DNA, genes, protein synthesis

• What are the three components of nucleotides?

  A pentose sugar, a phosphate group, an organic base
• How is DNA structured?

  It is double-stranded with a helix shape
• What role does DNA play in organisms?

  It carries genetic information and determines inherited characteristics
• What are the components of RNA?

  A ribose sugar, a phosphate group, an organic base
• What is the role of RNA?

  Transfers genetic information from DNA to ribosomes
• Which bases are classified as purines?

  Adenine and guanine
• Which bases are classified as pyrimidines?

  Cytosine, thymine, and uracil
• How does DNA in eukaryotic cells differ from prokaryotic cells?

  Eukaryotic DNA is long, linear, and found in the nucleus
• What is the genetic code?

  The order of bases on DNA that codes for amino acids
• What are the features of the genetic code?

  Non-overlapping, degenerate, and universal
• What is a gene?

  A sequence of bases that codes for amino acids
• What is a locus?

  The fixed position on a DNA molecule occupied by a gene
• What is an allele?

  Different versions of the same gene at the same locus
• What are exons and introns?

  Exons code for amino acids; introns do not
• Where are introns found?

  Between exons within genes
• What is the genome?

  The complete set of genetic information
• What is the proteome?

  The complete set of proteins produced by a cell
• Describe the structure of messenger RNA (mRNA).

  A long, single strand complementary to DNA
• What are the advantages of using mRNA rather than DNA for translation?

  Shorter, contains uracil, breaks down quickly
• What are the advantages of using mRNA for translation?

  • Shorter and contains uracil
  • Breaks down quickly, preventing excess polypeptide
  • Single-stranded and linear for ribosome movement
  • Contains no introns
• Describe the structure of transfer RNA (tRNA).

  A single strand folded into a clover leaf shape
• What is produced by transcription?

  mRNA
• Where does transcription take place?

  In the nucleus
• Outline the process of transcription.

  1. DNA uncoils into two strands with exposed bases
  2. One strand is used as a template
  3. Free nucleotides line up next to complementary bases
  4. Nucleotides are joined by RNA polymerase
• What happens to mRNA after transcription in eukaryotic cells?

  Pre-mRNA is spliced to remove introns
• Where does mRNA go after transcription?

  It moves out of the nucleus
• What is produced by translation?

  Proteins
• Where does translation take place?

  In the cytoplasm on ribosomes
• Outline the process of translation.

  1. tRNA anti-codon attaches to complementary mRNA bases
  2. Amino acids bonded to tRNA form peptide bonds
  3. Polypeptide chain continues until a stop codon is reached
  4. The process requires ATP