Chapter 16
Chapter 17
Chapter 18
Chapter 20
100
What are the major steps to replication?
Three primary stages: initiation (unwinding the helix), elongation (building new DNA strands), and termination (completing the strands and repairing errors)
MORE INFO BELOW IF IT IS OF INTEREST TO YOU. IT IS NOT OF INTEREST TO ME BUT GOD BLESS
- 1. Initiation (Unwinding): Proteins bind to the origin of replication, and the enzyme helicase unwinds and unzips the DNA double helix, breaking hydrogen bonds to form a "Y" shaped replication fork.
- 2. Primer Binding: A short piece of RNA, called a primer, binds to the 3' end of the leading strand to start the process.
- 3. Elongation (Synthesis): The enzyme DNA polymerase adds complementary nucleotides to the template strands, building new DNA.
- Leading Strand: Synthesized continuously towards the replication fork.
- Lagging Strand: Synthesized discontinuously away from the fork in short segments called Okazaki fragments.
- 4. Primer Removal & Gap Filling: Exonuclease enzymes remove RNA primers, and DNA polymerase fills in the resulting gaps with appropriate bases.
- 5. Ligation: The enzyme DNA ligase joins the Okazaki fragments on the lagging strand together, creating a seamless, continuous DNA molecule.
- 6. Termination & Proofreading: The process finishes, and enzymes proofread the new DNA, repairing any mismatched base pairs to prevent mutations.
100
What is gene expression?
Gene expression is the fundamental process by which information encoded in DNA is used to synthesize functional products, usually proteins, that enable cell function
100
What does the operon model attempt to explain?
A) the coordinated control of gene expression in bacteria
B) bacterial resistance to antibiotics
C) how genes move between homologous regions of DNA D) the mechanism of viral attachment to a host cell
E) horizontal transmission of plant viruses
A, the coordinated control of gene expression in bacteria
100
How are plasmids are used in bacterial transformation to clone genes?
Plasmids act as engineered vectors to carry foreign DNA into bacteria for cloning. They are cut with restriction enzymes, joined with a gene of interest using DNA ligase, and introduced into competent bacteria via transformation (heat shock or electroporation). The bacteria then replicate the recombinant plasmid, creating many copies of the gene
200
What is the difference between replication, transcription, and translation?
DNA replication copies the entire genome (DNA to DNA) for cell division, while transcription converts specific genes into messenger RNA (DNA to RNA), and translation uses that mRNA to assemble amino acids into proteins. Replication ensures genetic continuity, whereas transcription and translation express genetic information to create functional proteins.
200
What is transcription?
The first step of gene expression, where a specific segment of DNA is copied into a new, complementary RNA molecule (mRNA) by the enzyme RNA polymerase. It acts as a "blueprint" transfer, allowing genetic information to move from the nucleus to the cytoplasm for protein synthesis.
200
The role of a metabolite that controls a repressible operon is to
A) bind to the promoter region and decrease the affinity of RNA polymerase for the
promoter.
B) bind to the operator region and block the attachment of RNA polymerase to the
promoter.
C) increase the production of inactive repressor proteins.
D) bind to the repressor protein and inactivate it.
E) bind to the repressor protein and activate it.
E, bind to the repress or protein and activate it
200
How can gel electrophoresis can be used to separate DNA fragments or protein molecules?
Gel electrophoresis separates DNA or protein molecules based on size and charge by applying an electric field to move them through a porous gel matrix (agarose or polyacrylamide). Negatively charged molecules travel toward the positive electrode (anode), with smaller molecules moving faster and farther through the pores than larger ones.
300
What is the general differences between the bacterial chromosome and eukaryotic chromosomes?
Bacterial chromosomes are typically single, circular, double-stranded DNA molecules located in the cytoplasm's nucleoid region, lacking histone proteins and extensive introns. In contrast, eukaryotic chromosomes are multiple, linear, and housed within a nucleus, tightly packed with histone proteins and containing significant non-coding DNA
300
What is translation?
The process where ribosomes in the cytoplasm or endoplasmic reticulum decode messenger RNA (mRNA) to synthesize specific polypeptide chains (proteins). This step follows transcription, converting the genetic code of nucleotide sequences into amino acid sequences, essential for building cellular structures.
300
What even is gene regulation actually?
