1- Biological Molecules Flashcards
What is a monomer
Small units which make up larger molecules
What are three examples of monomers
Monosaccharides
amino acids
nucleotides
What happens when a condensation reaction joins two molecules together
A formation of a chemical bond
Elimination of a water molecule
What is a hydrolysis reaction
Breaks a chemical bond between two molecules
Through the use of a water molecule
What’s a polymer
Molecules made from a large number of monomers joined together
What’s a monosaccharide
Monomers which form larger carbohydrates
Three examples of monosaccharides
Glucose
Galactose
Fructose
What’s formed between two monosaccharides through a condensation reaction
Glycosidic bond
How is a disaccharide formed
Condensation of two monosaccharides
How is the disaccharide Maltose formed
Condensation of two glucose molecules
How is the disaccharide sucrose formed
Condensation of a glucose and fructose molecule
How is the disaccharide lactose formed
Condensation of glucose and galactose
What’s an isomer
Compounds with the same formula but a different arrangement of atoms in the molecule
What’s the difference between alpha and beta glucose
Alpha -OH points down from C1
Beta -OH points up from C1
What’s a polysaccharide
Many glucose units joined through a condensation reaction
What glucose makes up glycogen
Alpha
What is glycogen
Main energy store in animals
What’s the structure and function of glycogen
-1,4 and 1,6 glycosidic bonds, large number of side branches, energy is released quickly, enzymes act simultaneously
-Large but compact, maximises energy store
-Insoluble, doesn’t affect water potential
What glucose makes up starch
Alpha
What’s amylose
Single chain of alpha glucose joined by 1,4 glycosidic bonds
What’s amylopectin
Branched chain of alpha glucose joined by 1,4 and 1,6 glycosidic bonds
What’s the structure and function of starch
Mixture of amylose and amylopectin, hydrolyses, releasing alpha glucose so is transported easily
Insoluble, not effected by water potential
Compact, energy stored in a small space
What glucose is cellulose made from
Beta glucose
Structure and function of cellulose
Unbranched inverted chains of beta glucose joined by glycosidic bonds
Microfibrils, multiple strong cellulose chains parallel joined by hydrogen bonds, strong cross links
Exerts inward pressure, stops influx of water, turgid and rigid, maximise surface area for photosynthesis
What is a triglyceride
3 fatty acids, 1 glycerol
The fatty acid forms an ester bond with the glycerol through a condensation reaction
(Therefore the hydrolysis of a triglyceride produces 3 fatty acids and 1 glycerol)
What decides if a triglyceride is a fat or oil
Variations in fatty acids
Unsaturated, oil
Saturated, fat
Triglycerides with a single C-C bond in the carboxylic acid group are called
Saturated
Triglycerides with a double C=C bond in the carboxylic acid group are called
Unsaturated
How are triglycerides excellent stores of energy
High ratio of energy storing carbon to hydrogen bonds
Low mass to energy ratio, energy can be stored in a small volume, beneficial to animal, they can carry less mass
How are triglycerides unaffected by water potential when stored
Large, non polar molecules, they are insoluble in water
How do triglycerides provide a source of water
High ratio of hydrogen to oxygen atoms, release water when oxidised, important for organisms in dry deserts
What are phospholipids
2 fatty acids, 1 glycerol, 1 phosphate molecule attached to head
What does the phosphate molecule do to the head of the phospholipid
Hydrophilic, attracts water
It doesn’t interact with fat
What do the fatty acids do to the tail in a phospholipid
Hydrophobic, repels water
Mixes readily with fat
Why are phospholipids said to be polar
Two ends of the molecule behave differently
In water the hydrophilic ends are closest
Why are lipids good insulators
Fats are slow conductors of heat, help to retain body heat, electrical insulators (myelin sheath)
Why are lipids protective
Fat is stored around delicate organs like kidneys
What’s a polypeptide
A long chain of 3 or more amino acids
Formula of glycine
N
C2
H4
O (double bond)
OH
What’s the primary structure of a protein
Sequence of amino acids in a peptide chain
Coded for by the DNA in a gene
What’s the secondary structure of a protein
The way a chain folds due to hydrogen binding between the -NH and C=O group
Spiral- alpha helix
Folds- beta pleated
Hydrogen bonds are affected by pH
What’s the tertiary structure of a protein
Found in globular proteins (soluble in water)
Disulphide bridges (strong), ionic bonds (weaker than disulphide bonds, easily broken by changes in pH), weaker intermolecular forces form complex 3D shapes
Hydrophobic interactions (if two ‘R groups’ are hydrophobic will cluster away from water)
What’s the quaternary structure of a protein
More than one polypeptide chain
eg haemoglobin
These also contain prosthetic groups (non polypeptide components such as haem)
What’s a dipeptide
The condensation of two amino acids
What groups do amino acids consist of
Amino group -NH2
Carboxylic acid group -COOH
R group, variety of structures
What bond is formed between amino acids
A peptide bond
What’s the test for proteins
Biuret test, tests for peptide bonds
Add solution if proteins are present colour change from blue to purple
How to test for NON reducing sugars
Hydrolyse the sugar by placing food sample in a test tube with equal volume of HCL, boil in a water bath for 5 mins
Add sodium hydrogen carbonate to neutralise the acid
Add solution to equal volume of Benedict’s, if solution turns orange/ brick red high amounts of non reducing sugars are present
What type of protein is an enzyme
Globular protein
What do catalysts do
Speed up the rate of a chemical reaction
What makes catalysts reusable/economical
They aren’t used up in the reaction, provide an alternative pathway for the reaction to occur
What is activation energy
The minimum amount of energy required to activate a reaction
What is the active site of an enzyme
A small depression where the enzyme is functional
Where the substrate binds due to bonds between amino acids and groups in the substrate
Active site is complimentary to the substrate
Principals and limitations of an early model- lock and key
