Biological Molecules (1) Flashcards
What is a monomer?
Smaller units from which larger molecules are made
What are polymers?
Molecules made from a large number of similar monomers joined together
Examples of monomers?
Monosaccharides, amino acids and nucleotides
What is a condensation reaction?
2 molecules joining together forming a chemical bond; this involves the elimination of a water molecule (as in + H2O after)
What is a hydrolysis reaction?
The breaking of a chemical bond between 2 molecules; involves the use of a water molecule
What atoms are all present in (all) carbohydrates?
Carbon hydrogen and oxygen
What are the 3 carbohydrate groups?
Monosaccharides, disaccharides and polysaccharides
What is a monosaccharides?
Monomers of carbohydrates, mainly used in respiration to provide energy and in growth (during the formation of larger molecules).
Examples of monosaccharides include:
Glucose fructose and galactose, they all share the same formula so are hexoses
What formula do all monosaccharides have?
C6H12O6
Facts about monosaccharides:
Small, soluble molecules
Easy to transport
Sweet tasting
Reducing sugars
What does a reducing sugar mean in terms of tests?
They give a positive (brick red ppt) Benedict’s test result
Alongside glucose, fructose and galactose all being ____ (different structures), glucose also has 2 ____: alpha and beta glucose
Isomers
Structure of the 2 isomers are:
What is a disaccharides?
Double sugars. 2 monosaccharides joined together by a glycosidic bond with the release of water
Examples of disaccharides include:
Maltose lactose and sucrose
How are each of these 3 disaccharides formed?
Maltose - glucose + glucose
Sucrose - glucose + fructose
Lactose - glucose + galactose
How can you hydrolyse a disaccharides?
Heating with acid or by an enzyme
What is a polysaccharides?
Polymers of glucose, they differ in the number and arrangement of the glucose molecules they contain
Examples of polysaccharides include:
Cellulose starch and glycogen
Glycogen and starch are formed by ___ glucose, cellulose from ___ glucose
Alpha, Beta
Facts about polysaccharides:
- do not taste sweet
- relatively insoluble in water
- are non reducing
- function as storage or structural molecules
‘What is’ starch?
The storage carbohydrate found in plants, stored as starch grains in the cytoplasm of plant cells
What is the structure of starch?
Long branches chains of alpha glucose molecules linked by glycosidic bonds
Why is starch ideal for its function?
-large, can’t cross cell surface membrane
-insoluble so osmotically inactive
-helical shape for compact store
-branched so glucose easily released for respiration
‘What is’ glycogen?
The storage carbohydrate found in animal cells cytoplasm; in mammals it’s stored in large amounts in liver and muscle tissue
What is the structure of glycogen?
Condensation of alpha glucose, similar to starch but more branches meaning it can be hydrolysed more rapidly
Facts about glycogen:
-insoluble so osmotically inactive
‘What is’ cellulose?
Found in cell wall of plants; providing rigidity and shape to the cell, preventing cell bursting.
What is the structure of cellulose?
Polymer of beta glucose molecules joined by glycosidic bonds, producing long straight chains. In every other beta glucose the monomer is inverted
What is microfibril?
When cellulose hydroxyl groups form H bonds with other adjacent chains OH groups producing a 3D structure
What does microfibril do?
Provide strength
What are the 2 types of lipids?
Triglycerides and phospholipids
What elements do lipids contain?
Carbon hydrogen and oxygen
Lipids are insoluble in ___ but are soluble in a range of ____ like ___
Water, organic solvents, alcohol
What is a triglyceride?
Have 3 fatty acids joined to one glycerol - loses 3 water molecules in the process forming 3 ester bonds.
What is a phospholipid?
2 fatty acids and 1 phosphate group joined to 1 glycerol
What is the general formula of a fatty acid?
R-COOH (carboxylic acid group)
What is the difference between a saturated and unsaturated fatty acid?
Saturated has no double carbon-carbon bonds
Facts about triglycerides:
- possess a high proportion of carbon hydrogen bonds so they release twice as much energy as carbs during aerobic respiration
- high ratio of H to O atoms releasing water when respired
- non polar thus insoluble in water so ideal for storage
- present in waxy cuticle to reduce water loss
What is the structure of a phospholipid?
polar hydrophilic phosphate head and 2 non polar hydrophobic fatty acid tails
What is a phospholipid bilayer?
