UNIT+4-+GENETICS




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 **Vocabulary** : 1. genetics- the scientific study off heredity 2. fertilization- male and female reproductive cells join 3. true-breeding- if allowed to self pollinate, they would produce offspring identical to themselves 4. trait- a specific characteristic 5. hybrids- the offspring of crosses between parents with different traits 6. genes- the chemical factors that determine traits 7. alleles- the different forms of a gene 8. segregation- separation 9. gametes- sex cell 10. probability- the likelihood that a particular event will occur 11. Punnett square- a diagram used to determine gene combinations 12. homozygous- two identical alleles for a particular trait 13. heterozygous- two different alleles for the same trait 14. phenotype- physical characteristics 15. genotype- genetic makeup 16. independent assortment- genes for different traits can segregate independently during the formation of gametes 17. incomplete dominance- one allele is not completely dominant over another 18. codominance- both alleles contribute to the phenotype 19. multiple alleles- have more than two alleles 20. polygenetic traits- traits controlled by two or more genes 21. homologous- each of the 4 chromosomes that came from the male parent has a corresponding chromosome from the female parent 22. diploid- contains both sets of homologous chromosomes 23. haploid- contain only one set of chromosomes & a single set of genes 24. meiosis- process by which the number of chromosomes per cell is cut in half through the separation of homologous chromosomes in a diploid cell 25. tetrad- the structure formed when each chromosome pairs with its corresponding homologous chromosome 26. crossing-over- when chromosome tetrads exchange portions of their chromatids 27. gene map- show the relative locations of each known gene 28. transformation- process in which one strain of bacteria is changed by a gene or genes from another strain of bacteria 29. bacteriophage- a virus that infects bacteria 30. nucleotide- monomer of nucleic acids made up of a 5-carbon sugar, a phosphate group, and a nitrogenous base 31. base pairing- a principle that bonds in DNA can form only between adenine and thymine and between guanine and cytosine 32. chromatin- a tightly packed substance in eukaryotic chromosomes containing DNA and protein 33. histones- proteins that DNA is coiled around in chromatin 34. replication- when a cell duplicates its DNA before it divides 35. DNA polymerase- the principal enzyme involved in DNA replication 36. messenger RNA- contain instructions for assembling amino acids into proteins 37. ribosomal RNA- contained in ribosomes 38. transfer RNA- transfers each amino acid to the ribosome while its being specified bu coded messages in mRNA 39. transcription- when RNA molecules are created by copying part of the nucleotide sequence of DNA into a complimentary sequence in RNA 40. RNA polymerase- required for transcription 41. promoters- have specific base sequences and are the only things RNA polymerase binds to 42. introns- sequences of nucleotides in eukaryotic genes 43. exons- the DNA sequences that code for proteins 44. codon- consists of 3 consecutive nucleotides that specify a single amino acid that is to be added to the polypeptide 45. translation- the decoding of an mRNA message into a polypeptide chain (protein) 46. anticodon- 3 unpaired bases in a tRNA molecule that are complimentary to one mRNA codon 47. mutations- changes in the genetic material 48. point mutations- gene mutations involving changes in one or a few nucleotides 49. frameshift mutations- mutations that shift the reading frame of the genetic message 50. polyploidy- the condition in which an organism has extra sets of chromosomes 51. operon- a group of genes that operate together 52. operator- the region of chromosome in an operon to which the repressor binds when the operon is "turned off" 53. differentiation- when cells become specialized in structure and function 54. hox genes- genes that control the differentiation of cells and tissues in the embryo 55. selective breeding- allowing only certain breeds of animals to breed together 56. hybridization- crossing dissimilar individuals to bring together the best of both organisms 57. inbreeding- the continued breeding of individuals with similar characteristics 58. genetic engineering- making changes in the DNA code of a living organism 59. restriction enzymes- cuts DNA at a specific sequence of nucleotides