Chapter 11 Flashcards
What are the primary functions of DNA?
Inheritance and directing protein production for growth and reproduction.
What is the semiconservative model of DNA replication?
Each new DNA molecule consists of one old strand and one new strand.
Why is DNA replication important for bacteria?
It allows bacteria to reproduce via binary fission and maintain genetic continuity.
What are the three steps of DNA replication?
Initiation, elongation, termination.
What happens during initiation in DNA replication?
Enzymes unwind DNA at the origin of replication.
What enzyme adds new nucleotides during elongation?
DNA polymerase.
What happens during termination in DNA replication?
DNA replication stops at the termination site, producing two identical chromosomes.
What is the role of DNA ligase in replication?
It seals Okazaki fragments on the lagging strand.
Why do bacteria replicate DNA in two directions?
Their circular chromosomes allow bidirectional replication.
What is the role of RNA primers in bacterial DNA replication?
They provide a starting point for DNA polymerase.
What is binary fission?
A type of asexual reproduction where a bacterial cell divides into two identical daughter cells.
List the steps of binary fission.
DNA replication, cell elongation, septum formation, cell division.
Why is binary fission important for bacterial survival?
It allows rapid reproduction and population growth.
What is horizontal gene transfer?
The transfer of genetic material between bacteria without reproduction.
What are the three methods of horizontal gene transfer?
Transformation, transduction, conjugation.
Define transformation in bacteria.
Uptake of free DNA from the environment.
Define transduction in bacteria.
Transfer of bacterial DNA by a virus (bacteriophage).
What is bacterial conjugation?
Unidirectional transfer of genetic material from a donor bacterium to a recipient bacterium via a pilus.
What is an F plasmid?
A fertility plasmid that enables bacteria to form pili for conjugation.
Why is conjugation important for bacterial diversity?
Increases genetic diversity. It allows the spread of genes, including antibiotic resistance.
What is the Central Dogma of molecular biology?
DNA → RNA → Protein.
What is gene expression?
The process where information from DNA is transcribed into RNA and translated into protein.
Why is the Central Dogma unidirectional?
Information flows from DNA to RNA to protein and cannot reverse.
What is transcription?
The process of making RNA from a DNA template.
What enzyme is responsible for transcription?
RNA polymerase.
What are the three stages of transcription?
Initiation, elongation, termination.
What occurs during transcription initiation?
The sigma factor of RNA polymerase find & binds to the promoter region. The rest of the RNA pol subunits bind to sigma factor (forms holoenzyme) & begins RNA synthesis.
What is the role of the sigma (σ) factor in transcription?
It helps RNA polymerase recognize and bind to the promoter.
How does elongation proceed in transcription?
RNA polymerase moves along 1 DNA strand adding complementary nucleotides to the growing RNA strand.
What happens during transcription termination?
RNA polymerase reaches a terminator sequence and releases the RNA transcript.
How does transcription differ between prokaryotes and eukaryotes?
Eukaryotes have multiple RNA polymerases and process mRNA (splicing, 5’ cap, poly-A tail).
What is RNA splicing?
The removal of introns and joining of exons in eukaryotic mRNA.
What is a polycistronic mRNA?
An mRNA that encodes multiple proteins (common in bacteria).
What is translation?
The process in which robosomes use mRNA to synthesize proteins
What are the three types of RNA involved in translation?
mRNA (carries genetic info from chromosomes to robosomes), tRNA (delivers AAs to robosomes), rRNA (combines w/ ribobosoaml polypeptides to form ribosome).
What are the three stages of translation?
Initiation, elongation, termination.
What is the start codon in translation?
AUG (Methionine).
What are the stop codons?
UAA, UAG, UGA.
What are the three sites on the ribosome?
A site (accepts tRNA), P site (holds growing peptide chain), E site (exit site).
What occurs during translation initiation?
Small ribosomal subunit attaches to mRNA at ribosomal binding site to position start codon at P site. tRNA carrying methionine attaches to P site, then larger ribosomal subiunit attaches to form complete ribosomal initiation complex.
What happens during translation elongation?
tRNAs bring amino acids to A site of ribosome. Ribozyme (an enzymatic RNA mole.) in larger ribosomal subunit forms a peptide bonds between them. Ribosome moves down mRNA to the next codon, transferring tRNA to E site.
How does translation terminate?
Proteins called release factors recognize stop codons and modify the large ribosomal subunit to release the ribosome from the mRNA.
How does translation differ between bacteria and eukaryotes?
Bacteria translate while transcribing; eukaryotes separate these processes.
Where does translation occur in prokaryotes and eukaryotes?
Cytoplasm for both, but transcription occurs in the nucleus for eukaryotes.
Why is genetic diversity important in bacteria?
It allows adaptation to changing environments and resistance to antibiotics.
What are resistance plasmids?
Plasmids that carry genes for antibiotic resistance.
What are virulence plasmids?
Plasmids that carry genes enhancing pathogenicity.
What is the function of helicase?
Unwinds the DNA helix by breaking the hydrogen bonds.
What does topoisomerase do?
Relieves supercoiling during DNA replication.
What is the role of DNA polymerase I?
Replaces RNA primers with DNA. Removes RNA primers and reseal DNA.
How do mutations contribute to genetic diversity?
They create variations in DNA sequences.
What is the significance of antimicrobial resistance (AMR) genes?
They enable bacteria to survive antibiotic treatments.
What is the purpose of gene transfer in bacteria?
To increase genetic diversity and adaptability.
What are operons in bacterial DNA?
Clusters of genes controlled by a single promoter.
What is the role of single-strand binding proteins (SSBs)?
They stabilize unwound DNA and prevent the strands from reannealing.
What is a holoenzyme in transcription?
RNA polymerase plus sigma factor.
What is a peptide bond?
The bond linking amino acids in a polypeptide chain.
