Chapter One: Biochemistry Flashcards
What are the relative masses and charges of the 3 subatomic particles?
Proton: 1, +1
Neutron: 1, 0
Electron: 0, -1
Why are atoms in the elemental state neutral?
Equal number of protons and electrons
What does electron configuration determine?
How atoms of an element react with another type of atoms
What are atoms called when their electrons are in the lowest available energy level?
Ground state
When do electrons move to higher energy levels?
When they absorb energy
What is the state of electrons in higher energy levels?
Excited state
Explain how chlorophyll molecules make sugar using idea of energy
Chlorophyll absorbs light energy, excited electrons provide energy to make sugar as they release energy while returning to ground state
What are isotopes?
Atoms of the same element that vary only with neutron number
State uses of radioisotopes
Estimating age of fossils, medical diagnosis and treatment
When is a bond formed?
When nuclei attract the same electrons
Why are bonds made?
To obtain stability/full valency
State what happens to energy when bonds are made/broken
Made: released
Broken: supplied
How are ionic bonds formed? Which elements are ionic bonds formed in?
Electrons are transferred
In metals
What are anions and cations
Gains electrons: Anion: negative ion
Loses electrons: Cation: positive ion
How are covalent bonds made?
Electrons are shared to form molecules
What makes bonds non polar? (3+1)
Electrons are shared equally, and form between alike atoms ( mono/diatomic, *and C-H), and are symmetrical
What makes bonds polar? (3+1)
Electrons shared unequally, formed between unalike atoms, especially hydrogen bonds, asmmetrical
What is intermolecular force of attraction?
Force between molecules
What is polar-polar attraction? Determine the strength of polar molecules compared to that of non polar molecules
Attraction between positive and negative ends of polar molecules. Polar ones are stronger
Explain non polar molecule attraction
Balanced, and linear in terms of symmetry so they have the weakest attraction
Describe the terms hydrophobic and hydrophilic
Phobic:Water hating
Philic:Water loving
Non polar substances such as lipids do not dissolve in water. Why?
Like dissolves like.
State which things give water it’s special characteristics
It is asymmetrical->highly polar, strong intermolecular attractions->strong hydrogen bonding
Water has a high specific heat capacity. What does this mean?
It takes a lot of heat in order to raise the temperature of 1gram of water by 1°C
Water has a high heat of vaporisation. How does this apply in the cooling effect?
When sweat evaporates it takes along with it a lot of heat from the body
Why is water the universal solvent?
It is highly polar and can dissolve all polar and ionic substances
Why does ice float on water?
It is less dense
Explain the phenomenon of spring overturn
During winter, ice layers water and insulates and moderates climate for life below. When it melts in spring it becomes denser water and sinks and causes water circulation. This makes oxygen reach the depths, and nutrients from bacteria reach the surface. It is crucial for lake health
Explain what it means by water having strong cohesion tension
Water molecules stick to each other via hydrogen bonds. Oxygen has a higher EN value than hydrogen so it tends to pull electrons with more force and has a partial negative charge. This oxygen attracts to an opposite hydrogen in another molecule which is partially positive via electrostatic force of attraction. This dipole dipole interaction is the hydrogen bond. The intramolecular bond between oxygen and hydrogen in the same moleceule is polar covalent as electrons are shared unequally.
How is it possible for bugs to walk on water?
Cohesion forces and surface tension
What is water adhesion?
When water molecules cling to substances via hydrogen bonds
How is adhesion useful in plants?
Responsible for capillary action (water moves up a plant. Additionally, due to trnaspirational pull cohesion tension this can be done without spending energy)
State the general principle relating H+ ions to pH
As the concentration of H+ increases, pH decreases
What is pH?
A measure of acidity or alkalinity of a solution
What is unit for pH?
Concentration of H+ ion in moles per litre
How is pH regulated by human blood?
Bicarbonate hydrogen ions
What is the chemical formula for bicarbonate hydrogen?
HCO3-
What is a buffer?
A pH regulator, which can absorb excess or donate hydrogen ions
Which pollutants cause acid rain?
SO2, CO2, SO4
What is electronegativity?
The ability of an atom to attract electrons to obtain a full outer she’ll
Which type of elements are electronegative/postive
- = non mentals \+ = metals
What is the EN value for H?
2.1
What is the EN value of C?
2.5
What is the EN value for N?
3.0
What is the EN value for O?
3.5
What is the EN value for F?
4.0
What is the EN value for Cl?
3.0
What is the EN value for S?
2.5
What is the EN value for Br?
2.8
What is the EN value for I?
2.5
Why do noble gases not have EN values?
They are stable
What is the trend of EN across the periodic table?
It increases
What is the trend of EN down the periodic table?
It decreases
How do you calculate polarity of a bond?
Find the EN difference, if it is <0.5 it’s nonpolar, if it’s 0.5-1.9 it’s polar. If >1.9 it’s ionic
How does geometry affect polarity?
Linear=nonpolar
Asymmetrical=polar
What is the dipole moment?
It occurs when there’s a separation of charge. When atoms share electrons unequally.
Can all pairs of dipole moments cancel?
No. Only when they’re symmetrical/opposite.
