • Vitamins
• Growing microorganisms in the lab

  1. In nutrient broth solution

  2. On an agar gel plate
• Steps in making an agar gel plate
• Autoclave


  An oven used to sterilise Petri dishes and culture media before use
• Reasons for sterilising equipment
• Reasons for sealing Petri dish lid
• Reason for storing Petri dish upside down
• Reason for incubating at 25 degrees
• Testing antibiotic effectiveness

  1. Soak paper discs in antibiotics and place on agar plate with bacteria

  2. Leave plate for 2 days

  3. Measure zone of inhibition
• Inhibition zone

  The clear area around antibiotic discs where bacteria have died
• Formula for calculating cross-sectional area
• Chromosomes

  Contain coils of DNA, with each chromosome carrying many genes
• Gene

  A short section of DNA that codes for a protein and controls a characteristic
• Number of chromosomes

  23 pairs in body cells, 23 in sex cells
• Cell cycle and mitosis

  1. Interphase: cell growth, organelle increase, DNA replication

  2. Mitosis: chromosomes line up and are pulled to opposite sides

  3. Cytokinesis: cytoplasm and cell membranes divide to form two daughter cells