CHAPTER 1 INTRODUCTION TO GENETICS TERMS Alleles Alternative forms of genes Ex alleles for various eye colors Mutations Variations in genes alleles DNA sequence they are the source of genetic variation Gene functional unit of heredity Genotype The set of alleles for a given trait Phenotype The expression of the genotype Observable trait Translation The process of translating the coded mRNA into protein Transcription The process by which the information on a DNA strand is transcribed into a messenger RNA mRNA OCCURS IN THE NUCLEUS Wild type Functional version of a gene Natural selection Charles Darwins theory that explains evolutionary change Ex humans have 46 Diploid number 2n characteristic number of chromosomes in a species Haploid number n number of chromosomes in an organisms gametes Homologous chromosomes pair of diploid cells Nucleotides subunits that make up the linear strand of helix in DNA o These nucleotides form A Adenine T Thymine and G Guanine C cytosine complementary base pairing across the helix Codon nucleotide triplet On mRNA it is complementary to the information stored in DNA and specifies the insertion of a specific amino acid into a protein 1 1 Genetics has a rich and interesting history Schleiden and Schwann 1830 The cell Theory o All organisms are composed of basic units called cells that are derived from similar pre existing ones Cell replication requires genetic material replication o Mitosis o DNA replication o Somatic inheritance 1 2 Genetics Progressed from Mendel to DNA in less than a century 1866 passed his finding offering a general model of how Gregor Mendel traits are passed o Traits are passed from parents to offspring in predictable ways o Each trait is controlled by a pair of genes that separate during gamete Mendels work was rediscovered around 1900 and forms the foundation of formation genetics Eukaryotic cells undergo 2 types of cell division o Mitosis two resulting daughter cells receive a diploid set of o Meiosis Resulting cells gametes receive only half the number of chromosomes chromosomes Haploid n The Chromosomal theory of inheritance Sutton and Boveri o Inherited traits are controlled by genes residing on chromosomes Genes are transmitted through gametes A chromosome is composed of DNA complexed with proteins and many genes are found along the length of a single chromosome The White mutation is a heritable change in the DNA sequence of a gene involved in eye pigment deposition The white eyed mutant is the individual that expresses the mutant phenotype cause by that mutation DNA is the carrier of genetic information Sister chromatids come from DNA replication 1 3 Discovery of the Double Helix launched the Era of Molecular Genetics The structure of DNA was described by Watson and Crick 1953 DNA is an antiparallel double stranded Helix RNA Nucleic Acid similar to DNA except o It is usually single stranded o It has Adenine A Cytosine C and Guanine G but has Uracil U in place of Thymine T o The sugar in RNA nucleotides is ribose instead of Deoxyribose RNA World Hypothesis o proposes that self replicating ribonucleic acid RNA molecules were precursors to current life which is based on deoxyribonucleic acid DNA RNA and proteins RNA stores genetic information like DNA and catalyzes chemical reactions like an enzyme protein It may therefore have played a major step in the evolution of cellular life Transfer RNA tRNA recognizes the information encoded in the mRNA codons and carry s the proper amino acids for construction of the protein during translations The Central Dogma of molecular biology DNA transcribed RNA translated PROTEIN The genetic code consists of triplet nucleotides present in mRNA o Each triplet CODON encodes for insertion of specific amino acid into a growing protein chain o There are 20 amino acids commonly found in proteins Proteins are the end product of gene expression Once a Protein is made its action or location in a cell plays a role in producing a phenotype o Enzymes are the largest category of proteins Mutations altering a gene may modify alter or even eliminate the proteins usual function and cause an altered phenotype Sickle cell anemia is caused by a mutant form of hemoglobin the protein that transports oxygen from the lungs to cells in the body As a cellular phenotype sickle cell anemia exhibits a recessive mode of inheritance 1 4 Development of Recombinant DNA Technology began the Era of Cloning In the 1970 s researchers discovered restriction enzymes in bacteria s that cut viral DNA at specific sites o Recombinant DNA o Cloning o Molecular Cloning 1 5 The impact of Biotechnology is continually expanding Biotechnology the use of recombinant DNA technology and other molecular techniques to make products The transfer of heritable traits across species using recombinant DNA creates transgenic organisms 1 6 Genomics Proteomics and Bioinformatics are new and expanding fields Genomics analyses genome sequences to study the structure function and evolution of genes and genomes Proteomics identifies a set of proteins present in cells under a given set of conditions and studies their function and interactions Bioinformatics develops hardware and software for processing nucleotide 1 7 Genetic studies rely on the use of Model Organisms and protein data Model organisms o Easy to grow o Short life cycle o Production of many offspring o Genetic analysis straight forward E Coli bacterium S Cerevisiae yeast D Melanogaster fruit fly C Elegans nematode D Rerio zebrafish M Musculus mouse 1 8 We live in the Age of Genetics The time span from 1865 to 1962 encompassed the years leading up to the acceptance of Gregor Mendels work the discovery that genes are on chromosomes the experiments that proved DNA encodes genetic information and the elucidation of the molecular basis for DNA replication Terms CHAPTER 2 MITOSIS AND MEISOSIS Nucleus contains DNA which is complexed with an array of acidic and basic proteins into thin fibers chromatin Nuclear envelope membrane surrounding the genetic material in a cell Nucleolus resides in the nucleus and is the site of rRNA synthesis Nucleoid DNA containing region within the cytoplasm in prokaryotic cells Nucleotide building blocks of nucleic acids DNA and RNA Nucleosome The major structure associated with the organization of chromatin in the nucleus Nuclease An enzyme that breaks bonds in nucleic acid molecules Nucleolus organizer region NOR the areas of DNA that encode rRNA Glycocalyx surrounds
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