Topic 1 - Biological Molecules Flashcards
Why is Water described as a Polar Molecule
It has a +ve H group, and a -ve O group
What type of bonds are formed between different water molecules
Hydrogen Bonds
What are the 3 main elements that form Carbohydrates
Carbon, hydrogen and Oxygen
What is the General formula for all Carbohydrates
Cx(H2O)y
What is the simplest carbohydrate, and how is it defined
Monosaccharides, single sugars
What is the General formula for Monosaccharides
(CH2O)n
How does the formula of Monosaccharides vary
The N changes
What is the joining of 2 Monosaccharides called, and what reaction takes place
Disaccharides, condensation reaction
What is the definition of a condensation reaction
A chemical reaction in which 2 molecules are joined together and 1 water molecule is released
What are many Monosaccharides joined by condensation reactions called
Polysaccharides
How do you release hexoses sugars from Disaccharides and Polysaccharides
Hydrolysis
Give 2 Pentose Monosaccharides and 3 Hexose Monosaccharides
Pentose - Ribose and Deoxyribose
Hexose - a-glucose, b-glucose and fructose
Why is the Carbon 1,4 and 6 positions indicated on glucose diagrams
It is at these positions that different glucose molecules bond together
What is the difference between A-glucose and B-glucose
The -H and -OH group at Carbon 1 are reversed
Give 2 examples of Disaccharides and their products when Hydrolysed
Sucrose - A-glucose and Fructose
Maltose - 2 A-glucose
What is the function of Sucrose
How carbohydrates are transported in plants
What is Maltose
The product of starch digestion
What are the bonds formed between different monomers when joined by condensation reactions
Glycosidic Bonds
What is a Polymer
Many Molecules bonded together by Glycosidic bonds
Give 4 examples of Polymers
Amylose
Amylopectin
Glycogen
Cellulose
For Amylose, give the Monomer, Glycosidic Bonds, Shape of Polymer, Location in the Cell, and the Function
Monomer - A-glucose Glycosidic Bonds - a-1,4 Shape - unbranched, helical molecule Location - starch grains in living plant cells Function - Store of glucose
For Amylopectin, give the Monomer, Glycosidic Bonds, Shape of Polymer, Location in the Cell, and the Function
Monomer - A-glucose
Glycosidic Bonds - a-1,4 and a-1,6
Shape - Branched every 24-30 glucose units, helical molecule
Location - starch grains in living plant cells
Function - Store of glucose
For Glycogen, give the Monomer, Glycosidic Bonds, Shape of Polymer, Location in the Cell, and the Function
Monomer - A-glucose
Glycosidic Bonds - a-1,4 and a-1,6
Shape - branched every 8-12 glucose units, helical molecule
Location - Granules in liver and muscle cells of mammals
Function - Store of glucose
For Cellulose, give the Monomer, Glycosidic Bonds, Shape of Polymer, Location in the Cell, and the Function
Monomer - B-glucose
Glycosidic Bonds - b-1,4
Shape - Straight Chains cross-linked to parallel molecules
Location - Cell Wall of plant cells
Function - Structural support for plant cell
How are Amylose, Amylopectin and Glycogen adapted to being a storage molecule
Many glucose molecules can be stored in a cell
They are readily hydrolysed to release glucose molecules
They are insoluble and so cannot move out of cells
They do not affect the water potential of a cell
How are adjacent Cellulose molecules linked, and what does this produce
Hydrogen Bonds, microfibrils
What are lipids composed of
Carbon, hydrogen and a few oxygen atoms
What is the main difference between Lipids and Polysaccharides
Lipids are macromolecules, polysaccharides are polymers
List 4 examples of Lipids
Triglycerides, phospholipids, steroids and waxes
What is the main constituent of triglycerides and phospholipids
Fatty acids
How can fatty acids vary
The length of the hydrocarbon tail
Whether the hydrocarbon chain contains double bonds
What is the difference between unsaturated and saturated fatty acids
Unsaturated fatty acids have double bonds, saturated fatty acids have single bonds
What do Triglycerides consist of
A glycerol molecule with 3 fatty acids bonded by condensation reactions
What bond are formed between the fatty acids and glycerol molecule in Triglycerides
Ester bonds
How are constituent molecules of a triglyceride released
Hydrolysis reactions
How do triglycerides with unsaturated and saturated hydrocarbon tails differ
Unsaturated hydrocarbon tails tend to be liquid at room temperature, whereas saturated hydrocarbon tails tend to be solid
What is the function of triglycerides
They represent energy storage
Why are triglycerides better at their function than carbohydrates
They release more energy
What are some other things that Fats provide
Thermal insulating layer in mammals
Buoyancy in marine animals
A cushioning layer
Water when respiring
What is the difference between a Phospholipid and a tryglyceride
One of the fatty acid groups is replaced with a phosphate group
Out of the 2 ends of a Phospholipid, which ends are Hydrophobic and Hydrophilic
Hydrophobic - The Hydrocarbon tails
Hydrophilic - Glycerol - Phosphate head
What does the Phospholipid bilayer represent
The basis of membrane structure in cells
