Definitions and descriptions concerning in vitro embryos and their role in biotechnological research.
The importance of DNA in biotechnology reflected in practices of creating in vitro embryos.
DNA BIOTECHNOLOGY
Contextual information regarding the advancements and applications of DNA biotechnology as detailed by Copley News and the contributions from Gary Marksen.
BIOTECHNOLOGY
Observation: Genetic manipulation of organisms is an ancient practice.
Humans have been performing genetic modification for thousands of years, particularly through the practices of plant and animal breeding.
EVOLUTION AND BREEDING OF FOOD PLANTS
Case study on the evolution of maize (Zea mays) from ancestral teosinte to contemporary corn cultivars.
Illustration showing the developmental stages from wild varieties to selected food staples.
Discussion about the evolution of Brassica species, particularly wild mustard, elucidating its descendants.
ANIMAL HUSBANDRY/BREEDING
Explanation of animal breeding techniques and their significance in the biotechnology landscape.
BIOTECHNOLOGY TODAY
Overview of Genetic Engineering
Focus on DNA manipulation.
Necessity of tools for DNA engineering activities and exploration into the toolkit available for genetic manipulation.
BIOENGINEERING TOOLKIT
Basic Tools
Restriction Enzymes: Enzymes that cut DNA at specific sites.
Ligase: An enzyme that joins DNA strands.
Plasmids/Cloning: Vectors for DNA insertion in organisms.
DNA Libraries/Probes: Collections of DNA fragments used for research.
Advanced Tools
Gel Electrophoresis: A method for separating DNA fragments by size.
PCR (Polymerase Chain Reaction): A technique to amplify DNA sequences.
Southern Blotting: DNA transfer method to detect specific sequences.
Microarrays: Technique for analyzing gene expression.
DNA Sequencing: Determining the nucleotide sequence of DNA.
CUT, PASTE, COPY, FIND
Comparison of genetic engineering tools to standard word processing concepts:
Cut: Restriction enzymes.
Paste: Ligase.
Copy: Plasmids, bacterial transformation, and PCR.
Find: Southern blotting and probes applications.
CUT DNA
Restriction Enzymes
Definition
Also known as restriction endonucleases, these enzymes are evolved in bacteria to cut foreign DNA, providing a defense mechanism against viruses.
Discovered in the 1960s.
Explain methylation in bacteria as a protective mechanism for their own DNA.
Action of Restriction Enzymes
Description of enzyme activity: Cuts at specific sequences referred to as restriction sites.
Characteristics of restriction sites:
Symmetrical palindrome structure producing protruding ends, known as sticky ends.
Examples of different enzymes and their naming conventions, such as EcoRI, HindIII, BamHI, and SmaI, including their recognition sequences.
Visual representation indicating where restriction enzymes cut the DNA.
BIOTECH USE OF RESTRICTION ENZYMES
Diagrammatic representation showing how sticky ends of DNA fragments facilitate the joining of DNA sequences.
Concept of recombinant DNA creation through the joining of fragments.
DNA FINGERPRINTING
Definition and purpose:
Analysis of DNA fragments to distinguish individuals from one another.
Utilizes electrophoresis technique to separate DNA fragments.
ELECTROPHORESIS
Overview
Definition: A technique for separating molecules based on their charge, size, and shape, using an electrical current.
Description of the semi-solid matrix used for migration and separation of molecules.
ELECTROPHORESIS MATRIX
Agarose: Polysaccharide derived from red algae used in electrophoresis.
Purified form of agar.
VISUALIZATION OF DNA
Techniques for visualizing DNA fragments following electrophoresis.
Fluorescence by UV light, other fluorescent dyes such as EZ Vision Dye, and visual dyes like Coomassie Blue.
A GAROSE GEL ELECTROPHORESIS
Focus on DNA migration: Example layouts showing DNA bands, size markers, and wells for sample application.
PASTE DNA
Sticky Ends
How sticky ends enable hydrogen bonds between complementary bases to anneal.
Ligase
Function and importance of ligase in the sealing of DNA strands and the formation of covalent bonds within the DNA backbone.
COPY DNA
Plasmids
Definition: Small, self-replicating circular DNA molecules utilized as vectors for gene insertion.
Description of the transformation process which involves injecting recombinant plasmids into bacteria, resulting in numerous copies of the plasmid within the bacterial populations.
Process outlined: DNA → RNA → protein → trait.
RECOMBINANT PLASMID
Explanation of essential components within recombinant plasmids:
Antibiotic resistance genes used as selectable markers.
Restriction sites for splicing in the gene of interest.
Process for ensuring bacterial survival on antibiotic plates:
Non-transformed bacteria will die on antibiotic plates.
Transformed bacteria containing the plasmid will survive.
SELECTION FOR PLASMID UPTAKE
Process Overview
Use of ampicillin as a selective agent:
Only bacteria with the plasmid will survive on ampicillin plates, while all bacteria grow on LB plate.
