Biological Molecules

In a water molecule, which atoms form at the positive and negative regions that make the overall molecule polar?
Oxygen= Negative, Hydrogen= Positive
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Characteristics of water
High boiling point, lighter that co2 and o2, a liquid at room temp, less dense when frozen because of the hydrogen bonds formed, cohesive, adhesive
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Meaning of cohesive
Moves as one mass
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Meaning of adhesive
Attracted to other materials
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Roles of water in and for living organisms
Solvent, medium for chemical reactions, transport medium, coolant, stable environment
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How does water act as a solvent
Dissolves many compounds, ions and other polar molecules
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How does water act as a transport medium
Cohesion between water molecules and adhesion resulting in water exhibiting capillary action, the process by which water can rise up a narrow tube against gravity
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How does water act as a coolant
Buffers temperature changes during chemical reactions because of the large amount of energy required to overcome hydrogen bonding
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How does water act as a stable environment
Provides a habitat because it doesn't change temp easily, when ice is formed on top of lakes it creates an insulating layer, surface tension
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The concept of monomers and polymers
A monomer is a molecules that is able to bind in long chains to form polymers
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What is a condensation reaction
Involves 2 molecules joining together to make a larger, more complex molecule with the loss of water
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What is a hydrolysis reaction
Involves the addition of water molecules to split a larger molecule into smaller sections by breaking bonds
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What chemical elements make up carbohydrates
Carbon, oxygen, hydrogen
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What chemical elements make up lipids
Carbon, hydrogen, oxygen (phospholipids also contain phosphorus)
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What chemical elements make up proteins
Carbon, hydrogen, oxygen and nitrogen
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What is glucose
A monosaccharide composed of 6 carbons
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Properties of glucose
Polar and soluble in water, dissolved in the cytosol of cells
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How are glucose molecules joined
Two hydroxyl groups react which breaks bonds and reforms them in different places, 2 hydrogen atoms and one oxygen are removed to form water and a glycosidic bond forms between the two monosaccharides to form a disaccharide
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Where is the hydroxyl group on alpha and beta glucose
Alpha= bottom, Beta- top
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Structure of ribose
5 carbons
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Synthesis and breakdown of a di/polysaccharide by the formation and breakage of glycosidic bonds
Hydroxyl groups join to form a glycosidic bond and a water molecule is lost, hydrolysis reaction an oxygen atom and 2 hydrogens are needed so that the molecules can be split
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What is starch made up of
Amylose, amylopectin
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Amylose structure
Alpha glucose joined by 1-4 glycosidic bond, the angle of these bonds twists to form a relic which is further stabilised by hydrogen bonding within the molecule
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Amylose characteristics
More compact and less soluble than glucose
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What bonds does amylose contain
Hydrogen and glycosidic (1-4)
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Amylopectin structure
Glycosidic bonds between 1-4 alpha glucose, also some bonds between 1-6 which creates a branched structure, with 1-6 branches occurring every 25 glucose subunits
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Amylopectin bonds
Glycosidic (1-4 and every 25 subunits 1-6)
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Cellulose structure
Beta glucoses alternate 180 degrees so that they can join, straight chain
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Properties of glucose, starch, glycogen and cellulose
Glucose= dissolved in cell cytosol, starch= chemical energy store, glycogen= more compact and less space needed so good energy source, cellulose= strong and insoluble fibres used to make cell walls
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Structure of a triglyceride
One glycerol and 3 fatty acids
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Structure of glycerol
A member of the alcohols group, carboxyl group
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Structure of fatty acids
Carboxylic acids, a carboxyl group with a hydrocarbon chain attached
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Structure of phospholipids
Modified triglycerides and contain phosphorus
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Discuss the process of esterification
Hydroxyl groups interact, leading to the formation of 3 water molecules and bonds between the fatty acids and the glycerol molecules, called ester bonds
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How do the properties of lipids relate to their functions in living organisms
