General Study Notes Quiz

A mutation that changes the reading frame of a gene, leading to a complete change in the amino acid sequence.

This repair pathway specifically removes damaged or incorrect bases from DNA by using enzymes called DNA glycosylases.

A mutation that alters a codon but results in the same amino acid being coded for. This means no change to the protein sequence.

A DNA repair pathway that corrects errors made during DNA replication. It acts after replication is complete.

P53 is a crucial gene involved in cell cycle control and preventing tumor formation.

This protein is responsible for preventing the accumulation of DNA damage by slowing down the cell cycle.

A type of DNA damage caused by UV radiation where two adjacent pyrimidine bases (usually thymine) bind to each other.

This genetic disorder arises from defects in the nucleotide excision repair (NER) pathway, leading to an inability to repair UV-induced DNA damage.

DNA polymerase, an enzyme involved in DNA replication, can only add nucleotides to the 3' end of a growing polynucleotide strand.

The replication fork is a Y-shaped structure that forms during DNA replication where both strands of DNA are replicated simultaneously.

Helicase is the enzyme responsible for separating the two strands of DNA during replication, breaking the hydrogen bonds holding them together.

DNA gyrase is a topoisomerase enzyme that relieves stress on the DNA helix during replication by introducing breaks in the DNA to prevent supercoiling (knotting).

The lagging strand is synthesized discontinuously in small fragments called Okazaki fragments.

The leading strand is synthesized continuously in the 5' to 3' direction, while the lagging strand is synthesized discontinuously in small fragments (Okazaki fragments) also in the 5' to 3' direction.

Nucleotides are the building blocks of DNA and RNA. They can be produced by the cell via two pathways: salvage pathways and synthetic pathways.

DNA replication in eukaryotes starts at multiple origins of replication on each chromosome, and proceeds bidirectionally from each origin.

Cytosine makes up 25% of the bases in a DNA sample.

DNA bases Guanine and Cytosine are a purine and a pyrimidine, respectively. Purines have a double-ring structure, while pyrimidines have a single-ring structure.

They are histone proteins.

The template strand is read in the 3' to 5' direction, and mRNA is synthesized in the 5' to 3' direction.

D-Ribose is the sugar found in RNA. It differs from the deoxyribose sugar found in DNA by having an extra hydroxyl group.

It is found in all eukaryotic cells.

Histone acetylases can influence DNA structure by opening up its conformation. This is because acetylation neutralizes the positive charge of histones, making them less tightly bound to DNA.

An operator region is a feature of prokaryotic gene regulation, not eukaryotic. It is a DNA sequence that binds to the repressor protein to control gene expression.

A regulatory mechanism in prokaryotes that controls the expression of genes involved in lactose metabolism. The operon is turned on in the presence of lactose, allowing the production of enzymes necessary for lactose breakdown.

The lac operon consists of three structural genes (lacZ, lacY, and lacA) that encode for proteins involved in lactose utilization. These genes are regulated by a promoter (where RNA polymerase binds) and an operator site (where the repressor protein binds).

A protein that binds to the operator region of the lac operon, blocking the transcription of the structural genes. In the absence of lactose, the repressor binds to the operator, preventing gene expression.

A molecule that binds to the repressor protein, changing its shape so that it cannot bind to the operator. This allows the transcription of the lac genes and the production of lactose-utilizing enzymes.

The process by which a gene is transcribed into RNA. This is the first step in gene expression where information from a DNA gene is copied into messenger RNA.

A sequence of DNA that signals the start of transcription. RNA polymerase binds to the promoter to initiate the process of copying DNA into RNA.

A type of RNA that carries the genetic code from DNA to the ribosomes, where proteins are synthesized.

The process of translating the genetic code carried by mRNA into a protein. This occurs at ribosomes, where amino acids are linked together to form a protein chain.

Single-strand binding proteins bind to the separated DNA strands, preventing them from re-annealing and maintaining the single-stranded conformation necessary for replication.

Each Okazaki fragment, a short DNA sequence synthesized in the 5' to 3' direction on the lagging strand, begins with an RNA primer. This primer provides the necessary 3'-OH group for DNA polymerase to initiate synthesis.

A newly-synthesized protein's first amino acid is usually methionine. This is because the start codon (AUG) codes for methionine, initiating the translation process.

Ribosomes, the cellular machinery responsible for protein synthesis, are composed of two subunits: a large subunit and a small subunit. These subunits are composed of ribosomal RNA (rRNA) and proteins.

The anticodon, a three-nucleotide sequence in tRNA, is complementary to the mRNA codon. This pairing ensures the correct amino acid is added to the growing polypeptide chain.

The bottom strand, the sequence 3'CGC TAT TCG ACG CTT5', is referred to as the template strand in DNA replication. It acts as the template for the synthesis of the complementary strand.

Elongation factor, EF-Tu, helps in the delivery of an aminoacyl-tRNA to the A-site of the ribosome. This step is crucial for protein synthesis and requires the hydrolysis of GTP for energy.

There are 20 different aminoacyl-tRNA synthetases, each specifically recognizing and attaching a particular amino acid to its corresponding tRNA. This ensures the correct amino acid is added to the growing polypeptide chain.

Ethidium bromide intercalates into DNA, allowing it to absorb UV light, making DNA bands visible under UV light.

The two chromatids that make up a chromosome separate during meiosis II, each becoming a daughter chromosome.

DNA has negative charges due to the phosphate groups on the sugar-phosphate backbone.

Bivalents are pairs of homologous chromosomes that have synapsed together during prophase I of meiosis. Bivalent chromosomes become visible at prometaphase.

Non-disjunction is the failure of chromosomes to separate properly during either meiosis I or meiosis II. This can lead to aneuploidy, a condition where there is either an extra or missing chromosome.

The spindle assembly checkpoint is a critical control point that ensures proper chromosome attachment to the spindle fibers before sister chromatids are separated during mitosis and meiosis. Cohesin, securin, and separase are key proteins in this checkpoint.

Nondisjunction is the failure of chromosomes to separate properly during cell division. This can lead to aneuploidy, where there is either an extra or missing chromosome. While nondisjunction causes abnormal chromosome separation, it doesn't differentiate maternal chromosomes from paternal ones.

A karyotype of 45, Y means that there is only one sex chromosome present, and it is a Y chromosome. This is incompatible with survival due to the lack of an X chromosome, essential for development.