DNA Damage and Repair Mechanisms Quiz

A change in the chemical structure of DNA, which can be caused by various factors, including UV light, heat, and chemical agents.

A permanent change in the sequence of DNA bases, which can lead to changes in the protein coded by that DNA.

The process by which cells repair damaged DNA, restoring it to its original state.

A type of DNA repair that introduces mutations. While it's not always ideal, it can promote genetic variation.

A form of DNA damage caused by UV light, where two thymine bases on the same strand of DNA become linked together.

A category of chemical agents that can damage DNA by mimicking bases and pairing incorrectly during replication.

A category of chemical agents known for their ability to insert between DNA bases, disrupting its structure and potentially causing mutations.

A category of chemical agents that can damage DNA by altering its structure, often causing the formation of bonds between bases, leading to changes in its shape.

The most common form of DNA in living organisms, characterized by a right-handed helical structure.

A less common form of DNA, also right-handed, but with a wider helix and a shorter base spacing.

A rare left-handed form of DNA, characterized by an alternating purine-pyrimidine sequence, a shallow major groove, and a temporary nature.

The distance between two consecutive base pairs in a DNA helix.

The number of base pairs per complete turn of the DNA helix.

The wide, open groove present in DNA, where proteins can bind and interact.

The narrow, less open groove in DNA.

The angle of the base pairs relative to the helix axis.

The rotation of the base pairs relative to each other.

Single type of RNA polymerase (RNAP) responsible for synthesizing RNA in bacteria, which is a complex of proteins.

The strand of DNA that is read and used as a template during transcription to create a new RNA molecule.

The non-transcribed strand of DNA which has the same sequence as the newly synthesized RNA (except for uracil instead of thymine).

The fundamental unit of the RNA polymerase in bacteria, composed of α2ßß'ω subunits, excluding the sigma factor. Responsible for the elongation process.

A protein that helps initiate transcription by recognizing specific DNA sequences called promoters. Each σ factor binds to a different -35 region, allowing regulation of different genes.

Short sequences of DNA that signal the start of gene transcription. They contain specific motifs like the -10 region (Pribnow box) and the -35 region, recognized by RNAP.

The -10 region in a promoter typically contains a TATAAT sequence and is vital for RNAP binding.

A region in a promoter located roughly 35 base pairs upstream of the transcription start site, recognized by the σ factor.

The state of the promoter where RNAP is bound to DNA, but the DNA hasn't opened up yet.

The state of the promoter where RNAP has unwound the DNA, allowing access to the template strand for transcription.

The stage of transcription where RNAP starts synthesizing RNA using the template strand.

The process where RNAP moves along the DNA template strand, creating a new RNA molecule by adding ribonucleotides.

The termination of transcription, where the process of RNA synthesis stops.

A mechanism of transcription termination that relies on specific DNA sequences within the gene that form a hairpin structure in the RNA transcript.

A protein that helps terminate transcription by binding to RNA and unwinding it from the DNA template.

A sequence in the RNA, usually G-rich, that Rho protein binds to. It's crucial for Rho-dependent termination of transcription.

RNA uses ribose sugar, while DNA uses deoxyribose sugar. This difference in structure makes RNA less stable than DNA.

RNA contains uracil, while DNA contains thymine. Both bases pair with adenine, but uracil is found in RNA and is more reactive.

RNA is typically single-stranded, while DNA is double-stranded. This allows RNA to fold into complex structures.

RNA can have enzymatic activity, meaning it can act as a catalyst for chemical reactions. This property is uncommon for DNA.

RNA is typically shorter than DNA, and has a much shorter lifespan. This is due to its less stable structure.

RNA can fold back on itself, forming complex structures like hairpin loops, bulges, and internal loops.

Pseudoknots are complex RNA structures where a loop folds back on itself, creating a knot-like appearance. They are stable and can interact with other molecules.

Non-standard base pairing, where bases other than G-C and A-U pair, is possible in RNA but less common. These unusual pairings contribute to RNA's structural diversity.

Supercoiling refers to the tightly packed, coiled structure of DNA. It influences DNA's stability and accessibility for various processes.

RNA's ability to fold into diverse structures allows it to recognize and interact with specific molecules. This is crucial for its various roles in the cell.

The number of complete turns one strand of DNA makes around the axis of the helix. It depends on the length of the strand and can be positive (right-handed turns) or negative (left-handed turns).

The most energetically favorable form of DNA, with 10 base pairs per turn, has a twist of 1 (T=1).

The process of changing the twist of DNA, which can either decrease the twist (underwinding) or increase it (overwinding). This can lead to tension within the DNA molecule.

When DNA is underwound or overwound, it relieves tension by forming supercoils. Underwound right-handed DNA has negative supercoiling, while overwound right-handed DNA has positive supercoiling.

Enzymes that alter DNA coiling by creating transient breaks in the DNA molecule. This allows the DNA to relax or become more tightly coiled.

A type of topoisomerase that creates a transient single-strand break in DNA, allowing it to rotate. Type IA topoisomerases move in one direction and relax negative supercoiling without requiring ATP. Type IB topoisomerases move in any direction and can relax both negative and positive supercoiling without requiring ATP.

A type of topoisomerase that creates a transient double-strand break in DNA. Type II topoisomerases can move in any direction, require ATP, and can relax both negative and positive supercoiling.

The process by which topoisomerases relieve stress caused by underwinding or overwinding. This involves breaking and rejoining DNA strands to allow the DNA to relax and unwind.

The ability of DNA to move more easily through pores, allowing for processes like replication and transcription to proceed more efficiently.

The process of generating a new copy of a DNA molecule. Topoisomerases play a crucial role in DNA replication, relieving tension and allowing DNA to unwind and replicate efficiently.

DNA is wound tighter than its relaxed state, causing the molecule to coil up on itself. It's like a tightly wound spring.

DNA is wound looser than its relaxed state, causing the molecule to unwind. It's like a loose spring.

A type of topoisomerase that introduces negative supercoiling into DNA, using energy from ATP. It is a crucial enzyme in bacteria.

The creation of nucleotides, the building blocks of DNA and RNA, from simpler molecules. It's an essential process for cell growth and division.

The breakdown of nucleotides into their simpler components. It's important for recycling nucleotides and maintaining a balance within the cell.

A type of nucleotide synthesis that starts with ribose-5-phosphate and adds a series of molecules to build a purine base, ending with IMP (inosine monophosphate).

A complex pathway where IMP (inosine monophosphate) is converted to AMP (adenosine monophosphate) or GMP (guanosine monophosphate), creating the building blocks for DNA and RNA.

A pathway that breaks down purine nucleotides into simpler molecules, eventually ending with uric acid, which is excreted in urine. It's essential for recycling purines.