2014

1. GENE BINDING Výukový materiál GE 02 - 50 Tvůrce: Mgr. Šárka Vopěnková Tvůrce anglické verze: ThMgr. Ing. Jiří Foller Projekt: S anglickým jazykem do dalších předmětů Registrační číslo: CZ.1.07/1.1.36/03.0005 Tento projekt je spolufinancován ESF a SR ČR 2014

2. Mendel´s laws about independent combinability of alleles is in force only for alleles,which are placed on various pairs of homological chromosomes >> independent combination • all genes placed on one chromosome are mutually bound to each other = gene bound • a set of genes of one chromosome belongs to so called binding group of genes GENE BINDING

3. elementary knowledge of gene binding was first formed in 1920s by an American researcher Thomas Hunt Morgan • he experimented on Drosophila fly • 2 Morgan laws GENE BINDING

4. GENE BINDING

5. I. Law of location of genes • genes in chromosome are placed linearly in a row after each other at fully determined places = gene loci II. Law of gene binding • a set of genes in the chromosome makes up a binding group • all genes are reciprocally bound • independently combined are only with genes from other binding groups • the number of binding groups is given by the number of pairs of homologous chromosomes 2 MORGAN´s LAWS:

6. all genes placed on one chromosome form a binding group GENE BINDING A a A a the number of the binding groups = number of chromosome pairs b B B b by gametes formation – alleles are transmitted together new combinations – only as a consequence of the process of recombination AB ab Ab aB

7. coincidental exchange of a section between non-sister chromatids of the same chromosome • exchange in the configuration of alleles configuration of alleles on chromosome fibre = recombination of alleles CROSSING OVER

8. formation of recombined gametes – low probability • the further are the genes from each other, the higher the probability that there will be a coincidental break between them • the closer they are, the lower probability • according to the amount of gametes with recombined configuration can be considered the strength of the binding • according to the strength of the binding chromosome map can be retrospectively created GENE BINDING

9. GENE BINDING

10. it depends on probability with which the recombination can proceed • if between two bound genes on a chromosome can proceed crossing over = genes incompletely bound • if crossing over does not proceed = genes completely bound THE STRENGTH OF BINDING

11. Bateson number c1 • determines, how many times more often are in the complex present gametes with original genotypes contrary recombined • Morgan number p2 • determines relation of presence recombined gametes to whole gametic complex THE STRENGTH OF BINDING

12. For tomatoes, round shape of the fruit is dominant over the presence of elongated shape and glossy skin is dominant over dull skin. Allelic pairs controlling inheritance of these characters are in the same pair of homologous chromosomes. • What is the relative distance between the genes, if in retrospect dihybrid crossing with homozygous recessive plant there arose posterity by phenotypic composition: • 108 plants with round fruits and shiny skin, 13 round fruits with a matte skin, 12 with elongated fruits and shiny peel and 117 plants with elongated fruits with dull skin? • What was the original arrangement of dominant and recessive alleles of the respective genes on chromosomes of hybrid plants? WORKSHEET

13. KUBIŠTA, Václav. Obecná biologie: úvodní učební text biologie pro 1. ročník gymnázií. 3. upr. vyd. Praha: Fortuna, c2000, 103 s. ISBN 80-716-8714-6. SOURCES