What is the steroid cholesterol made of
A hydrocarbon chain with 4 Carbon-based rings
Where is Cholesterol found, and what is it used for
Cell membranes, and a number of steroid hormones are synthesised from cholesterol
What are all proteins made up of (elements)
Carbon, hydrogen, oxygen, nitrogen and usually sulfur
What are proteins made up of (structurally)
Chains of amino acids
What do amino acids consist of
A carbon atom with 4 groups: An amino group A carboxyl group A hydrogen atom An R-group (residue)
How do amino acids differ
The R-group
How do R-groups differ
Some carry a charge
Some are hydrophobic
Some contain sulfur
Some are involved in hydrogen bonding
How do Amino acids join, and what is the bond called
Condensation reactions, covalent peptide bond
What do you call 2 amino acids bonded together
A dipeptide
What do you called many amino acids bonded together
A polypeptide
What is the primary structure of a Polypeptide
A sequence of amino acids in a chain
What 2 types of structure make up a secondary structure of a protein, and and what are they
A-helix and b-pleated sheets, they are held in place by hydrogen bonds between peptide links in adjacent parts of the chain
What type of proteins have a tertiary structure
Globular
How does a protein gain it’s 3D shape
The polypeptide folds over on itself in a precise way
What type of proteins have a Quaternary structure
Proteins that consist of two or more polypeptide chains bonded together
Give an example of a Globular and Fibrous protein
Globular - Haemoglobin
Fibrous - Collagen
What does Haemoglobin consist of, and what does each of these contain
4 polypeptides : 2 a-chains and 2 b-chains
They each contain an iron-containing Haemoglobin group
What does Collagen consist of
3 similar polypeptides coiled round each other and held together by hydrogen bonds
What do Collagen molecules bonded together form
Strong fibres found in the skin, tendons and ligaments
What is the difference between a Conjugated protein and a Prosthetic group
A conjugated protein has a non-protein part attached, which is called the prosthetic group
Give the prosthetic group and location of Glycoproteins
Prosthetic Group - Carbohydrates
Location - Mucin, cell surface membrane
Give the prosthetic group and location of Lipoprotein
Prosthetic Group - Lipid
Location - Membrane Structure
Give the prosthetic group and location of Nucleoprotein
Prosthetic Group - Nucleic Acid
Location - Chromosome Structure, ribosome structure
Give the prosthetic group and location of Haemoglobin
Prosthetic Group - Haem
Location - Red Blood Cells
What is a prion
A misfolded protein that cause diseases
How does Prions affect mammals
The brain tissue becomes spongy with holes where there were once groups of neurones
Give examples of Prions
Transmissible Spongiform Encephalopathies (TSE)
Scrapie - sheep
Bovine spongiform encephalopathy (BSE) -cattle
Creutzfeldt-Jacob Disease (CJD) - humans
What do Prions do
They replace the normal, cell-surface glycoproteins with a structurally altered prion form.
What structure of a protein is affected by Prions
The secondary structure (particularly a-helixes)
Give 3 ways in which a Prion can be spread
Transmission through consumption of infected foods
Inheritance of a gene mutation
Sporadically
Give examples of 2 nucleic acids
DNA
RNA
What is the function of DNA and RNA
DNA carries genetic code
RNA assist the functioning of DNA
What is a Nucleotide
The subunits of nucleic acids
What does each Nucleotide consist of
A pentose sugar
A nitrogenous base
A phosphate group
How does the Nitrogenous bases of RNA and DNA differ
In DNA you have Adenine, Guanine Cytosine and Thymine
In RNA you have Adenine, Guanine, Cytosine and Uracil
How do Nucleotides join, and what is the bond formed
Condensation reactions, and are joined by Phosphodiester bonds
What does a DNA molecule consist of
Two anti-parallel strands with complementary bases pairings opposite each other joined by hydrogen bonds
What is the complementary base pairings in DNA and RNA
DNA - A-T, C-G
RNA - There isn’t one, and it is only 1 strand
What structure forms from many nucleotides bonded together
A double helix
How does RNA differ from DNA (structurally)
RNA is a single stranded molecule that is a lot shorter than DNA
What is the DNA replication mechanism called
Semi-conservative mechanism
How does DNA replication work
- DNA helicase breaks the hydrogen bonds between base pairings
- The enzyme DNA polymerase moves along each strand
- DNA polymerase catalysts the joining of the free base pairings with a new strand, according to the base paring rule
- The process of unzipping and joining continues along the whole strand
Why is the DNA replication called Semi-conservative
The new DNA molecule has 1 old strand and 1 new strand
What is the experiment for Semi-Conservative replication called
Meselson and Stahl experiment
In the DNA replication experiment, what is the evidence for Semi-Conservative replication
At Generation 0, there is all ‘heavy’ DNA
At Generation 1, there is all ‘intermediate’ DNA
At Generation 2, there is 50% ‘intermediate’ DNA, and 50% ‘light’ DNA
