DNA genes and proteinsynthesis

• Mitochondrion


  Double membrane. Responsible for aerobic respiration in eukaryotes.
• Chloroplast


  Organelle responsible for carrying out photosynthesis
• Chromosomes


  Threadlike molecules of DNA (and associated histones in eukaryotes)
• Universal


  Codons all code for the same amino acid in all living things
• Degenerate


  More than one codon can code for each amino acid
• Nucleic acid


  Pentose, phosphate and organic nitrogenous base
• Locus


  Position of a gene on a chromosome
• Histone


  A protein around which DNA is wrapped in chromosomes
• Non-overlapping


  Codons do not overlap. Each base is read only once.
• Non-coding multiple repeat


  An area of DNA, not in a gene, where the base sequence repeats multiple times.
• Triplet codon


  Three base sequence on mRNA that codes for an amino acid
• What is a Genome?

  The entire set of genetic material in an organism/complete set of genes in a cell
• What is a gene?

  A length of DNA that codes for a protein
• The gene is a base sequence of DNA that codes for:

  - the amino acid sequence of a polypeptide

  - a functional RNA (including ribosomal RNA and tRNAs)
• What is a proteome?

  The full range of proteins that a cell is able to produce
• What is a base sequence?

  Sequence of bases found in DNA or RNA
• What is DNA like in prokaryotes?

  short, circular and not associated with proteins
• What organelles contains DNA in eukaryotic cells? What is this DNA similar too?

  Mitochondria and chloroplasts, their DNA is like the DNA found in eukaryotes
• Pre-mRNA


  Only in eukaryotes. Copy of RNA from DNA. Contains introns and exons.
• What is mRNA?


  Messenger RNA. Pre-mRNA with introns spliced out
• Is the structure of mRNA?

  a long, single-stranded molecule consisting of nucleotides attached by phosphodiester bonds
• What is tRNA?


  Transfer RNA. Has anticodon. Brings amino acids to ribosomes.
• What is the structure of tRNA?

  a distinctive folded structure with three hairpin loops that form the shape of a three-leafed clover
• What is transcription?


  Copying of DNA to RNA. In the nucleus.

  The production of mRNA from DNA. RNA polymerase joins the mRNA nucleotides
• What are the steps of transcription?

  1. DNA helicase unzips and unwinds the DNA, breaking the hydrogen bonds between the bases.

  2. Free RNA nucleotides are complementary to one of the DNA strands. They are attracted to their complementary base by hydrogen bonds.

  3. RNA polymerase joins the nucleotides by making Phosphodiester bonds.

  -> This forms a single strand of pre-mRNA

  4. The pre-mRNA is spliced to remove the non-coding part of the mRNA.
• In prokaryotes, what does transcription result directly in?

  The production of mRNA from DNA
• What is splicing?


  Removing introns from RNA and sealing exons together
• What is a intron?

  sequence of DNA that is not involved in coding for a protein
• What is an extron?

  Genes that are expressed (code for protein)
• What is the first step of transcription?

  DNA helicase unzips and unwinds the DNA, breaking the hydrogen bonds between the bases.
• What is the second step of transcription?

  Free RNA nucleotides are complementary to one of the DNA strands. They are attracted to their complementary base by hydrogen bonds.
• What is the third step of transcription?

  RNA polymerase joins the nucleotides by making Phosphodiester bonds.

  -> This forms a single strand of pre-mRNA
• What is the fourth step of transcription?

  The pre-mRNA is spliced to remove the non-coding part of the mRNA.
• What is DNA helicase?

  the enzyme that breaks the h-bond bxt the two strands of DNA to "unzip" double helix
• What is RNA polymerase?

  An enzyme that links together the growing chain of RNA nucleotides during transcription, using a DNA strand as a template.
• In prokaryotes, what does transcription result directly in?

  The production of mRNA from DNA.
• In eukaryotes, what does transcription result directly in?

  The production of pre-mRNA which is the spliced to form mRNA.
• What is translation?


  Converting mRNA code into polypeptide. On ribosomes.
• What is the first step of translation?

  mRNA molecules attach to a ribosome. The codon on the mRNA is complementary to the anticodon on the tRNA.
• What is the second step of translation?

  A second tRNA molecule bonds with the next three exposed bases, this brings a different amino acid. The two amino acids are held together by a peptide bond.