DNA LIBRARIES
Creation of DNA libraries involves several steps:
Cut nuclear DNA from multiple cells using restriction enzymes.
Clone DNA fragments into plasmids simultaneously (shotgun cloning).
Store a collection of all cloned DNA fragments in a petri dish.
FIND YOUR GENE IN DNA LIBRARY
Locating a gene of interest requires knowledge of part of the gene’s sequence:
Techniques for sequencing include:
"Back translation" from protein sequence to DNA.
Utilizing sequence information from a similar gene from another organism.
DNA HYBRIDIZATION
Explanation of hybridization techniques:
Using a short, single-stranded DNA probe complementary to the gene of interest.
Utilizing tagged probes with radioactive or fluorescent markers.
Heating genomic DNA to denature the strands, allowing hybridization to occur.
LOCATING YOUR GENE OF INTEREST
Diagrammatic representation illustrating the probe's interaction with denatured DNA.
SOUTHERN BLOT
Procedure Overview
Perform restriction digest.
Gel electrophoresis.
Blot DNA off gel onto filter paper.
Wash filter with labeled probe.
Expose filter paper to X-ray film.
EDWIN SOUTHERN
Discussed the Southern blotting technique used for identifying specific genes within genomic DNA.
Illustrative steps involved in the Southern blotting process.
C-DNA (COPY DNA) LIBRARIES
Definition: Libraries containing only the coding sequences of expressed genes.
Extraction of mRNA from cells followed by reverse transcription to generate cDNA.
Application examples: Human insulin production through bacterial expression systems.
PCR (POLYMERASE CHAIN REACTION)
Definition
Explanation of PCR as a technique for amplifying specific DNA sequences.
PCR STEPS
Denaturation: Heating to separate DNA strands.
Annealing: Cooling to allow primers to bind to target DNA.
Elongation: DNA polymerase synthesizes new DNA.
Repeat: Cycle is repeated for exponential amplification.
PCR AMPLIFICATION CHART
Visual description of how the number of copies grows exponentially through successive PCR cycles, with a sample illustration indicating 34 billion copies after 35 cycles.
PCR TEMPERATURE CYCLING
Overview of temperature ranges needed at each step of PCR processes, detailing time intervals used.
PCR COMPONENTS
List of necessary components for PCR, including:
DNA polymerase: Key enzyme used in the PCR process.
Target DNA: The segment of DNA intended for replication.
Primers: Short complementary strands that initiate synthesis.
Nucleotides: The building blocks (A, T, C, G) added during elongation.
MICROARRAYS
Definition
Laboratory tool designed to monitor gene expression across thousands of genes simultaneously, involving slides with defined spots of known DNA sequences.
PROCESS OF MICROARRAY ANALYSIS
Extracting mRNA from cells and converting it into labeled cDNA that is hybridized to the DNA on the microarray slide.
Visualization of hybridization with active genes indicated by yellow spots.
ADVANCED TECHNIQUES: DNA SEQUENCING
Overview
The significance of DNA sequencing in understanding genetic information, identifying genes, and potential clinical applications.
ILLUMINA SEQUENCING TECHNOLOGY
Introduction to Illumina HiSeq2000, a modern sequencing technology capable of generating vast amounts of sequence data through automated processes and cluster generation.
SANGER METHOD
Detailed explanation of the Sanger sequencing process, utilizing dideoxynucleotides which terminate DNA synthesis.
Describes the in vitro conditions required for this method, including tubes containing normal N-bases and dideoxy N-bases.
READING THE SEQUENCE
Explanation of how sequencing results are visualized using polyacrylamide gel techniques and how sequences are read from different lanes.
ADVANCEMENTS IN SEQUENCING
Transition from radioactive markers to fluorescent tagging provides more efficiency.
Automated sequencing processes simplify data collection.
HUMAN GENOME PROJECT
Overview
Description of the U.S government's initiative, initiated in 1990 with a goal of completing the sequencing of the entire human genome within 15 years.
Key figures: Jim Watson and Francis Collins.
Introduction to Celera Genomics and Craig Venter's competing effort for faster sequencing methodologies.
DIFFERENT APPROACHES
Description of two methods of sequencing:
Map-based method: Involves cutting DNA into fragments and sequencing them based on overlapping sequences (government method).
Shotgun method: Fragments are cut and sequenced without prior arrangement (Craig Venter’s method).
SIGNIFICANT MILESTONE
Announcement of the "working draft" of the human genome on June 26, 2001, marking an historic development in genetics and medicine.
MAPPING HUMAN GENES
Diagrammed representation of gene mapping across the human genome indicating specific genes and their locations within the chromosomes.
ETHICAL IMPLICATIONS
Discussions around the potential ethical considerations of genetic manipulation, gene sequencing, and the responsibilities of researchers and society concerning genetic data management.