4.1 DNA, genes and chromosomes

• Sequence of 3 bases

  DNA- triplet

  mRNA- codon

  tRNA- anti codon
• genome is complete set of genetic material in an organism
• proteome is the full range of proteins that the cell is able to make
• his tones are proteins that dna is wound around
• introns are sections of Dna that don’t code for amino acids
• exons code for amino acids
• a gene is a sequence of DNA base that code for either a polypeptide or functional RNA
• the genetic code js a sequence of bases (ATCG) that code for specific amino acids
• each amino acid is coded for by a group of three bases known as a triplet code
• each polypeptide has a different length and sequence of amino acids. it’s the order of bases thag codes for and determines the sequence of amino acids
• hydrogen, ionic and disulphide bonds form between the R groups on the amino acids which causes the polypeptide to fold and form a tertiary structure protein, which determines the shape and function of the protein
• different species need to be able to make different proteins and therefor different genes with different base sequences
• DEGENERATE CODE: more than one base triplet can code for the same amino acid. only 20 amino acids, but 64 possible triplets
• Degenerate code can be an advantage for dna base sequence mutation because the same amino acid is coded for so there is no effect on the primary structure hence the tertiary structure
• NON- OVERLAPPING CODE: each base in the sequence is read only once
• UNIVERSAL CODE:

  the same specific base triplets code for the same amino acids in all living things - this shows everything has a common ancestor (evolution)
• DNA IS A POLYMER OF DNA NUCLEOTIDES
• chromosomes are long thread like structures of made of DNA and histones which carry genetic information
• LOCI is the specific fixed position of a gene or genetic marker on a chromosome
• allele is a variant form of a gene , different alleles have different traits
• homologous chromosomes are a pair of chromosomes one from each parent that have the same gene Loci but maybe different alleles
• prokaryote is a organic without a nucleus and membrane bound organelles
• Eukaryotic cells are organisms with membrane bound organelles and a nucleus
• mutation is a change in the DNA base sequence
• Gene is a section of DNA that codes for a sequence of amino acids that form a polypeptide or functional RNA