Biological Molecules Flashcards
Monomer
Small unit from which larger molecules are made
Polymer
Molecules made from a large number of monomers joined together
3 examples of monomers
Monosaccharides
Amino acids
Nucleotides
Condensation reaction
The joining of two molecules together
A chemical bond is formed and a molecule of water is eliminated
Hydrolysis reaction
Breaks a chemical bond between two molecules and involves the use of a water molecule
Monosaccharide
The monomer for larger carbohydrate
3 monosaccharides
Glucose and galactose and fructose
Joining of two monosaccharides
Disaccharide formed by condensation reaction
Glycosidic bond formed
Maltose is from
Two glucose
Sucrose is from
Glucose and fructose
Lactose is from
Glucose and galactose
To isomers of glucose
Alpha glucose and beta glucose
Polysaccharides are formed bye
The condensation of many glucose in units
Starch
Large polysaccharide joined by glycosidic bonds Formed by condensation reactions between alpha glucose monomers
Insoluble So doesn’t effet the water potential of the cell so water doesn’t move into the cell by osmosis
Amylose- Coiled compact molecule so can be stored in a small space alpha glucose monomers joined by 1,4 glycosidic bonds
Amylopectin- branched polymer with 1,4 glycosidic bond and 1,6 glycosidic bonds between adjacent c1 and c6
Test for reducing sugar
Benedict and heat red precipitate
Test for non reducing sugar
Test for reducing sugar add HCL boil add N a OH add Benedicks heat
RESULT??***
Test for starch
Add iodine
Turns black
Two groups of lipids
Triglycerides
Phospholipids
Triglycerides firmed by
Condensation Reaction between glycerol and three fatty acid and an Esta bond is formed
The r group Of a fatty acid can be
Saturated or unsaturated
phospholipids structure
One of the fatty acids is substituted by a phosphate containing group
The phosphate group is electrically charged polar which makes it attracted to water
The hydrocarbon chain is repelled by water and is hydrophobic
Phospholipid and triglyceride properties
Learn!!!
Test for lipids
Add ethanol shake a few drops of water
Structure of an amino acid
Nh2 amine group
CooH carboxyl group
R group - carbon containing side chain
Twenty amino acids
Common in all organisms differ only on their side group
Protein condensation reaction
Between two amino acids
Peptide bond forms
Dipeptide formed by
Condensation of two amino acids
Polypeptides are formed by
Condensation of many amino acids
Functional protein can contain
One or more polypeptides
Different bonds in proteins
Hydrogen
Ionic
Covalent
Disulphides bridge
Learn!!!
Protein structure
Primary
Secondary
Tertiary
Quaternary
Learn!!!
4 key biological molecules
Carbohydrates
Proteins
Lipids
Nucleic acids
Elements found on biological molecules
Carbon Hydrogen Oxygen Nitrogen Phosphorus Sulphur
Metabolism
The sum total of all the biochemical reactions taking placeIn the cells of an organism
Catabolic reaction
Breaking large molecules into smaller ones
Anabolic reactions
Joining the smaller molecules into larger ones
Properties of water
A very small dipolar molecule made up of two hydrogen atoms covalently bonded to one oxygen atom
The electrons in the water are not shared evenly between the hydrogen and oxygen
The larger oxygen pulls the electron closer and become slightly negative and the hydrogen become slightly positive
This forms a hydrogen bond which can be continually broken and reformed
Water
Metabolic role
Many metabolic reactions involve condensation and hydrolysis reactions
Water
High latent heat or vaporisation
The evaporation of water requires a lot of energy to break the hydrogen bonds when water evaporates it removes the heat and has a
Cooling effect
Water
Liquid with relatively high boiling point
The continual making and breaking of hydrogen bonds means that it is a liquid
It is difficult for a water molecule to escape liquid which means the boiling point is high
Water
Low density of ice
As water is called the Molecules slowdown and more hydrogen bonds form to form a crystalline structure
This is less dense than water so it floats and insulate the organisms beneath it
Water high specific heat capacity
The hydrogen bonds prevent the movement of the water molecules so large amount of energy required to increase the temperature
This means a large bodies of water are thermostable even when there are large external fluctuations of temperature
Water cohesion
Hydrogen bonds cause water molecules to stick together this results in surface tension which means some organisms can walk on water
Water can be transported up the xylem as cohesion between water molecules makes a long thin columns of water difficult to break
Adhesions is when water molecules stick to other services
Water
Solvent
Polar molecules like ions will dissolve well in the water
The negative irons will be attracted to the positive end of the water and the positive ions to the negative end
