Lec 2: Introduction to Biological Molecules Flashcards
“Explain some of the properties of carbon relevant to its role as the major constituent of biological molecules”
- carbon has 4/8 outer electrons
- carbon is tetravalent, this means that it can form 4 bonds other atoms/groups e.g. C,H,O,N,S
- It shares electrons with C-atoms and other electron deficient atoms to share electrron pairs
- carbon based molecules are often very large and held by strong covalent bonds
“Explain with the polar nature of water, hydrogen bonding and the biological importance of water”
Water’s Polarity:
- A water molecule is made up of 2 Hydrogen atoms and an Oxygen atom
- the oxygen atom in the molecule is highly electronegative so the electrons are pulled towards it and away from the hydrogen atoms
- therefore the hydrogen atoms a have a slightly positive charge
- the oxygen atom has a slightly negative charge
Hydrogen bonding:
when water molecules are close together their positive and negative regions are attracted to the oppositely charged regions of nearby molecule
the partially positive hydrogen atom forms a hydrogen bond with the lone pair on the highly electronegative atom e.g O,F,N,Cl,Br
Biological Importance:
because of water’s properties, water is important bc;
- poplar substances can dissolve in it (universal solvent) and it aids the movement of chemicals during diffusion
- It acts as a lubricant in joints and tissues aslo moistens the epithelial surface for effective gas exchange
- It regulates body temperature, qater requires heat to turn to vapour – Sweat absorbs heat from the skin when evaporating
“describe a variety of functional groups that are important in biology”
“explain the difference between biological polymers and monomers and describe how they are produced and broken down”
polymer: macromolecules composed of building blocks or monomers
monomer: where monomers join together with covalent bonds to form long chains or macromolecules
why is carbon the basis of living material?
-carbon can form 4 bonds with other atoms and a wide variety of chemical groups
How many protons, neutrons and electrons does a carbon atom have?
Protons: 6
Electrons: 6
Neutrons: 6
which atoms does carbon most commonly form covalent bonds with?
carbon C
hydrogen H
oxygen O
nitrogen N
sulphur S
what is meant when it is said that carbon is tetravalent?
can form 4 covalent bonds
NOTE about Carbon in Bio
Valence and low atomic weight give carbon unique properties that account for the diversity and stability of carbon-containing compounds and its role in biological molecules
Identify the functional group
alkene/ethene
Identify the functional group
alkyne/ethyne
Identify the functional group
thio/sulfydryl
Idenitfy the functional group
amine (amino)
Identify the functional group
thiol/sulfhydrdryl
Identify the functional group
Ketone
CO
Identify the functional group
aldehyde
CHO
Identify the functional group
Haloalkane
Identify the functional group
Ether
(oxygen atom bonded to two alkyl or aryl groups)
Identify the functional group
carboxylic acid
(alcohol and acyl halides, acid anhydrides, esters, and amides)
Identify the funcional group
ester
(carboxylic acid and alcohol)
Identify the funcional group
Amide/peptide
(secondary amines and carboxylic acids)
Identify the funcional group
phosphate
what is a macromolecule?
Large biological molecules with repeating subunits and many functional groups
what are the four biologically important macromolecules?
– Carbohydrates
– Lipids
– Proteins
– Nucleic acids
what are monomers?
macromolecules composed of building blocks or monomers
what are polymers
where monomers join together with covalent bonds to form long chains or macromolecules
give examples of monomers
- monosaccharides
- amino acids
- nucleotides
give examples of polymers
- polysaccharide
- protein
- nucleic acid
how are polymers formed?
formed by dehydration synthesis:
-a molecule of water is formed and removed from the reactants joined during the reaction
Requires energy in the form of ATP (adenosine 5’-triphosphate)
How are polymers broken down?
Broken down by hydrolysis (=opposite of dehydration synthesis):
Bonds between reactants are broken with the addition of a molecule of water H2O
Energy released from the bond is stored as ATP
what is the function of a water molecule?
makes up 80% of a cells content and is used in many chemical reactions
what is the function of a protein molecule?
used for growth and repair of tissues and also used for a transport structure
what is the function of a DNA molecule?