Membrane formation and the creation of hydrophobic barriers, hormone production, electrical insulation necessary for impulse transmission, waterproofing, long term energy storage, thermal insulation, cushioning to protect vital organs
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General structure of an amino acid
Amine group, r-group/ side chain, carboxyl group, carbon, hydrogen
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Primary level of protein structure
The sequence of amino acids, directed by information carried within DNA, the particular amino acids in the sequence will influence how the polypeptide chain folds to give the proteins final shape which in turn determines its function, peptide bonds
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Secondary level of protein structure
The O, H and N atoms of the basic repeating structure of the AA interact, h bonds may form within the AA chain, pulling it into a coil shape called an alpha helix, they can also lie parallel to each other by h bonds forming beta pleated sheets
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Tertiary level of protein structure
The folding of a protein into its final shape, can include sections of secondary structure, the coiling/folding brings R-groups of different AA together till they interact
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What are the bonds involved in the tertiary structure of proteins
Hydrophobic/philic- weak interactions between polar and non-polar R-groups, hydrogen- the weakest of bonds formed, ionic- stronger than hydrogen and form between oppositely charged r-groups, disulphide- covalent and the strongest
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Structure of globular proteins
Compact, water soluble, spherical, formed when proteins fold in their tertiary structures so that the hydrophobic r-groups are kept away from the aqeuous environment and the hydrophilic ones are on the outside making them soluble
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Function of globular proteins
Regulate many life processes e.g. chemical reactions
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Describe the structure of conjugated proteins
Globular proteins with prosthetic groups
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Properties and functions of keratin
Present in hair, skin and nails, many strong disulphide bonds, strong inflexible and insoluble
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Properties and function of elastin
Found in elastic fibres present in the walls of blood vessels and alveoli, flexibility to expand when necessary, quaternary protein made from tropoelastin
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Key inorganic ions involved in biological processes
Sodium, phosphorus, hydrogen,
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Test for sugars
Benedicts test
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Test for starchy carbohydrates
Iodine starch
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Test for lipids
Emulsion test
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Test for proteins
Biuret solution
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Structure of a nucleotide
Pentose monosaccharide, a phosphate group (acidic and -charged), a nitrogenous base
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How do nucleotides join/ bond
The phosphate group at the 5th carbon forms a covalent bond with the hydroxyl group at the 3rd carbon forming phosphodiester bonds
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What do nucleotides form
A polynucleotide/ sugar phosphate 'backone'
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Structure of ATP
Adenine nitrogenous base bonded to a pentose sugar (ribose) with three phosphate groups also attached to the 5 carbo, in order for energy to be released ATP needs to be hydrolysed
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Structure of ADP
A sugar backbone (ribose) attached to a molecule of adenine and 2 phosphate groups
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What makes up DNA
Pentose sugar deoxyribose (ribose with one less oxygen)
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Smaller bases which contain a single carbon ring, thymine and cytosine
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Bigger bases which contain a double carbon ring, guanine and adenine
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Semi- conservative DNA replication
DNA unwinds to create 2 stands, free nucleotides bind to the complementary bases and DNA reforms, forming 2 new molecules of DNA both of which contain one original strand
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Nature of genetic code
Non-overlapping, universal, degenerate
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Describe the first stage of protein synthesis
Transcription- DNA copied to mRNA via RNA polymerase so that it can leave the nucleus
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Describe the second stage of protein synthesis
mRNA bonds to the small sub-unit on a ribosome and then decodes the sequence of AA, tRNA anticodons nome to complementary codons along the mRNA, amino acids brought into the correct sequence to form the primary structure
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Other cards in this set

Card 2


Characteristics of water


High boiling point, lighter that co2 and o2, a liquid at room temp, less dense when frozen because of the hydrogen bonds formed, cohesive, adhesive

Card 3


Meaning of cohesive


Preview of the front of card 3

Card 4


Meaning of adhesive


Preview of the front of card 4

Card 5


Roles of water in and for living organisms


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