DETERMINATION TYPE SEX
SEX DETERMINATION
Chromosome sex No the only one decider type sex organism.
Ploidy individual, like on Lots hymenoptera (bee, ant, wasp), can
determine type sex; male is haploid And female diploid.
The allele mechanism can determine gender with a single or
multiple alleles alleles that are not linked to heteromorphic
chromosomes; even environmental factors can control sex. For
example, temperature determines the gender of some gecko, and
the sex of some marine worms and gastropods depends on the
substrate on which they land.
There is four type mechanism determination type sex
chromosomes: XY, ZW, X0, and compound chromosome
mechanisms. In the case of XY, as in humans or fruit flies,
females have one pair of chromosomes homomorphic (XX) and
heteromorphic male (XY). In ZW's case, men are homomorphic
(ZZ), and female heteromorphic (ZW), (XY and ZW are notations
chromosome And No imply about size or form chromosome This).
Incase of X0, the organism has only one sex chromosome, as in
some grasshopper And bee; woman usually XX And man X0, And
in case compound chromosomes, several X and Y chromosomes
combine to determine sex, as in bedbugs and some beetles. We
need to emphasize that chromosome That Alone No determine type
sex, but gene Which theybring do.
By general, genotype determine type gonads, Which Then
determines an organism's phenotype through the production of
male or female hormones.Determination type sex is process in
where gonads Which indifferent developbecome testes or ovaries.
While gender differentiation is a process in where the Wolffian or
Mullerian ducts develop into the final form of the organ
reproduction internal, for example duct Wolffi develop become
vesicles seminal, vase deferent, epididymide on man, whereas
channel Mullerian develops into the uterus, fallopian tubes, and
upper third of the vagina inwoman.
Gender determination is completely regulated by the determining
gender region Y And called SRY.
SRY stimulate cell Sertoli For produce Anti Mullerian Hormones
And furthermore push degeneration Mullerian tube. Thus the
mutation of the SRY gene in humans with XY causes complete
dysgenesis, in contrast to XX transgenic mice express SRY is
displayed phenotype man, own testicles, And behavior marryman.
Androgens required For development genitalia external.
Androgens is hormone Which cause androgenization genitalia
external including penis And scrotum And worthy from testicles
from urogenital ridge to position endin scrotum .
No like on man, estrogenization genitalia external on woman
including enlargement breast, development ovaries And uterus
silent until moment puberty And called process default or track
development negative SRY. However, studyRecent studies suggest
that female sex differentiation is also involved RSPO1, DAX-1, and
WNT4 genes that function as developmental antagonists testicle.
The mechanism by which sex is established is called sex
determination. We defineThe sex of an individual organism refers
to its phenotype. Sometimes something organism individual own
chromosome or gene Which usually linked with One type sex but
morphology Which relate with type opposite sex. For example,
human female cells usually have two chromosome X, And cells
man own One chromosome X And One chromosome Y.
Some people rarely have male anatomy, despite their cells each
contains two X chromosomes. Although these people genetic
female, we refer to her as male because of the sexual phenotype
they is a man.
There are many ways in which gender differences arise. On some
species, both sexes are present in the same organism, a condition
that called hermaphroditism; organisms containing male
reproductive structures and women are said to be monoecious
(meaning "of one house").
Species in which organisms having either male or female
reproductive structures is said to be dioecious (meaning "two
home"). Humans are dioecious. Among dioecious species, sex can
be determined chromosomally, genetic, or environment.
The sex of the baby or offspring is determined by the sex
chromosomes. Humans and mammals have two types of sex
chromosomes, namely the X chromosome and Y chromosome.
A person will be male if he has an X chromosome and Y
chromosome (XY). A person who has 2 X chromosomes (XX) will
have type sex Woman. On ovaries woman, chromosome sex (XX)
will undergoes segregation so that each egg cell has 1 X
chromosome (haploid). Meanwhile, in the testes, the sex
chromosomes (XY) will experience segregation so that There are 2
types of sperm cells, namely sperm that have an X chromosome (X
sperm) and sperm that have a Y chromosome (Y sperm).
In theory, sperm count Which own chromosome X (sperm X) The
same with amount sperm Which own chromosome Y so that
opportunity For opinion child man or Woman is50: 50
In non-mammalian species, sex determination is largely absent
determined by the XY system.
In grasshoppers, cockroaches, and some other insects,Sex is only
determined by one chromosome, namely the X chromosome.
