Biological Molecules

Question 1

What is a biological molecule?

Answer 1

An organic molecule produced by cells

Question 2

What are some examples of biological molecules?

Answer 2

Carbohydrates
Lipids
Amino acids
Nucleic acids

Question 3

What is an organic molecule?

Answer 3

Molecules that contain carbon bound to hydrogen

Question 4

How do many organic molecules exist?

Answer 4

As monomers and polymers

Question 5

Define a polymer

Answer 5

Many monomers in a set repeating sub-unit, forming a backbone

Question 6

How are polymers formed?

Answer 6

When many polymers join via a condensation reaction forming a chemical (covalent) bond, whilst expelling a molecule of water each time

Question 7

What is a monomer?

Answer 7

A small molecule, that when in a repeating sub-unit can form a polymer via condensation reactions

Question 8

True or False:
All the monomers in a polymer are identical

Answer 8

False- allows for different structures and codes, e.g. DNA and Proteins

Question 9

What is a backbone?

Answer 9

The repeating sub-unit that monomers form

Question 10

What does R stand for?

Answer 10

Variable/Radical/Rest of molecule

Question 11

How are polymers reverted to monomers?

Answer 11

Hydrolysis reactions: a molecule of water is inserted into each bond as to break the bond, and revert the polymer into the monomers

Question 12

What are the two main components of many lipids?

Answer 12

Glycerol and fatty acids

Question 13

What is the formula of glycerol?

Answer 13

C3H8O3

Question 14

What is the formula of fatty acids (saturated)?

Answer 14

COOH(CH2)nCH3

Question 15

How do fatty acids join to glycerol, break from glycerol and how many molecules of water are produced?

Answer 15

Condensation reaction
Hydrolysis reaction
3 molecules of water

Question 16

What does the fatty acid carbon chain start with?

Answer 16

A carboxyl (-COOH) group

Question 17

How do fatty acids have varying properties?

Answer 17

By having varying carbon chain lengths from 12-18 carbons to 10-30, and leafing to different structures

Question 18

What do complex saturated/unsaturated fatty acids have?

Answer 18

Sidechains such as whole molecules or oxygen

Question 19

How do glycerol-based lipids exist and what is their main function?

Answer 19

Phospholipids (with phosphate group): Main component of cell-membrane, fluid-mosaic model
Triglycerides: Storage in adipose (body fat) tissue, insulin

Question 20

Why are phospholipid heads hydrophilic?

Answer 20

The phosphate group allows for polarity so the water molecules will interact with the head of the phospholipid

Question 21

Why are phospholipid tails hydrophobic?

Answer 21

There is no polarity for the water molecules to interact with, so the fatty acids will repel the molecules

Question 22

State what an amphipathic molecule is

Answer 22

When the molecule contains both polar and non-polar regions, thus allowing molecules (like H2O) to attach and interact with them

Question 23

What are the health benefits of unsaturated fatty acids being more fluid like?

Answer 23

Allows the cell membrane to have more fluidity, fluid mosaic model
Lower chance of causing arterial plaque build up than more solid like fats, as the unsaturated fatty acids are pushed along

Question 24

What is an eicosanoid?

Answer 24

A form of fatty acid used as a signaling molecule

Question 25

What is a steroid?

Answer 25

A lipid consisting of four fused carbon rings, with a side chain Mostly associated with hormones like testosterone and oestrogen

Question 26

How are sterols formed?

Answer 26

If a steroid has a hydroxyl (-OH) group they become an alcohol and so a sterol e.g. cholesterol

Question 27

What are the functions of sterols and steroids?

Answer 27

Sterol: Regulates fluidity Steroid: Growth hormones

Question 28

What are carbohydrates?

Answer 28

Molecules that contain only carbon, hydrogen and oxygen atoms Also need multiple OH groups and a C=O bond in the linear monomer; aldehydes and ketones

Question 29

What are examples of simple sugars?

Answer 29

Monosaccharides: glucose, fructose, galactose Disaccharides: maltose, sucrose, lactose

Question 30

What are examples of complex sugars?

