Bio Tutorial

• mRNA


  Carries information from DNA to direct the synthesis of protein
• rRNA


  Makes up part of the ribosomes that are used to translate messenger RNAs
• tRNA


  Transfers amino acids to the ribosome during protein synthesis
• mRNA processing


  Introns are spliced out and the exons joined together

  5' guanosine cap and a 3' poly-A tail are added
• DNA replication


  Separation of DNA strands

  2. Each strand becomes a template for the assembly of a complementary strand from a supply of free nucleotides using DNA polymerase to synthesize one daughter strand

  3. The other strand is synthesized as a series of short pieces, which are then connected by the enzyme DNA ligase
• Role of tRNA in translation


  Delivers amino acids to the ribosome by binding to the appropriate codon on the mRNA being translated
• Differences between DNA and mRNA

  • mRNA is single-stranded, DNA is double-stranded

  mRNA bases are A, C, G, U, DNA bases are A, C, G, T
• The DNA segment TAC GAT CTA CGA would produce the polypeptide Methionine-leucine-Aspartate-Alanine
• Semi-conservative replication of DNA

  The idea of both original strands being copied and each new DNA molecule consists of one original and one new strand of DNA
• Asexual reproduction


  The creation of offspring carrying genetic information from a single parent
• Differences between DNA and RNA

  • - RNA (ribonucleic acid) uses the sugar ribose, while DNA uses deoxyribose
  • RNA has a nitrogenous base uracil (U) instead of thymine in DNA
• Sexual reproduction

  The creation of offspring carrying genetic information from two parents
• With the exception of identical twins, siblings who have the same two biological parents are likely to look similar, but not identical, to each other
• Sister chromatids


  Pair of identical structures that each chromosome of a eukaryotic cell consists of prior to mitosis
• Deafness


  Recessive trait associated with the abnormal allele d
• Normal hearing


  Associated with the normal allele D
• Dr. Smith's parents' genotypes

  • DD and dd
  • dd and dd
  • Dd and Dd
  • DD and DD
  • Dd and DD
• Most genetic disorders of humans are caused by recessive alleles
• The vast majority of people afflicted with recessive disorders are born to parents who were not affected at all by the disease
• Lethal disorders caused by dominant alleles

  • Usually cause the death of the embryo
  • Most individuals carrying a lethal dominant allele have the disorder and die before they reproduce, whereas individuals carrying a lethal recessive allele are more likely to be healthy and reproduce
• Most children with recessive disorders are born to healthy parents
• Recombinant DNA

  DNA from two sources combined into one single piece of DNA
• Vector


  Bacterial plasmid used in the process of human gene cloning

  
• Sex-linked gene


  Any gene located on a sex chromosome
• Recessive X-linked traits are more likely to be expressed in a male fruit fly than a female fruit fly
• DNA ligase


  Enzyme that binds nucleotides together
• A color-blind woman marries a man who is not color-blind. All of their sons, but none of their daughters, are color-blind
• Producing a desired protein using plasmids


  1. Desired gene is inserted into the plasmid

  2. Plasmid is returned to the bacterium by transformation

  
• Sex-linked conditions are more common in men than in women because men need to inherit only one copy of the recessive allele for the condition to be fully expressed
• Restriction enzymes


  Enzymes that specifically recognize and cut short sequences of DNA called restriction sites
• Female inheritance patterns cannot be analyzed by simply studying the X chromosome because the X chromosome is obtained from both father and mother

  
• Sticky ends


  Feature of DNA fragments that allows them to form hydrogen-bonded base pairs with complementary single-stranded stretches of DNA
• Reverse transcriptase

  Enzyme used to prepare a gene for cloning, resulting in a DNA strand that lacks introns

  
• Sex-linked trait


  Trait carried on the sex/X chromosome
• Vaccine

  Works by stimulating the immune system
• Genetic modification of plants increases the amount of tillage and use of chemical insecticides
• Sex-linked recessive allele

  • Only expressed if both chromosomes carry the allele/gene in females/homozygous
  • Always expressed in the male, (since Y is not homologous)

  
• Gel electrophoresis


  Sorts DNA molecules based on their size
• Duchenne muscular dystrophy (DMD) is a degenerative muscular disease caused by a sex-linked recessive allele
• DNA technology does not limit genomic studies to prokaryotes