CROSS MOVING AND LINK
LINK AND INHERITANCE LAW MENDEL
Law segregation free state that each individual diploid own 2 allele on A
locus Which will separate during meiosis where each allele will separate
on cell gametes Which different.
Whereas principle assortation free ( Independent assortment ), clarify
that process separation 2 allele Which occur at the same locus, occur
independently and are not influenced by alleles other (on locus Which
different). Separation in a way free alleles This produce recombinant new
ie combinations alleles Which gather in gametes at random.
A cross between individuals involving two different alleles ( AA BB X aa bb)
in a homozygous state. Parent AA BB , produces gametes with alleles AB ,
and the second parent, aa bb , produces gametes with the allele ab ,
produces F1 progeny with genotype Aa Bb . Recombination is defined in
this case as: when F1 offspring produce gametes containing that
combination of alleles different from the allele combination of the parent
gamete. Or in other words, offspring F1 besides produce gametes AB And
ab , Also produce gametes with allele combination Ab and aB .
Mendel explain principle law segregation And assertion free with method
observe phenotype descendants from cross genetic yes made, without
understand the explanation of the biological processes underlying these
events.
The theory states that genes located on the chromosome. This theory can
simply explain the principle Mendel easily. In the principle of segregation,
for example, where individuals are diploid which has 2 alleles in one trait,
each of which is located at the same locus or on 2 homologous
chromosomes.
Chromosomes These homologs will segregate during meiotic division,
where each gametes accept One chromosome homologous. On principle
assortation free ( independent assortment ), which also occurs during the
meiotic division event, respectively Homologous chromosomes will
choose their partners freely without being tied to each other other
homologous chromosomes. So that the combination of alleles is in the
gametes created independently and if the combination is different from
the combination of alleles parent gametes, then this is called recombinant.
Because of genes located on chromosomes, then the genes are located on
the same chromosome will tend to be inherited together and tend not to
be separated freely in determining its allele pairs during gamete
formation.
Genes that are located close together on the same chromosome are called
genes Which adrift And is at on group link Which The same. Genes Which
adrift will move in a way together on process meiosis And on Finally will
gather on same location (gametes the same one).
MOVE CROSS
Genes that lie in the same group tend to be similar inherited together too,
but there are times when these genes will moving from one homologous
chromosome to another through something mechanism Which called
with move cross (Crossing over).
Understanding gene Before the discovery of the electron microscope, it
was stated that genes were elements element Which separated, regular in
a way linear like beads on A rope.
Gen considered as a unit of heredity and cannot divide, which is inherited
from to subsequent generations.
Genes are known as small regions of the chromosome. Where there is no
visible crossing over or chromosome breaking. Something gene certain
from something individual can inherited through the gametes to 50
percent from his descendants.
MECHANISM CROSSING OVER
Crossing over or crossing over is the process of selecting string positions
manually random And exchange characters the string. Function crossing
over is produces daughter chromosomes from the combination of
material from two chromosome genes parent.
The crossing over probability (Pc) is determined to control the frequency
crossing over.
Crossing over or crossover is a process that forms a new chromosome
from two parent chromosomes by combining pieces of information from
each chromosome. Chromosome new generated from crossover Which
called child chromosome. Move cross is incident exchange material
genetic between chromosome homologous moment gametogenesis.
Process move cross produce A individual new Which called a child.
Crossing over events generally occur during every gametogenesis which is
found in every living creature, such as humans, animals and plant. Move
cross happen when phase meiosis 1A, phase the happen If moment
chromosomes have doubled into two chromatids. At the time of
chromosomes want to separate, namely in anaphase 1, the crossed
chromatids stick together And separated in part chiasma, then each the
piece stick on chromatids next to it in a way lead come back
Factor Which influence happen move cross between other exists
temperature. Temperature tall will speed up process homology And stage
diplotene during meiosis thereby increasing the frequency of crossing
over. Whereas temperature low precisely extend stage Pakistan. The more
long stage Pakistan taking place then recombination will occur the more
big.
Crossing over occurs after chromosome duplication, in prophase 1 of
meiosis The two homologous chromosomes are duplicated to form four
chromatids. Four fruit chromatids form synapse Which named tetrad.
Moment tetrad formed, crossing over occurs. Evidence of crossing over
occurs after the chromosomes Homologous duplications were obtained
from the results of genetic analysis in experiments mold.
Mold Neurospora crassa. often used for analytical purposes genetic
because in the asexual reproduction phase a haploid ascosopra occurs
which will undergo mitosis so that they germinate and grow into
multicellular mycelium Which Also haploid.
TYPE MOVE CROSS
MOVE CROSS SINGLE
A single crossover is a crossover that will form 4 like gametes. Two types
have the same gametes and genes as the same gene owned by the parent,
it is called a parental type gamete.
