2014 GONOSOMAL INHERITANCE Výukový materiál GE 02 - 52 Tvůrce: Mgr. Šárka Vopěnková Tvůrce...
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Transcript of 2014 GONOSOMAL INHERITANCE Výukový materiál GE 02 - 52 Tvůrce: Mgr. Šárka Vopěnková Tvůrce...
2014
GONOSOMAL INHERITANCE
Výukový materiál GE 02 - 52
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
GONOSOMAL INHERITANCE
heredity of signs whose genes are placed on sex chromosomes
(in the heterologous part of the chromosome)
SEXUAL CHROMOSOMES
chromosome X chromosome Y
www.uni-heidelberg.de/presse/news05/2501genetisch.html
SEXUAL CHROMOSOMES
chromosome Y much smaller than X big heterologous part of chromosome X
forms a special binding group= inheritance fully connected with the sex
genes on a small homologous section of both chromosomes are subjects to synapsis
crossing over can proceed > inheritance like autosomal genes = inheritance not fully connected with the sex
SEXUAL CHROMOSOMES
genes lying in the heterologous section of chromosome Y determine holandric features, e.g. excessive hair of auricle
genes carried on chromosome Y are transferred only on males (heterogametic sex) > they prove direct inheritance
genes lying in heterologous section of chromosome X prove so called X - chromosomal inheritance
SUMMARY on gomosomes there can be distinguished between
heterologous and homologous sections. heterologous sections: they determine features completely connected with sex homologous sections: they determine features not completely connected with
sex, i.e. Mendel´s lawns in force features incompletely connected with sex are
determined by genes lying in homologous sections of chromosomes (e.g. daltonism, blindness)
for these genes are valuable the same rules as for autosomal genes
GENES FULLY CONNECTED WITH THE SEX
they lie on the heterologous part of the chromosome X
a big number of genes genes whose recessive alleles cause: hemophilia Daltonism (colorblindness) absence of sweat glands (anhydrotic
ectodermal dysplasia) muscle dystrophy
HEMOPHILIA
genotype of a healthy woman: XX >> both dominant alleles
genotype of a woman-vector: Xx >> she has a dominant allele on one chromosome and on the other one a recessive defect allele
>> otherwise, she is healthy but she can transfer a defect on the next generation on sons
genotype of an ill woman: xx >> on both X chromosomes defect alleles
HEMOPHILIA
in the genotype of a man there is only one X chromosome, the alleles located on it do not have any counterparts = hemizygotic organism
these alleles always become evident in the phenotype
genotype of a healthy man: XY genotype of an ill man : xY
CROSS INHERITANCE
daughters inherit defect from the disabled father mother vector tranfers the disease on her sons = cross inheritance typical for genes fully connected with sex noticeable difference in the frequency of illnesses
between the sex > much more common by the individuals of type XY than XX
genes localized on heterologous part of chromosomes Y do not have their pair allele in genotypes XY, the organism hemizygotic for them > they can become evident by the sex XY only
CHROMOSOME Y
by mammals usually small few genes key gene SRY it influences: production of male hormon maturation of sperms these genes have direct inheritance
from father to son = holandric inheritance
INHERITANCE CONTROLLED BY SEX features whose genes are located
on autosomes they become evident in dependence
on the presence of sexual chromosomes in phenotype by both the sexes differently
formation of the most secondary sexual features
early hairlessness
early acomia (hairlessness) allele P responsible for early acomia by men: it appears in homozygotic dominant and
heterozygotic constitution men PP and Pp are bald (hairless), pp are
not women: they have this cosmetic fault only by
genotype PP women pp and Pp have normal hair
INHERITANCE CONTROLLED BY SEX
EARLY HUMAN ACOMIA
WORKSHEET
EXAMPLE 1:Father and son are colour-blind, while the mother distinguishes colors normally. Is it right, when we say that son has inherited this hereditary defect of sight from his father? The recessive allele, conditioning daltonism, lies in the non-homologous segment of chromosome X.
EXAMPLE 2:A daughter of a colour-blind father has married a man whose father was also colour-blind. However, neither the woman nor the man suffer from daltonism. What will their children be like? The recessive allele, conditioning daltonism, lies in the non-homologous segment of chromosome X.
CHALUPOVÁ-KARLOVSKÁ, Vlastimila. Obecná biologie: středoškolská učebnice : evoluce, biologie buňky, genetika : s 558 řešenými testovými otázkami. 2., opr. vyd. Olomouc: Nakladatelství Olomouc, 2010, 206 s. ISBN 978-80-7182-282-0
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