introduction to genetics ch. 11. write the information on the slides that show this symbol or that...
Post on 03-Jan-2016
217 Views
Preview:
TRANSCRIPT
Introduction to Genetics
Ch. 11
Write the information on the slides that
show this symbol or that is this color.
Genetics
• The scientific study of heredity
Gregor Mendel
• Father of modern genetics
• Combined plant breeding, statistics, careful record keeping
Mendel studied pea plants traits (characteristics)
Genetic Information
• Gene – basic unit of genetic information
Allele – one form of a gene
Principle of Dominance
• Some alleles are dominant and others are recessive
Dominant vs. Recessive
•Dominant alleles express a trait. (capital letter)
•Recessive alleles are only visible when paired with another recessive allele. (lower case letter)
Segregation
Gamete
Separation of alleles during gamete formation
Sex cells
Punnett Square
• Diagram used to predict and compare variations resulting from a genetic cross
Homozygous vs. Heterozygous
• Homozygous - having two dominant or two recessive alleles. (BB or bb)
•Heterozygous - having both a dominant and recessive allele. (Bb)
Genotypes Phenotypes
• Genotype - genetic make up
• Phenotype – physical characteristics
Genotypes Phenotypes (example)
genotypes
phenotypes
Hybrid• Offspring of crosses between parents with
different traits
Principle of Independent Assortment
• Genes for different traits can segregate independently during the formation of gametes.
• Example: genes for seed shape segregate independently of those for seed color
Incomplete Dominance
• One allele is not completely dominant over another
Incomplete Dominance
• A flower has genes for white petals (w) and red petals (r). When you mix white flowers with red flowers you get pink flowers. How is this possible? The w gene does not dominate over the r gene and vice versa. Both genes express themselves equally so you get a pink color in the petals.
w w
r wr wr
r wr wr
Codominance
• Both alleles contribute to the phenotype
Polygenetic Traits
• Traits controlled by two or more genes
Meiosis
• reproduction of gametes
(Similar to mitosis, but there are 2 divisions, ending with ½ the number of chromosomes of the parent cell.)
Diploid vs. Haploid
• Diploid – contains both sets of homologous chromosomes
• Haploid – contains a single set of chromosomes
Crossing-over is the process in which homologous chromosomes exchange portions of their chromatids during
meiosis.
Gene Map
• Diagram showing the relative locations of each known gene on a particular chromosome
top related