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AS unit 1 biology summary
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- WJEC
summary of the 6 topics required to learn in unit 1 of AS biology.
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UNIT 1;1IRON FUNCTION
Mg Component of chlorophyll
Fe Component haemoglobin
K Component nucleic acids and phospholipids
Ca Hardens bones and teeth.
Chemical elements:
PHOSPURUS- required to synthesise phospholipids
SULFUR- required to synthesise some amino acids
structure of water-
- chemical formula of h20
- one oxygen atom and 2 hydrogen atoms - covalent bonds.
- Molecule=dipole.
- Oxygen atom- slight negative charge. Hydrogen atom- slight positive charge- polar.
Properties of water:
Ice is less dense than water- ice floats insulating the water below- allowing
organisms to survive
Polar solvent- All chemical reactions occur in aqueous solutions. Polar
molecules and ions can dissolve and therefore be transported
Metabolite- Involved in chemical reactions
High specific heat capacity- Requires a lot of energy to cause water to heat up /
cool down therefore creating thermostable environments
Cohesive / forms hydrogen bonds- Water molecules form hydrogen bonds
allowing the movement of water
glucose
Alpha glucose – OH on C1 down
Beta glucose- OH on C1 up
Formed by: condensation
Broken by: hydrolysis
monosaccharide (CH20) n
triose- 3- metabolism
pentose – ribose-part of nucleotides
hexose- glucose
disaccharide
glycosidic bonds
sucrose – glucose and fructose. Transported in plants-phloem
, lactose – glucose and galactose. (Mammalian milk)
maltose- glucose and glucose. Produces- when amylase breaks down starch.
polysaccharide
glycosidic bonds
starch – polymer alpha- glycosidic bonds. (a1;4) amylose(helical ) and amylopectin(branched) (1,4 &
1,6 bonds) . Branched- easy to add and remove glucose. &Makes molecule compact.
Glycogen- amylopectin (a 1;4 and 1;6)- rapidly hydrolysed to release glucose.
cellulose – beta- alternate units rotate – 180 rotation – straight chain no branches. Crosslinking
between chains & hydrogen bonds; gives stability- forming microfibrils. Strengths to plant cell wall.
Chitin- has amino acid added, exoskeleton- strong & waterproof. provides strength to fungal cell
wall.
Starch and glycogen
- Insoluble therefore osmotically inert
- Storage molecules- glucose can be added and removed.
- They have a compact structure.
LIPIDS:
Two functions of lipids in plant cells- energy storage and leaf waterproofing- membrane structure.
Bonds- ester
TRIGLYCERIDES:
- Functions in a mammal- energy storage, thermal insulation, buoyancy.
- 3 FA and glycerol- joined by ester bonds formed during condensation reaction. Used as
energy reserves in p&a cells.
- Polymers-glycerol and fatty acids have different structures
- Properties of triglycerides dependent upon the fatty acids they contain.
- Compact structure
- Insoluble- osmotically inert
PHOSPHOLIPIDS:
- Phosphate head & 2 FA.
- Phosphate head-hydrophilic and attracted to water
- FA -hydrophobic and repel water
- arranged in a bilayer in the membrane
Phospholipid triglyceride
2 fatty acids 3 fatty acids
Phosphate head do not contain a phosphate head
phosphate head (p) hydrophilic. fatty acids- Nonpolar-hydrophobic
hydrophobic (NP)
Unsaturated and saturated
Saturated fatty acids contain only C-C single bonds
Unsaturated fatty acids contain at least one C=C double bond.
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