Carbohydrates, Proteins And Fats Flashcards
What 4 key elements are needed to make biological molecules?
Carbon, hydrogen, oxygen and nitrogen
What are covalent bonds?
Strong bonds formed when two atoms share electrons
What are polymers?
Large molecules made up of many repeating smaller molecules monomers, which are joined together by covalent bonds
What is condensation?
A type of chemical reaction in which molecules are joined together when a covalent bond is formed by the elimination of water, this forms a polymer
What is hydrolysis?
A chemical reaction in which a molecule is broken down when a covalent bond is broken by the addition of a water molecule, this forms monomers
Carbohydrates are?
Molecules containing C, H and O
What are the 3 main functions of carbohydrates?
.energy source-glucose
.energy store-starch (plants) and glycogen (animals)
.mechanical support-cellulose
What are the three main types of carbohydrates?
.monosaccharides
.disaccharides
.polysaccharides
What are monosaccharides, disaccharides, and polysaccharides?
-single , simple sugar molecules such as pentode sugars (5-carbon sugars) and heroes sugars (6-carbon sugars)
-molecules made by joining two single sugars together
-polymers made by joining many simple sugars together
Glucose is a …?
Monosaccharide
There are two different types of glucose which are isomers of each other, this means?
They are heroes sugars with the same molecular formula (C6H12O6) but their atoms are arranged differently
The two forms of glucose are called?
Alpha glucose and beta glucose
Hundreds of alpha glucose molecules join to make?
Starch and glycogen (polysaccharides)
Hundreds of beta glucose Join to make?
Cellulose
Explain ABBA
Alpha has the hydroxide below, beta has the hydroxide abve
Disaccharides are made by?
Joining two monosaccharides by condensation
What does
Alpha glucose + alpha glucose =
Alpha glucose + galactose =
Alpha glucose + fructose =
Maltose + water
Lactose + water
Sucrose + water
During condensation of maltose, what happens?
Water is removed by losing OH from c1 of one alpha glucose molecule and H from C4 of the second a glucose molecule, this forms a 1,4 glycosidic bond
What is a function of starch?
It’s an energy store in plants
Starch is a mixture of?
Two polysaccharides called amylose and amylopectin
Compare the functions of starch and glycogen
Starch is an energy store in plants (starch grains in chloroplasts) whereas, glycogen is an energy store in animals(mainly stores as glycogen granules in liver and muscle cells)
Compare how amylose and glycogen are formed
Amylose and glycogen are both formed from hundreds of alpha glucose molecules joined together by 1,4 glycosidic bonds formed by condensation
Compare the structures of amylose and glycogen
Chains of amylose coil into a compact helix shape in which hydrogen bonds between glucose monomers help hold the helix to keep its shape, whereas, glycogen is highly branded, making it even more compact , these branches are made of 1, 6 glycosidic bonds between alpha glucose molecules
Why are starch and glycogen ideal energy stores ?
-they are helical or branched, meaning they are compact
-large molecules, so can’t leave the cell
-insolvable, so don’t affect the water potential of cells where they are stored
Describe the iodine test for starch
Iodine solution is yellow-brown, when added to starch, the iodine molecules get trapped in the amylose coils, producing a blue black colour
What is cellulose?
A structural polysaccharide in plant cell walls, it is insoluble and very strong. It is a polymer of thousands of beta glucose molecules joined together by 1,4 glycosidic bonds formed by condensation
Describe the structure of cellulose
Because of the structural differences between alpha lactose and beta glucose, every second beta glucose molecules is rotated 180 degrees compared to the first
Compare the structure of cellulose with amylose and glycogen
Cellulose molecules are straight, not coiled (like amylose) , and unbranded (unlike glycogen)
Celluloses structure allows molecules to…?
Line up close together forming bundles of microfibrils
Describe the hydrogen bonds in cellulose
Hydrogen bonds form cross-links between cellulose molecules in the microfibrils, these bonds are weak forces of attraction but are collectively strong and in large numbers, give cells rigidity
How are macro-fibrils formed?
Microfibrils are held together by H bonds to form larger bundles called macrofibrils
Proteins are made up of?
One or more chains of polypeptides
What are polypeptides?
Polymers of monomer molecules called amino acids
What do all proteins contain?
C, H, O and N, some contain sulphur
Name some functions of proteins
structural proteins eg components of muscle and bone
-all enzymes are proteins
-many hormones are proteins
-active transport and facilitated diffusion uses membrane proteins
-antibodies are proteins
What are amino acids?
