1.1 Biological compounds

what is a carbohydrate

organic molecules composed of three elements: carbon, oxygen and hydrogen

what is the general formula for carbohydrates

(CH₂O)_n where n is the number of carbons

what are the three main groups of carbohydrates

-monosaccharide (one sugar molecule)

-disaccharide (two sugar molecules)

-polysaccharides (many sugar molecules)

what is the name based on for monosaccharides

number of carbons

what form do monosaccharides when they dissolve in water

ring structure

what are the different types of monosaccharides and give examples

-triose (3 carbons): glyceraldehyde

-tetrose (4 carbons): oxabacetate

-pentose (5 carbons): ribose and deoxyribose-important constituents of RNA and DNA

-hexose (6 carbons): glucose, fructose and galactose

what are the differences in structure between glucose, galactose and fructose

glucose: OH below carbon four

galactose: OH above carbon four

fructose: CH₂OH below carbon one

what is the definition of isomer

same molecular formula but different structural forms

what are the two forms of glucose and draw them

alpha and beta

what is the difference between alpha and beta glucose structure

beta: hydroxyl group is above on carbon one

alpha: hydroxyl group is below on carbon one

how is glucose adapted to being an energy source

-soluble: hydroxyl group can form hydrogen bonds with water, so it can be transported around organisms

-bonds store a lot of energy- the energy is released when the bonds break

what is a disaccharide

sugars made of two monosaccharide units joined together in a condensation reaction

what is the formula for disaccharides

C₁₂H₂₂O₁₁

what happens when two monosaccharide join together and give a general word equatio 

-a glycosidic bond is formed

-a molecule of water is lost

monosaccharide + monosaccharide —> disaccharide + water

what are three word equations for monosaccharide into disaccharide

glucose + glucose ➝ maltose + water

glucose + fructose ➝  sucrose + water

glucose + galactose ➝ lactose + water

draw a diagram of two alpha glucose monosaccharide joining together

diagram:

What is the function of starch and how is it good for it

To store glucose in plants

-insoluble: does not affect osmotic balance in the cell

-large: cannot diffuse out of cell

-amylopectin side branches: allows enzymes to hydrolyse the glycosidic bonds easily and quickly to release glucose

-amylose being coiled: makes it compact so lots of glucose can be stored in smaller spaces

What is glycogen

Storage polysaccharide found in animals

What are some features of glycogen

-made of alpha glucose monomers

-1,4 and 1,6 glycosidic bonds

-larger and more branched than starch

How and why is glycogen good for storing energy

insoluble: does not dissolve in water, doesnt affect cell’s water balance

compact:packs a lot of glucose into a small space

more branched: allows enzymes to hydrolyse the glysosidic bond bonds easily

large: cannot diffuse out of the cel

what is cellulose

structural polysacccahride found in plant cell wall

what is some features of cellulose

-beta-glucose monomers

-1,4 glycosidic bonds

-every other beta-glucose is flipped

-difficult to digest since there are a lot of hydrogen bonds between chains

→high tensile strength meaning cells are less likely to burst

explain microfibrils and macrofibrils for cellulose

hydrogen bonds form between adjoining chains giving it its structural stability and the chains of glucose monomers linked this way are called microfibrils

several microfibrils group together into a macrofibril

where is chitin used 

fungi: used to strengthen cell wall

insects: gives strength to exoskeleton (the hard part outside the body)

what is the structure of chitin

similar in structure to cellulose: 

-B-glucose monomers

-1,4 glycosidic bond

-every other flips

contains acetylamine groups, forming a mucopolysaccharid

what are some properties of chitin

-waterproof

-lightweight

-the nitrogen on the acetylamine group means more hydrogen bonds can form and so it has a higher tensile strength

what do lipids consists of

consists of three elements: carbon, hydrogen and oxygen

→but it has a lot less oxygen than carbohydrates

are lipids polar or non polar

non-polar→hydrophobic in water but soluble in organic solvents such as alchohols

what are the two types of triglycerides and what is the difference

fats: solid at room temp (tend to be longer chained)

oil: liquid at room temp (tend to be shorter chained)

what are triglycerides made of

made of one molecule of glycerol and three fatty acid

how are triglycerides broken down and what are they broken down into

triglyceride + 3 water → glycerol + 3 fatty acids

(hydrolysis)

what are the differences between saturated and unsaturated triglycerides

saturated:

-no carbon-carbon double bond

-all carbon attached to max hydrogen

-generally from form fats at room temp since they are straight and pack closely together and so have stronger forces of attraction

unsaturated:

-at least one C=C double bond

-C=C causes a kink and so cannot pack closely together which means the forces of attraction are less and generally from oils at room temp

what are waxes

its a type of lipid that melt at temperatures above 45 degrees Celsius

what is the function of waxes for animals and plants

waterproof - reduces water loss from insect exoskeleton or plants 

what are the different roles of triglycerides and explain each

-efficient energy storage: contains more carbon-hydrogen bonds than carbohydrates (since carbohydrates have more oxygen and so less carbons and hydrogen) it releases twice more energy than carbohydrates

-thermal insulation: when stored under the skin it acts as an insulator against heat loss

-protection: fats often are stored around delicate internal organs such as kidneys providing protection against physical damage

-metabolic water: they produce a lot of metabolic water when oxidised. Important for desert animals like Kangaroos which survive on metabolic water from the respiration of its fat intake.

