DNA and Inheritance

• What is the structure of DNA?

  Two long chains of alternating sugar and phosphate, joined by bases (A, T, C, G), twisted into a double helix.
• What are the four DNA bases and how do they pair?

  A = Adenine, T = Thymine, C = Cytosine, G = Guanine. A pairs with T, C pairs with G.
• How does DNA code for proteins?

  The order of bases forms a genetic code that determines the sequence of amino acids in a protein.
• What is the role of a triplet code in protein synthesis?

  Each triplet of bases (codon) codes for one amino acid.
• What is genetic profiling?

  Cutting DNA into fragments and separating them into bands to create a DNA profile.
• How is genetic profiling used?

  To compare DNA samples in crime, paternity, and species classification cases.
• What are some benefits of DNA profiling?

  Identifies disease-related genes, supports personalised medicine and early diagnosis.
• What is a gene?

  A section of DNA that codes for a particular characteristic.
• What is an allele?

  A different form of a gene.
• Define: Dominant and Recessive Alleles.

  Dominant: always expressed; Recessive: only expressed if both alleles are recessive.
• Define: Homozygous and Heterozygous.

  Homozygous: two identical alleles; Heterozygous: two different alleles.
• Define: Genotype and Phenotype.

  Genotype: genetic makeup (e.g. Bb); Phenotype: physical trait (e.g. brown eyes).
• What are F1 and F2 generations?

  F1: first generation offspring; F2: offspring of the F1 generation.
• What is ‘selfing’?

  Self-fertilisation – crossing an organism with itself.
• What is single gene inheritance?

  Inheritance involving one gene with two alleles; outcomes can be predicted using Punnett squares.
• What is polygenic inheritance?

  When a trait is controlled by multiple genes, e.g., height or skin colour.
• How is sex determined in humans?

  By the 23rd pair of chromosomes: XX = female, XY = male; inherited randomly at fertilisation.
• What is genetic engineering?

  Artificial transfer of genes from one organism to another.
• What are advantages of genetic engineering?

  GM crops, medical treatments, improved food production.
• What are disadvantages or concerns of genetic engineering?

  Ethical issues, environmental risks, unknown health effects.
• How do amino acids make proteins?

  They join together through peptide bonds in a condensation reaction, forming a polypeptide chain. This chain folds into a specific three-dimensional shape, determining the protein's function.