Essay on Dna and homologous Chromosomes

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CH 11 GENETICS: fertilization: process of sexual reproduction where male an female reproductive cells join. Genetics: scientific study of heredity. True-breeding: if plant can self-pollinate, the offspring will be identical to them. [(GREGOR MENDEL: PEA PLANTS PROJECT) . To cross-pollinate pea plants, mendel cut off the male parts of flower, then dusted it with pollen from another flower. He concluded that some alleles are dominant and some recessive. P generation- f1 generation- f2 generation./ trait: a specific characteristic. Hybrids: offspring of crosses between parents with different traits. Genes: chemical factors that determine traits. Alleles: the different forms of a gene. THE PRINCIPLE OF DOMINANCE STATES THAT SOME ALLELES ARE DOMINANT AND OTEHRS RECESSIVE. During gamete formation, alleles segregate from each other so that each gamete carries only one single copy of each gene. Each F1 plant produces two types of gametes- those with alleles for tallness, and those for shortness. Gametes: sex cells. Probability: the likelihood something will happen. THE PRINCIPLES OF PROBABILITY CAN BE USED TO PREDICT THE OUTCOME OF GENETIC CROSSES. [punnett square] Punnett squares can be used to predict and compare the genetic variations that will result from a cross. Homozygous: two identical alleles for a particular trait [TT], heterozygous: two different alleles for the same trait [Tt]. Phenotype: physical characteristics. Genotype: genetic makeup. [PRINCIPLE OF INDEPENDENT ASSORTMENT: states that genes for different traits can segregate independently during the formation of gametes. Independent assortment helps account for the many genetic variations observed in plants, animals, and other organisms.] When Mendel crossed plants that were heterozygous dominant for round yellow peas, he found that the alleles segregated independently to produce the F2 generation. Some alleles are neither dominant nor recessive, and many traits are controlled by multiple alleles or multiple genes. [incomplete dominance: when an allele is not completely dominant over another allele.] [codominance: both alleles contribute to the phenotype.] [multiple alleles: more than 2 alleles] [polygenic traits: traits controlled by two or more genes] [homologous: a chromose has a corresponding pair in the opposite sex] [diploids: have 2 sets of homologous chromosomes (2N)] [haploid: one single set of genes (N)] Meiosis is a process of reduction division in which the number of chromosomes per cell is cut in half through the separation of homologous chromosomes in a diploid cell. [MEIOSIS STEPS: [INTERPHASE 1] [(meiosis 1) PROPHASE 1] [METAPHASE 1] [ANAPHASE 1] TELOPHASE 1 AND CYTOKINESIS] [(meiosis 2) PROPHASE 2] [METAPHASE 2] [ANAPHASE 2] TELOPHASE 2 AND CYTOKINESIS]. 4 chromatids in a tetrad made up of homologous chromosomes. [Meiosis produces 4 genetically different haploid cells] [Mitosis results in the production of two identical diploid cells]
CH 12 DNA: [Frederick Griffith] injected mice with bacteria. [transformation: process in which one strain of bacteria is changed by a gene from another strain of bacteria]. Avery and other scientists discovered that the nucleic acid DNA stores and transmit’s the genetic information from one generation of an organism to the next. [bacteriophage: a kind of virus that infects bacteria] Hershey and chase concluded that the genetic material of the bacteriophage was DNA, not protein. [NUCLEOTIDE: (3 parts) [deoxyribose molecule] [phosphate group] [nitrogenous base] (4 different bases in DNA) Purines [Adenine & Guanine] Pyrimidines [Cytosine & Thymine] [Rosalind Franklin: X-ray Diffraction] [Watson and Crick’s model of DNA was a double helix, in which two strands were wound around each other] [A]=[T] & [G]=[C] :base pairing. [prokaryotic cells lack nuclei]. Eukaryotic chromosomes contain both DNA and protein. When tightly packed together they form chromatin. [chromatin consists of DNA tightly coiled around proteins
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