I. Molecular Biology and Genetic Elements Flashcards
(37 cards)
What is a gene? a genome?
A gene is a segment of DNA that contains the instructions for building a specific protein or set of proteins. A genome is the complete set of genes or genetic material present in a cell or organism.
Why are nucleic acids and proteins called informational macromolecules?
They are called informational macromolecules because they carry and transmit the information necessary for the growth, development, and functioning of living organisms.
What are the major structural features of DNA? of RNA?
DNA is double-stranded and has a deoxyribose sugar, while RNA is single-stranded and has a ribose sugar.
How are DNA and RNA similar? How are they different?
Both DNA and RNA are nucleic acids that store genetic information. They differ in structure, with DNA being double-stranded and RNA being single-stranded, and in their sugar and base composition.
What is a nucleotide? What are the three major components of a nucleotide?
A nucleotide is the basic building block of nucleic acids, composed of a phosphate group, a sugar, and a nitrogenous base.
What is a nucleoside?
A nucleoside is a compound formed when a nitrogenous base is attached to a sugar, without the phosphate group.
What are purines and pyrimidines?
Purines are nitrogenous bases with a double-ring structure (adenine and guanine), while pyrimidines have a single-ring structure (cytosine, thymine, and uracil).
What are the major structural features of the DNA double helix?
The DNA double helix features two strands that run antiparallel, a sugar-phosphate backbone, and complementary base pairing between adenine-thymine and guanine-cytosine.
What is the functional significance of the major groove?
The major groove provides access for proteins to bind to the DNA, allowing for regulation of gene expression and other functions.
What is supercoiling and why is it necessary in Bacteria and Archaea?
Supercoiling is the twisting of DNA strands that helps compact the DNA, making it fit within the cell and facilitating processes like replication and transcription.
What enzyme (give both names) produces supercoiling?
The enzyme that produces supercoiling is DNA gyrase (also known as topoisomerase II).
What are negative supercoils?
Negative supercoils are twists in the DNA that result in the strands being underwound, which can facilitate processes like replication and transcription.
Under what conditions would positive supercoils be needed?
Positive supercoils may be needed during processes that require DNA to be tightly packed or when DNA is being unwound for replication or transcription.
How is DNA compacted in eukaryotic cells?
DNA is compacted in eukaryotic cells by wrapping around histone proteins to form nucleosomes, which further coil and fold to form chromatin.
What is the central dogma of molecular biology?
The central dogma of molecular biology describes the flow of genetic information from DNA to RNA to protein.
What are three major types of RNA? What is the function of each?
The three major types of RNA are messenger RNA (mRNA) which carries genetic information from DNA to ribosomes, transfer RNA (tRNA) which brings amino acids to ribosomes during protein synthesis, and ribosomal RNA (rRNA) which forms the core of ribosome structure and catalyzes protein synthesis.
What is replication? transcription? translation?
Replication is the process of copying DNA. Transcription is the synthesis of RNA from a DNA template. Translation is the process of synthesizing proteins from mRNA.
What is the primary enzyme involved in DNA replication? in transcription?
The primary enzyme involved in DNA replication is DNA polymerase, while in transcription it is RNA polymerase.
What organelle is involved in translation?
The ribosome is the organelle involved in translation.
What is coupled transcription and translation and why does it occur in prokaryotes but not in eukaryotes?
Coupled transcription and translation is the simultaneous process of synthesizing RNA and protein in prokaryotes, occurring because there is no nuclear membrane separating the two processes, unlike in eukaryotes.
What type of “microbe” may violate the central dogma?
Certain retroviruses, such as HIV, may violate the central dogma by transcribing RNA back into DNA.
What is a genetic element?
A genetic element is a segment of DNA that has a specific function, such as a gene or a regulatory sequence.
What are four examples of genetic elements?
Four examples of genetic elements include genes, operons, plasmids, and transposable elements.
How are typical prokaryotic genomes different from typical eukaryotic genomes?
Typical prokaryotic genomes are usually circular and consist of a single chromosome, while eukaryotic genomes are linear and contain multiple chromosomes.
