2.2 - Biological molecules

A student mixed an unknown substance with water and ethanol. A white suspension formed in the tube. What is present? [1]

Lipids are present

Buoyancy of triglycerides

Fat is less dense than water, it is used by aquatic animals to help them stay aflot

Chloroplast

It is a steroid alcohol - a type of lipid which is not made from glycerol or fatty acids

Cohesion in water

water molecules stick together as a result of hydrogen bonding

Density of water

It provides an ideal habitat for living things.

Describe amylose

It contains alpha glucose, with 1-4 glycosidic bonds and all monomers are in the same orientation.

Describe and explain how the structure and properties of different carbohydrate and lipid molecules suit them to their role as energy storage molecules in plants and animals. [6]

q19

Describe how an enzyme, such as pepsin, breaks down a substrate.

substrate shape is complementary to active site, it then fits into the active site. It is an induced fit and forms enzyme-substrate complex, then products leaves

Describe how to do the emulsion test for lipids and how a positive result would be identified.

mix with / add , ethanol / alcohol , and water ;
(goes) cloudy

Describe the formation of a hydrogen bond between two molecules of water and explain why water can form these bonds.

between O and H between electropositive H and electronegative O as it is polar

Describe the formation of a hydrogen bond between two molecules of water and explain why water can form these bonds. [3]

1.between O and H (of adjacent molecules);
2. between, electropositive / δ+ / delta+ (H), and, electronegative / δ- / delta- (O);
3.water molecule, is polar / has charge separation;

Describe the primary level of protein structure.

peptide bonds and the sequence of amino acids

Describe the process of adhesion [2]

attraction of water molecules to the impermeable walls of xylem tissue

Describe the role of cholesterol in cell surface membranes in the human body

Cholesterol binds to phospholipid fatty-acid tails/phosphate heads, increasing the packing of the membrane, therefore reducing the fluidity of the membrane.

Disulfide links

The strongest of attractions, this is a covalent chemical bond that crosslinks different protein strands together, giving someone's hair the natural tendency to be straight or curly

Draw a condensation reaction

Draw a pentose sugar

Draw a saturated fatty acid

Draw a unsaturated fatty acid

Draw an alpha glucose

Draw an beta glucose

Draw glycerol

Draw glycerol

Draw primary structure of a protein

Draw the formation of a triglyceride

Draw the general structure of an amino acid molecule in the space below.

Draw the molecular structure of an amino acid

They can be broken down in respiration to release energy and generate ATP.

Energy source of triglycerides

Its insoluble in water, they can be stored without affecting the water potential of the cell.

Energy store of triglycerides

hydrophilic head and hydrophobic tails (1) hydrophobic part / tails, repelled / AW, by water head / hydrophilic part, forms H bonds with water

Explain how the structure of phospholipids allows them to form the bilayer of a plasma membrane.

idea that the glycogen deposited is, in long chains / not branched, so not compact (which damages liver cells);

Glycogen storage disease type IV occurs when the liver is unable to catalyse the addition of branches of glucose molecules. People with this disease may develop liver damage over time. Suggest why this disease may result in liver damage.

Water requires a lot of energy to change temperature

High specific heat capacity

The phosphate group has a negative charge making polar, however the fatty acid tails are non-polar and are repelled by water.

How do phospholipids behave in water?

Hydrolyse the ester bonds and then both glycerol and the fatty acids can be broken down completely to carbon dioxide and water. Respiration of a lipid produces more water than respiration of a sugar

How do triglycerides break down for respiration?

2

How many hydrogen atoms for one oxygen atom in a carbohydrate?

Very weak bonds; occurs when a hydrogen atom in one molecule is attracted to the electrostatic atom in another molecule

Hydrogen bonds

water loving

Hydrophilic

Water fearing

Hydrophobic

Adipose tissue is a storage location for lipids in whales acting as a heat insulator.

Insulation of triglycerides

Formed when one or more electrons are transferred from one atom to another

Ionic bonds

starch AND glycogen

Name the carbohydrate molecules used to store energy in plants and animals

peptide bond

Name the covalent bond between two adjacent amino acids in a chain of amino acids.

hydrolysis; water is added

Name the type of reaction involved in breaking this bond and describe what happens in this reaction.

subunits
quaternary

Polypeptides known as alpha (α) and beta (β) _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ form part of the _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ structure of haemoglobin.

Humans have fat around delicate organs to act as a shock absorber.

Protection of triglycerides

primary structure

State the name given to the sequence of amino acids in a protein molecule.