Female grasshoppers own chromosome sex XX And grasshopper
male only own chromosome sexX.
there are 2 types of grasshopper sperm cells, sperm cells that
carry the X chromosome (Sperm X) and sperm cells that do not
carry the X chromosome (sperm 0). Egg Which fertilized by cell
sperm Which bring chromosome X (sperm X) willproduces female
offspring (XX). Eggs are fertilized bysperm cells that do not carry
the X chromosome (sperm 0) produce offspring with type sex man
(X0). Because type sex species This only determined by the X
chromosome, the sex determination system is called the X-0
system.
SEX LINKAGE
In system chromosome XY determination type sex, pattern
inheritance locus on chromosome sex heteromorphic different
from pattern locus on chromosome autosomal homomorphic
because sex chromosome alleles are inherited in relationships
with the gender of the offspring. The allele on the male's X
chromosome goes to the child daughters but not sons, due to the
presence of chromosomes His X usually determines that the
offspring will be a girl.
As example, pattern inheritance hemophilia (failure freezing blood),
form general Which caused by allele Which located on
chromosome X, has known since end century18th. It is known that
most men have the disease, while women Can transmit disease
without really have it.
Since both X and Y are sex chromosomes, three patterns of
inheritance are different are possible, all sexes are linked (for loci
only found on the X chromosome, only the Y chromosome, or
both). However, terms sex linked usually refer on locus Which
only found on chromosome X; the term Y-linked is used to refer to
loci found only in Y chromosome, which controls holandric traits
(traits found only in man). Locus Which found on chromosome X
And Y called pseudoautosomal. On man, at least four hundred
locus is known is at onX chromosome; only a few are known to be
on the Y chromosome.
Genes located on the sex chromosomes are called sex-linked genes.
Genes located on the Y chromosome are called Y-linked genes
(genes linked to the Y chromosome). Meanwhile, the genes
located in The X chromosome is called an X-linked gene (X
chromosome gene). Genes associated with chromosome Y
determine type sex.
Temporary gene Which related with The X chromosome is largely
unrelated to sex determination. Mammals a male or male will pass
an X chromosome to a girl but notwill pass the X chromosome to a
boy. On the other hand, mammals female or Mother can lower
chromosome X to child Woman / Woman orman / man.
The pattern of chromosomal inheritance will also influence the
phenotype of the associated gene with the X chromosome. An
example is color blindness. Color blindness is a genetic mutation
that occurs in a gene located on the X chromosome a woman will
suffer from color blindness if she has the homozygous recessive
genotype. But because they only have one X chromosome, men
suffer from blindness color if they have one allele that carries the
color blindness gene.
A man a colorblind person who marries a homozygous normal
woman will pass on the allelemutant to a girl but won't pass it on
to a boy man. Girls who inherit the mutant allele do not suffer
from color blindness because they only have 1 mutant allele that
causes color blindness (heterorigine). Girl That only will become
carrier disease blind color.
TYPE DETERMINATION TYPE SEX
Male individuals / man is heterogametic (XY) whereas female /
Woman is homogametic (XX). On the other hand, in chickens or
male ducks it is actually homogametic (ZZ). in heterogametic (ZW)
hens.
Determination of sex in humans / Mammals are said to follow the
XY system, while for birds such as chickens and others as well as
fish follow the ZW system. Most of the determining mechanisms
(determination) sex/gender sex is at in lower control genetic And
can classified to in error one category.
Male Heterogametes
In humans and most mammals, the presence of the Y chromosome
is decisive a tendency towards male traits. Chromosomally normal
males are XY And female XX. Matter This produce ratio sex 1:1 on
every generation. BecauseMales produce two gametes, so they are
said to have sex heterogamete. Meanwhile, females only produce
one type of gamete, so called homogametes. This method of
determining sex is generally stated as a method XY.
Role Chromosome sex:
There are phenotypic abnormalities in humans as a result of
numerical anomalies chromosome sex like on Klinefelter's sufferer
syndrome (XXY or XXYYor XXXY) or in Turner Syndrome (having
only one chromosome X), indicates that the sex chromosomes (X and
Y) in humans have an important role in determining sex and also an
important physiological role other. Among them:
The X chromosome contains important genetic information
for male individualsas well as women. At least one X
chromosome is required for development of the sexual
system on man.
The gene that determines maleness in humans is located on the Y
chromosome. Required at least one Y chromosome to determine
male sex inman although there is more from One chromosome X
on individual the.
