2.3 : biological molecules

monomers and polymers, carbohydrates, lipids, proteins, biochemical tests

what is an amino acid

a monomer which makes up proteins

what is the central carbon in an amino acid bonded to (4)

carboxylic acid group

amino group

hydrogen atom

R group

what is a condensation reaction

a process in which two molecules combine to form a more complex one with an elimination of a simple substance (usually water)

what is hydrolysis

the breaking down of large molecules into smaller ones by the addition of water molecules

what is a monomer

one of many small molecules that combine to form a polymer

what is a monosaccharide (2)

a single sugar

the monomers of long chain carbohydrate polymers

what is a nucleotide

a compound consisting of an organic base and ribose sugar linked to a phosphate group

what do nucleotides form

monomers of nucleic acids such as DNA

what is an organic molecule

molecules containing carbon that can be found in living things

what are the 4 classes of organic molecules

carbohydrates

lipids

proteins

nucleic acids

what elements do the molecules of life all contain

carbon hydrogen oxygen

what are carbohydrates (2)

respiratory substances which provide energy for cells

also used in membranes and cell walls in plants

what are lipids (2)

respiratory substrates which provided energy for cells and form a bilayer in cell membranes

they also make up some hormones

what are proteins

orm enzymes, cellular structures and chemical messengers

what do nucleic acids do (2)

form polymers which make up genetic material

code for the sequence of amino acids which make up proteins

what evidence supports the theory plants and animals share a common ancestor

all organism use the same nucleic acid as genetic material, the same 20 amino acids for proteins and lipids and carbohydrates as energy stores / cell membranes

what are polymers

molecules made from lots of repeating units (monomers) joined together

what is the monomer, covalent bond type and polymer for carbohydrates

monosaccharides

glycosidic bond

polysaccharides

what is the monomer, covalent bond type and polymer for proteins

amino acids

peptide bond

polypeptide

what is the monomer, covalent bond type and polymer for nucleic acids

nucleotides

phosphodiester bond

polynucleotide

what are 3 examples of carbohydrate polymers

glycogen

cellulose

starch

what are 4 examples of protein polymers

enzymes

antibodies

channel proteins

haemoglobin

what are 2 examples of nucleic acid polymers

DNA

RNA

what is alpha glucose

an isomer of glucose that can bond to form starch or glycogen

what is beta glucose

an isomer of glucose that can bond to form cellulose

what is cellulose

a polysaccharide made of beta glucose bonded by 1-4 glycosidic bonds

what is a disaccharide/polysaccharides

two/many monosaccharides joined together through a condensation reaction by glycosidic bonds

what is a hexose sugar

a sugar made up of 6 carbons

what is a hydrogen bond

chemical bond formed between the positive charge of a hydrogen ion and the negative charge on another atom of an adjacent molecule

what is an isomer

two or more molecules with the same formula but different arrangement of molecules and therefore different properties

what is a non-reducing sugar

a su.gar that can’t be used as a reducing agent such as sucrose

what types of sugars are reducing

all monosaccharides and some disaccharides

what is starch

a polysaccharide found in plant cells made of alpha-glucose (amylose - 1-4 bonds and amylopectin - 1-4 and 1-6 bonds)

what are 3 examples of monosaccharides

glucose fructose and galactose

where is the glycosidic bond

between the 3 OH groups

what are 3 examples of disaccharides and what are they made from

lactose - glucose + galactose

sucrose - glucose + fructose

maltose - glucose + glucose

what are the components of triglycerides

a glycerol molecule and 3 fatty acids

what are the components of a phospholipid

glycerol molecule phosphate group and 2 fatty acids

what are the bonds in lipids

ester bonds through condensation reactions between the OH group on the fatty acids and the OH groups on the glycerol molecule

what is a property of a triglyceride

it’s hydrophobic so it’s insoluble in water

what is

why can saturated fatty acids in triglycerides pack closer together than unsaturated ones

unsaturated fatty acids contain a carbon-carbon double bond which causes it to bend meaning the next one has to be spaced further away

how do the melting points in saturated and unsaturated fatty acids compare

saturated fats have higher melting points so are usually solids at room temp while unsaturated fats have lower melting points and so are usually liquids at room temp

what are the charges and properties like of a phospholipid

the phosphate is charged and polar and hydrophilic while the lipid part is non-polar and hydrophobic

how is the phospholipid bilayer arranged in the cell membrane

the phosphate heads of the inner layer face inwards while the fatty acid tail faces outwards and isn’t in contact with water as it is hydrophobic and the phosphate heads of the outer layer face outwards so the hydrophobic fatty acids are protected

what are 7 functions of lipids

forming phospholipids for cell membranes

buoyancy

insulation of heat and electricity

waterproofing (e.g. wax)

hormone production

energy store/source

protecting organs

why are lipids a good energy store

they are insoluble so they won’t release their energy