Overview

• What is the process by which mRNA is formed in eukaryotic cells?

  Transcription
• What happens to hydrogen bonds between DNA bases during transcription?

  They break
• Which DNA strand acts as a template for mRNA formation?

  Only one DNA strand
• What aligns next to their complementary bases on the template strand during transcription?

  Free RNA nucleotides
• In RNA, which base is used in place of thymine?

  Uracil
• What does RNA polymerase do during transcription?

  Joins adjacent RNA nucleotides
• What type of bonds does RNA polymerase form during transcription?

  Phosphodiester bonds
• What is formed after splicing pre-mRNA?

  Mature mRNA
• How does mRNA production differ in eukaryotic and prokaryotic cells?

  • Pre-mRNA is produced in eukaryotes
  • mRNA is produced directly in prokaryotes
  • Prokaryotic genes lack introns, no splicing occurs
• What is the first step in translation?

  mRNA attaches to a ribosome
• What brings a specific amino acid during translation?

  tRNA
• What binds to the complementary mRNA codon during translation?

  tRNA anticodon
• What forms between two amino acids during translation?

  Peptide bond
• What provides energy for peptide bond formation during translation?

  Hydrolysis of ATP
• What happens to tRNA after it joins an amino acid to the polypeptide?

  It is released
• What does the ribosome do as it moves along mRNA?

  Forms the polypeptide
• What is the role of ATP in translation?

  Releases energy for peptide bond formation
• What are the roles of tRNA and ribosomes in translation?

  tRNA:

  • Attaches to specific amino acids
  • Anticodon pairs with mRNA codon
  • Brings amino acids together for peptide bond formation

  
  

  Ribosomes:

  • Bind mRNA and tRNAs
  • Catalyze peptide bond formation
  • Move along mRNA during translation
• How can the base sequence of nucleic acids relate to the amino acid sequence of polypeptides?

  Using a genetic code to identify codons
• What is the complementary tRNA anticodon for the mRNA codon ACG?

  UGC
• How does the sequence of codons on mRNA relate to the DNA template strand?

  They are complementary
• What is the base sequence of the DNA template strand for mRNA sequence ACG UAG AAC?

  TGC ATC TTG
• What is a gene mutation?

  A change in the base sequence of DNA
• What can cause gene mutations to arise?

  Spontaneously during DNA replication
• What is a mutagenic agent?

  A factor that increases mutation rate
• How can a mutation lead to a non-functional protein?

  Changes amino acid sequence in polypeptide
• What happens to the protein's tertiary structure due to a mutation?

  It changes shape
• What is the effect of a substitution mutation?

  Changes one amino acid in polypeptide
• How does a deletion mutation affect the DNA sequence?

  Changes sequence of DNA triplets
• What is the outcome of a deletion mutation on the protein?

  Changes tertiary structure of protein
• What are the features of homologous chromosomes?

  • Same length
  • Same genes at same loci
  • May have different alleles
• What is the difference between diploid and haploid cells?

  Diploid has 2 sets, haploid has 1
• What happens during meiosis I?

  Homologous chromosomes are separated
• What is the outcome of meiosis II?

  Separates chromatids
• Why is the number of chromosomes halved during meiosis?

  Homologous chromosomes are separated
• How does crossing over create genetic variation?

  Exchanges alleles between non-sister chromatids
• What does independent segregation create during meiosis?

  Diverse combinations of chromosomes
• How is genetic variation increased within a species?

  • Random fertilization of gametes
  • New allele combinations formed
  • New maternal and paternal chromosome combinations
• What are the outcomes of mitosis and meiosis?

  Mitosis:

  • Produces 2 daughter cells
  • One division

  
  

  Meiosis:

  • Produces 4 daughter cells
  • Two divisions
• What is the difference between eukaryotic and prokaryotic DNA in terms of structure?

  Eukaryotic DNA is linear; prokaryotic DNA is circular