-waterproofing: fats are insoluble in water (hydrophobic) which reduces water loss. Animals can coat their fur with it.

what bonds are present in triglycerides

ester bonds

health implication of fatty acids

-a high intake of saturated fats in the body can contribute to heart disease

-arteries contain endothelium which is a thin layer of cells that keep arteries smooth. Too much saturated fats raises cholesterol/LDL (low density lipoprotein) in the blood which can increase the chance of an atheroma forming which clogs up the artery.

-if the body contains a higher proportion of unsaturated fats the body will make more HDL which carries harmful fats away to the liver for disposal

what is the structure of phospholipids and what happens in water

-molecule of glycerol

-phosphate head which is a negative ion - hydrophilic (soluble in water)

-two fatty acid side chains - hydrophobi

what elements are present in protein 

always made of these four

hydrogen 

oxygen 

nitrogen 

carbon

often sulfur is present and other elements too

what is the structure of an amino acid

-an amino group (NH₂₎

-carboxyl group (COOH)

-variable group (written as R sometimes)

show the reaction of two amino acids

-condensation reaction between amino acids.

-the carboxyl group of one reacts with the amino group of another

-molecule of water is lost and a peptide bond is formed

what is the definition of polypeptide and protein

polypeptide: 4-50 amino acids joined together

protein: over 50 amino acids joined together

describe the primary structure of a protein and state what bonds are present 

-linear sequence of amino acids 

-determined by the DNA sequence of one strand of the DNA molecule

-bonds: peptide bonds

describe the secondary structure of a protein and state what bonds are present 

-folding of the primary structure into a 3D shape held together by hydrogen bonds

-alpha helix or beta pleated sheet

-bonds: hydrogen and peptide

describe the tertiary structure of a protein and state what bonds are present 

-formed by the bending and twisting of the polypeptide helix into a compact 3D shape 

-bonds: hydrogen bonds, ionic bonds, disulphide bridges and hydrophobic interaction

hydrogen bonds: where there are small differences in charge

ionic: between ionised R groups

disulphide bridges: between cysteine groups (contains -SH) of amino acids (type of covalent bond S-S)

hydrophobic interactions: the R group can either be hydrophobic or hydrophilic 

describe the quaternary structure of a protein and state what bonds are present 

-combination of two or more polypepetide chains in tertiary form

-haemoglobin is an example of protein with a Quaternary structure and it has 4 polypeptide chains

bonds: hydrorgen, ionic, hydrophobic interactions and sometimes disulphide bridges

what is an inorganic ion

ion that does not contain carbon

what is macronutrients and micronutrients

macronutrients: needed in small amounts like zinc

micronutrients: needed in minute amounts

what are the inorganic ions we need to know 

magnesium

iron

calcium

phosphate

what is the role of magnesium

constituent of chlorophyll and so needed for photosynthesis

without it leaves appear yellow

what is the role of iron ions

constituent of haemoglobin so is involved in transport of oxygen

diet deficient in iron can lead to anaemia

what is the role of calcium ions

structural component of bones and teeth (phosphate also required)

what is the role of phosphate ions 

needed for making nucleotides including ATP 

a constituent part of phospholipids in cell membranes

why is water said to be dipolar

has a slightly positively charged end (hydrogen) and a slightly negatively charged end (oxygen) but has no overall charge

why is water able to dissolve sodium chloride

-dipolar (positive and negative)

-attracts polar molecules

-opposites attract

-oxygen will face sodium and hydrogen will face chlorine

what are all the properties of water and explain each of its biological importance

solvent: involved in many biochemical reaction (hydrolysis and condensation) and allows polar molecules to dissolve and acts as a transport medium

high specific heat capacity: large fluctuations in temp are prevented - aquatic environments

high latent heat of vaporisation: large amount of heat needed to vaporise water so often used as cooling mechanism (sweating in mammals)

metabolite: involved in many biochemical reaction (hydrolysis, condensation and reactant in photosynthesis)

cohesion: water molecules attract each other and form hydrogen bonds between themselves - allows water to be drawn up xylem vessels of trees and creates surface tension allowing insects like pond skater to be supported 

high density: ice floats and can acts as insulator preventing water underneath from freezing

transparent: light passes through for photosynthesis