1. 1-4 glycosidic
2. maltose

State the precise name of the covalent bond that forms between the two glucose molecules and the name of the disaccharide that is formed. [2]

(enzymes are) globular, proteins / polypeptide; hydrophilic / water soluble, (R-)groups on outside (of enzyme);

State why the structure of enzyme molecules allows them to be detected in solution using the biuret test.

facilitated diffusion (1) conversion of ornithine into citrulline creates concentration gradients

Suggest the method by which these molecules move into and out of the organelle during the cycle. Give reasons for your choice

protein/polpeptide

Sulfur atoms are required for the synthesis of which type of biological molecule? [1]

The water molecules at the surface ar ehydrogen bonded to the molecules un

Surface tension in water

secondary

The _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ structure of collagen is described as a left-handed helix because of the direction in which the polypeptide twists.

The phospholipid bilayer

A double layer of phospholipids that makes up plasma and organelle membranes.

The secondary structure of a protein is determined by the arrangement of _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ bonds, which stabilise the structure.

hydrogen

The secondary structure of a protein may contain many regions folded in zig-zag patterns known as .....

beta- pleated sheet

Water as a reactant

Foods are broken down into their building blocks by adding water. This would be an example of which characteristic of water?

Water as a solvent

many substances dissolve well in water because their polar molecules bond easily with other polar molecules

What are amino acids?

building blocks of proteins

What are disaccharides?

double sugars

What are ester bonds?

bonds between fatty acids and glycerol

What are fatty acids?

carboxylic acids, typically with a single long chain, although they can be branched

What are lipids?

A group of substances that are soluble in alcohol rather than water.

What are polysaccharides made out of?

Hundreds or thousands of monosaccharide monomers bonded together

What are polysaccharides?

polymers of monosaccharides

What are the 3 main groups of carbohydrates?

monosaccharides, disaccharides, polysaccharides

What are the 3 most important lipids?

triglycerides, phospholipids, steroids

What are the different types of disaccharides?

maltose, sucrose, lactose and cellobiose

What are the different types of polysaccharide?

Amylose, amylopcetin and glycogen

What are the features of monosaccharides?

Sweet, soluble in water and crystalline. They are easily oxidised and so are called reducing sugars

What are the features of phospholipids?

The phosphate head is hydrophilic and the fatty acid tail as hydrophobic

What are the functions of triglycerides?

Energy source
Energy store
Insulation
Buoyancy
Protection

What are the properties of water?

cohesion and surface tension , high specific heat, high heat of vaporization, density, reactant and solvent

What charge is hydrogen?

positive

What charge is oxygen?

negative

What do carbohydrates contain?

carbon, hydrogen, oxygen

What do carbohydrates do?

They act as a source of energy, as structural units and are also part of other molecules such as nucleic acids

What do lipids contain?

carbon, hydrogen, oxygen

What do nucleic acids contain?

carbon, hydrogen, oxygen, nitrogen, phosphorus

What do phospholipids look like in the presence of detergent?

B

What do proteins contain?

carbon, hydrogen, oxygen, nitrogen, sulfur

What do proteins do?

Help build and maintain cells.

What does amylopectin contain?

it contains 1-4 and 1-6 glycosidic bonds between α-glucose monomers

What does it mean if a fatty acid is saturated?

every C atom is bonded to at least two H atoms, max number of H

What does it mean if a fatty acid is unsaturated?

there is at least one double bond between successive C atoms (liquid at room temp)

What does polar mean?

unequal sharing of electrons

What does the carboyxl group ionsies into?

Into H+ and a -COO- group

What elements are in ATP?

C,H,O,N,S

What elements are in cholestrol?

C,H,O

What elements are in insulin?

C,H,O,N,S

What elements are in sucrose?

C,H,O,N

What happens in a condensation reaction in disaccharides?

Two hydroxl groups line up next to each other from which a water molecule is removed leaving an oxygen atom acting as a link between the 2 monosaccaride units

What happens when 2 disaccharide join?

A condensation reaction occurs to form a glycosidic bond

What is a carbohydrate?

compound made up of carbon, hydrogen, and oxygen atoms; major source of energy for the human body

What is a condensation reaction?

A reaction in which two molecules combine to form a larger molecule, producing H2O as a by product

What is a glycosidic bond?

When two monosaccharide rings are bonded using a C-O-C bond

What is a hetropolysaccharide?

A polysaccharide that contains two different kinds of monosaccharide

What is a homopolysaccharide?

A polysaccharide that contains only one kind of monosaccharide

What is a hydrogen bond?

a weak bond between two molecules resulting from an electrostatic attraction between a proton in one molecule and an electronegative atom in the other.

What is a macromolecule?

large molecule

What is a molecular formula for deoxyribose?

C5H10O4

What is a monomer?

A molecule that can be bonded to other identical molecules to form a polymer.