Genetics

• Gene: a sequence of bases in DNA that codes for a polypeptide or functional RNA
• Genes consist of DNA (deoxyribonucleic acid) which means DNA holds the genetic information
• Genes control production of proteins by transferring the genetic information from DNA to the ribosomes via RNA (ribonucleic acid)
• Proteins are what determine the characteristics of an organism
• DNA and RNA are both polynucleotides
• polynucleotide: a polymer of nucleotides
• Each nucleotide contains a pentose (5 carbon sugar), a nitrogen containing organic base and a phosphate group
• In RNA the pentose is Ribose
• In DNA the pentose is deoxyribose
• In RNA the organic bases are Adenine, Cytosine, Guanine and Uracil
• In DNA the organic bases are Adenine, Cytosine, Guanine and Thymine
• Sugar-Phosphate backbone: where the nucleotides are joined together in long chains by phosphodiester bonds between the pentose sugars
• Phosphodiester bonds are formed in a condensation reaction
• DNA is a double helix where two very long polynucleotide chains are wound around each other and held together by hydrogen bonds between complementary base pairs
• Adenine pairs with Thymine and Cytosine pairs with Guanine
• RNA is a short single stranded polynucleotide chain
• 1st stage of DNA replication: the DNA helix is progressively unwound by the enzyme helicase which breaks the hydrogen bonds between the bases, allowing the strand to separate.
• 2nd stage of DNA replication: Each strand now has unpaired bases
• 3rd stage of DNA replication: the strands now act as templates to assemble new strands. DNA nucleotides in the cytoplasm bind to the newly unpaired bases through complementary base pairing.
• 4th stage of DNA replication: The enzyme DNA polymerase catalyses the formation of the phosphodiester bonds between the nucleotides.
• Semi-conservative replication: DNA strands are separated and each strand is used to make a new strand
• Mutation: A change in the DNA sequence of an organism that can lead to a change in the allele
• Allele: a variant of a gene
• Genetics: the study of how single genes function and how they affect the appearance and functioning of the organism
• Genomics: the study of how all genes in an organism interact
• Genome: the entire genetic material of an organism
• DNA holds genetic information
• RNA transfers genetic information from DNA to the ribosome where proteins are synthesised
• nucleotides are the molecules from which DNA and RNA are formed
• each nucleotide is formed from pentose, a nitrogen containing base and a phosphate group
• the components of a DNA nucleotide are deoxyribose, a phosphate group and one of the organic bases
• organic bases in DNA nucleotides are: adenine, cytosine, guanine and thymine
• the components of an RNA nucleotide are ribose, a phosphate group and one of the organic bases
• the organic bases in RNA nucleotides are: adenine, cytosine, guanine and uracil
• a condensation reaction between 2 nucleotides formed a phosphodiester bond
• a DNA molecule is a double helix with 2 polynucleotide chains held together by hydrogen bonds between specific complimentary base pairs
• an RNA molecule is a short single stranded polynucleotide chain
• Adenine pairs with Thymine through a hydrogen bond
• Guanine pairs with Cytosine through a hydrogen bond
• In an RNA polynucleotide Adenine bonds with Uracil through a hydrogen bond