Replication
This process must occur before cell division to ensure each daughter cell receives a complete copy of the genome, and it is tightly regulated by the cell to happen only once per cycle.
What is DNA replication?
When this enzyme acts on DNA, it initiates the process of transcription to synthesize RNA.
What is RNA polymerase?
The sequence of codons on mRNA follows these rules to determine the order of amino acids in a protein.
What is the genetic code?
A change in the DNA sequence that affects only a single nucleotide is called this.
What is a point mutation?
This type of RNA carries the instructions from DNA to the ribosome for protein synthesis, and its production is regulated by the cell.
What is messenger RNA (mRNA)?
This term describes the accuracy of DNA replication, ensured by proofreading and error-correcting mechanisms to prevent mutations.
What is replication fidelity?
DNA cannot leave the nucleus because it is too large and complex, so the cell uses this type of RNA to carry its instructions to the ribosomes.
What is messenger RNA (mRNA)?
This cellular machinery reads mRNA sequences and assembles amino acids into a polypeptide chain using tRNA molecules.
What are ribosomes?
When insertions or deletions of nucleotides occur in a gene, the reading frame shifts, often producing completely nonfunctional proteins and potentially severe phenotypes.
What is a frameshift mutation?
The process of controlling gene activity by turning on or off genes in response to signals from the environment or the cell itself.
What is gene regulation?
These structures form at multiple locations along a DNA molecule to allow simultaneous copying and speed up replication.
What are replication bubbles?
With four nucleotide bases, this is the total number of possible triplet codons that can be generated.
What is 64?
These molecules bring specific amino acids to the ribosome and have anticodons complementary to mRNA codons.
What is transfer RNA (tRNA)?
During DNA replication, this enzyme activity corrects errors by removing incorrectly paired nucleotides.
What is proofreading by DNA polymerase?
These proteins bind to DNA and help turn genes on or off by controlling transcription.
What are transcription factors?
DNA replication is described this way because each new molecule contains one original strand and one newly synthesized strand.
What is semiconservative?
This three-nucleotide sequence on tRNA pairs with the complementary codon on mRNA to ensure the correct amino acid is added during translation.
What is an anticodon?
This end of the mRNA strand attaches to the small ribosomal subunit to initiate translation.
What is the 5’ end?
A single-nucleotide substitution escapes proofreading and does not change the amino acid coded due to the redundancy of the genetic code. This mutation type is often phenotypically silent.
What is a silent mutation?
In prokaryotes, this cluster of genes is controlled together and can be turned on or off in response to environmental signals, such as the presence of lactose.
What is an operon?
DNA strands grow only in this direction because DNA polymerases can add nucleotides only to the 3’ end, where the 5’ phosphate of a new nucleotide bonds with the existing strand.
What is 5’ to 3’?
During transcription, mRNA separates from DNA when these relatively weak bonds between base pairs are broken.
What are hydrogen bonds?
After a polypeptide is released from the ribosome, it undergoes folding, post-translational modifications, and may join with other molecules to become this macromolecule.
What is a functional protein?
Despite cellular repair mechanisms, some DNA replication errors persist, and these mutations in critical genes can lead to diseases such as cancer or cystic fibrosis.
What are deleterious mutations?
This type of epigenetic modification adds a methyl group to DNA, often at CpG sites, which can silence gene expression without changing the DNA sequence.
What is DNA methylation?