Download gene binding

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
GENE BINDING
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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
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
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GENE BINDING
2 MORGAN´s LAWS:
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

all genes placed on
one chromosome
form a binding group
GENE BINDING
A
a
A
a
B
b
b
B
the number of the
binding groups =
number of
chromosome pairs
by gametes formation
– alleles are
transmitted together
AB
ab
Ab
aB
new combinations – only
as a consequence of the
process of recombination
CROSSING OVER
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
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GENE BINDING
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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
THE STRENGTH OF BINDING
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
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THE STRENGTH OF BINDING
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
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WORKSHEET
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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?
SOURCES
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KUBIŠTA, Václav. Obecná biologie: úvodní učební text biologie pro 1.
ročník gymnázií. 3. upr. vyd. Praha: Fortuna, c2000, 103 s. ISBN 80716-8714-6.