Rifat Ali Kheshgi Student At Nwfp Agricultural University Peshawar Cell

GENETICS RIFAT ALI KHESHGI Student at NWFP AGRICULTURAL UNIVERSITY PESHAWAR Cell # 03139556067

Genetics • Genes are located on chromosomes and exist in alternative forms called alleles. A dominant allele can mask the expression of a recessive allele

Genetics • When Mendel crossed pea plants differing in one trait, one form of the trait disappeared until the second generation of offspring. To explain his results, Mendel formulated the law of segregation.

Genetics • Mendel formulated the law of independent assortment to explain that 2 traits are inherited independently

Genetics • Events in genetics are governed by the laws of probability.

Genetics • Heredity- passing on of characteristics from parents to offspring • Genetics- branch of biology that studies heredity • Trait- characteristic that is inherited; can be either dominant or recessive • Gamete- male and female sex cells; sperm and egg

Genetics • Pollination- transfer of male pollen grains to the pistil of a flower • Fertilization- fusion of male and female gametes • Hybrid- offspring formed by parents having different forms of a trait • Allele- alternative forms of a gene for each variation of a trait of an organism

Genetics • Dominant- observed trait of an organism that masks the recessive form of a trait • Recessive- trait of an organism that can be masked by the dominant form of a trait

Genetics • Law of Segregation- Mendelian principle explaining that because each plant has two different alleles, it can produce two different types of gametes. During fertilization, male and female gametes randomly pair to produce 4 combinations of alleles

Genetics • Phenotype- outward appearance of an organism, regardless of its genes • Genotype- combination of genes in an organism • Homozygous- paired chromosomes with genes for the same traits arranged in the same order • Heterozygous- when there are 2 different alleles for a trait

Genetics • Law of Independent Assortment- Mendelian principle stating that genes for different traits are inherited independently of each other

Genetics • Diploid- cell with 2 of each kind of chromosome; is said to contain a diploid, or 2n, numbers of chromosomes • Haploid- cell with 1 of each kind of chromosomes; is said to contain a haploid of n, number of chromosomes

Genetics • Homologous Chromosome- paired chromosomes with genes for the same traits arranged in the same order • Meiosis- type of cell division where one body cell produces 4 gametes, each containing half the number of chromosomes as a parent’s body cell • Sperm- haploid male sex cells produced by meiosis • Egg- haploid female sex cells produced by meiosis • Zygote- diploid cell formed when a sperm fertilizes an egg • Sexual reproduction- pattern of reproduction that involves the production and subsequent fusion of haploid sex cells

Genetics • Crossing Over- exchange of genetic material between nonsister chromatids from homologous chromosomes during prophase 1 of meiosis; results in new allele combinations • Genetic Recombination- major source of genetic variation among organisms caused by reassortment or crossing over during meiosis • Nondisjunction- failure of homologous chromosomes to separate properly during meiosis; results in gametes with to many or to few chromosomes

Genetics