2.1.2 Biological Molecules Flashcards
Define a carbohydrate
- Contains carbon, hydrogen, and oxygen
Explain how carbohydrates are classified and give examples
Sugars
- monosaccharides - glucose, fructose, galactose
- disaccharides - sucrose, maltose, lactose
Polysaccharides
- storage - glycogen, starch
- structural - cellulose
Characteristics of a monosaccharide?
- are soluble in water
- have a sweet taste
- form crystals
Explain how the amount of carbons ina sugar correlates to the type of monosaccharide
- if they have 3 carbons they are triose sugars
- 5 carbons = pentose sugar
- 6 carbons = hexose sugar
What is the general formula of a monosaccharide?
(CHO2O)n, where n is >= to 3
Explain how you distinguish between a-glucose and b-glucose
- In a-glucose the OH group on carbon 1 is below the plane of the ring
- In b-glucose the OH group on carbon 1 is above the plane of the ring
How does glucose contasing lots of bonds relate to it’s function?
It can contain lots of energy
What is a disaccharide?
Sugars composde of two monosaccharides bopnded together by a glycosidic bond
What monosaccharides make up:
- maltose
- sucrose
- lactose
- maltose = glucose + glucose
- sucrose = glucose + fructose
- lactose = glucose + galactose
How is a a-1,4-glycosidic bond formed?
- between carbon 1 of one glucose molecule and carbon 4 of another glucose molecule
- two OH groups bond to form a water molecule (H2O)
- O boned to carbon in one molecule and carbon in another
- C-O-C link formed
What are the two types of storage polysaccharides and in which species are they found
- starch - plants
- glycogen - animals
What are the two different polysaccharides that make up starch?
- amylose (coiled)
- amylopectin (coiled and branched)
What bonds do amylose and amylopectin use?
- amylose = a-1.4-glycosidic bonds
- amylopectin = a-1,4glycosidic + a-1,6 glycosidic bonds
Give key points about starch
- carbohydrate consiting of two polysacchardies, amylose and amylopectin
- stored in chloroplast and elsewhere in plants
- stored in cells as starch grains
- can be broken down into a-glucose which are respired to produce ATP
Explain the structure of glycogen
- a-1,4glycosidic + a-1,6 glycosidic bonds
- same overall satrucutre as amylopectin, but signifficantly more branching and 1,4 chains are smaller
Where and how is glucose stored?
- stored as glycogen granules
- found in large amounts in the liver + skeletal muscles
Give key points about glycogen
- polymer of a-1,4 glycosidic bonds
- many side chains due to a-1,6 glycosidic bonds
- insoluble, compact, energy dense
- does not affect water poetion of cell
- branches for rapid hydrolysis by enzymes
How do storage polysacchrides’s structures and properties relate to their function?
Structure
- both are made by bonding thousands of a-glucose molecules together (condenstation reactions)
- a-glucose stored is used in respiration
Function
- compact - lots of energy stored in small volume (energy dense)
- metagbolically inactive (doesn’t take part in metabolic reactions)
- insoluble in water - do not dissolve in water, so does not affect cell water potential
- chain molecules - glkucose held by chains which can be hydrolysed by enzymes
- branched - branches ahve ends where enzymes can add or remove glucose - can be quickly hydrolysed
Give an example of a structural polysaccharide and it’s properties
cellulose - high tensdile strength + insoluble
Explain the structure of the cell wall, and the glucose used
- beta glucose
- forms cellulose fibres, which form microfibril, which form macrofibril, which form the wall
- alternate beta glucose molectules roatet 180 degress - forms hydrogen bonds between OH groups
Give examples of lipids
triglycerides, phospholipids and steroid alcohols
Explain the key functions of lipids
Triglycerides
- enmergy storage and source
- insulation
- protection of organms
Phospholipds
- plasma membrane
Sterols
- make up some hormones
Explain the structure of a triglyceride
- made from 1 glyercol + 3 fatty acids
- not built from repeating units - not a polymer
- macromlecule - a large molecule
Why is water a polar molecule?
- more positive protons in its nucleus
- uneven distribution of electrons
- oxygen atoms become partially negative
- hydrogen atoms become partially positive
Give key aspects of hydrogen bonds
- weak electrostatic interaction
- molecules contain a partially negativley charged atom (N,O,F) bonded to partially positivley charged hydrogen atom
- weaker than a covalent bond
- thousands of hydrogen bonds can stabalise structures
Define metabolism
All the biochemical reactions happening inside the cells of an organism
What are catabolic and anabolic reactions?
Catabolic reactions: Breaking down large molecules (hydrolysis reactions)
Anabolic reactions: Building large molecules (condensation reactions)
What are the functions of carbohydrates?
- energy storage and supply
- structure (plant cellulose cell wall)
What are the functions of proteins?
- structure (keratin in hair, collagen in skin)
- transport (channel and carrier)
- enymes
- antibodies
- most hormones
What are the functions of lipids?
- plasma membranes
- energy storage and supply
- insulation of animals
- nerve cell insulation
- some hormones (steroid hormones)
What are the functions of vitamins and minerals?
- form parts of larger molecules
- vitamins used as co-enzymes
- minerals used as inorganic cofactors + prosthetic groups
What are the functions of nucleic acids?
- contain genes that code the amino acid sequence of proteins
What are the functions of water?
- support plants
- solvent for metabolic reactions
- transport medium
Give key aspects of carbon
- 4 electrons in its outer shell
- becomes stable via sharing 4 outer electrons with other atoms (8 electrons in outer shell)
- forms covalent bonds (single or double)
What is the difference between a monomer and a polymer?
Monomer: Single molecule units repeated to make polymers
Polymers: Large molecules made from joining monomers together (Monomers must be of the same type)
Give examples of monomers and polymers of carbohydrates
Monomer: Monosaccharide e.g. glucose/fructose/galactose
Polymer: Polysaccharide e.g. starch/cellulose/glycogen
Give examples of monomers and polymers of proteins
Monomer: Amino acids e.g. Glycine/Tyrosine
Polymer: Polypeptides + proteins e.g. haemoglobin/enzymes
Give examples of monomers and polymers of nucleic acids
Monomer: Nucleotides
Polymer: Polynucleotides e.g. DNA & RNA
Give key aspects of hydrolysis
- water molecule used
- covalent bond breaks
- monomer molecules from polymer
- normally requires an enzyme
- e.g. digestion
Give key aspects of condensation
- water molecule is released
- covalent bond forms
- polymer molecules from monomers
- normally requires an enzyme
- e.g. protein synthesis