Gene regulation controls cell functions by determining which genes are transcribed. This process involves transcription factors, activators, enhancers, repressors, and silencers. Prokaryotes rely on gene regulation for environmental adaptation, while eukaryotes have more complex interactions and a nuclear envelope for added control
300
What is biotechnology?
covers the use of living systems, organisms, or their derivatives to create, modify, or improve products and processes for specific uses. It encompasses genetic engineering, molecular biology, and bioengineering applied to medicine, agriculture, and industry to manipulate genetic material
400
How is DNA is packaged into a chromosome?
DNA is packaged into chromosomes through a hierarchical, multi-level folding process that compacts6 feet of DNA into a microscopic nucleus. It wraps around histone proteins to form nucleosomes ("beads on a string"), which coil into 30-nm fibers, then loop and fold using scaffolding proteins to achieve maximum compaction during cell division.
The following means nothing to me but seems like it could be of relevance.
Levels of DNA Packaging:
- Nucleosomes (First Order): DNA double helix wraps around protein cores called histones, forming nucleosomes. This shortens the DNA significantly and resembles "beads on a string".
- 30-nm Fiber (Second Order): Nucleosomes coil together to form a 30-nanometer fiber, known as solenoid or zigzag fiber, increasing packing density.
- Looping and Scaffolding (Third Order): The 30-nm fiber forms loops, which attach to a non-histone scaffold protein structure, creating even more condensed chromatin.
- Chromosome Condensation: During metaphase in cell division, these fibers fold further, achieving a 10,000:1 packing ratio to form the classic, visible X-shaped chromosome.
400
How do eukaryotic cells modify RNA after transcription?
Eukaryotic cells modify pre-mRNA after transcription in the nucleus to form mature mRNA, ensuring stability and correct translation. Key steps include adding a 5' cap (7-methylguanosine) for ribosome binding, a 3' poly-A tail for stability and export, and splicing to remove non-coding introns and join coding exons.
400
What are positive v negative controls?
Negative control: operons are switched off by active form of repressor protein
Eg. trp operon, lac operon
Positive control: regulatory protein interacts directly with genome to increase transcription
Eg. cAMP & CAP
400
What is rDNA?
- Recombinant DNA (rDNA): DNA formed by combining genetic material from different sources.
500
Describe the structure of DNA?
DNA is structured as a double helix, resembling a twisted ladder. It consists of two antiparallel strands made of sugar-phosphate backbones, linked by complementary nitrogenous base pairs (adenine with thymine, cytosine with guanine) via hydrogen bonds. The sequence of these bases encodes genetic information.
And again the following might be relevant but you also might not care. I know I sure don't.
Core Structural Components
- Double Helix: The overall shape is a right-handed helix, which twists every 10 base pairs.
- Nucleotides: The building blocks (monomers) of DNA, consisting of a phosphate group, a deoxyribose sugar, and a nitrogenous base.
- Backbone: Alternating sugar (deoxyribose) and phosphate groups form the structural "rails" of the ladder, connected by covalent phosphodiester bonds.
- Base Pairs: The "rungs" of the ladder consist of four bases: Adenine (A), Thymine (T), Cytosine (C), and Guanine (G).
- A pairs with T (via two hydrogen bonds).
- C pairs with G (via three hydrogen bonds).
- Antiparallel Structure: The two strands run in opposite directions, with one running 5' to 3' and the other 3' to 5'.
The Explorer's Guide to Biology +6
Structural Features
- Major and Minor Grooves: The helix structure creates large (major) and small (minor) grooves, which are crucial for protein binding and DNA regulation.
- Packaging: Eukaryotic DNA wraps around proteins called histones, forming nucleosomes ("beads on a string") to fit within the cell nucleus.
- Stability: The pairing rules (A-T, C-G) allow for faithful DNA replication and repair, with hydrogen bonds offering stability.
500
How do point mutations can change the amino acid sequence of a protein?
Point mutations change a protein's amino acid sequence by substituting one DNA nucleotide base for another, altering a single mRNA codon. This can result in a different amino acid (missense), a premature stop signal (nonsense), or no change at all (silent mutation). These changes often alter the protein's final 3D shape and function.
500
What is Epigenetic Inheritance?
Modifications on chromatin can be passed on to future generations
Unlike DNA mutations, these changes to chromatin can be reversed (de-methylation of DNA)
Explains differences between identical twins
500
What are the techniques of genetic engineering?
Transformation: bacteria takes up plasmid (w/gene of interest)
PCR (Polymerase Chain Reaction): amplify (copy) piece of DNA without use of cells
Gel electrophoresis: used to separate DNA molecules on basis of size and charge using an electrical current (DNA 🡪 + pole)
DNA microarray assays: study many genes at same time