Biological Molecules Flashcards
Fundamentals
What is a biological molecule?
An organic molecule produced by cells
What are some examples of biological molecules?
Carbohydrates
Lipids
Amino acids
Nucleic acids
What is an organic molecule?
Molecules that contain carbon bound to hydrogen
How do many organic molecules exist?
As monomers and polymers
Define a polymer
Many monomers in a set repeating sub-unit, forming a backbone
How are polymers formed?
When many polymers join via a condensation reaction forming a chemical (covalent) bond, whilst expelling a molecule of water each time
What is a monomer?
A small molecule, that when in a repeating sub-unit can form a polymer via condensation reactions
True or False:
All the monomers in a polymer are identical
False- allows for different structures and codes, e.g. DNA and Proteins
What is a backbone?
The repeating sub-unit that monomers form
What does R stand for?
Variable/Radical/Rest of molecule
How are polymers reverted to monomers?
Hydrolysis reactions: a molecule of water is inserted into each bond as to break the bond, and revert the polymer into the monomers
What are the two main components of many lipids?
Glycerol and fatty acids
What is the formula of glycerol?
C3H8O3
What is the formula of fatty acids (saturated)?
COOH(CH2)nCH3
How do fatty acids join to glycerol, break from glycerol and how many molecules of water are produced?
Condensation reaction
Hydrolysis reaction
3 molecules of water
What does the fatty acid carbon chain start with?
A carboxyl (-COOH) group
How do fatty acids have varying properties?
By having varying carbon chain lengths from 12-18 carbons to 10-30, and leafing to different structures
What do complex saturated/unsaturated fatty acids have?
Sidechains such as whole molecules or oxygen
How do glycerol-based lipids exist and what is their main function?
Phospholipids (with phosphate group): Main component of cell-membrane, fluid-mosaic model
Triglycerides: Storage in adipose (body fat) tissue, insulin
Why are phospholipid heads hydrophilic?
The phosphate group allows for polarity so the water molecules will interact with the head of the phospholipid
Why are phospholipid tails hydrophobic?
There is no polarity for the water molecules to interact with, so the fatty acids will repel the molecules
State what an amphipathic molecule is
When the molecule contains both polar and non-polar regions, thus allowing molecules (like H2O) to attach and interact with them
What are the health benefits of unsaturated fatty acids being more fluid like?
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
What is an eicosanoid?
A form of fatty acid used as a signaling molecule
What is a steroid?
A lipid consisting of four fused carbon rings, with a side chain
Mostly associated with hormones like testosterone and oestrogen
How are sterols formed?
If a steroid has a hydroxyl (-OH) group they become an alcohol and so a sterol e.g. cholesterol
What are the functions of sterols and steroids?
Sterol: Regulates fluidity
Steroid: Growth hormones
What are carbohydrates?
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
What are examples of simple sugars?
Monosaccharides: glucose, fructose, galactose
Disaccharides: maltose, sucrose, lactose
What are examples of complex sugars?
Polysaccharides: starch, cellulose, glycogen
How are complex sugars formed?
Condensation reactions of many simple sugars
What are some uses of carbohydrates?
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
What formula do most but not all dietary monosaccharides have?
C6H12O6
How are the sugars named?
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
What do DNA and RNA nucleotides consist of?
A phosphate group, a pentose sugar and a nitrogenous base
What are the 5 possible nitrogenous bases
Adenine
Guanine
Cytosine
Thymine (DNA only)
Uracil (RNA only)
What are the two main types of nitrogenous bases?
Purine: Two C-N rings
Pyrimidine: One C-N ring
Which bases are purines and which bases are pyrimidines?
Adenine and Guanine= purines (Adenosine and Guanosine nucleotides)
Cytosine, Thymine and Uracil= Pyrimidines (Cytidine, Thymidine and Uridine nucleotides)
What is are examples of polymers of nucleotides (polynucleotides)?
Chromosomes/Chromatin
mRNA strands
miRNA strands
How can the strands form hydrogen bonds and why?
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
What are amino acids and how many of them are there in standard human proteins?
Monomers of polypeptides
20 variants
What is the structure of an amino acid?
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
What are proteins?
A functional group comprised of polypeptides
Where do polypeptides start and end?
They start at the “N” terminus and end at the “C” terminus
How can you describe the structure of a polypeptide?
Repeating N-C-C backbone with R groups and oxygen and hydrogen atoms attached to it
How can proteins be materials/nutrients?
When they are referred to by the individual chemical materials they are predominantly formed from, amino acids and/or polypeptide chains
How can proteins be individual structures?
When referred to as the functional unit predominately made of that material, e.g., polypeptides
What is the primary structure of a protein?
The sequence of amino acids, held together by covalent (peptide) bonds, only altered by chemical reactions
What is the secondary structure of a protein?
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
What is the tertiary structure of a protein?
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
What is the quaternary structure of the protein?
The number of polypeptide chains or the number of prosthetic groups
What is a prosthetic group?
The non-amino acid component
Why do proteins denature and what are the consequences of this?
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.
