lecture 5 - dna replication Flashcards
(23 cards)
Why does DNA need to replicate?
DNA needs to replicate before cell division to ensure that each new cell receives a complete set of genetic instructions.
What is semi-conservative replication?
It is a process where half of the strands in each new DNA molecule come from the original DNA molecule.
What are the components of DNA?
DNA is composed of deoxyribose/pentose sugar, nitrogenous bases (purines and pyrimidines), and a phosphate group
What is the structure of DNA?
DNA has a double helix structure with two antiparallel strands held together by hydrogen bonds. Base pairs are adenine-thymine and cytosine-guanine.
What are the steps of DNA replication?
- DNA untwists as helicase breaks hydrogen bonds.
- Free-floating nucleotides pair with exposed bases on the template strand.
- DNA polymerase joins adjacent nucleotides via condensation reactions.
- Two strands retwist into a double helix.
What are gene mutations?
Mutations are changes in the genome that can occur during DNA replication.
What are examples of DNA mutations?
• Substitution: One base is replaced (e.g., ATT → ACT).
• Deletion: A base is removed (e.g., ATCCT → ATCT).
• Addition: A base is added (e.g., ATGCCT → ATGACCT).
• Duplication: A sequence is duplicated (e.g., ATGCCT → ATGCCCT).
• Inversion: A sequence is reversed (e.g., ATCGT → AGTCT).
• Translocation: A sequence is moved to a different location.
What is the purpose of mitosis?
To produce two genetically identical cells for growth, repair, or replacement of damaged cells.
Why is DNA negatively charged?
DNA is negatively charged because of the phosphate groups in its backbone.
In gel electrophoresis, how do DNA fragments move?
DNA fragments move towards the positive anode because of their negative charge.
In gel electrophoresis, which fragments move faster?
Shorter DNA fragments move faster than longer fragments.
How can an individual be described based on STR analysis?
An individual can be either heterozygous or homozygous for a specific STR.
How is the size of a DNA fragment determined?
Fragment size (e.g., 1 kb, 10 kb) is determined by comparing it to a DNA ladder in gel electrophoresis.
What is the guilty suspect in DNA profiling?
The suspect whose DNA matches the crime scene evidence.
What is semiconservative replication?
It is the process in which the double helix of a DNA molecule unwinds, and each strand acts as a template for constructing a new strand.
What is the role of DNA helicase in replication?
DNA helicase is an enzyme that breaks the hydrogen bonds between DNA bases, separating the two strands and exposing the nucleotide bases.
What does DNA polymerase do?
DNA polymerase joins DNA nucleotides together in a condensation reaction, forming phosphodiester bonds during DNA replication.
What is ATP, and why is it important?
ATP (Adenosine triphosphate) is an activated nucleotide that serves as an energy carrier. Its hydrolysis, catalyzed by ATP hydrolase, releases energy by forming ADP and inorganic phosphate.
How is ATP synthesized?
ATP is synthesized from ADP and a phosphate molecule in a condensation reaction catalyzed by ATP synthase.
What is the function of ATP hydrolase?
ATP hydrolase catalyzes the hydrolysis of ATP into ADP and inorganic phosphate, releasing energy.
What are polymerases?
Polymerases are a group of enzymes that catalyze the formation of polymers, such as DNA or RNA, from monomers.
Why is ATP critical for DNA replication?
ATP provides the energy required for enzymatic activities such as the action of helicase and polymerase during DNA replication.
What are the steps in DNA replication?
- DNA helicase unwinds the double helix and separates the strands.
- Each original strand serves as a template for complementary base pairing.
- DNA polymerase joins nucleotides together to form the new strand.
- ATP supplies energy for the process.
