2.2 biological molecules

• covalently bonded Hydroegna nd water • oxygen has a greater share of electrons so is slightly negative • hydrogen is slightly positive • seperation in charge is due to electron in covalent bonds being unevenly shared • hydrogen bond form between other water molecules due to positive and negative regions of molecules attarcting each other • hydorgen bond are weak therefore they constantly break and reform constantly moving the molecules

• excellent solvent • good transport medium • has a high boiling point/ shc • has a high latent heat of vaporisation • is a good raegant • water as a solid is less dense than when liquid • cohesive • adhesive

substances such as ions or covalently bonded molecules are attracted to the polar water molecules therefore allowing for them to dissolve therefore making it a good transport medium

• high boiling point so is a liquid at room temperature due ot the bydrogen bonding of molecules • takes a lot of energy to increase temeperature of water and cause it to become gaseous

• necessary for water to maintain a liquid in seas, rivers and ice at poles to provide habitats for animals • also a little water is required to vaporate from an organism to loose a large amount of heat so useful for animals to stay cool

• h bonds fix the position of polar molecules slightly further apart than in a lquid state producing a giant rigid open structure with every O atom at the ecentre of a tetrahedral arrangment of H atoms resultting in a solid that is less dense than liquid therefore ice floats on water • useful to provide animals habitats at poles

• water molecules are attracted to each other due to polarity • water also has a high surface tension making it more cohesive due to strong hydrogen bonds • allows plants tp draw up water from roots up through the xylem

H2O molecules attracted to other surfaces since water is polar so attracts other polar molecules

• since h2o polar many ions and covalently bonded substances can dissolve in it • allows for chemical reactions to occur within cells • cytoplasm mainly water wich allows for substance exchange • many solutes are polar molecules eg amino acids proteins and nucleic acids

• provides habitats in aquatic eg lakes and ocean • able to maintain constant temperature as water is able to absorb a lot of heat wihtout big temperature fluctiation –> vital in maintaing temepratures that are optimal for enzyme activity • water in blood plasma is also vital in transfering heat around the body helping maintain fairly constant temperature —> as blood passes through more reactive region of body heat energy is absorbed but temperature fairly constant —-> water in tissue fluid also plays important regulates role in maintainign a constant body temperature ALL this due to hydrogen bonds

• acts as a coolant due to a little water reuired to evaporate for an organism to loose a large amount of heat

• molecules containgin only carbon hydrogen and oxygen • genral formula Cx(H2O)y • also known as sacharides/sugars • single sugar unit - monosacharide • 2 monosacharides form a disacharide • multiple disacharides form polysacharides

• a monosicharide or disacharide that can donate electrons because carboxyl group becmes oxidised • works in benedicts since it reduces oluble copper sulphate

yeth! eg glucose

• a sugar that can’t donate an electron therfore can’t be oxidised • don’t work in benedict have ot hydrolsye first by breaking the disacharide in to the 2 monosacharide • eg sucrose

glucose, fructose and galactose

• monosaccharide • C6H12O6 • energy sources in organisms • used in respiration —> releases energy for production of ATP • soluble so can be transported in water • exists as alpha and beta glucose

has H above 1st carbon ring Haha im the alpha, H is the alpha so on the top xx in glycogen and starch

has OH above the 1st carbon in the ring makes up cellulose

• pentose sugar since contain 5 carbon molecules • make up DNA • on second carbon has a H below it • deoxy, similair to di which liek means 2 so that means it has 2 H’s on the 2

• pentose sugar since contains 5 carbon molecules • makes up RNA • has OH below 2nd carbon

Maltose

• when two hydroxyl (-OH) groups (on different saccharides) interact to form a strong covalent bond • forms a disacharide/polysacharide • always forms H2O • condensation reaction • hydrolsiss reaction when breaking it - H2O needs to be present

Sucrose