DNA as the Genetic Material Flashcards
The 2 helical strands of DNA run parallel to each other, but go in opposite directions.
Antiparallel
Nitrogen base + the sugar =
without the phosphate group
Nucleosides
Nitrogenous base, sugar, and 1-3 phosphates =
Nucleotides
An array of nucleotides.
DNA
RNA base pairs:
A + U
C + G
DNA base pairs:
A + T
C + G
Process of copying DNA for proper cell division to occur.
Replication
Part of cell cycle.
Cell grows, carries out cell processes, and replicates its DNA.
Interphase
Part of cell cycle.
Cell undergoes cell division.
Mitosis
How DNA is copied to make DNA for new cells.
Replication
Enzyme that separates the DNA strands into a lagging strand and a leading strand.
Unzips the double helix.
Helicase
Easily replicated because it runs in the same direction as the original strand.
Replicated continuously.
Leading Strand
Important enzymes in DNA replication:
Helicase
DNA Polymerase
Primase
Ligase
Topoisomerase
Process of replication is described this way because each DNA molecule is made up of 1 old conserved strand of DNA and 1 newly synthesized strand.
Semi-Conservative
Adds the appropriate base pairs.
DNA Polymerase
Opposite in direction.
DNA polymerase can’t replicate as easily.
Lagging Strand
On the lagging strand.
RNA primer attaches and the DNA polymerase adds small groups of base pairs.
What are these small groups of base pairs called?
Okazaki Fragments
DNA sequence with altered nucleotides.
Can change the function of the DNA sequence or even render it unstable.
Mutation
The parent DNA separates and a newly synthesized strand is added to each parent strand.
Each double helix of DNA created by replication contains 1 DNA strand from the parent and 1 newly synthesized DNA strand.
Semi-Conservative Replication
Main steps in DNA replication:
Initiation
Elongation
Termination
Runs 5’ to 3’.
Leading Strand
Runs 3’ to 5’.
Antiparallel strand. Complementary to the leading strand.
Lagging Strand
Helicase (enzyme) break down the hydrogen bonds between base pairs (“unzips”). —> 2 strands of DNA must be separated to use the DNA as a template for replication. —> DNA replication fork.
Topoisomerase (enzyme) surround the “unzipped” separated strands of DNA and relax the twisting of helices.
Parent DNA is separated into 2 strands: leading strand and lagging strand.
Primase (enzyme) builds short stretches of RNA called primers that are required to start elongation.
Initiation
Enzyme breaks down the hydrogen bonds between base pairs.
Separates strands to be used as a template.
“Unzips” DNA strand.
Helicase
Enzyme that surrounds the “unzipped” separated strands of DNA and relax the twisting of helices.
Relaxes DNA and controls supercooling (occurs as DNA double helix is unwound).
Topoisomerase
Helicase unzips the strands and the DNA develops a “forked” structure, which lets replication happen.
DNA Replication Fork
Enzyme builds short stretches of RNA called primers that are required to start elongation.
Is the initializer.
Required to lay down short stretches of RNA nucleotides that are complementary to the DNA template before DNA nucleotides can be added to the template.
Primase
Enzyme responsible for forming new copies of DNA.
Travels down the DNA strand. —> Works in the 5’ to 3’ direction.
Adds DNA nucleotides complementary to the template strand to form the new strand of DNA.
DNA Polymerase
DNA polymerase travels down the DNA strand and adds new nucleotides to each of the 2 DNA strands (leading strand and lagging strand).
Elongation
DNA oriented in 5’ to 3’ direction.
DNA polymerase adds the new nucleotides to the RNA primer and then to the newly synthesized DNA strand in a continuous fashion.
Leading Strand
Antiparallel and runs in the 3’ to 5’ direction. —> DNA polymerase MUST work in the 5’ to 3’ direction. —> This leads to the creation of short, discontinuous fragments called Okazaki fragments.
Lagging Strand
Short, discontinuous fragments on the lagging strand.
Okazaki Fragments
Helps glue the Okazaki fragments together to form a complete DNA molecule.
Joins Okazaki fragments together to create a continuous DNA strand.
Ligase
Prokaryotic chromosome first replicates, then 2 copies of the chromosome associate with different part of the cell membrane, the the cell pulls apart into 2 identical cells.
Asexual reproduction.
Binary Fission
Difference between RNA and DNA:
RNA is a single helix, DNA is a double helix.
RNA has uracil (U), DNA has thymine (T).
RNA has the sugar ribose, DNA has the sugar deoxyribose.
RNA has fewer base pairs than DNA.
