2.2 Biological molecules Flashcards
What is a covalent bond?
Two atoms sharing a pair of electrons
What is a condensation reaction?
The addition of two molecules with the removal of water
What is a hydrolysis reaction?
The separation of two molecules by adding water
What is a molecule made up of 2 monomers called?
A dimer
What is a chain of monomers called?
A polymer
What are carbohydrate molecules (C,H and O) monomers and polymers?
- monosaccharides (e.g glucose)
- Polysaccharides (e.g starch)
What are proteins (C,H,O,N and S) monomers and polymers?
- amino acids
- polypeptide and proteins
What are nucleic acids (C,H,O,N and P) monomers and polymers?
- nucleotides
- DNA and RNA
What is a hydrogen bond?
A bond between hydrogen atoms and oxygen, commonly found in water with 2 hydrogens (+) bonded to one oxygen (-) atom. This can become polarised.
What are the properties of water?
- liquid
- density
- solvent
- cohesion and surface tension
- specific heat capacity
Why is liquid a good property of water?
- provides habitat for living things
- major component of tissues in organisms
- reaction medium for chemical reactions
- effective transport medium (e.g blood)
Why is the density of water a good property?
Ice becomes less dense than water when it cools, making it a suitable habitat for animals in the winter, as well as insulating the heat.
Why is being a solvent a good property of water?
- Water molecules are slightly charged meaning they can react with charged molecules
^ 70% of the cytoplasm is water so can react better - ions can be transported while dissolved in water
Why is cohesion and surface tension a good property of water?
- Water can be transported in the vascular bundles in plants
- insects like pond skaters can walk on water
Why is a high specific heat capacity a good property of water?
- provides a stable environment as more energy is required to break H bonds so high SHC, meaning temperature remains the same
What is a monosaccharide?
The simplest carbohydrate which can exist in straight chains or in ring or cyclic forms as a hexose sugar
What is a hexose sugar?
A sugar containing 6 carbon atoms
What is an isomer?
One of two or more compounds that have same atoms but different chemical structure
What are the two glucose isomers?
alpha glucose and beta glucose
What disaccharides do α-glucose + α-glucose form?
maltose
What disaccharides do α-glucose + fructose form?
sucrose
What disaccharides do β-glucose + α-glucose form?
lactose
What disaccharides do β-glucose + β-glucose form?
cellobiose
What bond is formed between two monosaccharides?
a glycosidic bond
Which molecule is on top in an α-glucose?
The Hydrogen
Which molecule is on top in a β-glucose?
The OH group
How many carbons and oxygens does ribose have?
5 carbons
5 oxygens
C5H10O5
How many carbons and oxygens does deoxyribose have?
5 carbons
4 oxygens
C5H10O4
What type of sugar are alpha and beta glucose?
Hexose
What type of sugar are ribose and deoxyribose?
Pentose
What is α-glucose role in the body?
Energy source
Component of starch and glycogen
What is β-glucose role in the body?
Energy source
Component of cellulose for structural support in plant cell walls
What is ribose role in the body?
RNA, ATP and NAD
What is deoxyribose role in the body?
DNA
Why are polysaccharides good energy stores?
- glycogen (animals) and starch (plants) are compact
- glycogen is held in a chain that can be easily hydrolysed and ‘snipped off’
- branched chains can be hydrolysed easier, amylase enzyme for 1-4 bonds and glucosidase for 1-6 bonds
- less soluble than monosaccharides, if soluble excess water would diffuse in from the water potential
What is the structure of amylose (in plants)?
glycosidic bonds 1-4, hydrogen bonds hold a spiral shape with the hydroxyl groups on the inside making it less soluble
What is the structure of amylopectin (in plants)?
glycosidic bonds 1-4 and 1-6, spiral shape held together by hydrogen bonds
What is the structure of glycogen (in animals)?
glycosidic bonds 1-4 and 1-6, chains small so don’t coil but branches make it more compact.
What is cellulose ?
an insoluble fibrous homopolysaccharide made from up to 15000 β-glucose molecules found in the cell walls of plants (structural polysaccharide)
What is a microfibril?
A group of 60-70 chains of cellulose
What is a macrofibril?
400 microfibrils
Why is cellulose good for plant cell walls?
- macrofibrils and microfibrils are strong
- glycosidic bonds are strong so cannot be digested
- space between microfibrils for water and ions to pass through (fully permeable)
- cannot burst when turgid
- macrofibril can be reinforced with waxes like cutin and suberin for waterproof
What makes up bacterial cell walls?
peptidoglycan made from long polysaccharide chains side by side connected by a small peptide chain
What are exoskeletons made out of?
chitin
What are lipids made out of?
large amounts of carbon and hydrogen but little oxygen
Why are lipids insoluble?
