Chapter 7 Flashcards
(37 cards)
What are the possible arrangements of the bacterial genome?
Circular chromosome, linear chromosome, multiple chromosomes, and presence of plasmids.
What is vertical transmission?
Genetic material passed from parent to offspring during cell division.
What is horizontal transmission?
Genetic material transferred between unrelated bacteria through transformation, transduction, or conjugation.
What are structural genes?
Genes that encode functional proteins.
What are DNA control sequences?
Sequences that regulate gene expression and do not encode proteins (e.g., promoters, operators).
What is conjugation?
A process where one bacterium transfers DNA (often a plasmid) to another through direct cell-to-cell contact via a pilus.
How does non-coding DNA differ in eukaryotes and prokaryotes?
Eukaryotes have a higher percentage of non-coding DNA; prokaryotes have minimal non-coding DNA.
What is a gene?
A sequence of DNA that encodes a functional product.
What is an operon?
A cluster of genes transcribed as a single mRNA, under the control of a single promoter (e.g., lac operon).
What is a regulon?
A collection of operons regulated by the same regulatory protein.
What is the structure of DNA?
Made of nucleotides (sugar, phosphate, nitrogenous base) with base pairs A-T and G-C.
What are the differences between RNA and DNA?
RNA is single-stranded, has ribose sugar, and uses uracil (U) instead of thymine (T).
What is the antiparallel nature of DNA?
The two DNA strands run in opposite directions: one 5’ → 3’, the other 3’ → 5’.
What stabilizes DNA besides hydrogen bonds?
Base stacking interactions (Van der Waals forces) between nitrogenous bases.
How do proteins contact nucleotide bases?
Proteins recognize specific sequences in the major groove of the DNA helix.
What is DNA denaturation?
Separation of double-stranded DNA into single strands, reversible by cooling.
What is DNA supercoiling?
DNA becomes supercoiled to compact the genome, controlled by topoisomerases.
What is localized supercoiling relaxation?
Loops in bacterial chromosomes can relax independently without affecting others.
What type of supercoiling occurs in bacteria?
Negative supercoiling to make DNA easier to unwind for replication and transcription.
What are the two types of topoisomerases?
Type I relaxes supercoiling by nicking a single strand; Type II introduces or removes supercoils using ATP.
How does supercoiling in thermophiles differ?
Positive supercoiling helps stabilize DNA at high temperatures.
Why is DNA gyrase a good antibiotic target?
Inhibiting DNA gyrase prevents supercoiling, blocking DNA replication.
What is semiconservative replication?
Each new DNA molecule consists of one original strand and one newly synthesized strand.
What is a replication fork?
The site where DNA is unwound and replication occurs.