Water molecules cluster around any charge parts of solute molecules
This allows metabolic reactions such as photosynthesis and respiration take place in the cytoplasm
Water
Transport medium
Good transport medium as water is a good solvent and remains liquid over a wide range of temperatures
Water
Transparent
Support
Lubricant
Aquatic animals can undergo photosynthesis
Turgid plant cells
Constituents of synovial fluid
Inorganic ions
Generally ions that don’t contain carbon
Hydrogen ions and PH
Inorganic ions
PH is a measure of the H+ concentration in solution
Iron ions in haemoglobin
Inorganic ions
Iron atom can attract and hold an oxygen molecule
Sodium ions in co transporters
Inorganic ions
The sodium ion is linked with either glucose or amino acid molecules in the same direction across the membrane
Phosphate ion
Inorganic ions
DNA RNA and ATP all contain phosphate groups
The phosphate bonds in ATP store energy
The phosphate groups in DNA and RNA allow phosphodiester bonds to form between nucleotides forming polynucleotide
Alpha glucose
Beta glucose
Alpha-easily transported and used in respiration OH group below the carbon on C1 and C4
Beta- Found in Celulose OH group below carbon on C4 and above on C1
Glycogen
Similar to starch with more branches and shorter
Large and insoluble formed by condensation reaction between alpha glucose
Doesn’t affect the water potential
Compact and can be stored in small spaces
Highly branched so glycosidic bonds can be rapidly hydrolysed by enzymes to form alpha glucose monomers which can be easily transported and used in respiration
Cellulose
Straight, unbranched, forms plant cell walls
Made of beta glucose held together by 1,4 glycosidic bonds formed by condensation reactions
Each beta glucose is rotated 180 degrees
Parallel chains of beta glucose link by hydrogen bonds between the OH groups to form bundles called microfibrils which are very strong and prevent the cell wall bursting
Insoluble and un reactive
Cellulose can’t be digested by animal as they don’t have the right enzyme
Lipids are not
Polymers
4 functions of triglycerides
Source of energy- lipids have a higher proportion of hydrogen to oxygen atoms and when oxidised released twice the energy as the same mass as carbohydrates and proteins
Insulators- slow conductor of heat and help retain body heat as an electrical insulator as the myelin sheath in nerve cells
Non polar Insoluble in water therefore useful for waterproofing
Protection Fat is stored around delicate organs and acts as a shock absorber
Saturated triglycerides
Mono- unsaturated
Polyunsaturated
No C=C bonds
One C=C
More than one C=C
Phospholipid found in
Cell membranes
Phospholipid bilayer
The hydrophobic tail points towards the centre the hydrophilic head points outwards
Phospholipid bilayer forms a barrier which controls the movement of molecules through it
The hydrophobic tail prevents water soluble molecules passing through however lipid soluble Molecules can diffuse through directly
Protein function
Structural- used in making new cells for growth and repair Enzymes- control metabolic reactions Hormones Antibodies in the immune response Protein receptors Transport proteins Antigens
Protein primary structure
Sequence of amino acids held together by peptide bonds
Primary structure determines secondary and then tertiary structure
Protein secondary structure
Coils to form alpha helix
Folds to form beta pleated sheet
Held together by many weak hydrogen bonds which overall make the structure
Tertiary structure protein
Further folding of polypeptide chain to give more complex 3D shape and is closely related to the function. Stabilised by
H bonds- weak and between R groups
Ionic bonds- between positive and negatively charged R groups
Disulphides bonds- strong covalent bonds formed between sulphurs in the R group of the amino acid cysteine
Hydrophobic interactions- between non polar R groups which tend to cluster together towards the centre of the molecules
Protein quaternary structure
Made up of one or more polypeptide chain
Fibrous protein
Form long fibres
Regular repetitive sequence
Usually insoluble in water
Tend to have structural roles
Fibrous protein example
Collagen- found in skin bones and ligaments
Made of three identical left handed helix polypeptide chains wound around each other to form a triple helix
Every third amino acid is glycine which is small so allows three polypeptides to pack closely
3 chains held together by hydrogen bonds
Collagen molecules cross link through covalent bonds to form fibres which give it great strength
Globular proteins
Fold up into a compact ball shape
Hydrophobic r groups on amino acids tend to be turned inwards towards the centre of the protein And hydrophilic r groups tend to be on the outside
They tend to be more water soluble
Metabolic role
Wide range of amino acid sequence in their structure
Globular protein example
Haemoglobin
Quaternary structure
2 alpha and 2 beta
Compact ball shape
