Gene Control and Biotechnology in Biology

What was the first mammal to be cloned?

An adult ewe (female sheep) in 1996.

What are common issues faced by cloned animals?

Cloned animals often exhibit abnormalities, shortened life spans, and increased incidences of age-related diseases.

What is gene expression?

The process by which genetic information flows from genes to proteins, determining an organism's phenotype.

What is gene regulation?

The turning on and off of genes to help organisms respond to environmental changes.

How does E. coli respond to environmental changes?

E. coli can quickly shift its metabolic activities, breaking down different nutrients based on availability.

What are operons in prokaryotes?

Clusters of genes for related enzymes that are controlled together.

What role do regulatory proteins play in gene expression?

Regulatory proteins bind to control sequences in DNA to turn genes on or off.

How does chromosome structure affect gene expression?

DNA is wound around histones, forming nucleosomes that can block transcription proteins from accessing DNA.

What is X chromosome inactivation?

A process in female mammals where one X chromosome is inactivated to prevent gene expression.

What is alternative RNA splicing?

A process after transcription that can generate two or more types of mRNA from the same transcript.

How can just under 21,000 human genes produce more than 100,000 polypeptides?

Through alternative RNA splicing, allowing for multiple protein products from a single gene.

What is the significance of differentiation in multicellular organisms?

Cells become specialized in structure and function, maintaining specific gene expression regimens.

What is the relationship between gene expression and cell types?

Differences between cell types arise from selective gene expression, not from different genes being present.

What is the role of cell-to-cell signaling in gene expression?

Signaling molecules carry messages from signaling cells to target cells, coordinating cellular activities.

How do signaling molecules typically function?

They bind to receptor proteins in the plasma membrane of target cells.

What is the impact of DNA packing on gene expression?

DNA packing can block gene expression by preventing transcription proteins from accessing DNA.

What are histones?

Small proteins around which DNA is wound to form nucleosomes.

What is methylation in the context of gene expression?

A chemical modification that can turn genes off.

What is the function of nucleosomes?

They help package DNA into a compact form, affecting gene accessibility.

What is a checkpoint question regarding nerve and skin cells?

Despite having the same genes, nerve and skin cells differ in structure and function due to selective gene expression.

What is the primary mechanism for gene expression control in eukaryotes?

Chromosome structure and chemical modifications, including histone modification and DNA methylation.

What is the significance of the tortoiseshell pattern in female cats?

It is a result of X chromosome inactivation, demonstrating the effects of gene regulation.

What is a signal transduction pathway?

A series of molecular changes that converts a signal on a target cell's surface to a specific response inside the cell.

What is a clone?

An individual organism created by asexual reproduction that is genetically identical to a single parent.

What is nuclear transplantation in the context of cloning?

A process where DNA from a donor cell is inserted into a nucleus-free host egg, resulting in a clone of the DNA donor.

What is reproductive cloning?

Cloning that can result in the birth of a new living individual, typically involving the implantation of a blastocyst into a surrogate mother.

Who was the first mammal successfully cloned and in what year?

Dolly the sheep, cloned in 1996 by Ian Wilmut.

What was the survival rate of cloned embryos in the case of Dolly the sheep?

Out of 277 zygotes, only one resulted in a live birth, indicating a survival rate of less than 10%.

What is the definition of totipotent cells?

Cells capable of producing every kind of specialized cell in an organism.

What is the goal of therapeutic cloning?

To produce embryonic stem cells for various therapeutic purposes.

How do embryonic stem cells differ from adult stem cells?

Embryonic stem cells can form any type of cell in the body, while adult stem cells typically give rise to a limited range of cell types.

What is the difference between reproductive cloning and therapeutic cloning?

Reproductive cloning uses egg cells to produce copies of whole animals, while therapeutic cloning produces embryonic stem cells for creating tissues.

What causes cancer at the genetic level?

Mutations in genes that control cell division, affecting proto-oncogenes and tumor-suppressor genes.

What is a proto-oncogene?

A normal gene that helps control cell division, which can become an oncogene through mutation.

How can viruses contribute to cancer?

Viruses can insert oncogenes into the DNA of host chromosomes, leading to uncontrolled cell division.

What are carcinogens?

Agents that alter DNA and make cells cancerous.

What is the second-leading cause of death in most industrialized nations?

Cancer.

What lifestyle choices can help reduce the risk of cancer?

Reducing exposure to carcinogens and making healthier lifestyle choices.

What happens when tumor-suppressor genes are mutated?

Mutations that inactivate tumor-suppressor genes can lead to cancer.

What is the significance of embryonic stem cells in medical research?

They have great potential for therapeutic uses, including tissue regeneration and treatment of diseases.

What is the expected lifespan of Dolly the sheep compared to her actual lifespan?

Dolly had a normal life expectancy of 12 years but died at 6 years old.

What are the two main types of stem cells mentioned in the notes?

Embryonic stem cells and adult stem cells.

What is the role of environmental factors in cancer development?

Most cancers arise from mutations caused by environmental factors.

What is the relationship between mutations and cancer?

Mutations in genes that regulate the cell cycle can lead to uncontrolled cell division and cancer.

What is the process of turning on a gene in relation to signal molecules?

A signal molecule does not need to enter the target cell to turn on a gene; it can activate a pathway on the cell surface.

What is gene cloning?

Gene cloning is the manipulation of organisms or their components to make useful products, involving the insertion of foreign genes into bacterial plasmids.

How are recombinant DNA plasmids created?

Researchers manipulate bacterial plasmids to contain genes from other organisms, which can then be inserted into bacteria.

