Chapter 1 : The Chemistry of Life Flashcards
What is an atom?
It is the smallest unit of matter that can take part in a chemical reaction
What is a molecule?
Two or more atoms that combine with one another chemically
What is an element?
A pure substance that is not made up of other similar substances
What is a compound?
A pure substance that is made up of simpler substances (2 or more elements that are chemically combined)
What is the formula for water?
H2O
- consists of hydrogen and oxygen
- made up of atoms of H and O
- 2 hydrogen atoms and 1 oxygen atom
What are the 7 basic characteristics of life?
- nutrition
- response to stimuli
- growth
- reproduction
- respiration
- excretion
- locomotion
What is a cell?
The smallest unit of life that contains cellular inclusions (organelles)
What is a tissue?
A group of similarly differentiated cells that perform a common function
What is an organ?
A group of differentiated tissues, each of which performs its own function, but together performs a common function
What are the two groups that chemical compounds are divided into?
Inorganic compounds and organic compounds
What are inorganic compounds?
It is chemical compounds that do not contain the element carbon and are not produced by living organisms
- eg) water, mineral salts, gases
What are organic compounds?
It is chemical compounds that contain the element carbon and are produced by living organisms
- composed of carbon, hydrogen, oxygen, and also sometimes nitrogen, phosphorus, sulphur
- eg) carbohydrates, lipids, proteins, nucleic acids and vitamins
Water
- most important inorganic compound for living organisms
- no water, no life
- 75% of plant and animal bodies
What are the different functions of water in living organisms?
- Solvent
- Medium in which chemical reactions occur
- Reagent during hydrolysis
- Transporting agent
- Lubricant
- Regulates body temperature
- Gives shape and rigidity
Solvent
- solvent for inorganic and organic
- hydrophyllic (dissolves in water) (eg. minerals dissolve in water for roots to absorb)
- hydrophobic (does not dissolve in water) (eg. fats and oils)
Medium in which chemical reactions occur
- all chemical reactions in living organisms occur in water
Reagent during hydrolysis
- water breaks polymers down into their monomers
Transporting agent
- digested nutrients, metabolic waste products, gases, mineral salts are transported in water
Lubricant
- makes chewing and swallowing easier
- aids the movement of food through the rest of the alimentary canal
- watery fluids surround eyeballs and joints to prevent friction
Regulates body temperature
- body loses water through sweat, which evaporates and cools body
Gives shape and rigidity
- animals like jellyfish have hydrostatic skeletons that gives shape
- water in vacuoles of plant cells cause internal pressure that pushes against cell wall (turgor pressure)
Mineral salts
- needed and absorbed by living organisms
- plant roots absorb from soil
- humans and animals obtain from food
What are macro elements?
Mineral salts that are needed in large quantities (everyday) (plants : soil)
What are micro elements?
Mineral salts that are needed in smaller quantities (animals : food)
What are some macro elements?
- Calcium
- Phosphorus
- Sodium
- Potassium
Calcium
- builds strong teeth and bones
- necessary for blood coagulation
- Humans : rickets
- Plants : weak plant growth
Phosphorus
- component of ATP, DNA, RNA
- part of phospholipids in cell membranes
- Humans : seldom occurs
- Plants : stunted plant growth
Sodium
- important for maintaining water balance in body
- controls rhythm of heart
- Humans : muscle cramps
- Plants : unknown
Potassium
- important for maintaining water balance in body
- controls heart rhythm
- Humans : seldom occurs
- Plants : yellow and brown leaf margins
What are the micro elements?
- Iron
- Iodine
Iron
- helps to form haemoglobin that transports O2 in blood
- helps to form chlorophyll molecules
- Humans : anaemia
- Plants : chlorosis
Iodine
- component of hormone thyroxin
- Humans : goitre
What are some mineral compounds?
- Phosphates (main source of P in plants)
- Nitrates (main source of, needed for protein synthesis)
Carbohydrates
- made up of C, H, O
- ratio of H and O is 2:1
What are carbohydrates made up of?
- made up of ring shaped units called saccharides
- divided into 3 groups according to number of saccharides
- monosaccharides (sugar)
- disaccharides (sugar)
- polysaccharides (not sugar)
Monosaccharides
(single sugar)
- 3 types
- glucose, fructose, galactose
(glucose is the basic building block of all carbohydrates)
Disaccharides
(double sugars)
- when two monos are joined
- one water molecules is removed to form a di
- known as condensation reaction
- 3 types
- maltose, sucrose, lactose
Glucose + Glucose =
Maltose + H2O
Glucose + Fructose =
Sucrose + H2O
Glucose + Galactose =
Lactose + H2O
Polysaccharides
- long chains of mono that bind one another
- 3 types
- starch, glycogen, cellulose
What is starch?
