Lecture 3 / Test

• What is an example of a virus causing cancer?

  A virus can penetrate a cell's DNA and hijack its machinery.
• What happens during DNA replication between cell divisions?

  DNA is replicated to ensure each new cell has a complete set of genetic information.
• How does DNA direct the synthesis of specific proteins?

  DNA sequences are transcribed into RNA, which is then translated into proteins.
• What was the scientific community's initial belief about genetic material?

  They believed that proteins carried genetic information, not DNA.
• How many amino acids make up proteins?

  22 amino acids.
• What are the four constituents of DNA?

  Nitrogenous bases, deoxyribose sugar, phosphate group, and nucleotides.

  
• Who discovered that DNA is the transforming factor in bacteria?

  Oswald Avery.
• What did Frederick Griffith's experiment demonstrate?

  That non-pathogenic and pathogenic strains of bacteria could affect each other.
• What is the full form of DNA?

  Deoxyribonucleic Acid.
• What are the two types of nitrogenous bases in DNA?

  Purines and pyrimidines.
• What sugar is found in DNA?

  Deoxyribose.

  
• What is a nucleoside?

  A base plus a sugar.

  
• What sugar is found in RNA?

  Ribose.

  
• What is a nucleotide?

  A base plus a sugar plus a phosphate group.

  
• Who proposed the double-helix structure of DNA?

  Watson and Crick.
• What did Erwin Chargaff discover about DNA?

  There is an equal amount of adenine to thymine and cytosine to guanine.
• What is the diameter of the DNA double helix?

  2 nm.

  
• What does it mean for DNA strands to be anti-parallel?

  They run in opposite directions, 5' to 3' and 3' to 5'.

  
• What is the role of helicase in DNA replication?

  It unwinds the DNA double helix by breaking hydrogen bonds.

  
• What is the function of DNA polymerase during replication?

  It synthesizes new DNA strands in a 5' to 3' direction.

  
• What are Okazaki fragments?

  Short sections of DNA synthesized on the lagging strand.
• What is the role of primase in DNA replication?

  It creates an RNA primer for DNA polymerase to start synthesis.
• What enzyme joins Okazaki fragments together?

  DNA ligase.
• What is the origin of replication?

  The specific sequence where DNA replication begins.
• How do prokaryotic chromosomes differ from eukaryotic chromosomes?

  Prokaryotic chromosomes are circular and have a single origin of replication.
• Where is mitochondrial DNA inherited from?

  It is exclusively inherited from the mother.
• What is a karyotype?

  The number and form of chromosomes within a cell's nucleus.

  
• What are some differences between RNA and DNA?

  RNA contains ribose, is usually single-stranded, and has uracil instead of thymine.
• What are the steps of DNA replication?

  1. Helicase unwinds the DNA double helix.
  2. DNA polymerase synthesizes new strands in a 5' to 3' direction.
  3. Primase adds RNA primers for the lagging strand.
  4. DNA ligase joins Okazaki fragments together.

  
• What is the significance of multiple origins of replication in eukaryotic chromosomes?

  It allows for faster replication of long linear chromosomes.
• What concept does Richard Dawkins' "The Selfish Gene" propose?

  Adaptive evolution is about the competitiveness of genes, not individuals.
• What is the role of the sugar-phosphate backbone in DNA?

  It provides structural support to the DNA molecule.

  
• What is the function of the nitrogenous base pairs in DNA?

  They encode genetic information through specific sequences.
• What is the significance of hydrogen bonding between nitrogenous bases?

  It stabilizes the DNA double helix structure.

  
• How does the directionality of DNA strands affect replication?

  DNA polymerase can only synthesize in a 5' to 3' direction, affecting how strands are replicated.
• What is the role of the replication fork during DNA replication?

  It is the area where the DNA double helix is unwound and replication occurs.

  
• What happens to the mitochondria in sperm cells during fertilization?

  They are destroyed, leading to maternal inheritance of mitochondrial DNA.
• What is the significance of the 5' and 3' ends of DNA strands?

  They indicate the directionality of the DNA strands, which is crucial for replication.

  
• How does the structure of eukaryotic DNA differ from prokaryotic DNA?

  Eukaryotic DNA is linear and packaged in a nucleus, while prokaryotic DNA is circular and not membrane-bound.
• What is the role of histones in DNA packaging?

  Histones help to tightly pack DNA into a compact structure within the nucleus.