Topic 2

Question 1

Organic molecules

Answer 1

• contain carbon, hydrogen and oxygen

- most are macromolecules- due to large size

Question 2

4 types of macromolecules

Answer 2

• 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

Question 3

name of reaction for creating polymers from monomers

Answer 3

Condensation polymerisation reaction

Question 4

polymer

Answer 4

very large molecule, composed of a chain of many similar/identical monomers bonded together

Question 5

Condensation (dehydration) reactions

Answer 5

• putting together
• endergonic/anabolic reaction- requires energy
• water is released in reaction

Question 6

hydrolysis reactions

Answer 6

• breaking apart
• exergonic/catabolic reaction- energy is released
• polymer is broken down into its constituent monomers.
• water is required

Question 7

Inorganic molecules

Answer 7

• 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.

Question 8

Nucleotides

Answer 8

monomer of nucleic acid

• consist of:
• five carbon sugar (ribose RNA, deoxyribose DNA)
• negatively charged phosphate group
• organic nitrogen-containing base

Question 9

Purine bases

Answer 9

Adenine and guanine

Question 10

Pyrimidine bases

Answer 10

Thymine, Cytosine and uracil (RNA only)

Question 11

Types of RNA

Answer 11

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

Question 12

differences between DNA and RNA

Answer 12

DNA - double stranded, contains deoxyribose sugar, has bases A, G, C, T
RNA- single stranded, contains ribose sugar, has bases A, G, C, U

Question 13

DNA structure

Answer 13

• 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

Question 14

Chromosome structure

Answer 14

• DNA wraps around proteins (histones) to form chromosome

- as DNA wraps around histones- forms nucleosomes

Question 15

properties of genetic code

Answer 15

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

Question 16

structure of amino acid

Answer 16

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

Question 17

primary structure of proteins

Answer 17

• 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

Question 18

Secondary structure

Answer 18

• 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

Question 19

Tertiary Structure

Answer 19

• 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

Question 20

quaternary structure

Answer 20

-consists of two or more polypeptide chains

Question 21

types of conjugate proteins

Answer 21

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)

Question 22

Denaturation

Answer 22

• 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

Question 23

proteome

Answer 23

complete array of proteins produced by single cell of organism in particular environment

Question 24

genome

Answer 24

complete set of genes carried by organism