- Describe and compare the regulatory mechanisms of the lac operon, trp operon, and operons using activators.
- Lac operon: An operon used to encode for enzymes that break down lactose and uses lactose’s monomers as energy. Inducible operon as well meaning it’s usually turned off but can be induced/stimulated by a molecule.
- If lactose is absent, a repressor protein binds to the operator –> blocks transcription of the lac operon genes.
- Trp operon: Operon that encodes for enzymes for amino acid tryptophan. Repressible operon since it’s normally turned on but can be inhibited/repressed when there are high amounts of a specific molecule present, like tryptophan.
- When tryptophan is highly present, the repressor protein binds to the operators.
Operons using activators: Operons that use proteins that turn them on by binding to DNA and stimulating gene transcription. Makes it easier for RNA Polymerase to bind to the promoter.
- Explain how selective gene expression yields a variety of cell types in multicellular eukaryotes.
Differentiation involves becoming specialized in structure and function and is controlled by a specific sets of genes on or off. So, some genes are expressed to perform a specific function.
- Explain how DNA is packaged into chromosomes.
DNA is wrapped around histones, forming a string of bead-like nucleosomes.
- Explain how a cat’s tortoiseshell coat pattern is formed and why this pattern is only seen in female cats.
This pattern is formed by the inactivation of X-chromosomes, one black and one orange allele for each X-chromosome. Female cats mainly have this because female cats have two X-chromosomes and there could be a black and orange allele on each chromosome.
- Explain how eukaryotic gene expression is controlled.
The eukaryotic gene expression is controlled by a variety of regulatory proteins/transcription factors that interact with DNA that activate or repress gene expression. Processes include RNA splicing, breakdown of mRNA, etc.)
- Describe the process and significance of alternative DNA splicing.
Alternative DNA splicing is the production of different mRNAs from the same transcript. This process is important because it allows one gene to produce multiple proteins.
- Explain how mRNA breakdown, initiation of translation, protein activation, and protein breakdown regulate gene expression.
- mRNA breakdown: After mRNA is transcribed from DNA, it can be broken down by specific enzymes which help control the amount of mRNA available for translation.
- Initiation of translation: When translation starts, the ribosome binds to the mRNA and factors decide if protein synthesis occur.
- Protein activation: Helps regulate the activity and function of a protein.
- Protein breakdown: Ensures that proteins in excess or no longer needed are not present anymore. Degraded by proteasome.
- Describe the significance of miRNA molecules.
miRNA molecules can bind to complementary sequences on mRNA molecules which help regulate gene expression.
- Describe the roles of homeotic genes in development.
Regulates how body parts are developed and shaped.
- Explain how scientists can monitor the expression of specific genes.
Scientists can monitor the expression of specific genes by nucleic acid hybridization which allows researchers to identify cells in which a target gene is expressed. And using a DNA microarray which tells which genes are turned on or off in a specific cell.
- Explain how a signal transduction pathway triggers a specific response inside a target cell.
Converts a signal on the target cell’s surface to a specific response inside the cell.
- Compare the cell-signaling systems of yeast and animal cells.
Yeast identify their mates by chemical signaling (a and alpha). Animal cells has a very similar cell-signaling system.
- Explain how plant cloning demonstrates the potential of differentiated cells.
Plant cloning demonstrates the potential of differentiated cells since a small part of a plant that has been cut can go through cell division and become an adult plant. A clone is created by sexual reproduction and thus genetically identical to a single parent.
- Describe some of the practical applications of reproductive cloning and the process and goals of therapeutic cloning.
Reproductive cloning is used to produce animals with desirable traits to produce better agricultural products,produce therapeutic agents, and restock populations of endangered animals
The ultimate aim of therapeutic cloning is to supply cells for the repair of damaged or diseased organs
- Explain how viruses, proto-oncogenes, and tumor-suppressor genes contribute to cancer.
- Viruses: Inserting their DNA into a host cell.
- Proto-oncogenes: Can be turned into an oncogene which causes cells to divide excessively.
- Tumor-suppressor genes: If they become inactivated, cancerous cells can enter the body and cause cancer.
- Explain why the development of most cancers is a slow and gradual process.
More than one somatic mutation is needed to produce one full-fledged cancer cell.
