Inheritance biology

• DNA location


  Located in the nucleus of a cell
• Genome

  The entire set of genetic material of an organism, including all the alleles of all the genes in their DNA
• A gene provides the instructions that code for the amino acid sequence required to build a protein
• What is a Gene

  A section of DNA which codes for a specific protein
• Chromosome


  Structures formed by the coiling of DNA double helices in the nucleus of a cell, visible during cell division, and containing genetic information in the form of genes
• Each chromosome holds genetic information coding for multiple different proteins
• Human body cells contain 23 pairs of chromosomes, totalling 46 chromosomes in diploid cells
• Homologous chromosome pairs

  Two chromosomes (one from each parent) that are similar in size, shape, and gene content, carrying corresponding genes, although they may have different alleles for each gene
• Haploid

  The number of chromosomes in gametes (sperm and egg cells), which is half the diploid number found in body cells
• Chromosome numbers differ between species
• Chromosomes are only visible during cell division
• Nucleotide bases found in DNA


  • Thymine
  • Adenine
  • Guanine
  • Cytosine
• Complementary base pairing


  The specific pairings of nucleotide bases in DNA: Adenine pairs with Thymine, Guanine pairs with Cytosine
• Adenine does not pair with Guanine in DNA
• Significance of nucleotide base pairing


  Allows for accurate DNA replication during cell division
• Structure of DNA


  A polymer made up of two strands coiled around each other to form a double helix, with a sugar-phosphate backbone and nitrogenous bases attached via complementary base pairing
• Components of a nucleotide base


  The backbone is formed from the deoxyribose sugar of one nucleotide base and the phosphate molecule of the adjacent nucleotide base
• Polymer

  A large molecule made up of many repeating subunits
• Nucleotide bases found in RNA


  • Adenine
  • Guanine
  • Cytosine
  • Uracil
• Polynucleotide

  A polymer, or large molecule, made up of many nucleotide monomers linked together in a chain
• Key differences between RNA and DNA


  • RNA is single-stranded, DNA is double-stranded
  • RNA contains Uracil instead of Thymine
  • RNA contains Ribose sugar, DNA contains Deoxyribose sugar
• DNA and RNA are both nucleic acids
• Protein synthesis


  Uses mRNA as a messenger to carry the code from the DNA to the ribosome in order to make proteins
• tRNA


  A molecule in the cytoplasm that binds to the mRNA using complementary base pairing and delivers the specific amino acid coded for by the mRNA
• RNA relies on complementary base pairing during the formation of mRNA in transcription and pairing with tRNA for polypeptide synthesis in translation
• Uracil


  The base present in RNA but not in DNA
• Sugar in RNA


  Ribose sugar
• Main types of RNA involved in protein synthesis

  • Messenger RNA (mRNA)
  • Transfer RNA (tRNA)
• Protein synthesis


  The process by which proteins are made in a cell, split into Transcription and Translation
• Transcription occurs in the nucleus of the cell
• Transcription


  The process of producing an mRNA copy of a gene's DNA sequence
• mRNA


  Messenger RNA, a single-stranded RNA molecule that carries genetic information from DNA to ribosomes for protein synthesis
• Translation

  The process during which mRNA is decoded to produce a specific sequence of amino acids, producing a protein. It occurs on ribosomes.
• tRNA

  Transfer RNA, which has an anticodon region and carries specific amino acids to the ribosome where the anticodon pairs with an mRNA codon during translation
• Anticodon


  A triplet of unpaired bases on tRNA that is complementary to a specific mRNA codon during translation
• Translation occurs in the cytoplasm of the cell, specifically at ribosomes
• DNA is transcribed and translated one gene at a time
• Allele


  A version of a gene
• Individuals have two alleles of each gene; one on each chromosome of a homologous pair, one inherited from each parent
• Phenotype depends on genotype because different alleles code for different proteins in a cell