What happens when recombinant bacteria multiply?

When recombinant bacteria multiply, the foreign genes are also duplicated, allowing for the harvesting of copies of the gene or its protein product.

What is the role of restriction enzymes in DNA technology?

Restriction enzymes cut DNA at specific sequences, forming restriction fragments that can be used in gene cloning.

What is the function of DNA ligase?

DNA ligase 'pastes' DNA fragments together, facilitating the creation of recombinant DNA.

What are 'sticky ends' in the context of DNA manipulation?

Sticky ends are overhangs of single-stranded DNA that can bond with complementary sequences, aiding in the joining of DNA fragments.

What are genetically modified organisms (GMOs)?

GMOs are organisms that have acquired one or more genes by artificial means, often used in agriculture.

What is a transgenic organism?

A transgenic organism is a recombinant organism that has received a gene from another species.

Why can't all human proteins be synthesized in E. coli?

Bacteria cannot correctly produce some proteins, such as glycoproteins, which require mammalian cells for proper synthesis.

What is the purpose of golden rice?

Golden rice is a transgenic variety created to produce beta-carotene, which helps combat vitamin A deficiency.

What is DNA profiling?

DNA profiling is the analysis of genetic markers to determine whether two DNA samples come from the same individual.

What are short tandem repeats (STRs)?

STRs are stretches of DNA that contain short nucleotide sequences repeated many times in a row, used in DNA profiling.

How does the polymerase chain reaction (PCR) work?

PCR amplifies a DNA sample by using specific primers to copy only a particular subset of the DNA.

What is the significance of PCR in DNA analysis?

PCR can generate billions of copies of a DNA segment from a minute sample, enabling the construction of DNA profiles.

What is the role of genetic markers in DNA profiling?

Genetic markers, such as STRs, are used to identify and compare DNA samples in forensic analysis.

How has DNA technology transformed forensics?

DNA technology has enabled the scientific analysis of evidence, allowing for accurate identification of individuals in crime scene investigations.

What is the relationship between gene cloning and biotechnology?

Gene cloning is an application of biotechnology that involves manipulating genetic material to produce useful products.

What is the impact of genetically modified crops on agriculture?

Genetically modified crops have led to the development of varieties that can withstand environmental challenges, such as salinity.

What is the primary benefit of using recombinant cells in biotechnology?

Recombinant cells can mass-produce gene products for medical and other applications.

What is the significance of the salinity-resistance gene in rice?

It allows new varieties of rice to grow in highly salty water, improving food security in drought conditions.

What is the role of gel electrophoresis in DNA profiling?

Gel electrophoresis is used to separate DNA fragments based on size, aiding in the analysis of genetic markers.

What is the purpose of using specific primers in PCR?

Specific primers flank the desired DNA sequence to ensure that only that particular segment is amplified.

What are genetic markers?

Sequences in the genome that vary from person to person.

What is the significance of the DNA that lies between genes in humans?

Much of it consists of genetic markers.

What is the purpose of DNA profiling by STR analysis?

It involves amplifying and quantifying 13 STRs, with a 1 in 10 billion chance of finding the same profile in two unrelated people.

What does gel electrophoresis do?

It separates macromolecules, usually proteins or nucleic acids, based on size, electrical charge, or other physical properties.

What causes DNA molecules to move toward the positive pole during electrophoresis?

The negatively charged phosphate groups of DNA are attracted to the positive pole.

Why do larger DNA molecules move more slowly than smaller ones during electrophoresis?

Longer fragments are more restricted by the tangle of fibers in the gel.

What are some applications of DNA profiling?

Solving crimes, establishing paternity, and identifying victims.

How can DNA profiling be valuable for determining innocence as well as guilt?

It can provide evidence that excludes individuals from suspicion.

What was the Human Genome Project (HGP)?

A massive scientific endeavor to determine the nucleotide sequence of all DNA in the human genome and identify the location and sequence of every gene.

How many genes does the human genome contain according to the HGP?

Just under 21,000 genes.

What is the significance of noncoding DNA revealed by the HGP?

It consists of a huge amount of repetitive nucleotide sequences.

What is a nucleosome?

A structural unit of DNA packing, consisting of a segment of DNA wound around a core of histone proteins.

What is the difference between reproductive cloning and therapeutic cloning?

Reproductive cloning aims to create a new organism, while therapeutic cloning aims to produce cells for treatment.

What is the difference between adult stem cells and embryonic stem cells?

Adult stem cells are multipotent and found in specific tissues, while embryonic stem cells are pluripotent and can differentiate into any cell type.

What are tumor-suppressor genes?

Genes that help prevent uncontrolled cell growth.

What are oncogenes?

Genes that can promote cancer when mutated or expressed at high levels.

What is a carcinogen?

A substance that can lead to cancer.

What are the steps involved in creating recombinant DNA?

Involves cutting DNA with restriction enzymes, joining DNA fragments with sticky ends, and sealing them with ligase.

What does alternative splicing of mRNA mean?

It refers to the process by which different combinations of exons are joined together to produce multiple protein variants from a single gene.

What is golden rice a product of?

It is a transgenic product designed to produce vitamin A in rice.

What is meant by 'transgenic'?

An organism that has been genetically modified to contain a gene from another species.

What is the purpose of PCR?

To amplify specific DNA sequences.

What is the role of restriction enzymes?

To cut DNA at specific sequences, allowing for the manipulation of genetic material.

What is the purpose of gel electrophoresis in DNA analysis?

To visualize and separate DNA fragments based on size.