Mod 2 Chap 3: Biological Molecules Flashcards
Define a monomer.
A small molecule that binds to other identical molecules to form a polymer.
Define a dimer.
Two monomers joined together.
Define a polymer.
A large molecule made from many small monomers.
What elements make up the biological molecules carbohydrates?
Also, what are their monomers and polymers?
Elements: C, H, and O
Monomer: Monosaccharides (e.g. Glucose)
Polymer: Polysaccharides (e.g. Starch)
What elements make up the biological molecules proteins?
Also, what are their monomers and polymers?
Elements: C, H, N, O and S.
Monomer: Amino acids
Polymer: Polypeptides
What elements make up the biological molecules Nucleic Acids?
Also, what are their monomers and polymers?
Elements: C, H, O, N and P.
Monomer: nucleotides.
Polymer: DNA.
What is covalent bonding?
A bond in which atoms share electrons with other atoms. This allows them to ‘fill’ their outer shell and results in a strong bond with the other atom.
What is a condensation reaction?
A condensation reaction occurs when two molecules are joined together with the removal of water.
What is a hydrolysis reaction?
A hydrolysis reaction occurs when two molecules are split up by the addition of water.
What elements make up the biological molecules Lipids?
Elements: C, H and O.
How does hydrogen bonding occur between water molecules?
- water = 2 H atoms, each covalently bonded w/ O atom.
- but, as O atom has greater number of protons in its nucleus, it exherts a stronger attraction for shared electrons (O atom has a greater electronegativity), it has greater pull on electrons.
- so O atom becomes slightly negative + H atoms become slightly positive
- when this happens, we say molecule is polar (e.g. Structure of water is polar).
- in structure of water: H = delta positive, O = delta negative.
- so water forms hydrogen bonds
- in water molecules, hydrogen bonds are weak + covalent bonds are strong
Describe the properties of water.
- it’s a solvent
- high specific heat capacity: large heat energy needed to increase kinetic energy
- has high latent heat of vaporization (heat energy / has an unusually high BP): is a liquid at room temp due to H bonds, takes a lot of energy to increase its temp + turn it gaseous
- when freezes it turns to ice, + actually then becomes less dense, this due to H bonds as they fix positions of polar molecules slightly further apart than average distance in liquid state, when cooled below 4 degrees
- has cohesive properties + surface tension: moves as one mass as molecules are attracted to eachother
- has adhesive properties: water molecules are attracted to other materials, e.g. When you wash hands they become wet
- it’s a reactant
- it’s a liquid at room temp
- it’s dense
Relate the properties of water to its role in living organisms / how this benefits life.
SOLVENT:
- molecules + ions can move around + react in it
- so many reactions happen in cytoplasm of cells (as is 70% water)
- molecules + ions can also be transported around living things when dissolved in water
HIGH LATENT HEAT OF VAPORISATION:
- so water can help cool living things + keep their temp stable
- e.g. mammals cooled when sweat evaporates
- e.g. plants cooled when water evaporates from mesophyll cells
COHESION AND SURFACE TENSION:
- columns of water in plant vascular tissue are pulled up xylem tissue together from roots in transpiration stream
- insects like pond-skaters can walk on water
HIGH SPECIFIC HEAT CAPACITY:
- living things need a stable temp for enzyme-controlled reactions to happen properly
- aquatic organisms need a stable environment in which to live
REACTANT:
- important for digestion + synthesis for large biological molecules
LIQUID:
- provides habitats for living things in rivers, lakes + seas
- forms major component of tissues in living organisms
- provides a reaction medium for chemical reactions
DENSITY:
- water more dense than ice, so aquatic organisms have stable environments to live in through winter
- ponds + other water bodies are insulated against extreme cold, as ice layer reduces heat loss.
What are the roles of carbohydrates?
- energy store
- energy source
- structural
- form part of other molecules
Describe the three main groups of carbohydrates.
Monosaccharides: (simple sugars)
Disaccharides: (complex sugars)
Polysaccharides: (complex carbohydrates)
How are sugars held together?
Glycosidic bonds
Describe monosaccharides (+ structure, role + how they are categorised).
- simple sugars
- energy source due to large number of C-H bonds
- soluble
- exist as single ring shape or straight chain
- no glycosidic bonds
- categorized by their number of C atoms, into:
- hexose: 6 carbons
- pentose: 5 carbons
- triose: 3 carbons
- roles in organisms: energy, transported in blood, monomers for other carbohydrates
Describe glucose as a hexose monosaccharide.
- hexose monosaccharide so has 6 carbons
- two forms of it: alpha / beta glucose
- alpha + beta glucose structures drawn differently (draw)
- alpha + beta glucose are isomers of eachother
Describe ribose as a pentose monosaccharide.
- pentose monosaccharide so has 5 carbons atoms
- is the sugar present in RNA nucleotides
Describe glucose’s molecules’ properties.
- polar
- soluble in water, due to H bonds between hydroxyl groups + water molecules
- important they are soluble as means glucose is dissolved in cytosol of cell.
Describe disaccharides (+ structure, role + examples).
- two single sugar molecules joined by a condensation reaction / covalently joined
- soluble
- have one single glycosidic bond
Examples: - sucrose (glucose + fructose)
- lactose (glucose + galactose)
- maltose (glucose + glucose)
- roles in living organisms: energy release, storage and transport in plants
Two monosaccharides will form a…
Disaccharide
Describe oligosaccharides.
- 3-10 sugar molecules joined into a chain
- not easily digested
- found in leaks, onions, garlic etc
Describe polysaccharides ( + structure, role + types).
- polymers or monosaccharides
- many molecules covalently joined
- insoluble
- have many glycosidic bonds
- long chains that may be branched / coiled
- two types of them:
- homopolysaccharides: (monomers are all the same)
- herteropolysaccharides: (more than one type of monomer)
- roles in living organisms: energy storage, structural component of cell walls
