Podcast
Questions and Answers
Which base pairs with adenine in the DNA structure?
Which base pairs with adenine in the DNA structure?
What direction does DNA replication occur?
What direction does DNA replication occur?
Which of the following statements is true about DNA strands?
Which of the following statements is true about DNA strands?
What is the function of primase in DNA replication?
What is the function of primase in DNA replication?
Signup and view all the answers
Which term describes the method of DNA replication?
Which term describes the method of DNA replication?
Signup and view all the answers
What role does DNA helicase play in DNA replication?
What role does DNA helicase play in DNA replication?
Signup and view all the answers
Which protein is primarily responsible for adding DNA nucleotides during elongation?
Which protein is primarily responsible for adding DNA nucleotides during elongation?
Signup and view all the answers
Which protein is responsible for reducing supercoiling ahead of the replication fork?
Which protein is responsible for reducing supercoiling ahead of the replication fork?
Signup and view all the answers
What is the role of aminoacyl tRNA synthetase in translation?
What is the role of aminoacyl tRNA synthetase in translation?
Signup and view all the answers
What happens at the P site of the ribosome during translation?
What happens at the P site of the ribosome during translation?
Signup and view all the answers
Which site requires energy for the translocation of tRNA?
Which site requires energy for the translocation of tRNA?
Signup and view all the answers
During translation initiation, which component binds to the start codon AUG?
During translation initiation, which component binds to the start codon AUG?
Signup and view all the answers
Which statement is true about the elongation phase of translation?
Which statement is true about the elongation phase of translation?
Signup and view all the answers
Which of the following correctly describes the exit (E) site of the ribosome?
Which of the following correctly describes the exit (E) site of the ribosome?
Signup and view all the answers
How many main steps are involved in the translation process?
How many main steps are involved in the translation process?
Signup and view all the answers
What feature of ribosomes helps facilitate the binding of charged tRNA during elongation?
What feature of ribosomes helps facilitate the binding of charged tRNA during elongation?
Signup and view all the answers
Which method of horizontal gene transfer is primarily used by researchers to alter bacterial genomes?
Which method of horizontal gene transfer is primarily used by researchers to alter bacterial genomes?
Signup and view all the answers
What is the first step in the process of transcription?
What is the first step in the process of transcription?
Signup and view all the answers
Which of the following molecules is essential for the elongation phase of transcription?
Which of the following molecules is essential for the elongation phase of transcription?
Signup and view all the answers
During transcription, how many strands of RNA are synthesized from a DNA template?
During transcription, how many strands of RNA are synthesized from a DNA template?
Signup and view all the answers
What is the process called when genes are expressed continuously without regulation?
What is the process called when genes are expressed continuously without regulation?
Signup and view all the answers
Which nucleotide triphosphate (NTP) is used during transcription instead of deoxyribonucleotide triphosphates (dNTPs)?
Which nucleotide triphosphate (NTP) is used during transcription instead of deoxyribonucleotide triphosphates (dNTPs)?
Signup and view all the answers
Which strand of DNA serves as the template for mRNA synthesis during transcription?
Which strand of DNA serves as the template for mRNA synthesis during transcription?
Signup and view all the answers
What is the relationship between the template strand of DNA and the corresponding mRNA sequence?
What is the relationship between the template strand of DNA and the corresponding mRNA sequence?
Signup and view all the answers
What effect does UV radiation have on DNA?
What effect does UV radiation have on DNA?
Signup and view all the answers
Which repair mechanism involves the recognition and removal of mismatched base pairs?
Which repair mechanism involves the recognition and removal of mismatched base pairs?
Signup and view all the answers
After mismatch repair (MMR), what is the rate of mistakes in new nucleotides?
After mismatch repair (MMR), what is the rate of mistakes in new nucleotides?
Signup and view all the answers
What does the Ames Test measure?
What does the Ames Test measure?
Signup and view all the answers
What is horizontal gene transfer (HGT)?
What is horizontal gene transfer (HGT)?
Signup and view all the answers
Which of the following mutations leads to the formation of thymine dimers?
Which of the following mutations leads to the formation of thymine dimers?
Signup and view all the answers
What is the primary function of excision repair in DNA management?
What is the primary function of excision repair in DNA management?
Signup and view all the answers
In which organisms is horizontal gene transfer (HGT) especially common?
In which organisms is horizontal gene transfer (HGT) especially common?
Signup and view all the answers
Under what conditions is the Lac Operon transcribed?
Under what conditions is the Lac Operon transcribed?
Signup and view all the answers
What occurs if sucrose-digesting structural genes are placed downstream of the Lac promoter?
What occurs if sucrose-digesting structural genes are placed downstream of the Lac promoter?
Signup and view all the answers
What is the role of reporter genes in genetic research?
What is the role of reporter genes in genetic research?
Signup and view all the answers
Which of the following best describes how eukaryotic Pre-mRNA differs from prokaryotic mRNA?
Which of the following best describes how eukaryotic Pre-mRNA differs from prokaryotic mRNA?
Signup and view all the answers
How do researchers manipulate genomes to create inducible systems?
How do researchers manipulate genomes to create inducible systems?
Signup and view all the answers
Which of the following is a famous reporter gene that causes fluorescence?
Which of the following is a famous reporter gene that causes fluorescence?
Signup and view all the answers
What is the primary function of regulatory regions in operons?
What is the primary function of regulatory regions in operons?
Signup and view all the answers
What characterizes the Central Dogma of molecular biology in prokaryotes and eukaryotes?
What characterizes the Central Dogma of molecular biology in prokaryotes and eukaryotes?