They are not charged so cannot attract water molecules
What are the 3 main lipids?
triglycerides, phospholipids and steroids (macromolecules)
What is triglyceride structure (overall)?
glycerol and fatty acids
What is glycerol?
An alcohol with 3 carbons and 3 OH groups
What are fatty acids?
A carboxyl group (-COOH) on one end with a hydrocarbon tail
What does saturated mean?
no carbon = carbon bonds
What is the structure of a triglyceride?
One glycerol bonded to 3 fatty acids (because there are 3 OH groups)
What is an ester bond?
The bond formed from the condensation reaction of glycerol and fatty acids, carbon bonded with a single bond oxygen and a double bond oxygen
What are the functions of triglycerides?
Energy source (respiration)
Energy store (insoluble)
Insulation (adipose tissue)
Buoyancy (fat < water density)
Protection (of organs)
What is the structure of a phospholipid?
A glycerol with 2 fatty acids (with even carbon atoms) and a phosphate group
What is a micelle phospholipid structure?
A sphere shape with the hydrophobic fatty acid tails on the inside and the hydrophilic phosphate on the outside
What is a phospholipid bilayer?
2 rows of hydrophobic fatty acid tails facing inwards and hydrophilic phosphate heads facing outwards
What is the function of a phospholipid bilayer?
20-80% of all plant and animal membranes are made from this structure
Why is phospholipid bilayer a good membrane?
- individual phospholipids can move but only in a way that the tails will not touch water, providing stability
- Selectively permeable that only allows small and non-polar molecules to move through
What is cholesterols structure?
4 carbon-based rings or isoprene units
What is the function of cholesterol?
The hydrophobic molecule can sit in the hydrophobic tails of the phospholipid bilayer and regulate the fluidity of the membrane, not too fluid or too stiff
What hormones contain cholesterol?
testosterone, oestrogen and vitamin D
What are proteins?
large polymers made up of long chains of amino acids
What is the function of proteins?
- Structural components in animals, e.g muscles
- Tendency to adopt specific shapes being important in enzymes, antibodies and some hormones
- Used in membranes
What is the structure of amino acids?
amino group (-NH2) at one end and carboxyl (-COOH) group at the other, with an R group and a carbon and hydrogen molecules
What bond is formed between amino acids?
peptide bonds (covalent)
What are 2 amino acids joined together called?
a dipeptide
What is a chain of amino acids called?
a polypeptide
What structure is the sequence of amino acids in a chain called?
Primary structure
What structure is a helix made up of the chain of amino acids called?
Secondary structure
What structure is the shape made from the coils folded called?
tertiary structure
What structure is the protein molecule made from many polypeptide chains?
Quaternary structure
What bonds hold amino acid chain shapes?
Hydrogen bonds, ionic bonds, disulfide bonds (amino acid cysteine) and hydrophobic and hydrophilic interactions
What is a fibrous protein?
Regular repetitive sequences of amino acids and are usually insoluble in water e.g collagen, elastin and keratin
What is a globular protein?
Specifically shapes (spherical) protein that have hydrophobic R groups on the inside making the protein soluble e.g enzymes, hormones and haemoglobin
for globular and fibrous proteins look at the sheet or pages 70-71 in the textbook
i literally cannot be asked to copy down these two pages bc we already did them, sorry :(
What is the quantitative test for reducing sugars?
Using the benedict’s solution and a colorimeter (reed filter) to create a calibration curve
how’s ur day going :)
daily affirmation: you are awesome
What is the structure and function of collagen?
- Three chains of amino acids wound in a triple helix
-artery, tendons, bones and connective tissue
What is the structure and function of keratin?
- Matrix structure with a superhelical twist, rich in cysteine and disulfide bridges between its polypeptide chains, and also has hydrogen bonds
- Found in fingernails, hair, horns, hoofs, claws, fur and feathers.
- Impermeable barrier and strong protection
- prevents entry of water-borne pollutants
What is the structure and function of elastin?
- Short repeated sequences of 3 to 9 amino acids
- Cross linking and coiling structure
- Skin stretches around bones and muscles
- lungs to inflate and deflate
- blood vessels stretch and recoil, helping maintain the pressure
What is the structure and function of haemoglobin?
Quaternary structure of 4 polypeptide chains; 2 alpha and 2 beta globin
Haem group on the outside made up of an iorn ion
Carries ocygen from the lungs to tissue by attaching to the 4 haem groups
