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Globular protein molecule around which DNA is tightly coiled in chromatin
One strain of bacteria (the harmless one)changed permanently into another (the disease-causing strain)
Avery & NAD
Discovered (so did other scientists) that the nucleic acid DNA stores and transits the genetic information form on generation to the next
-One kind of virus -Infects bacteria -Known as "bacteria eater" -C composed of a DNA or RNA core and protein coat -When this enters a bacterium , it attaches to the surface of the cell and injects its genetic information into it
Hershey and Chase
Concluded that the genetic material of the bacteriophage was DNA not protein
-What DNA is made up of -Made up of 3 basic components: a 5-carbon sugar called deoxyribose, a phosphate group, and a nitrogenous (nitrogen-containing) base
Watson and Crick
-Their model of DNA was a double helix, in which two strands were wound around each other Base Pairing -Explained Charagaff's rules -For every adenine one thymine molecule of each cytosine molecule, there was one guanine molecule
Gel Electrophoresis
-A mixture of DNA fragments is placed at one end of a porous gel, and an electric voltage is applied to the gel -When the power is turned on, DNA molecules, which are negatively charged, move toward the positive end of the gel -The smaller the DNA fragment, the faster and farther it moves -Can be used to located and identify on particular gene out of the tens of thousands of genes in an individual's genome
Recombinant DNA
DNA produced by combining DNA form different sources
Polymerase chain reaction (PCR)
Technique that allows molecular biologists to make many copies of a particular gene
Base Pairing
-Explained Charagaff's rules -For every adenine one thymine molecule of each cytosine molecule, there was one guanine molecule
Granular material visible within the nucleus; consists of DNA tightly coiled around proteins
DNA Replication & Duplication
During DNA replication, the DNA molecule separates into two strands, then produces two new complementary strands following the rules of base pairing. Each strand of double helix of DNA serves as a template, or model for the new strand
DNA polymerase
Enzyme that "proofreads" new DNA strands, helping to ensure that each molecule is a nearly perfect copy of the original DNA
Genetic Engineering
Making changes in the DNA code of a living organism
DNA Extraction
The cells are opened and the DNA is separated from the other cell parts
Cutting DNA
Biologists cut the DNA molecules precisely into smaller fragments using restriction enzymes
Restrictions Enzymes
-Hundreds are known -Each one cuts DNA at a specific sequence of nucleotides -Like a key fits into one lock
Transforming Bacteria
During transformations, a cell takes in DNA from outside the cell; this external DNA becomes a component of the cell's DNA
-Found naturally in some bacteria -Have been very useful for DNA transfer -Have 2 essential features: It has a DNA sequence that helps promote plasmid replication & Genetic marker
Genetic marker
-A gene that makes it possible to distinguish bacteria that carry the plasmid (and the foreign DNA) from those that do not -If the transformation of successful, the DNA will be integrated into one of the cells chromosomes
Transgenic Organisms
Genetic engineering makes it possible to transfer DNA sequences, including whole genes form one organism to another
-Means that they contain genes from other species -Using the basic techniques of genetic engineering, a gene from one organism can be inserted into cells from another organism -Genetic engineering has spurred the growth of biotechnology a new industry that is changing the way we interact with the living world
Transgenic Animals
-Have been used to study genes and to improve the food supply -Some transgenic livestock now have extra copies of growth hormone genes -These animals tend to grow faster and produce leaner meat than ordinary animals -In the future, transgenic animals might also provide us with an ample supply of out own proteins
Transgenic Plants
-Are now an important part of out food supply, -In the year 2000:52% of the soybeans& 25% of the corn -Many of these plants contain genes that produce a natural insecticide -So these crops don’t need to be sprayed with synthetic pesticides
-A member of a population of genetically identical cells produced form a single cell -Cloned colonies of bacteria and other microorganisms are always to grow, but this is not always true of multicellular organisms, especially animals
-Scottish scientist Ian Wilmot stunned biologists by announcing that he had cloned a sheep -The adult sheep is Dolly, the 1st mammal cloned from an adult cell -The fact that Dolly was cloned did not affect her ability to produce a live offspring
-From the Latin word meaning "to change" -Changes in the genetic material -Come in many shapes and sizes -Gene mutations result from changes in a single gene -Gene Mutations
Point Mutations
-Occur at a single point in the DNA sequence -Mutation that affects a single nucleotide -Usually by substitutions one nucleotide for another
Frameshift Mutations
-Shift the "reading frame" of the genetic message -By inserting or deleting a nucleotide
Chromosomal Mutations
-Involve changes in the number or structure of chromosome -These may change the location of genes on chromosomes, and may even change the number of copies of some genes
Neutral Mutations
-Meaning that they have little of no effect on the expression of genes or the function of the proteins for which they code -Mutations are also the source of genetic variability in a species -Some variations can be highly beneficial
-The conditions in which an organism has extra sets of chromosomes -Polyploid plants are often larger and stronger than diploid plants
-Are coded DNA instructions that control the production of proteins within the cell? -RNA, like, DNA, consists of a long chain of nucleotides
3 main types of RNA
-Messenger RNA -Ribosomal RNA -Transfer RNA -Messenger RNA
Ribosomal RNA
Makes up the major part if ribosomes
Transfer RNA
Transfers each amino acid to the ribosome as it is specified by coded messages in mRNA
Process in which past of the nucleotide sequence of DNA is copied into a complementary sequence in RNA
RNA polymerase
Enzyme similar to DNA polymerase that binds to DNA and separates the DNA strands during transcription
-Have specific base sequences -Signals in DNA that indicate to the enzyme where to bind to make RNA
-Intervening sequence of DNA -Does not code for a protein
Consists of three consecutive nucleotides that specify a single amino acid that is to be added to the polypeptide
-Aka protein synthesis -The cell uses information from messenger RNA to produce proteins -The cell uses all three main forms of RNA during this process
A group of three bases on a tRNA molecule that are complementary to an mRNA molecule Selective Breeding
Selective Breeding
-Allowing only those animals with desired characteristics to produce the next generation -Humans have produced many different breeds of dogs
-Crossing dissimilar individuals to bring together the best of both organisms -The individuals produced by such crosses are often hardier than either of their parent
-Technique often used to maintain the desired characteristics if a line of organisms -The continued breeding of individuals with similar cells -Example -Golden Retriever
Increasing Variation
-Selective breading would be impossible without the wide variation that is found in natural populations
A group of genes that operate together
-Region of chromosome in an operon to which the repressor binds when the operon is "turned off" -When the lac repressor binds to the O region, RNA polymerase is prevent3ed from beginning the process of transcription
Process in which cells become specialized in structure and function
Hox Genes
-Control the differentiation of cells and tissues in the embryo -A mutation in one of these "master control genes" can completely change the organs that develop in specific parts of the body

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