The other two gametes is a new gamete that occurs as a result of the
crossing over process, then gamete This is called a recombination type
gamete. More parental type gametes are formed than type gamete
recombination.
Without there is a crossing over event between 2 non-homologous
chromosomes, then gametes are formed will be like gametes formed by
the parent ( AA BB and aa bb ) or no type of gamete has a recombinant
genotype. But with one move cross single between allele A And B, will
generated combination gametes new or recombinant genotype.
MOVE CROSS DOUBLE
Double crossing over is crossing over that occurs in two places. Crossing
over takes place between two linked genes, so it happens a process of
crossing over that will not be visible in the phenotype, because the
gametes are formed only from parental types and recombination types
resulting from crossing over single.
Double crossing over involves at least 3 loci together. The probability of a
crossover event is highly determined by the distance between the two loci
(genes), the further the position between the two loci, then The potential
for crossover events to occur is also greater. So are conversely, the closer
the position between 2 loci, the more potential there is for a move to
occur cross between second locus the more small.
RECOMBINATION GENES CONNECTED MOVE CROSS
Linked genes do not sort independently because the genes are located in
the same chromosomes and tend to move by meiosis and fertilization
does not expect genes adrift combine become choice allele Which No
found on parent, but Actually recombination between gene adrift of
course happen For see How matter This Can happen will discussed on fly
Drosophila Melanogaster.
In this case the result of a cross Drosophila offspring from a test cross for
color body And form wing Which No in accordance with ratio phenotype
his 1 : 1 : 1 :1. As expected if the genes for these two traits located on
chromosome Which different And choose in a way Alone. But If second
These genes are completely linked because the loci for both are different
on the same chromosome The same so will obtained ratio 1 : 1 Where only
phenotype. Results Which Actually it is not in accordance with with that
estimate expected.
Descendants most have parent phenotype which indicates that there is a
difference between the two genes. But approx 17% of the flies despite an
imperfect link, Morgan explain that mechanism certain Which reverse
segment between Homologous chromosomes must occasionally break the
link between the two genes.
Subsequent experiments have shown that such crossover exchange occurs
is reason happen process recombination gene adrift. Temporary
Homologous chromosomes pair at synapses during prophase of meiosis 1.
Chromatids Which No you Can disconnected on point certain And
exchange fragment.
Crossing over between homologous chromosomes forms recombinant
chromosomes which can cause several alleles to come together in new
combinations. Phase furthermore on meiosis distribute chromosome
recombination to gametes.
DIVISION MEIOSIS
The process of forming new characters in crosses is thought to occur
during meiosis division process. Crossing over that occurs in meiotic
division occurs at the end of prophase 1 or the beginning of metaphase 1
when the chromosomes have double become two chromatids. On
generally move cross happen on The middle chromatids are chromatids
number two and three of the chromatid tetrad, but it does not rule out the
possibility of crossing over between chromatids another.
The crossing over mechanism is followed by chromatids breaking and
attaching during prophase during the process of meiosis. Homologous
chromosome pairs separate And exchange material genetic so that change
arrangement gene And Finally form recombination new on the gametes.
MEIOSIS I
Stage beginning meiosis 1, chromosome Which has replicate thickened
And condense.
Prophase 1 of meiosis differs from prophase of mitosis in that it is
structured Homologous chromosomes become side by side in pairs which
is called a synapse. A pair of chromosomes that synapse is called a
bivalent (two chromosome) or tetrad (four chromatid).
On stages This, each chromosome consists on two chromatids identical
(Which has replicate); cell contain One set chromosome from parent
female And One set Again from parent male.
Moment synapse, chromatids can move cross And exchange material
genetic in process crossing over and recombination. The events of
prophase 1 are complex and can divided into five substage.
Zygonema (Zygotene or thread-joined stage)
On stage This, couples chromosome homologous meet And combined by
A structure proteins like tape Which called complex synaptoneme.
Synapsis occurs along paired chromosomes, at sites where there is
similarity in genetic information on both homologous chromosomes. If
complex synaptoneme No formed, caused synapse No complete And
move cross very reduced or even No there at all.
Pakinema (Pakiten or stage thread-thick)
Synapses have formed and recombination nodules begin to appear in the
along the synapsing chromosomes. Non-sister chromatids (One from each
chromosome Which pair) from tetrad experience crossing over,
separating, and rejoining, resulting in exchange genetic material. When
viewed with a microscope, these exchange points are visible cross-shaped
and called chiasma (plural chiasmata). On any chiasma, only two from
four chromatids Which move cross in a way random.
1. Metaphase 1. In this phase, the bivalents orient themselves randomly
field equatorial.
