DNA RNA SYNTHESIS

• What is the central dogma of molecular biology?

  DNA is transcribed to RNA, which is translated into proteins.
• What are the components of a nucleotide?

  Nucleotides are composed of a nitrogenous base, a sugar, and a phosphate group.

  
• How do nucleotides determine the function of genes?

  Nucleotides code for proteins, which determine the function of genes.
• What are the nitrogenous bases found in DNA?

  The nitrogenous bases in DNA are adenine (A), thymine (T), guanine (G), and cytosine (C).

  
• What are the nitrogenous bases found in RNA?

  The nitrogenous bases in RNA are adenine (A), uracil (U), guanine (G), and cytosine (C).

  
• What is the sugar component of RNA nucleotides?

  RNA nucleotides contain ribose sugar.
• How does RNA differ from DNA in terms of structure?

  RNA is single-stranded, while DNA is double-stranded.
• What is the role of the enzyme helicase in DNA replication?

  Helicase separates the two strands of DNA by breaking hydrogen bonds between nitrogenous bases.

  
• What is the function of DNA polymerase during DNA replication?

  DNA polymerase synthesizes the new strand of DNA using the old strand as a template.
• What is the process of DNA replication?

  1. Separation of the two strands of DNA.
  2. Breaking of hydrogen bonds by helicase.
  3. Use of the old strand as a template.
  4. Synthesis of the new strand by DNA polymerase.
  5. Resulting in two identical DNA molecules, each with one old and one new strand.

  
• What is the result of DNA replication?

  The result is two identical pieces of DNA with identical nucleotide sequences.

  
• What does each piece of DNA contain after replication?

  Each piece of DNA contains one "new" strand and one "old" strand of polynucleotide.

  
• What is synthesized at the leading strand during DNA replication?

  One RNA Primer
• In which direction does DNA polymerase build new polynucleotides on the leading strand?

  In the 5’ to 3’ direction
• What is generated as the replication fork extends away from the origin of replication (ORI)?

  An existing piece of DNA
• What does DNA polymerase do on the lagging strand?

  Builds a new short strand of polynucleotides in the 5’ to 3’ direction
• What does DNA polymerase reach on the lagging strand during synthesis?

  An existing piece of DNA
• What are the segments synthesized on the lagging strand called?

  Okazaki fragments
• How are RNA primers removed from Okazaki fragments?

  By DNA polymerase
• What enzyme joins Okazaki fragments together?

  DNA ligase
• Where does DNA replication begin?

  At particular sites called origins of replication (ORI)
• What is created when two strands of polynucleotides are separated during replication?

  A replication bubble
• What is located at the end of each replication bubble?

  A replication fork
• What is the function of helicase in DNA replication?

  To unwind the double helix at the replication forks
• What do single-strand binding proteins do during DNA replication?

  Bind to and stabilize single-stranded DNA
• What is the role of topoisomerase in DNA replication?

  To relieve the strain of twisting of the double helix
• What are the required proteins/materials for the addition of nucleotides during DNA replication?

  DNA polymerases, RNA primers, primase, and DNA ligase
• To which end do DNA polymerases add nucleotides?

  To the free 3’ end of an existing strand
• In which direction can a new DNA strand be built?

  In the 5’ to 3’ direction
• Why does DNA polymerase require an existing 3’ end to add a nucleotide?

  Because it needs a primer
• How do leading and lagging strand synthesis differ in terms of rate?

  They are synthesized at different rates
• Why does DNA polymerase synthesize DNA in the 5’ to 3’ direction?

  Because DNA is antiparallel