-long term storage information on a cell, contains instructions to construct other components of the cell such as RNA and protein molecules
what is the function of an enzyme molecule?
biological catalyst made from proteins
what is the function of lipid and fat molecules?
an energy source, insulation and protection to make some of the molecules we study
for the monomer, amino acid, give the polymer and an example
polymer= protein (polypeptide)
example= haemoglobin
for the monomer, monosaccharide, give the polymer and an example
polymer= carbohydrate (poly-saccharide)
example= starch
for the monomer, Nucleotide, give the polymer and an example
polymer= nucleic acid
example= DNA
what is the difference between an alpha glucose and beta glucose
a beta glucose is the isomer of a alpha glucose, this means that it has the same molecular formula but a different structural formula.
when are disaccharides formed?
they are formed by the condensation of two monosaccharides
give examples of disaccharides and state what monosaccharides they are made from
- sucrose= fructose + glucose
- lactose= galactose + glucose
- maltose= glucose + glucose
what enzyme is required to break down sucrose to glucose and fructose?
sucrase
what enzyme is required to break down lactose to galactose and fructose?
lactase
what enzyme is required to break down maltose into glucose and glucose?
maltase
NOTE of the chemical makeup of humans
what is the most abundant molecule in the human body?
water (60-95% of fresh mass in living organisms)
talk about the importance of water in metabolsim
a metabolic reaction is a chemical reaction that happens in a living organism to keep the organism alive
- a hydrolysis reaction requires a molecule of water to break a bond
- a condensation reaction releases a molecule of water so a new bond is formed
- chemical reactions takes place in an aqueous medium
- water is a major raw material in photosynthesis
talk about water as a solvent
- universal solvent and aids movement of chemicals during diffusion
- water’s polarity makes it a useful solvent it readily dissolves substances such as:
- gases e.g oxygen and CO2
- wastes e.g ammonia and urea
- inorganic ions and small hydrophyllic molecules e.g amino acids, monosaccharides and ATP
- enzymes whose reactions take place in solution
discuss water and its relatively high specific heat capacity and its buffering changes in temperature (NOT PART OF CLIN SCI)
- because some water moelcules stick together (by hydrogen bonding) it takes more energy to separate them than would be needed if they did not bond to one another
- for this reason the boiling point of water is higher then expected and without its hydrogen bonding water would be gas at temperatures commonly found on earth and life as we know it would not exist
- for the same reason it takes more energy to heat a given mass of water (aka its high specific heat capacity)
- water therfore acts as a buffer against sudden temperature variations, making th aquatic environment a temperature-stable one and as organisms are mostly water, it also buffers them against sudden temperature
How does water regulate body temperature?
– Water requires heat to turn to vapour
– Sweat absorbs heat from the skin when evaporating
discuss water’s large latent heat of vapourisation (NOT PART OF BIO CLIN SCI)
- the hydrogen bonding between water molecule means that it requires a lot of energy to evaporate 1 gram of water (aka the latent heat fo vapourisation)
- this is useful for living organisms because it meands they can use water loss through evaporation to cool down e.g humans sweat to cool down, without losing too much water
discusss the cohesive property of water
cohesion is the tendancy of molecules to sticke together
- with its hydrogen bonding water has a large cohesive forces and these allow it to be pulled up througha tube, such as xylem vessel in plants
- strong cohesions means water also has a high surface tension when the molecules meet air, (they tend to be pulled back into the body of water rather than escaping from it)
e. g sweat froms droplets, which evaporate from the skin to cool an organism down or the surface of the water is strong enough to support small organisms such as pond skaters
discuss water and its transparency
-water is transparent and therefore aqauitc plants can photosyntesise and also light rays can penertrate the jelly-like fluid that fills the eye and so reach the retina.
why is that large bodies of water rarely freeze over entirely at colder temperatures?
- at colder temperatures the cooler water (ice) becomes less dense than warmer water.
- ice floates on warmer water, forming a layer that insulates the water beneath with the result that large bodies of water rarely freeze over entirely
Why is water important for lubrication
-It moistens the epithelial surfaces so gases can be dissolved easily
how much water do we need a day?
1.5L
how is dehydration treated?
fluid replacement therapy- oral or intravenous (IV)
draw the interaction between two water molecules
why are all polar (charged) molecules and ions water solubles?
They can form hydrogen bonds with water
Are nonpolar molecules hydrophobic or hydrophillic?
Nonpolar molecules repel water and are thus hydrophobic
are polar molecules hydrophillic or hydrophobic?
Polar molecules attract water so are hydrophillic
what do you call complexes that have a mixture of both properties (polar/nonpolar)
amphiphilic
what is the 3D shape in many biological molecules influenced by?
hydrophobic forces
Define surface tension
lastic tendency of a fluid surface which makes it acquire the least possible surface area
At liquid–air interfaces, results from the greater attraction of liquid molecules to each other (due to cohesion) than to the molecules in the air (due to adhesion)
what is a surfactant
amphiphilic subtsances which reduces the surface tension of a liquid in which they are dissolved
Why do premature babies lacking surfactants need treatment?
surfactants are substances which reduce the surface tension of a liquid in which they are dissolved
- so babies with less surfactants have increased surface tension which tends to make lung alveoli collapse (atelectasis)
- they prescribed surfactant inhaler therapy