Like water, the shape is important (linear/asymmetric). Water is diagonal and and if drawn with vectors parallel vectors cannot cancel and make net D=0.
State 2 factors affecting the size of dipole moment and relate them
-EN difference
-Distance between charge
The greater they are, the larger the dipole.
What is the measure of polarity?
Dipole
What is a hydrogen bond?
It is an intermolecular bond/force of attraction which is dipole-dipole between charged hydrogen atoms and oxygen/nitrogen/fluorine atoms.
What is molarity in terms of pH?
It is the concentration of H+ ions in moles/litre.
What is the unit for molarity?
Molar
What is the molarity for pH 1?
1l × 10^-1 = 0.1molar
And so on for each pH, replacing the power
What are organic compounds?
Containing carbon
What are carbohydrates made of?
Carbon
Hydrogen
Oxygen
Which type of organic compounds supply quick energy and how much per gram in a calorimeter
Carbohydrates
4cals released on burning 1g
State the chemical formula of of monosaccharides
C6H12O6
How are glucose, galactose, and fructose related to each other?
They are monosaccharides that are isomers of each other
What are isomers?
Compounds with the same molecular formulae but different structures
What is a disaccharide?
Made of 2 monosaccharides joined by dehydration synthesis
Monosaccharide + Monosaccharide gives?
Disaccharide + WATER
Which monosaccharides need to be added to get maltose?
Glucose + Glucose
Which monosaccharides need to be added to get lactose?
Glucose + Galactose
Which monosaccharides need to be added to get sucrose?
Glucose + Fructose
What is hydrolysis?
It the reverse of dehydration synthesis, the breakdown of compounds through the addition of water
What are polysaccharides?
Polymers of carbohydrates
How are polymers formed?
Addition of many monosaccharides by dehydration synthesis
How do plants store carbs?
Starch
How do animals store carbs?
Glycogen
Where is glycogen found in humans?
Liver
Skeletal muscles
Which polysaccharide makes up plant cell walls?
Cellulose
Which polysaccharide makes up the exoskeleton of arthropods, and cell walls of mushrooms?
Chitin
What do lipids consist of?
1 glycerol
3 fatty acids
What is glycerol?
An alcohol
C3H5(OH)3
What is a fatty acid?
A hydrocarbon with a carboxyl group at one end
What is the structural difference between saturated and unsaturated fatty acids?
Saturated: carbon-carbon single bonds
Unsaturated: carbon-carbon double bonds (fewer Hydrogen)
State 3 functions of lipids
Energy storage: 9cals/gram
Structural: phospholipid membranes
Endocrine: hormones
What are proteins made of?
They are polypeptides made of amino acids linked by peptide bonds
State the composition of an amino acid
Carboxyl group
Amine group
Variable (R) which differs with the 20 different amino acids
What are complex macros such as proteins responsible for?
Growth and repair
What is a dipeptide?
Molecules of 2 amino acids
What affects the function of a protein?
It’s structural level
What is the primary level?
A sequence of amino acids giving a protein chain
What is the secondary level?
Hydrogen bonding within the molecule (such as the helical nature of DNA)
What is the tertiary level?
A 3D conformation as a result of intramolecular attraction and most directly determines the way a protein functions and it’s specificity
What is the quaternary level?
More than one polypeptide chain (eg haemoglobin has 4)
What are enzymes?
Large proteins that speed up reaction by lowering the activation energy
What is the induced fit model?
A substrate enters the active site and it induces the enzyme to alter shape to fit better
What is one very important principle of biological catalysts?
They are not degraded, instead reused
How are most enzymes named?
After the substrate they hydrolyse, end in ‘ase’
What do enzymes take the help of to function?
Cofactors (minerals)
Coenzymes (vitamins)
What 2 factors affect enzyme efficiency?
Temperature
pH
What causes denatured enzymes to be unable to function?
They lose their unique shape because the tertiary structure is damaged beyond repair
What is a prion protein and how can it adversely affect one’s brain cells?
An infectious glycoprotein found on the cell surface of the CNS that sometimes misfolds, and proliferates by inducing the normal protein to convert. Makes cells resist recycling, form hardy gunk and form lethal spongey holes
What are nucleic acids?
Polymers of nucleotides
State the composition of a nucleotide
A phosphate group, a 5-Carbon sugar (either deoxyribose, or ribose), Ajt a nitrogenous base
State the nitrogen bases in pairs in DNA
Adenine - Guanine
Cytosine - Thymine
State the bases in RNA
Adenine
Guanine
Cytosine
Uracil
State the bond between bonds in DNA
Hydrogen bond
Why are there no hydrogen bonds in RNA?
There are only single stands of nucleotides
Explain how like substances dissolve like substances.
Solvent particles move to make room for solute ones this requires energy to overcome force of attraction/endo. Solute particles move from neighbours also endo to overcome FOA. Solvent moves between solute and intermolecular FOA hold and they move closer and this releases energy/exo
State why polar can dissolve polar and vice versa for non polar but not one with the other
Polar- they have the same partial charge eg strong H-bonding so they can attract and form intermolecular forces
Nonpolar- weak London forces so they can be broken easily/little resistance and become miscible
Strong forces in polar keep nonpolar out
