P1: Biology- Cell Biology

• Sub-cellular structures within an animal cell:

  -Nucleus

  -Cytoplasm

  -Cell Membrane

  -Mitochondria

  -Ribosomes
• Function of a nucleus:

  Controls activities of the cell and contains genetic material
• Function of cytoplasm:

  where most chemical reactions take place
• Function of Cell Membrane:

  controls the passage of substances into and out of the cell
• Function of mitochondria:

  Where aerobic respiration takes place
• Function of ribosomes

  where protein synthesis takes place
• Plant cells contain all the sub-cellular structures of an animal cell but also have...

  -A cell wall made of cellulose

  -A permanent vacuole

  -Chloroplasts
• Function of the Cell Wall:

  to strengthen the cell
• Function of the vacuole:

  -To support the cell (filled of cell sap)
• Prokaryotic Cells are:

  -Smaller in size

  -Genetic material is not stored in the nucleus

  -Genetic material is stored in a DNA loop (may be one or more small rings of DNA called plasmids)

  -Do not contain mitochondria or chloroplasts
• Eukaryotic cells are:

  -larger in size

  -genetic material is stored in the nucleus

  -contain mitochondria and chloroplasts
• Bacterial cells contain:

  -Plasmid DNA

  -Chromosonal DNA

  -Flagella

  -Cytoplasm

  -Cell Wall
• Plasmid DNA:

  A small section of DNA, that can replicate independently of chromosomal DNA
• Chromosomal DNA:

  Where the DNA is found as one circular chromosome not within the nucleus
• Flagella are:

  tail like structures which rotate to help some bacteria move
• Cell Wall (bacterium)

  Supports the cell but not made out of cellulose
• The size of cells:

  Plant cells: 0.1mm in diameter

  Animal cells: 0.02mm in diameter

  Prokaryotic cells: 0.002mm long
• How many micrometers (µm) are in a meter

  1,000,000
• How many nanometers (nm) are in a meter?

  1,000,000,000
• The ability to see two or more separate objects is called...

  resolution
• What did light microscopes allow scientists to see?

  Plant, animal and bacterial cells but not sub cellular structures
• When were electron microscopes created?

  1933
• What can you see with an electron microscope and why?

  Sub-cellular structures:

  -eg. structure inside mitochondria and chloroplasts

  -ribosomes and their role in protein making
• Why do electron microscopes have a better resolution than light?

  As they pass electrons rather than light
• What is magnification?

  How many times larger the image is than the real object
• Magnification formula:

  Magnification= size of image/actual size
• How do bacteria cells divide?

  Binary fission which is an example of asexual reproduction
• How often can bacteria multiply?

  Every 20 minutes with the right temperature and enough nutrients
• Bacteria can be grown as colonies on...

  agar
• The bacteria grown on agar is called a...

  culture
• Agar is usually on the bottom of a...

  petri dish
• How to keep cultures uncontaminated:

  1.Petri dishes must be sterilised before use

  2.An inoculating loop is sterilised by passing it through a flame

  3.Cooled inoculating loop is used to transfer bacteria to the agar

  4.Lid of the Petri dish must be quickly removed and replaced when transferring bacteria and must be taped to stop from coming off

  5.Dish is stored upside down to stop condensation from dripping onto the agar
• The procedure that ensures only the required microorganisms are grown is called...

  aseptic technique
• What temperature are cultures incubated in school?

  25 degrees celcuis
• Why are cultures in school only incubated at 25 degrees C


  To stop the growth of harmful bacteria
• A chromosome is contained in the:

  Nucleus
• Chromosomes are made of:

  DNA
• Chromosomes carry:

  Hundreds to thousands of genes
• Chromosomes are found in:

  Pairs, one from each parent
• Humans have...chromosomes

  23