Unit 2a-Genetic information

• What is a gene?

  small section of DNA that codes for an amino acid sequence of a polypeptide and functional RNA
• Name the fixed position occupied by a gene on a DNA molecule?

  locus
• What is the triplet code?

  3 bases of DNA which code for a specific amino acid
• What does it mean if the triplet code is described as degenerate?

  there is more than one triplet code for one amino acid
• What are the bases of a complimentary mRNA sequence from the bases ATCG from a DNA sequence?

  UAGC
• What nature of the genetic code makes genetic engineering possible?

  universal
• What are the 3 properties of the genetic code?

  universal

  non overlapping

  degenerate
• What is the difference between the DNA found in eukaryotes and in prokaryotes?

  longer

  linear

  condensed and coiled into chromosomes

  contains histones
• What is the name for the point which joins the chromatids?

  Centromere
• What is the function of histone proteins?

  structural support for chromosomes

  allows DNA to wrap around it to condense into chromosomes
• Name the protein associated with DNA in a chromosome?

  Histones
• When are chromosomes visible under a microscope?

  Prophase
• How many homologous pairs of chromosomes does a human have?

  23
• What are alleles?

  different forms of a gene
• What is a gene mutation?

  change in the sequence of DNA bases
• Explain why not all mutations cause a change in the structure of a polypeptide?

  triplet codes are degenerate and a large amount of an organisms DNA is non coding
• What is a homologous pair of chromosomes?

  two chromosomes that carry the same genes
• What are the 2 types of RNA involved in protein synthesis?

  mRNA and tRNA
• What is a codon?

  3 bases on an mRNA strand that code for a specific amino acid
• What is a genome?

  entire set of genes in an organism
• What is a proteome?

  entire set of proteins produced by the genome
• Once the mRNA leaves the nucleus and reaches the ribosome what does it act as?

  Template for protein synthesis
• What is the structure of tRNA?

  single stranded chain that folds into a clover leaf shape and held together with hydrogen bonds with an amino acid binding site and an anticodon region
• What are the 3 bases on the amino acid binding site in a tRNA molecule?

  ACC
• What is transcription?

  DNA is transcribed and a mRNA molecule is produced
• What is translation?

  mRNA is translated and an amino acid sequence is produced
• Describe how mRNA is formed by transcription in eukaryotic cells?

  Hydrogen bonds between DNA base pairs are broken

  One DNA strand acts a template

  Free RNA nucleotides line up in complimentary base pairs

  Uracil pairs with Adenine and ( T-A, C-G )

  RNA polymerase joins nucleotides which forms phosphodiester bonds

  Pre-mRNA is spliced to form mRNA
• From what direction is mRNA transcribed from?

  5 prime to 3 prime
• From what direction is DNA unzipped in?

  3 prime to 5 prime
• What are exons?

  triplet sequence that codes for a polypeptide
• What are introns?

  non coding DNA
• What is splicing?

  introns are removed and exons are stuck back together
• Describe where the introns are found within a genome?

  between genes
• Describe how a polypeptide is formed by translation of mRNA?


  mRNA attaches to ribosomes

  tRNA anticodons bind to complementary mRNA codons

  tRNA brings a specific amino acid

  Amino acids join by peptide bonds with the use of ATP

  tRNA released after amino acid joins the polypeptide

  ribosomes moves along the mRNA to form the polypeptide
• Which subunit of the ribosomes does tRNA bind on?

  large subunit
• What are the 3 types of RNA?

  mRNA

  tRNA

  ribosomal RNA ( rRNA)
• Which 2 types of RNA are functional RNA?

  tRNA

  rRNA