DNA and Protein

• DNA replication is semi-conservative: each strand of the original double-stranded molecule acts as a template for the formation of a new strand.
• The genetic code is degenerate, meaning that more than one codon can specify the same amino acid.
• What does DNA stand for?

  deoxyribonucleic acid
• What are the 4 nitrogenous bases found in DNA?

  Adenine, Thymine, Guanine, Cytosine
• What are the 4 nitrogenous bases found in RNA?

  Adenine, Uracil, Guanine, Cytosine
• How many bonds join adenine and thymine/uracil?

  Two
• How many bonds join cytosine and guanine?

  Three
• What type of bonds are formed between the bases?

  Hydrogen bonds.
• What type of bonds are formed between the backbone?

  Covalent bonds.
• What are the three components of a nucleotide?

  sugar, phosphate, nitrogenous base
• What is the replication fork?

  the fork created by the partially unzipped DNA
• What does helicase do?

  unravels the DNA and unzips the bases by breaking the hydrogen bonds
• What does DNA ligase do?

  joins the sugar and phosphate backbone together
• What does DNA polymerase do?

  binds free DNA nucleotides to the open strands
• Which way does DNA polymerase work?

  5' to 3'
• What are the Okezaki fragments?

  Short DNA chunks on the lagging side, joined by polymerase
• What is RNA used for?

  Coding for proteins
• What are the two stages in protein synthesis?

  Transcription and translation
• Where does transcription occur?

  IN the nucleus
• Where does translation occur?


  In the cytoplasm, at the ribosome
• what does RNA stand for?

  ribonucleic acid
• what does mRNA stand for?

  messenger RNA
• What does tRNA stand for?

  transfer RNA
• What does rRNA stand for?

  ribosomal RNA
• In transcription, which side of the DNA are the RNA nucleotides added to?

  the template strand
• How does RNA polymerase know where to begin transcription?

  a promoter protein attaches to the beginning of the gene
• What stage occurs between transcription and translation?

  RNA processing (splicing)
• Which sections of DNA are removed in RNA splicing?

  Introns
• Which enzyme removes introns?

  the splicesome
• What is the mRNA referred to before and after splicing?

  before: pre-mRNA; after: mature mRNA
• What is a codon?


  A set of three bases on the mRNA strand
• What is an anti-codon?


  A set of three bases attached to a tRNA and amino acid which binds to the codons
• What are the four levels of protein folding?

  primary, secondary, tertiary and quarternary
• What is primary structure?

  a polypeptide chain
• What is secondary structure?

  hydrogen bonds are formed between some amina acids, forming alpha helixes and beta pleated sheets
• What is tertiary structure?

  disulphide bridges are formed between alpha helices and beta pleated sheets
• What is quarternary structure?

  multiple proteins bond
• What are the two key types of proteins?

  Fibrous and globular
• What are fibrous proteins?

  they're usually structural, with only primary or secondary bonding
• What are some examples of fibrous proteins?

  ketatins, collagens and elastins