Cambridge International AS and A Level Biology Coursebook with CD-ROM
3500 word summary + pictures of AS syllabus covering main ideas from:
-Cell structure
-Biological molecules
-Enzymes
-Cell membranes and transport
-The mitotic cell cycle
-Nucleic acids and protein synthesis
-Transport in plants
-Transport in mammals
-Gas exchange and smoking
-Infectious ...
Revison chapters (gaps)
UNIT 1
Structures only found in plant cells:
-Chloroplasts
-Cell wall
-Large Permanent Vacuole
Structures only found in animal cells:
-Centrosomes
-Centrioles
How to calibrate eyepiece graticule:
Stage micrometer/eyepiece graticule on matching points
X1000 for micrometers Typical prokaryotic cell
Multiply size of cell x value of calibration
Resolution of light microscope: 200nm, 25nm ribosomes can´t be seen (1500X
magnification)
Resolution of electron microscope: 3-20nm
Lysosomes: Contain hydrolytic enzymes that dissolved worn out organelles and engulf
bacteria
Ribosomes: 70s and 80s, produce protein, found near the rough ER
Viruses self-replicate their DNA or RNA, often have a protective protein coat (capsid)
and all are parasitic (live by infecting other cells).
UNIT 2
Macromolecule are polymers (many subunits) monomers (subunits)
BONDS:
Carbohydrates (glucose): Glycosidic bonds
Lipids: Ester bonds ALL by condensation and hydrolysis
Proteins: Peptide bonds
,Food tests:
-Benedicts for reducing sugar (glucose)
-Iodine for Starch
-Biuret for Protein
-Ethanol for Lipids (cloudy)
Carbohydrates:
Hydroxyll
group
Simple sugars are monosaccharides and disaccharides, smaller in size.
Complex sugars are polysaccharides, made of many monosaccharides such as starch,
glucose and glycogen. These are insoluble in water and don´t taste sweet.
Starch is a polymeric carbohydrate consisting of a large number of glucose units
joined by glycosidic bonds. This polysaccharide is produced by most green plants as
an energy store. It is the most common carbohydrate in human diets and is contained
in large amounts in staple foods such as potatoes, wheat, maize (corn), rice, and
cassava. Molecules of amylose is linear and amylopectin is branched.
Pollysaccharides are polymers whose subunits are monosaccharides. The most
important ones are starch, glycogen and cellulose. THEY ARE NOT SUGARS.
Glycogen, the glucose store of animals, is a more branched version of amylopectin.
(formed by 1,4 and 1,6 linkages 1,6 to form branch, 1,4 the rest)
Cellulose is a large structural molecule. It is made of B-glucose and forms part of cell
walls in plants. It is formed by glycosidic bonds on the OH groups after the second
molecule has been rotated 180 degrees. Cellulose fibres have a high tensile strength
but let water and solutes through. B-Glucose fibres microfibrils cellulose fibre
cell wall
Lipids
They are organic molecules which are insoluble in water.
, Acidic group
Unsaturated C
atom, oils.
They will form ester bonds by condensation reactions between the glycerol head and 3
hydrocarbon tails to form a triglyceride. Phospholipids form with a hydrophobic head,
a glycerol and 2 fatty acids.
Triglycerides are energy reserves, insulator (blubber), provide buoyance, metabolic
source of water.
Proteins
AMINO ACID
They have many important roles such as:
Enzymes are proteins
Components of cell membranes
Some hormones are proteins
Haemoglobin and myoglobin are proteins
Keratin – nails, hair and surface of skin
Muscle contraction (myosin and actin)
Antibodies
Amino acids are the “building blocks” of proteins, they consist of a NH2 group and a
carboxylic acid group with an R group, which will determine the properties of the
protein. They form peptide bonds between amino acids and can form a long
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