Topic 2 Flashcards
Organic molecules
- contain carbon, hydrogen and oxygen
- most are macromolecules- due to large size
4 types of macromolecules
- proteins
- lipids
- carbohydrates
- nucleic acids
- all apart from lipids are classified as polymers- link up of smaller repeating monomers, to form long chains- polymers
- lipids are made of distinct chemical groups of atoms
name of reaction for creating polymers from monomers
Condensation polymerisation reaction
polymer
very large molecule, composed of a chain of many similar/identical monomers bonded together
Condensation (dehydration) reactions
- putting together
- endergonic/anabolic reaction- requires energy
- water is released in reaction
hydrolysis reactions
- breaking apart
- exergonic/catabolic reaction- energy is released
- polymer is broken down into its constituent monomers.
- water is required
Inorganic molecules
- small molecules do not contain all of carbon, hydrogen and oxygen
- still essential substances for living organisms e.g CO2, oxygen
- mineral ions are important as they determines osmotic pressure of cell.
Nucleotides
monomer of nucleic acid
- consist of:
- five carbon sugar (ribose RNA, deoxyribose DNA)
- negatively charged phosphate group
- organic nitrogen-containing base
Purine bases
Adenine and guanine
Pyrimidine bases
Thymine, Cytosine and uracil (RNA only)
Types of RNA
transfer RNA (tRNA- transports specific amino acids to ribosomes for incorporation of growing polypeptide chain
- messenger RNA (RNA)- contains coded information, in groups of 3 bases called codons
- specify the order of amino acids to be joined together to make protein (mRNA is complimentary to DNA template strand of gene)
- Ribosomal RNA- many chains of rRNA, together with proteins make up ribosome
- holds mRNA, tRNA, amino acids and growing polypeptide chain in correct orientation for protein synthesis
differences between DNA and RNA
DNA - double stranded, contains deoxyribose sugar, has bases A, G, C, T
RNA- single stranded, contains ribose sugar, has bases A, G, C, U
DNA structure
- two strands of nucleotides, running antiparallel to each other
- one strand runs 3’ to 5’, other 5’ to 3’
- sugar of one nucleotide joins to phosphate of next nucleotide
- occurs through CPR
- bond between phosphate and sugar- phosphodiester linkage
Chromosome structure
- DNA wraps around proteins (histones) to form chromosome
- as DNA wraps around histones- forms nucleosomes
properties of genetic code
triplets on DNA, codons on RNA, anticodons on tRNA
- degenerate/redundant- each triplet codes for one amino acid- but single amino acids may have more than one triplet coding for it
- non-overlapping- code doesn’t overlap- 12 bases code for 4 amino acids
- universal- DNA is essentially same in all known organisms and codons code for same amino acids.
- start and stop- one start codon and 3 stop sequences
structure of amino acid
amino group NH2 carboxyl group COOH hydrogen atom central carbon atom varying r group -r group difference distinguishes amino acids/ and change amino acid properties
primary structure of proteins
- specific linear sequence of amino acids
- bonds between amino acids are peptide bonds
- OH on carboxyl group and H on amino group bond- release water
Secondary structure
- once polypeptide chain is formed, various parts undergo folding due to H bonds between amino acids
- three configs
- tight coils- alpha helix- tough and flexible
- folding forms- beta pleated sheets- soft and flexible
- unchanged- random coils- binding/ active sites of proteins
- H bonds between amino acids provides strength/stability/ ability to contract/stretch or active site shape contribution
Tertiary Structure
- total irregular folding- held together by ionic or hydrogen bonds- forms complex shape
- based on r groups-amino acids have different properties
- hydrophilic attracts hydrophilic
- negative attracts positive
- causes polypeptide chain to become folded, coiled or twisted- forms 3D shape-determines function of most protein.
- tertiary structure determined by hydrogen, ionic or disulphide bonds and r group interaction or adjacent amino acids
quaternary structure
-consists of two or more polypeptide chains
types of conjugate proteins
nucleoproteins- (protein + nucleic acid) found in nucleus
lipoproteins- (protein+ lipid) found in membrane
glycoproteins- (protein + carbohydrate)- plays important roles in cell recognition and cell defense mechanisms
chromoproteins- (proteins + pigments)
metalloproteins- (proteins + metal elements)
Denaturation
- process in which a protein unravels and loses its native conformation, thus becoming biologically inactive
- caused by high temperature, strong acid/base, strong salt.
- these cause protein to denature- irreversible
proteome
complete array of proteins produced by single cell of organism in particular environment
genome
complete set of genes carried by organism
