Biology Questions and Answers
- Besides the XY system are
there other sex determination
systems?
Some animals havsystem different from the XY system.e a sex determination
The X0 systemsystem of many i is the sex determinationnsects; in this system
the females aronly one X chromosome XX and the males have (a conditionede
represented by X0).
In birds, in some fishes and in
lepidopterae (butterflidetermination is made by the ZWes) insects the sex
system; in this system females are ZW
and males are ZZ.
In another system, the haploid-diploid
sex determination sexes is represented by the fertilizesystem, one of thed
diploid individual and the individual of
the opposite sex is foparthenogenesis, being haploid (itrmed by (^)
occurs in bees and other insects).
- What are X-linked traits?
X-linkeconditiond traitsed by genes located are phenotypical traitsin the
nonhomologous (heterologous) portions
of the X chromosome.
- How many alleles of genes
that condition X-linked traits
do female and male
individuals respectively
present?
For each correspondent gene to an X-
linked trait women present alwaysalleles since they have two X two
chromosomes. Men present only one
allele of genes related to X-linksince they have one X chromosome.ed traits- What is the clinical
deficiency presented by
hemophilic people? What is
the genetic cause of that
deficiency?
Hemophilia is a disease characterized by
impaired person is more prone to internal ablood clotting and the affectednd
external hemorrhages.
Patients with hemophilia A have
alteration factor VIII of blood clotting, a in the gene that codifies thgene e
located in the non-homologous portion
of the X chromhemophilia B prosome. Patients withesent a defect of the (^)
gene that codifies the factor IX of
clotting, a homologous region of the Xgene also located in the non-
chromosome. Thus both diseases are X-
linked diseases.
- What are all possibilities
of genotypes and phenotypes
formed in the combination of
alleles responsible for the
production of factor VIII?
Considering the alleles Xh aXh represents the allele that cond X, wherenditions
hemophilia A, in genotypes are XX, XXh anwomen the possibled XhXh. In (^)
men the possible genotypes are XY and
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