The absence of the Y chromosome will cause the
appearance of genderwoman.
Genes that influence fertility are found on both sex
chromosomes (XAnd Y). A woman minimum need One set (pair)
chromosomeX to be fertile.
An excess number of X chromosomes will result in
problems normal development is good at individual
man as well as women.
Genes found on the Y chromosome in both humans and some
most other mammals, determining an individual's maleness. In
humans the SRY gene (Sex Determining Region Y) is the main gene
that determines determination male gender. The SRY gene encodes a
transcription factor protein that will stick on DNA And induce
transcription genes other Which stimulate growth testicles. Besides
gene SRY, there is also genes other on chromosome X, Y nor
autosomes Which Also contribute in determination fertilityAnd type
male sex.
In several types of insects, especially the order Hemiptera (true
ladybugs) and Orthoptera (grasshoppers), the males are also
heterogametes. But it produces sperm bearing an X, or gametes
without sex chromosomes. In male animals this species, the X
chromosome does not have a homologous pair due to its absence
Y chromosome. So the chromosome complement of male animals
shows the number odd. The presence of one-X determines male
traits and two-X determines female traits.
A single X chromosome is always contained in one of two types of
gametes formed in male animals, a 1:1 sex ratio will result in his
descendants. This method of decreasing sex is usually referred to
as the XO method, the symbol O indicates the absence of a
chromosome analogous to Y in the system XY.
FEMALE HETEROGAMET
This method of determining sex is found in various groups of
animals comparative big, including butterfly, silverfish, ladybug
water, caterpillar silk And on a number ofbirds and fish. There are
one-X and two-X in these species respectively determine female
and male characteristics.
Females of some species (eg chicken domestic) have chromosome
Which similar with commosomes Y on man. The chromosomes
given symbol Z And W consecutive For replace X And Y.
Chromosome W on chicken not a element decidertype sex female
the strong one.
SYSTEM BALANCE GENIC
In some insects, X and Y chromosomes are also found, such as only
in humans, but in the end it was discovered that the Y chromosome
in insects It does not determine and does not contribute to
determining gender male of the insect. In fruit flies (Drosophila
melanogaster), for example, in male flies XY chromosomes are
found while in female flies XX.
On Drosophila, the Y chromosome does not determine an
individual's maleness at all who has it, but it is more determined by
the balance between the genes located on the X chromosome and
the autosomal chromosome (A). This can happen becauseOn the X
chromosome there are genes that influence the formation of sexual
characteristics females, while the autosomal chromosomes contain
genes that contribute produce characteristic sex male. As a
consequence, type sex Drosophila determined by ratio
chromosome X : chromosome autosomes (A), Where amount
chromosome X shared with amount set haploid chromosome
autosomes. System determination type sex this is called with
balance system genic
.
Drosophila
sex is influenced by the ratio or balance between
number of x chromosomes and ploidy of autosomes (x/A). Based on
Bridges theory, typessex
Drosophila
in differentiate become female
super (3×/2A), female triploid(3×/3A), super male (×/3A), normal
female (2×/2A), normal male (×/2A) And intersex (sissy) (2×/3A).
Theory determination type sex from Bridges said the factor that
encourages the embryo to grow into a female lies in chromosome x.
Means, chromosome x is decider female (female determine). The
male determinant (maledetermine) is autosomal. Triploid
autosomes are results from fail
Drosophila
Also influenced by
induction nerve autonomous, specifically on chromosome xx.
Autonomic nerve induction stimulates xx to carry out oogenesis,
butNo on xy. This resulting in the x/A ratio change.
On individual with ratio X:A = 1.0 produce individual female,
whereas individual with ratio X:A = 0.5 produce individual male. If
ratio X : A not enough from 0.5, so will generated individual
phenotype male, However in a way physique individual This weak
And sterile. Individual male sort of This often called withmetamale .
Individuals with an X : A ratio between 0.5
–
1.0 produce intersex
flies,Which own character male And female. If ratio X : A more big
from 1.0, so The female phenotype will be obtained with female
characters but is generally problematic in the development process.
Females with a ratio above 1.0 are often referred to with
metafemale.
TYPE PLOIDY
Some insects can carry out parthenogenesis, meaning from egg
cells New creatures can form without being preceded by
fertilization by spermatozoa. For example on species Hymenoptera
like ant, bee, And wasp, individual male develop with method
parthenogenesis, that is through egg Which No fertilized.