When the hydrophilic heads face out from the cell to the source of water/outside of the cell and the hydrophobic tails face in towards the cell away from the source of water, forming a bilayer
What is a protein?
Polymer of amino acids. Containing carbon hydrogen oxygen nitrogen and sometimes Sulfur.
What is the general structure of a AA?
Facts about AA:
- all AAs have an amine group (NH2) and a carboxylic acid group but differ in the carbon group (R)
- they are joined together by peptide bonds (CONH)
- 2 AAs joined together is called a dipeptide
What is a polypeptide?
Multiple amino acids joined together in a chain
What are the 4 structures of proteins?
Primary, Secondary, tertiary and quaternary
What is primary structure?
Refers to the sequence of amino acids in the polypeptide chains, this sequence determines the specific shape of the protein
What is the secondary structure?
This represents the folding or cooking of the polypeptide chain as a result of H bonding between amino acids
What are examples of these Secondary structures?
Alpha helix and beta pleated sheet
What is the tertiary structure?
Further folding and coiling of the secondary structure due to hydrogen ionic and disulfide bonds forming between R groups
What does the tertiary structure do?
Determines the (active site and) specific function of protein
What is the quartenary structure?
When a protein consists of more than one polypeptide chain
Globular proteins are…
Soluble and consist of a highly folded and coiled polypeptide chain to produce a Compact complex tertiary structure.
This includes enzymes and antibodies
What is denaturation?
An alteration in the tertiary structure of a protein; often irreversible and causes a loss of function
How can denaturation occur?
High temperatures
Extreme changes in pH
What is an enzyme?
A biological catalyst that regulate biological processes in living organisms
What is enzyme specificity?
A feature of the unique tertiary structure of an enzyme that determines the shape of the active site and therefore it’s complementary substrate
What are the 2 models related to enzyme specificity?
Lock and key
Induced fit
What are all the factors that affect the rate of enzyme reactions?
Effect of substrate conc
Effect of enzyme conc
Effect of temperature
Effect of pH
What are the 2 enzyme inhibitors and what do they do?
Competitive - ‘fight’ for the active site and take it up not allowing the similar structure substrate to get in
Non-comp - attaches away from the active site and causes the enzyme to change in tertiary structure
What is DNA?
Deoxyribonucleic acid, a polymers of nucleotides
What is the structure of DNA?
One Pentose sugar deoxyribose, a phosphate group and an organic base
How are nucleotides joined together?
Phosphodiester bonds
What bonds are bases joined by?
Hydrogen
What are the structures of DNA and their function?
What are the differences between DNA and RNA?
- pentose is ribose in RNA not deoxyribose
- organic base Uracil replaces Thymine in RNA
- mRNA And tRNA are single stranded in RNA compared to DNAs double strand
What is the details of semi conservative DNA replication?
1- DNA Helicase breaks bonds between bases separating the 2 strands and exposing the bases
2- each strand acts as a template
3- DNA nucleotides align and attach by hydrogen bonding to the exposed complementary bases
4- AT and CG
5- the nucleotides are joined together by phosphodiester bonds in the new strand catalysed by DNA polymerase
6- 2 DNA molecules containing one original strand and one new strand are formed
What is ATP?
Adenosine triphosphate, immediate energy source for biological processes - ATP is made of one adenine 3 phosphate groups and one ribose
What purpose does the phosphate have?
Used to phosphorylate other compounds often making them more reactive
ATP can be resynthesised with the help of?
ATP synthase
What is water?
2 Hydrogen Atoms covalently bonded to an oxygen molecule - these are weak hydrogen bonds
What are the 4 main roles/properties of water?
Metabolic reactions, solvent, temperature regulation, support
What are the 4 main ions?
Sodium iron hydrogen phosphate
What is the role of sodium?
Cotransport glucose and amino acids across cell membranes
What is the role of iron?
Component of haemoglobin which transports oxygen
What is the role of hydrogen?
Important in determining pH and thus affecting protein structure and enzyme activity
What is the role of phosphate?
Important as a structural component of DNA, RNA and ATP