Principals, substrate is complimentary to active site and will only fit that enzyme
Limitations, enzyme is considered to be rigid, but is flexible and can adapt to shape of substrate
Principals of induced fit model for enzymes
Active site of an enzyme is complimentary to substrate
Enzymes active site changes shape slightly to form an enzyme substrate complex
How does an enzymes tertiary structure determine the properties of an enzyme
Enzymes have a specific tertiary structure, active site has a specific shape, complimentary to one type of substrate
Why are enzymes specific
Each enzyme can only catalyse a reaction of a specific substrate
The effect of temperature on enzyme action
As temp increases so does kinetic energy, more frequent successful collisions, more enzyme substrate complexes are formed, increases rate of reaction
However as temp become too high hydrogen bonds in the enzyme break, enzymes active site denatures
Effect of pH on enzyme action
A pH too high or low decreases the rate of enzyme action, charges on amino acids are altered, ionic and hydrogen bonding can be broken altering the tertiary structure, changes shape of active site denaturing it
Effect of enzyme concentration on rate of reaction
As enzyme conc increases so does rate of reaction, however once the substrate becomes a limiting factor the rate of reaction levels off
Effect of substrate concentration on rate of reaction
As substrate conc increases so does rate of reaction, however once the conc of enzymes becomes a limiting factor the curve levels off
What are competitive inhibitors
Bind to the active site of an enzyme interfering with its function
What are non competitive inhibitors
Bind to an enzyme not at the active site interfering with its function
How does the concentration of competitive inhibitor affect rate of reaction
Decreases rate of reaction, takes longer to reach max rate of reaction, occupies active site of enzyme instead of substrate
How does concentration of non competitive inhibitor affect rate of reaction
Decreases rate of reaction, alters shape of enzymes active site by binding elsewhere so enzyme is not functional
Due to this an increase in substrate concentration wouldn’t solve the issue
What reactions do enzymes catalyse and what does this determine
Intracellular and extracellular
Determine structures and functions of cells and organisms
What does DNA do
Hold genetic information
What does RNA do
Transfer genetic information from DNA to ribosomes
What’s a ribosome made of
RNA and proteins
What’s DNA and RNA a polymer of
Nucleotides
What’s a nucleotide composed of
Pentose
Nitrogen containing organic base
Phosphate group
What’s DNA composed of
Pentose (deoxyribose)
Phosphate group
Organic bases (adenine, cytosine, guanine, thymine)
What’s RNA composed of
Pentose (ribose)
Phosphate group
Organic base (adenine, cytosine, guanine, uracil)
What reaction occurs between two nucleotides and what bond forms
Condensation reaction forming a phosphodiester bond
What shape is a DNA molecule
Double helix
What forces hold the two polynucleotide chains together between specific complimentary base pairs
Hydrogen bonds
What size is a RNA polynucleotide chain
Short
What’s are the base-base pairs
Adenine-Thymine (uracil in RNA)
Guanine-Cytosine
Why did scientists question whether DNA caries the genetic code
Simplicity, 4 different bases
What’s semi conservative replication
In each new DNA molecule, one strand of the molecule is from the original DNA molecule, the other strand is created by the cell
Importance of semi conservative replication
Ensures continuity between parent cell and daughter cells DNA
When cells are replaced they can carry out same role as old ones
Process of semi conservative replication of DNA
Enzyme DNA helicase breaks hydrogen bonds which are inbetween complimentary bases
2 strands are both separated and they both act as template strands
Free DNA nucleotides are attracted to exposed bases on each template strand by base pairing
Adenine and thymine are complimentary, cytosine and guanine are complimentary
Enzyme DNA polymerase joins adjacent nucleotides forming a phosphodiester bond through a condensation reaction
If 28% of bases on a section of DNA were cytosine what are the frequencies of the other three bases
Guanine- 28%
Adenine- 22%
Thymine- 22%
Evaluate Watson and Crick DNA model
Tested by growing bacteria in a medium of N 15 isotope, this is original bacteria.
Bacteria transferred to N 14 only replicating once.
The mass of the DNA was dependant on the method of replication.
DNA was centrifuged, lighter DNA collected at the top of the tube.
1st generation had one heavy strand and one light strand proving semi conservative replication
What’s a nucleotide derivative
A single molecule of adenosine triphosphate (ATP)
What makes up ATP
Pentose sugar- Ribose
Adenine
3 phosphate groups
How is ATP synthesised
Through a condensation reaction of ADP and an inorganic phosphate.
Catalysed by enzyme ATP synthase during photosynthesis or respiration
What happens in the hydrolysis of ATP
Forms adenosine diphosphate (ADP) + inorganic phosphate
Catalysed by enzyme ATP hydrolase
Releases energy
Inorganic phosphate can be used to phosphorylate compounds, make them more reactive
How is water a metabolite
Takes place in many metabolic reactions like hydrolysis and condensation reactions
How is water an important solvent
A solvent which allows metabolic reactions to occur
What does it mean if water has a high specific heat capacity
Buffers changes in temperature
What does a high latent heat of vaporisation for water mean
Provides a cooling effect with little water loss through evaporation
Why is waters strong cohesive properties important
Supports columns of water in tube like transport cells of plants
Provides surface tension where water meets air
Where are inorganic ions found
As a solution in the cytoplasm or In bodily fluids
What’s the function of hydrogen ions
Determine pH of solutions, functioning of enzymes
What’s the function of iron ions
Found in haemoglobin, transport oxygen
What’s the function of sodium ions
Cotransport glucose and amino acids across plasma membranes
What’s the function of phosphate ions
Structural role in DNA molecules and storing energy in ATP molecules
What’s the formula of a fatty acid
RCOOH
