3.4 Genetic information, variation and relationships

• What is DNA like in prokaryotes?

  are short, circular and not

  associated with proteins.
• What is DNA like in eukaryotic?

  very long, linear and associated with proteins, called histones.
• What does a chromosome consist of?

  DNA molecule packed together with proteins
• what sub-cellular organelle also contain DNA?

  mitocondria and chloroplast
• what is the DNA like in mitochondria and chloroplasts?

  hort, circular and not associated with protein.
• What is a gene?

  A base sequence of DNA
• What does a gene code for?

  the amino acid sequence of a polypeptide

  a functional RNA (including ribosomal RNA and tRNAs).
• what does a gene occupy for?

  a fixed position, called a locus, on a particular DNA molecule.
• what is a triplet?


  a sequence of 3 DNA bases
• what does a triplet code for?


  for a specific amino acid
• what is the genetic code?

  universal, non-overlapping and degenerate.
• what does universal mean?

  The same specific base triplets code for the same amino acids in all living things
• What does non-overlapping mean?

  Each base in the sequence is only read once
• What does degenerate mean?


  Some amino acids are coded for by more than one base triplet
• in eukaryotic cells what does nuclear DNA not code for?

  polypeptides
• What are exons?


  coding regions of DNA
• What are introns?


  non-coding regions
• what is the genome?


  complete set of genes in a cell
• What is a proteome?


  full range of protein that a cell is able to produce
• How may amino acids are there?

  20
• what is the structure of a messenger RNA?

  mRNA is a long, single-stranded molecule consisting of nucleotides attached by phosphodiester bonds.
• what is the function of messenger RNA?


  Carries information specifying amino acid sequences of proteins from DNA to ribosomes
• what is the structure of transfer RNA?

  tRNA has an L shaped 3D structure
• what is the function of transfer RNA?

  the transfer RNAtransfers each amino acid to the ribosomeas it is specified by coded messages in mRNA.
• What does transcription produce?

  mRNA from DNA
• What is the role of RNA polymerase? (transcription)

  joining mRNA nucleotides
• what results after transcription in eukaryotic?

  the production of pre- mRNA; this is then spliced to form mRNA.
• what results after transcription in prokaryotic?

  the production of mRNA from DNA.
• what does translation produce?

  polypeptides from the sequence of codons carried by mRNA.
• What is the role of Ribosomes in Translation?

  Ribosomes use the sequence of codons in mRNA to assemble amino acids into polypeptide chains.
• What is the role of tRNA in translation?

  It binds to an mRNA codon and carries the corresponding amino acid.
• what is the role of ATP in translation?


  ATP breaks into ADP provides the energy needed for the bond between the amino acid and the tRNA molecule to form
• what is the structure of ATP?

  
• What is splicing?


  Removing introns from RNA and sealing exons together
• what does gene mutations involve?

  a change in the base sequence of chromosomes
• how does gene mutations occur?

  rise spontaneously during DNA replication and include base deletion and base substitution
• how does a gene mutation not causes any harm?

  Due to the degenerate nature of the genetic code meaning that ot all base substitutions cause a change in the sequence of encoded amino acids
• What are mutagenic agents?

  Outside factors that increase basic mutation rate.
• What do mutagenic agents do?

  can increase the rate of gene mutation
• what are some examples of mutagenic agents?


  Ultraviolet radiation, poor diet, occupation, nuclear radiation, smoking, stress, age