Signup and view all the answers
Study Notes
Aminoacyl tRNA Synthetase
- Each aminoacyl tRNA synthetase is specific to a single amino acid and tRNA
- No other amino acid can bind to the synthetase
- No other tRNA can bind to the synthetase
Ribosomes and Translation
- Ribosomes are made up of two subunits, a large and a small subunit
- The large subunit has three binding sites: the A site, the P site, and the E site
- The A site binds to the anticodon of the charged tRNA
- The P site binds to the tRNA holding the growing polypeptide chain
- The E site is where the uncharged tRNA exits the ribosome
Translation
- Translation involves three steps: initiation, elongation, and termination
- Initiation requires a charged tRNA, a small ribosomal subunit, and an mRNA molecule
- In prokaryotes, the small ribosomal subunit binds to the Shine-Dalgarno sequence on the mRNA
- In eukaryotes, the small ribosomal subunit binds to the 5' cap of the mRNA
- The start codon is AUG, which codes for methionine
- The first tRNA always binds to the P site
- Elongation requires energy, which is used to bring a new charged tRNA into the A site
- The rRNA in the large subunit catalyzes the transfer of the growing polypeptide chain from the tRNA in the P site to the tRNA in the A site
- Elongation does not require energy
- The newly-uncharged tRNA translocates to the E site, while the tRNA with the growing polypeptide chain translocates to the P site
- Elongation requires energy
- Termination occurs when a stop codon is encountered, which signals the release of the polypeptide chain from the ribosome
DNA Replication
- DNA replication is semi-conservative, meaning that each new DNA molecule contains one old strand and one new strand
- DNA replication occurs in the 5' to 3' direction
- DNA replication involves three steps: initiation, elongation, and termination
- Initiation involves unwinding the double helix to create two template strands
- Elongation involves the sequential addition of complementary nucleotides linked by phosphodiester bonds
- Termination occurs when all regions of the DNA have been replicated
- The origin of replication is the site where DNA replication begins
- Prokaryotes have a single origin, while eukaryotes have multiple origins
- Topoisomerase reduces supercoiling in the DNA
- DNA helicase unwinds the DNA using energy from ATP hydrolysis
- Single-strand binding proteins (SSBs) prevent the separated DNA strands from re-annealing
- Primase synthesizes short RNA primers, which are required for DNA polymerase to initiate DNA synthesis
- DNA polymerase is the main enzyme that catalyzes elongation of DNA
- DNA polymerase has an active site for adding nucleotides and finger-like domains that recognize nucleotide bases
DNA Repair
- DNA repair mechanisms are crucial for maintaining the integrity of the genome
- Proofreading occurs during DNA replication where DNA polymerase recognizes mismatched pairs and removes incorrectly paired bases
- Mismatch repair (MMR) involves other proteins scanning newly replicated DNA for mismatches and correcting them
- Excision repair involves enzymes scanning DNA for bulky lesions, excising them, and replacing them with undamaged nucleotides
- The Ames test uses bacteria to screen for carcinogenic potential of new chemical compounds.
Horizontal Gene Transfer
- Horizontal gene transfer (HGT) involves the transfer of genes between organisms that are not directly related, such as through transformation, transduction, or conjugation
- HGT is common in microorganisms, but less so in eukaryotes
- HGT can make it difficult to determine evolutionary relationships between organisms
Gene Expression
- Gene expression involves two steps: transcription and translation
- Transcription copies a DNA sequence into a complementary RNA sequence
- Translation uses the RNA sequence as a template to synthesize a polypeptide (protein) sequence
- The central dogma of molecular biology describes how information flows from DNA to RNA to protein
- Transcription is similar to DNA replication, but uses RNA polymerase instead of DNA polymerase
- Transcription occurs in three steps: initiation, elongation, and termination
- RNA polymerase needs the help of a sigma factor to bind to the DNA
- Transcription involves the use of NTPs instead of dNTPs.
- Transcription produces many different small mRNA molecules, unlike DNA replication which produces a single large DNA genome
- Transcription does not require primers
Template and Non-Template Strands
- The template strand of DNA is used as a base to build mRNA
- The template strand is complementary to the mRNA sequence
- The non-template strand is identical to the mRNA sequence (except it has T's instead of U's)
- The non-template strand is not actually involved in transcription
Constitutive Expression
- Constitutive expression is when genes are always expressed, or transcribed and translated, all the time
- Some genes, such as those involved in energy production, are constitutively expressed
- Not all genes are constitutively expressed
The Lac Operon
- The Lac Operon is a group of genes that are involved in the metabolism of lactose
- The lac operon is only transcribed when lactose is present and glucose is absent
- The regulatory region of the lac operon controls whether or not the genes are transcribed
- The structural genes of the lac operon are the genes that are actually transcribed
- The lac operon is an example of an inducible system, which is a system where the expression of genes is controlled by an inducer
Reporter Genes
- Reporter genes can be used to monitor the expression of other genes
- Reporter genes are often designed to monitor transcription and are called transcriptional fusions or operon fusions
- Examples of reporter genes include Green Fluorescent Protein, LacZ, Luciferase, and Red Fluorescent Protein
Eukaryotic Pre-mRNA Processing
- Eukaryotic pre-mRNA transcripts are processed prior to translation
- The overall Central Dogma works the same in prokaryotes and eukaryotes
- There are differences in gene structure and whether or not the nucleus separates transcription and translation, between prokaryotes and eukaryotes
Studying That Suits You
Use AI to generate personalized quizzes and flashcards to suit your learning preferences.
