2005_campbl14

2005_campbl14 - Important Point: Chapter 14: Mendel and the...

Info iconThis preview shows pages 1–4. Sign up to view the full content.

View Full Document Right Arrow Icon
1 Chapter 14: Mendel and the Gene Idea Important Point: Gregor Mendel “The best way to gain an understanding of genetics is to work with it. The fundamental principles discussed (below) will become clear to you, and you will grasp them more surely, if you carefully think through . . . problems which illustrate the various patterns of inheritance…” (Keeton, 1980, Biological Science third edition, W.W. Norton & Company, p. 621) Alleles and Loci Gene location on chromosome An allele is a gene variant (often differ only by one or few nucleotides) A gene is a discrete heritable unit Different alleles may or may not code for different phenotypes Crossing Peas Controlled breeding, with specific characters scored for specific traits (e.g., character = flower color, trait = purple vs. white) “Crossing” is mating First Generation Offspring First filial generation
Background image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
2 Note difference between “character” and “trait” Note 3:1 ratios A trait is a variant of a character The interaction between non- identical alleles results in interesting non-correspondences between genotype and phenotype Even more… True Breeding True breeding results when both parents are homozygous for the same trait , e.g., a purple purple x purple purple cross can result only in purple purple Æ purple- flowered progeny; similarly ww x ww Æ only ww progeny Monohybrid Cross Recessive phenotype Dominant phenotype Heterozygote Genotype unknown (homo- vs. heterozygote) Genetics Problem-Solving Secrets! ± Known Genotype can be used to infer unknown Phenotype ± (but not always, due to complications, e.g., penetrance) ± Known Phenotype can be used to infer unknown Genotype ± (but not always due to lack of 1:1 correspondence: more than one genotype can give rise to a given phenotype) ± Genotype (diploid) gives rise to Gametes (haploid) via Meiosis ± Gametes (haploid) give rise to “Progeny” (diploid) via Fertilization ± Fertilization (syngamy) always results in Diploidy (I.e., >ploidy than haploid) ± Meiosis always results in Haploidy (I.e., anaphase I reduction division from diploidy to haploidy)
Background image of page 2
3 Monohybrid Cross = monohybrid = monohybrid Homozygous dominant Genotype vs. Phenotype
Background image of page 3

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Image of page 4
This is the end of the preview. Sign up to access the rest of the document.

This note was uploaded on 06/03/2011 for the course BIO 113 taught by Professor Swenson during the Spring '08 term at Ohio State.

Page1 / 9

2005_campbl14 - Important Point: Chapter 14: Mendel and the...

This preview shows document pages 1 - 4. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online