- form in which glucose is stored in plant
What is glycogen?
- form which excess glucose is stored in liver and skeletal muscles of humans and animals
- when energy is needed, transfers back to glucose
What is cellulose?
- forms structural component of plant cell walls
What is the importance of carbohydrates in animals and plants?
- source of energy
- source of reserve energy
- structural component
What can we use to test for the presence of glucose?
Benedict’s solution
- it is a deep blue liquid that indicates presence of mono and di
- if blue = no glucose
- orange/red = gluscose
Testing for starch
- use yellow-brown iodine
- turns blue/black = starch present
Lipids
- made up of the same 3 elements as carbohydrates
- C, H, O
- ratio H:O, far greater than 2:1
- contain double the number of H and O
What does lipids consist of?
- glycerol
- fatty acids
(different types of lipids contain different fatty acid molecules)
What are the characteristics of lipids?
- insoluble in water
- soluble in ether and alcohol
- hydrophobic
2 types of lipids
- saturated fats
- unsaturated fats
What are saturated fats?
- mainly derived from animals
- solid at room temperature
- eg) butter
What are unsaturated fats?
- mainly derived from plants (olive oil)
- liquid at room temperature (oils)
- used by body to synthesize cholesterol
What is cholesterol?
It is a white, wax-like substance that forms part of cell membranes and hormones
- formed by excessive intake of saturated fats in the blood
- causes fatty deposits (plaque) in arteries, and narrows them
- narrowing known as atherosclerosis
What is the importance of lipids in animals and plants?
- source of reserve energy
- insulating material
- shock absorption
- structural component of cell membranes
- waterproofing
- absorption of vitamins (A,D,E,K)
- source of water
How do we know when fats are present during a test?
When there is a translucent greasy spot left on the filter paper
What are proteins?
It is a polymer with amino acids as monomers
What are amino acids made up of?
- C, H, O, N
- some amino acids have P, S, Fe present
- 20 different amino acids
What does the sequence of amino acids determine?
It determines the type of protein
What is a peptide bond?
It is a bond/link formed between 2 amino acids
What are the different types of peptide bonds?
- Dipeptide = 2
- Tripeptide = 3
- Polypeptide = long chain
- Protein = 51+ amino acids
- each protein has own shape, it determines the function that must be performed
Why are proteins sensitive to temperature and pH?
They are sensitive as they will denature at high temperatures and will lose their shape and function
What is the importance of proteins in animals and plants?
- structural component of protoplasm
- building materials
- structural component of cell membranes
- play a role in the permeability of cell membranes
- source of reserve energy
- hormones regulate processes in the body
- haemoglobin transports O2 and CO2 in blood
- protect the body against disease
- chromosomes carry hereditary material
- act as buffers
- enzymes control metabolic processes in body
How can we test for proteins?
- biuret test
- blue - no protein present
- purple - protein present
What are enzymes?
It is a biological catalyst that acceleratse chemical reactions inside living cells and lowers the activation energy without itself being changed by the reaction
What are reactions called that take place in living cells called?
Metabolic reactions
2 types of metabolic reactions
- anabolic
- catabolic
Anabolic reaction
- when a complex molecule is built up from simple molecules
- energy required
Catabolic reaction
- when a complex molecule is broken down into simple molecules
- energy released
Some digestive enzymes
maltose + water = maltase = glucose + glucose
sucrose + water = sucrase = glucose + fructose
lactose + water = lactase = glucose + galactose
starch + water = amylase = maltose
lipid + water = lipase = glycerol and 3 fatty acids
proteins + water = protease = smaller polypeptides
Nucleic acids
- made up of elements C, H, O, N, P
2 types of nucleic acids
- DNA
- RNA
DNA
- found in nucleus of cell
- carries hereditary characteristics and controls structure and function of cell
RNA
- found in nucleus and cytoplasm
- forms part of ribosomes
- plays a role in protein synthesis to ensure amino acids bind together
Vitamins
- essential for normal metabolism, growth and development of body
- needed in smaller quantities
- produced by plants
2 types of vitamins
- water-soluble (B,C)
- fat-soluble (A,D,E,K)
