Biological Molecules
- Created by: rubes_darwin
- Created on: 15-12-18 13:14
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- Biological Molecules
- monomers & Polymers
- Monomer: a single unit in a polymer
- Polymer: similar monomers binding together
- Formed by condensation (removal of water)
- OH groups bind with water
- Broken down by hydrolysis (adding water)
- Formed by condensation (removal of water)
- Food Tests
- proteins
- add sodium hydroxide - makes it alkaline
- then add biuret reagent (copper (ii) sulphate)
- if present it will go from blue to purple
- reducing sugars
- add benedicts reagent
- heat it
- If a positive result goes blue to orange/ red colour
- non reducing sugars
- do the test for reducing sugars
- get a negative result
- take a fresh sample & heat with dilute acid
- Neutralise it with an alkali then test with pH paper
- add benedicts then heat again
- Positive result will go from blue to orange/ red
- do the test for reducing sugars
- lipids
- dissolve sample in ethanol
- If a positive result a white emulsion forms
- starch
- add iodine dissolved in potassium iodine
- a positive result - orange to blue black
- proteins
- Carbohydrates
- Mono-saccharide
- bonded by glycosidic-bonds
- Joined by condensation reaction - form poly-saccharides
- examples:
- glucose
- joins with glucose to form maltose
- fructose
- Joins with glucose to form sucrose
- galactose
- joins with glucose to form lactose
- glucose
- Disaccharide
- 2 mono-saccharides that join together & form glycosidic bonds
- made by candensation reactions
- forms a glycosidic bond
- water is released
- breaks the glycosidic bond between disaccharides
- uses water
- forms two mono-saccharides
- Poly-sacchqride
- formed by poly-merisation
- a large molecule made of many smaller monosaccharides.
- Starch
- amylase
- alpha glucose
- unbranched
- coiled structure due to angles of the glycosidic bonds
- almost cylinder
- amylopectin
- alpha glucose
- branched
- has side branches
- allows enzymes to break down molecule - glycosidic bond
- glucose is
- Good for storage because
- doesn't affect water potential
- branched
- large - cant' cross cell membranes
- polymer of glucose - respiration
- amylase
- Glycogen (animals only)
- excess glucose that is stored
- alpha glucose
- has loads of side branches
- stored glucose quickly released
- very compact
- good for storage
- Cellulose
- unbranched
- beta glucose
- forms straight chains
- joined by hydrogen bonds
- form strong micro fibils
- form structural support
- joined by hydrogen bonds
- Mono-saccharide
- Lipids
- Triglycerides
- 3 fatty acids & 1 glycerol
- properties
- insoluble
- contains a lot of chemical energy
- makes it good for storage
- uses
- storage cells
- cell membranes
- Phospholipid
- 1 clycerol, 2 fatty acids & 1 phosphate group
- the phosphate & glycerol is hydrophillic
- fatty acids are hydrophobic
- can form a phospholipid bilayer
- 1 clycerol, 2 fatty acids & 1 phosphate group
- Fatty acid
- can be saturated
- no double bond
- can be unsaturated
- double bond
- can be saturated
- Glycerol
- can bind with fatty acids
- forms an ester bond
- can bind with fatty acids
- Triglycerides
- Proteins
- are made from amino acids
- can form polypeptides or dipeptides
- Polypeptide: when 2+ amino acids join together
- Dipeptide: when amino acids join tigether
- formed by a condensation reaction
- forms a polypeptide bond
- broken by hydrolysis
- can form polypeptides or dipeptides
- Proteins Shape
- amino acids in a protein = residue
- a proteins shape determines its function
- anti bodies
- involved in immune response
- found in the blood
- amino sequences vary - have variable regions
- made up of 2 light, short polypeptides & 2 long, heavy polypeptides
- haemoglobin
- used for carrying oxygen around the body
- easy to transport
- compact and soluble protein
- transport proteins
- con tain amino acids which fold up & form chains due to being hydrophillic & hydrophobic
- transport molecules & ions across the membrane
- e.g. channel proteins in membranes
- structural proteins
- e.g collagen - hair & nails
- physically strong
- consits oflong polypeptide chains with parralell crosslinks
- e.g. keratin - connective tissue
- 3 polypeptide chains tightly coiled together
- strong
- 3 polypeptide chains tightly coiled together
- enzymes
- spherical shape - tightly folded polypeptide chains
- help synthesise other molecules
- can be used in digestion
- anti bodies
- Structures
- Primary
- a sequence of polypetide chains
- Secondary
- poly peptide chain doesnt stay flat
- hydrogen bonds form between amino acids
- forms either and alpha helix or a beta pleated sheet
- Tertiary
- more bonds form including hydrogen, ionic & disulfide bridges
- disulfide bridges
- amino acids cystiene come cloese together
- sulphur bonds come together
- disulfide bridges
- coiled/ folded sheets are coiled/ folded more
- more bonds form including hydrogen, ionic & disulfide bridges
- Quaternary
- final 3d structure
- polypeptides assemble together
- prosthetic bond forms
- made of multiple polypeptides together
- Primary
- Fuctions
- muscle
- active transport
- hormones
- insulin/ oestrogen
- membranes
- haemoglobin
- contractile
- transport
- enzymes
- Structural
- immuno-proteins
- are made from amino acids
- Chroma-tography
- two main stages
- staionary phase
- doesn't move
- Mobile phase
- does move
- staionary phase
- Two types
- gas chromatography
- a method of separating volatile compounds
- Process
- 1) The sample that is going to be tested is first turned into a gas
- 2) Then it's carried through a column by a nonreactive 'carrier' gas such as helium or other inert gas such as nitrogen.
- 3) As the sample is carried through the column it is separated into its individual components.
- 4) achieve this the column is housed inside an oven, where the temperature is controlled to allow the individual components to exit the column at different times.
- takes place inside a box - graph chroma-tograph
- Limitations
- Potentially, thousands of chemicals may have the same retention time, peak shape and detector response
- Not all of the substance will be separated and detected
- Compounds cannot be identified.
- gas chromatography
- Chromatography: an analytical technique used to separate compounds within a mixture
- two main stages
- monomers & Polymers
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