Genetics Terms. Genetics Heredity – passing of traits from one generation to the next. Genetics...
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Transcript of Genetics Terms. Genetics Heredity – passing of traits from one generation to the next. Genetics...
Genetics Terms
Genetics • Heredity – passing of traits from one generation to
the next.
• Genetics – “study of heredity”
• Traits – inherited characteristics
Genetics
• Allele – different copies or forms of a gene controlling a certain trait (eye, hair color)
• Dominant – the observed or expressed trait (prevents the expression of a recessive allele)
• Recessive – trait that can be hidden by a dominant gene. * not expressed unless homozygous
Genetics• Gene – “basic unit of heredity”
• Gamete – egg or sperm cells with haploid # of chromosomes (sex cells)
• Homozygous – when alleles for a specific trait are the same (BB/bb)
• Heterozygous – when alleles for a specific trait are different (Bb)
Genetics
• Genotype – genetic makeup of an organism. The combo of alleles that an organism inherits for a certain trait. “Letters” (BB, Tt, Dd)
• Phenotype – the expression of the genotype or physical appearance that an organism shows. “Look like” (brown, tall, dimples)
Genetics
• Haploid – (n) ½ the # of chromosomes *having 1 set of chromosomes
• Diploid – (2n) 2x’s the haploid # of chromosomes*having 2 sets of chromosomes
• Chromosome – a strand of DNA that functions in the transmission of traits.
• Zygote – a cell resulting from the union of the gametes*fertilized egg
Genetics
• Hybrid – organisms that are heterozygous and result from two different pure lines.
• Parent generation – 1st generation of parents • F1 generation – 1st generation of offspring
• F2 generation – 2nd generation of offspring
Genetics • Law of Dominance – when pure organisms are
crossed with contrasting traits, all offspring will show the dominant trait.
• Law of Segregation – during egg/sperm formation, the pair of genes/alleles for a trait separate so that each gamete has only one of the genes for the trait (one
from mom and one from dad)
Genetics
Genetics • Law of Independent Assortment – as gametes are
formed the genes for various traits separate independently of each other. Exp….eye color does not influence hair color
Exp: The eye color genes are Brown (B) and blue (b) and the ear lobe genes are free (F) and attached (f). The genes assort independently, so that each egg or sperm obtains 1 of each trait (BF, Bf, bF, bf).
Genetics
Punnett square – indicates ratio of genotypes and phenotypes of possible offspring.
Cross – an exchange of genetic information.
• Test cross – cross an unknown genotype with a known genotype (an individual showing the recessive trait, homozygous recessive)– # 8 in your monohybrid crossList 3 reasons why Gregor Mendel used pea plants1. Easy to grow/grow fast 2. Easy to pollinate b/c produce 2 distinct sex cells 3. Show sharply contrasting traits (round vs
wrinkled, green vs yellow, tall vs short)
Genetics