뒤로Gene Regulation and Cloning in General Biology
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Gene regulation is the process by which cells turn on certain genes while keeping others off, allowing cells with the same DNA to develop into different types with specialized functions.
An operon is a cluster of related genes and control sequences in bacterial DNA that are turned on or off together to coordinate gene expression.
The lac operon controls the expression of genes that enable E. coli to digest lactose, turning them on when lactose is present and off when it is absent.
The operator is a DNA segment acting as a switch that controls whether RNA polymerase can attach to the promoter and transcribe the genes.
Eukaryotic gene regulation is more complex, involving multiple control points such as DNA packing, transcription factors, RNA processing, and protein activation.
X chromosome inactivation is the random inactivation of one X chromosome in female mammals' cells, leading to gene expression from only one X chromosome per cell.
Transcription factors are proteins that bind to DNA sequences like enhancers and promoters to turn gene transcription on or off.
Alternative RNA splicing allows a single gene to produce multiple mRNA variants by including or excluding different exons, increasing protein diversity.
miRNAs are small RNA molecules that bind to complementary mRNA sequences to block gene expression by preventing translation or promoting mRNA degradation.
Proteins can be activated by chemical modification, cleaved into active forms, or selectively broken down to regulate gene expression post-translation.
A signal transduction pathway is a series of molecular changes triggered by a signal molecule binding to a receptor, leading to a specific cellular response such as gene transcription.
Homeotic genes are master control genes that regulate groups of other genes to determine the development of body parts in specific locations during embryonic development.
A DNA microarray is a tool that allows researchers to study the expression of many genes simultaneously by detecting which genes are active in different tissues.
Cloning is producing genetically identical organisms from a single cell, demonstrating that differentiated cells retain the full genetic potential.
Reproductive cloning involves nuclear transplantation to create a new organism genetically identical to the donor, such as Dolly the sheep.
Reproductive cloning is used in agriculture to produce animals with desirable traits, in research for control animals, and to help restock endangered species.
Embryonic stem cells are cells from early embryos that can divide indefinitely and potentially develop into many specialized cell types for therapeutic use.
Adult stem cells are partially differentiated cells that can generate a limited range of specialized cells and are less ethically controversial than embryonic stem cells.
Cancer results from mutations that cause uncontrolled cell growth by activating oncogenes or inactivating tumor-suppressor genes.
Proto-oncogenes are normal genes that can become oncogenes when mutated, leading to excessive cell division and cancer.
Tumor-suppressor genes encode proteins that inhibit cell division; mutations that disable these genes can contribute to cancer development.
Inherited mutations in oncogenes or tumor-suppressor genes increase the likelihood of accumulating mutations that lead to cancer.
Carcinogens like UV radiation, tobacco use, alcohol consumption, and excessive sun exposure increase cancer risk.
Eating plant fiber, reducing animal fat, and consuming vitamins C, E, and compounds in cabbage and relatives can lower cancer risk.