Section2- Biological molecules

What does dipolar mean?

Two charges

Is water dipolar and if so why?

Yes

It has a +ve and -ve charge

What bond holds together water molecules?

Hydrogen bonds

What is cohesion ?

Water molecules being held together

Water+water

What is adhesion?

Water+another molecule

What is high specific heat capacity?

Takes a lot of energy to change temperature

Why is water important?

Reactant- in lots of chemical reactions including hydrolysis

Ice floats- water is less dense when it is solid and forms an insulating layer

Habitat- organisms survive and reproduce in it

Solvent- some substances dissolve in it. Most biological reactions take place in solution (in cytoplasm)

Transports substances- like glucose and oxygen around plants and animals

Temperature control- high specific heat capacity and high latent heat of evaporation

Explain how the temperature of water might affect its ability to hold oxygen

Water is held together by hydrogen bonds

As water cools the distance between water molecules increase

Water can hold more oxygen

How does being a solvent help water molecules?

Being a solvent allows water molecules to attach themselves to other molecules. This allows water to be transported, absorbed and be used in metabolic reactions. Examples of this are water attaching to sodium atoms in blood as a form of transport.

What are the three types of carbohydrates?

Monosaccharides (one)

Disaccharides (two)

Polysaccharides (many)

Describe the structure of a monosaccharide

Carbon backbone made from 3,4,5 or 6 carbon atoms

One C forms a double bond with an oxygen atom

The other carbons in the chain are bonded to one hydrogen atom(H) or one hydroxyl group(-OH)’

Draw a glucose molecule

What type of ring does a glucose have and what makes it classify as one of these?

Pyranase ring

5 carbon ring with an oxygen

What are the three monosaccharides?

Glucose, fructose and galactose

What type of reaction occurs to bind together two glucose molecules?

Condensation reaction

What is removed in a condensation reaction?

Water (H2O)

What bond is formed in a condensation reaction between glucose molecules?

1,4 glycosidic bonds

What is made from a condensation reaction?

Made a bigger molecules

Covalent bond is formed

What are the two types of glucoses?

Alpha and beta

What is isomerism ?

In solution, glucose can take up a number of different shares. Alpha and beta are isomers of each other. They have the same chemical formula but different structural formula. Fructose, glucose and galactose are all isomers

What are disaccharides?

Formed from two monosaccharides joined by a glycosidic bond during a condensation reaction.

What disaccharides do these monosaccharides make?

(Alpha)glucose+(Alpha) glucose =

(Alpha) glucose+(beta) galactose=

(Alpha) glucose+fructose=

Maltose(malt sugar)

Lactose

Sucrose

What is a hydrolysis reaction?

Opposite of condensation

Adding water to break the glycosidic bond to form two monosaccharides j

What type of structure does amylase have?

Coil

What type of shape is amylopectin?

Branching

What shape is Alpha glucose?

Coil shape meaning it is more compact and can fit in more smaller spaces

What type of bond is formed when the bond is branches?

1,6 glycosidic

Is glycogen insoluble or soluble ?

Insoluble- doesn’t affect water potential (osmosis)

Glycogen is a polysaccharide of what type of glucose?

Alpha

What are important features of glycogen?

Stored in the liver and muscles in animals

Metabolically inactive so doesn’t use up energy

Has lots of side branches(higher surface are) excellent for fast release of energy

Branches are shorter than starch which allows for quick release of energy

Compact and good for storage

What type of glucose is cellulose made from?

Beta

What are important features of cellulose?

Long straight unbranched chains of Beta glucose

Hydrogen bonds form between the chains forming strong fibres called micro fibrils

Insoluble

Each alternate glucose molecule flips 180degrees to allow hydrogen bonding of the hydroxyl group

Many chains of microfibrils which gives cellulose its stability and mechanical strength

What are the uses of lipids?

Thermal insulation

Buoyancy

Cell membranes

Protection(around vital organs)

Store of energy(adipose fat tissue)

Electrical insulation(insulate nerve cells)

What two components make up a lipid?

Carboxyl group and fatty acid

What does hydrophilic mean?

Water loving

What is hydrophobic?

Water hating

In a lipid, which part is hydrophilic and which is hydrophobic?

