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Flashcards in Mod 2 Chap 3: Biological Molecules Deck (64)
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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.

- 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
- 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
- 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
- living things need a stable temp for enzyme-controlled reactions to happen properly
- aquatic organisms need a stable environment in which to live
- important for digestion + synthesis for large biological molecules
- provides habitats for living things in rivers, lakes + seas
- forms major component of tissues in living organisms
- provides a reaction medium for chemical reactions
- 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
- 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...



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


Describe the structure of the polysaccharide starch through amylose.

- a type of starch
- formed by alpha glucose molecules joined together by 1-4 glycosidic bonds
- is a polysaccharide in starch
- angle of bond means long chain of glucose twists to form a helix
- helix further stabilized by H bonds within molecule
- makes polysaccharide more compact + much less soluble than glucose molecules used to make it


Describe the structure of the polysaccharide starch through amylopectin.

- another type of starch
- formed when glycosidic bonds form in condensation reactions between carbon 1 + 6 on two glucose molecules, unlike amylose
- so, amylopectin has branched structure
- made by 1-4 glycosidic bonds between alpha glucose molecules


Describe the structure of the polysaccharide glycogen.

- equivalent energy storage molecule in animals + fungi to starch in plants
- forms more branches than amylopectin so is more compact + less space needed for it to be stored
- coiling or branching of it also makes it v compact for ideal storage
- branching also means free ends where glucose molecules can be added or removed, speeding up process of storing / releasing glucose required by cell
- key properties (as in amylopectin): insoluble, branched + compact, so ideally suited to storage roles they carry out


Describe the structure of the polysaccharide cellulose.

- straight chain molecule, formed when polysaccharides formed from glucose are unable to coil / form branches
- cellulose molecules make H bonds w/ eachother forming micro fibrils
- micro fibrils join together forming macro fibrils, which continue to produce fibres
- these fibres = strong, insoluble + used to make cell walls
- cellulose = v hard to breakdown into its monomers + forms fibre necessary for a healthy digestive system


Describe lipids.

- have large amounts of carbon + hydrogen, but low amounts of oxygen
- insoluble in water as non-polar, but water is polar
(Only polar molecules are soluble in polar solvents)
- soluble in alcohol

3 most important lipids:
- triglycerides
- phospholipids
- cholesterol


Describe the lipid triglycerides (as an example of a macromolecule).

- made of fatty acids + glycerol
- 3 fatty acids per 1 glycerol