Monomer subunits of polypeptides
What groups does amino acids have?
amino group NH2
-variable group R
-acid group COOH
Describe condensation of amino acids
Two amino acids join by condensation and forms a peptide bond and a dipeptide, further condensation of many amino acids makes a polypeptide
Describe the primary protein structure
Amino acids join together by peptide bonds formed in condensation reactions between the amino group of one amino acid and the acid group of another amino acid. A long polypeptide chain is created , containing s string of amino acids, joined together by peptide bonds
Describe the secondary protein structure
Hydrogen bonds form and hydrogen atoms on one part of the polypeptide chain bond to nitrogen, oxygen or fluorine regions on another part of the polypeptide chain. The long polypeptide chain starts to coil and fold into an alpha helix structure, or a beta sheet structure
Describe the tertiary protein structure
4 different bonds form, more hydrogen bonds, ionic bonds and disulphide bonds (involving sulfur) hydrophobic and hydrophilic. The coiled and folded alpha helical and beta plated structure folds further into a 3D structural shape. Some proteins stop at this structural stage if they only have one polypeptide chain
Describe the quaternary protein structure
Intermolecular and intramolecular bonds form to bind more than 1 polypeptide chain together. If a protein is made up of more than one polypeptide chain, the individual polypeptide chains must bind together to give the final 3D structural shape
Compare the structure of globular protein with fibrous protein
Globular protein rolls up to form complex 3D tertiary ball structures, whereas fibrous proteins form long parallel chain fibres which are cross-linked for strength
Compare how soluble the proteins are
Globular protein is usually solvable in water, due to hydrophilic regions exposed on the surface, where’s fibrous proteins are usually insoluble in water, due to long, large and cross-linked structure
Compare the roles of the proteins
Globular protein usually have metabolic roles, whereas, fibrous proteins usually have structural roles
An example of globular proteins:
the enzymes found in all organisms
-plasma proteins, haemoglobin and antibodies found in blood of mammals
An example of fibrous proteins:
- collagen found in bond and cartilage and connective tissues
-keratin found in fingernails and hair
What type of protein is collagen?
Fibrous
Describe the structure of collagen
two identical polypeptide chains and 1 different polypeptide chain that bundle together to form a triple helices
-tensile strength and rigidity varies depending on the extent of mineralisation
-several collagen molecules can cross-link to form collagen fibres
What roles does collagen have?
A strong protein fibre holds cell together and provides a scaffold for extra cellular matrix
What is the location of collagen?
bones
-cartilage
-tendons
-ligaments
-skin
-muscle
-blood vessels
-teeth
Explain two ways in which collagen is suited for its role
- It is insoluble in tissue fluid so that it does not dissolve
- Fibrils are rigid because of tightly coiled multiple helices which allows strength across tissues because it can form cross-links between collagen fibres
What are lipids made of?
C, H, and O, they are not polymers but some contain subunits joined by condensation
Are lipids soluble?
All lipids are insoluble in water, but dissolve in organic solvents such as ethanol, this forms the basis of emulsion test for lipids
What are the 2 groups of lipids?
Triglycerides and phospholipids
Triglycerides are made of?
1 glycerol molecule and 3 fatty acid molecules
What is glycerol ?
An alcohol molecule with three OH groups
What are fatty acids?
Hydrocarbon chains which end in a carboxylate acid group
Animal fats are?
Triglycerides containing mainly saturated fatty acids (they contain c-c single bonds within the hydrogen carbon chain, meaning they are saturated because no more H atoms could be added to the chain)
Animals fats are what at room temperature?
Solid
Plant oils are?
Triglycerides containing mainly unsaturated fatty acids, these are fatty acids which contain c=c double bonds
Plants oils are what at room temperature?
Liquid matey boy
Describe condensation of triglycerides
Glycerol and fatty acids join by condensation to form ester bonds
Why are triglycerides good energy stores?
- Triglycerides are insoluble in water, so can be stored in cells without affecting a cells water potential (a cell wont take up too much water)
- Triglycerides are a concentrated energy store, because the hydrocarbon tails of fatty acids contain a lot of stores energy, their energy content per gram is 2x higher than carbohydrate
What do steroids and lipids have in common?
They are both insoluble in water (hydrophobic)
What is the most common and simple steroid?
Cholesterol
What are the two types of cholesterol?
High-density lipoprotein and low-density lipoprotein
Describe HDL
Viewed as “good” cholesterol because it doesn’t stay in the bloodstream for long, it goes to the liver where it is safely processed and stored
HDL is 20% cholesterol and 50% protein
Describe LDL
Viewed as ‘bad’ cholesterol because it stays in the bloodstream and may aggregate into plaques which lead to cardiovascular disease
LDL is 50% cholesterol and 25% protein