It is a type determination systemsex which has nothing at all to do
with sex chromosomes but only depend to amount genome (device
chromosome). , for example determination type sex on bee honey
(
Apis
sp.).
In honeybees, sex is normally determined by fertilization status
from the egg, rather than the presence of sex chromosomes.
Models of sex determination like this was first discovered by
Johann Dzierzon, a Catholic priest in 1845. Dzierzon reported that
the queen bee had not yet performed Fertilization will only
produce male offspring. This discovery is 50 years old precede
before published it invention chromosome sex.
Model determination type sex use system
haplodiploid
like on bee
honeyAt least more than 20% of animal species also experience this.
On the system haplodiploidm descendants male generally develop
from egg Which No fertilized so it only has a haploid number of
chromosomes or only has one set chromosome. Meanwhile,
fertilized/fertilized eggs will develop become bee worker or queen
bee Which own amount chromosome diploid.
It is clear that sex determination in honey bees is not influenced by
chromosome sex on creature other, but by characteristic ploidy
from the creature. Diploid (2n) bees are female, while haploid (n)
bees is male.
FACTOR LINK AND DETERMINATION TYPE SEX
Genes are genetic factors main role in determining the type sex or expression
sex. In general, gene Which responsible answer In determining sex in
living creatures, there is not just one thing but a number of install gene.
These genes are located in gonosomes and autosomes. Theory genetics say
that genotype each other interact with environment produce phenotype.
There is some factors which influence link Andtype gender, namely:
1
.
Factor genetic
Genetic factors have a major role in determining a person's
gender organism Because determined by material genetic
Which There is in in chromosome, specifically gonosomes
(chromosomes sex).
2
.
Environmental factor
Factor environment is every matter Which dapt influence the
life of an organism. If the level of sex hormones in the body is
not balanced, the phenotype of a living creature can change.
On a number of invertebrates type sex influenced by factor
environment not genetic. For example, sex determination in
marine mollusks (
Crepidula fornicata
) known as limpet. Each
limpet begins life as a larva swimming. The first larvae to settle on
the solid substrate will develop into The female limpet, then
produces chemicals to attract other larvae stay on. Larvae This
will develop become male And Then serves as his partner.
Determination type sex invertebrates Also influenced by
temperature environmentwhen the egg is incubated. For example,
Nhrusema victa
(turtle) eggs are incubated at high temperatures
female turtles will give birth, and if incubated at high
temperatures low will give birth to males. Instead,
Lacertilia
(lizard) eggs are incubatedat high temperatures male lizards will
give birth while at low temperatures they will giving birth to
female lizards.
Determination of sex in certain plants as well is known influenced
by condition environment. For example on Equisetum (plant), if it
is grown in a comfortable environment for its life grow become
plant female. On the contrary, when grow in environment Which
not enoughrate Hara then will grow become male plants.
Influence environment to determination type sex
Drosophila
expressed in two appearances, namely penetration and
expressivity (expressivity). Penetration states what percentage (%)
of the genotype shows phenotype Which expected. For example,
consequence influence environment How many percent
Drosophila
XX become female. Or, what percentage of
Drosophila
XY become males and what percentage are females.
Transformation of
Drosophila
XX into male And
Drosophila
XY
become female is consequence from influence environment, for
example temperature And radiation, on period critical in its
development.
Appearance The second thing that changes the ratio of
Drosophila
males to females
is expressivity. Also due to environmental
influences in the critical period,
Drosophila
XX is transformed
become male, female, and intersex .
CHROMATIN SEX
On man cell somatic woman there is A chromatin sex temporarycell somatic
man No have it. Furthermore is known that many sex chromatin turns out to
be equal to the number of X chromosomes minus one. So, woman normal
own chromatin sex Because own pair X chromosome, whereas males do not
have sex chromatin because only own one X chromosome.
HORMONE AND DIFFERENTIATION SEX
Determination type sex organism is known that factor gene ethical
hold role main in expression primary sexual characteristics.
Furthermore, the hormonal system will regulate physiological
conditions in body individual so that influence development
characteristic sex secondary.
In higher animals and humans sex hormones are synthesized by
ovaries And testicles each have function double, that is as producer
sex cells (gametes) and as producers of sex hormones. Meanwhile,
glands Adrenaline produces steroids that are chemically closely
related to the gonads.