Hydrophilic- carboxyl group

Hydrophobic- fatty acid

What do saturated fats consist of?

Single carbon bonds

Solid fats

Straight compacted structure

Differ at state at 20degrees

What are unsaturated fats like?

Oils

Double carbon bond

Monounsaturated- has one c=c bond

Polyunsaturated- has more than one c=c bond

Kinked by c=c

What are phospholipids and triglycerides examples of?

Macromolecule

What two components make up a triglyceride?

Glycerol and fatty acid

What reaction happens in triglycerides?

Condensation

What bond is formed in a triglyceride?

Ester linkage/bond

Is a triglyceride insoluble or soluble In water?

Insoluble

Due to hydrophobic tail

What are the functions of triglycerides?

Storage of energy( almost twice as much energy is released compared to carbohydrates as hydrogen atom proportion is higher

Acts as thermal insulator

What makes a phospholipid different to a triglyceride?

One of the fatty acids of the triglyceride is substituted by a phosphate group

What charge does the phosphate group have in water and how does this compare to fatty acids in water?

A negative charge (attracting the water)

Fatty acids tail are non-polar and repelled by water

Does the heads or tails need to be unsaturated?

Tails

What are the roles of phospholipids?

Cell membranes(also membranes of organelles)

Forms a bilayer with extracellular fluid and cytoplasm

Double bonds in fatty acid tails will increase the fluidity which is beneficial for animals in cold environments

Draw cholesterol

What are some of the features of cholesterol?

Made from four carbon rings with a hydrocarbon tail

The ring has a polar hydroxyl (OH) group

Fits in-between phospholipids and regulates the fluidity of the cell surface membrane

They bind to the hydrophilic tails causing them to pack more closely together=more rigid

What are proteins made from?

Amino acids

What groups can be found in a protein?

Amine/amino group(-NH2)

Carboxyl group(-COOH)

R group- variable region(1of20)

How do we obtain essential and non essential amino acids?

Essential- nutrition and diet

Non-essential - body makes them

What does amphoteric mean?

The amino acid can act as both an acid and a base

How can the amino group act as a base and then the Carboxyl group as an acid?

Amino group can accept a proton (+H) and act as a base

Carboxyl group can donate a proton and act as an acid

What reaction fuses two amino acids together?

Condensation

What bond is formed between two amino acids?

Peptide bond

What reaction can separate two amino acids?

Hydrolysis

What are the four structures?

Primary

Secondary

Tertiary

Quaternary

What is the primary structure?

Order, number and sequence of amino acids

What is the secondary structure?

Either Alpha helix or beta pleated sheets which contain hydrogen bonds

What is the tertiary structure?

Combination of secondary structure

What is quaternary structure?

Arises from a combination of:

• A number of different polypeptide chains

• Non-protein group (prosthetic group)

What are the two forms of tertiary and quaternary structures?

Globular proteins and fibrous proteins

What are globular proteins like?

• roughly spherical in shape

• Soluble in water due to position of hydrophilic/phobic R-groups

What are fibrous proteins like?

• repetitive sequence of amino acids

• Insoluble in water

• Structural

What are the three examples of globular protein and give some info on them

Haemoglobin

• Made up of two alpha globing and two globin polypeptide chains

• Haem group called prosthetic group

• Conjugated protein

Insulin

• Made of two polypeptide chains

• Chains joined by disulphide bonds

• Hydrophilic r-groups are on the outside which makes it soluble

Amylase

• Catalyses the break down of starch to maltose

• Single chain of amino acid with both alpha helix and beta pleated sheet

What are the three examples of fibrous proteins and what are they like?

Collagen

• Repeating sequences of amino acids

• Each 3rd amino acid is glycine resulting in a left-handed alpha helix shape

• Made of 3 polypeptide chains

• Hydrogen bonds hold them together

Keratin

• Rich in cysteine so lots of disulfide bridges between polypeptide chains

• Hydrogen bonds make it very strong

• Provides mechanical protection and is also waterproof

Elastin

• Cross-linking ans coiling make the structure of elastin strong and flexible

• When subjected to stretching the proteins elongate but remain attached to each other