Answer 30

Polysaccharides: starch, cellulose, glycogen

Question 31

How are complex sugars formed?

Answer 31

Condensation reactions of many simple sugars

Question 32

What are some uses of carbohydrates?

Answer 32

Release energy for respiration Store glucose as glycogen Form glycoproteins and glycolipids by combining with proteins and lipids, leading to hormones and cell signaling Incorporation into and synthesis of other biological molecules

Question 33

What formula do most but not all dietary monosaccharides have?

Answer 33

C6H12O6

Question 34

How are the sugars named?

Answer 34

Dependent on the number of carbon atoms in the carbon chain, e.g. glucose= C6H12O6 so is a hexose sugar, and can be broken into two triose sugars

Question 35

What do DNA and RNA nucleotides consist of?

Answer 35

A phosphate group, a pentose sugar and a nitrogenous base

Question 36

What are the 5 possible nitrogenous bases

Answer 36

Adenine Guanine Cytosine Thymine (DNA only) Uracil (RNA only)

Question 37

What are the two main types of nitrogenous bases?

Answer 37

Purine: Two C-N rings Pyrimidine: One C-N ring

Question 38

Which bases are purines and which bases are pyrimidines?

Answer 38

Adenine and Guanine= purines (Adenosine and Guanosine nucleotides) Cytosine, Thymine and Uracil= Pyrimidines (Cytidine, Thymidine and Uridine nucleotides)

Question 39

What is are examples of polymers of nucleotides (polynucleotides)?

Answer 39

Chromosomes/Chromatin mRNA strands miRNA strands

Question 40

How can the strands form hydrogen bonds and why?

Answer 40

The strands can link intermolecularly to form double stranded molecules- but need to be between complementary base pairs as to be physically possible A and T/U C and G

Question 41

What are amino acids and how many of them are there in standard human proteins?

Answer 41

Monomers of polypeptides 20 variants

Question 42

What is the structure of an amino acid?

Answer 42

A central carbon atom with a carboxyl terminal on the left, and an amine terminal on the right, with a hydrogen atom below it and an R chain

Question 43

What are proteins?

Answer 43

A functional group comprised of polypeptides

Question 44

Where do polypeptides start and end?

Answer 44

They start at the "N" terminus and end at the "C" terminus

Question 45

How can you describe the structure of a polypeptide?

Answer 45

Repeating N-C-C backbone with R groups and oxygen and hydrogen atoms attached to it

Question 46

How can proteins be materials/nutrients?

Answer 46

When they are referred to by the individual chemical materials they are predominantly formed from, amino acids and/or polypeptide chains

Question 47

How can proteins be individual structures?

Answer 47

When referred to as the functional unit predominately made of that material, e.g., polypeptides

Question 48

What is the primary structure of a protein?

Answer 48

The sequence of amino acids, held together by covalent (peptide) bonds, only altered by chemical reactions

Question 49

What is the secondary structure of a protein?

Answer 49

How the polypeptide folds locally; folding in a specific part of the chain- as they will fold into or onto each other Can fold into alpha helices or beta pleated sheets Held together by hydrogen bonding

Question 50

What is the tertiary structure of a protein?

Answer 50

The 3D shape of the polypeptide, how the entire polypeptide folds up Held together by: Hydrogen bonds, electrostatic forces, hydrophilic/hydrophobic interactions, and covalent bonds (disulphide bridges) as of the R groups Only partially broken by heat as disulphide bridges>H bonds, so stronger than secondary structure

Question 51

What is the quaternary structure of the protein?

Answer 51

The number of polypeptide chains or the number of prosthetic groups

Question 52

What is a prosthetic group?

Answer 52

The non-amino acid component

Question 53

Why do proteins denature and what are the consequences of this?

Answer 53

Proteins are mostly held in a shape by intermolecular forces Attractions and repulsions within the molecule and with the surroundings Heat and pH can break these bonds, causing the folded structure of the protein to unravel (denature) The shape of a protein is often directly related to its function. It can not work when denatured.