PROTEIN SYNTHESIS

• What are the long chains of nucleotides in DNA called?

  DNA
• How are two adjacent DNA chains held together?

  By hydrogen bonds
• What are the four nitrogenous bases in DNA?

  Adenine, Thymine, Cytosine, Guanine
• What does the genetic code consist of?

  Sequence of nucleotides
• What does a triplet code specify?

  Single amino acid
• What is a triplet in DNA?

  A sequence of three nitrogenous bases
• What is a gene?

  Functional unit of heredity
• What does a gene contain?

  All DNA nucleotides for a specific protein
• How many nucleotides can a gene vary in size?

  ~300 to 3000 nucleotides
• What is gene activation?

  Removal of histones and DNA uncoiling
• What is messenger RNA (mRNA) assembled by?

  Enzymes
• What does mRNA contain information in?

  Triplets (codons)
• Where does mRNA leave the nucleus?

  Through pores
• What does transfer RNA (tRNA) contain?

  Triplets (anticodons)
• What does each type of tRNA carry?

  A specific amino acid
• What are the key events of protein synthesis?

  1. DNA triplets determine mRNA codons.
  2. mRNA codons determine tRNA sequence.
  3. tRNA sequence determines amino acid sequence in polypeptide.
• What is transcription?

  Production of RNA from DNA template
• What types of RNA are formed during transcription?

  All three types of RNA
• What occurs during gene activation in transcription?

  Occurs at control segment of gene
• What does RNA polymerase do?

  Binds to promoter and assembles mRNA
• What is the complementary mRNA for the DNA triplet TAC?

  mRNA AUG
• When does transcription end?

  When stop codon is reached
• What happens to mRNA after transcription?

  Detaches and DNA strands reassociate
• What is immature RNA?

  Contains triplets not needed for protein synthesis
• What are introns?

  Removed nonsense regions from RNA
• What are exons?

  Remaining coding segments in RNA
• What does editing of RNA create?

  Shorter, functional mRNA
• How does translation relate to mRNA?

  Uses mRNA created in nucleus
• Where does translation occur?

  In cytoplasm
• What binds to the small ribosomal subunit during translation?

  mRNA
• What happens during the binding of mRNA and tRNA?

  mRNA codons pair with tRNA anticodons
• What assembles around the mRNA strand during translation?

  Small and large ribosomal subunits
• How many kinds of tRNAs are there?

  More than 20 kinds
• What does the ribosome do during translation?

  Links amino acids forming dipeptide
• When does translation stop?

  Once stop codon is reached on mRNA
• What does the ribosomal subunits do after translation?

  Detach from mRNA
• How long does it take to produce a typical protein?

  ~20 seconds
• What can mRNA do after translation?

  Interact with other ribosomes
• How many ribosomes can attach to a single mRNA strand?

  Multiple ribosomes
• What does the plasma membrane act as?

  A barrier separating cytosol and ECF