2. Anaphase 1. In this phase, the centromeres do not separate, but continue
unite fellow chromatids you.
3. Telophase 1. Occurs when the nuclear membrane re-forms and the
chromosomes chromosome has reach pole goal.Next happen cytokinesis
Which produce division cell parent diploid become two cell sapling
haploid. Each haploid cell receives a random pair ( assortment ) of
chromosomes paternal and maternal; in other words, the chromosomes
obtained from The male parent and female parent in one daughter cell
are not uniform. Besides That is, as a result of crossing over , the sister
chromatids still remain together attached in centromere) No more
identical in a way genetic. Division meiosis First end in here.
CONNECTION DIVISION MEIOSIS WITH MOVE CROSS
In prophase 1, homologous chromosomes form pairs. pairs are called bivalents.
The process of pairing homologous chromosomes is called synapse. Then every
member bivalent split elongated so that formed 4 chromatids. Fourth
chromatids on One bivalent named tetrad. During synapse here it is can happen
move cross. Move cross is incident segments of chromatids exchange in a tetrad
and crossing over occurs between chromatids Which No pair. Process final This
covers splitting and rejoining only two of the four threads at the point where just
on the chromosome. There is crossover is possible enlarge variation genetic
descendants, ie when two gene or more is at in One chromosomes, then
crossing over can produce gametes that have the same genes on initially No
There is, Because happen move cross so produce gametes Which own
chromosomes from type recombinant.
MAPPING CHROMOSOME
Mapping genetic ( genetic mapping ) is something business For knowing
the locus or position of a gene/genetic marker relative to other genes
genes or other genetic markers. The result obtained is a sequence of
positions a number of loci in a different group ( linkage group ).
In principle, arrangement or order mark in something relatedness
calculated based on draft segregation And recombination. The availability
of high-resolution genetic maps will make things easier determining the
locus of a gene in a chromosome, the number of genes and the strength of
the genes responsible answer to character certain.
Mapping genetic is stages which is important in genomics. Comparison
of genomes in various types of organisms can be carried out and the
results can be used in the fields of forensics, agriculture, medicine and
anthropology. There are two ways to carry out genetic mapping , namely
mapping linkage and physical mapping
Map chromosome is picture Which state distance genes Which located at
the locus arranged in a row on a chromosome.
Example:
1. In corn, colored seeds (C) are dominant over colorless (c). Seed non-wrinkled
(S) dominant over wrinkled seeds (s). Corn has it colored and non-wrinkled
seeds (CCSS) crossed with varieties that the seeds are colorless and wrinkled
(ccss). Then its F1 is cross tested and will get F2.
Completion :
Parental P1. CCSS P2. CCSS
Crossover: CCSS X ccss
Filial I (F1) CCSs
Back cross CCSS X CCSS
Filial II ( F2) CCSS : 4032 stem
CCSS : 4035 bars CCss : 149 sticks CCSS : 152 stem
Total : 8368 stem
Results cross the No in accordance with law Mendel 1:1:1:1 Because gene C And
S adrift. From results cross the, so can is known mapping its chromosomes.
Frequency parents : (4032 + 4035) / 8368 X 100% = 96.40%
Recombinant frequency: (149 + 152) / 8368 X 100% = 3.60%
Conclusion:
Frequency parents > 50% show that gene C And S is at on the same chromosome.
The recombinant frequency of 3.60% indicates that the distance between the C
and S genes is 3.6 centi morgan or map units.
Advances in molecular marker techniques provide convenience for
breeders plant in determination location gene Which control character
Which desired.
Determination gene Which control a number character important with
use mark genetic has succeed done on various type plant. Before mapping
a molecular marker to the desired character is required genetic mapping
constructed from a number of molecular markers.
Genetic markers generally used in germplasm characterization activities,
isolation of a gene, selection allele target Which integrated on something
individual And protection varieties.
Mapping of regions within the controlling chromosome qualitative and
quantitative character gets very attentive big inside breeding program.
Determination of genes that control qualitative and character traits
Quantitative requires mapping populations. Common methods used in
determining the location of genes that control qualitative characters is
Bulk Segregant Analysis (BSA).
Approach the proven capable speed up determination location gene with
cost Which relatively low. On the contrary, determination location gene
Which controlling quantitative traits is done through Quantitative Trait
Loci mapping (QTL). Compared to determining the location of genes
controlling qualitative traits, mapping QTL more complex And need
ability analysis statistics For determine the chromosome region
associated with the quantitative character.
Morphological markers have disadvantages, mainly their number is very
limited, level polymorphism is low, and is influenced by environmental
factors. Even though it's deep Morphological marking practices are easier
to monitor, some morphological markers, such as Flower color usually
appears later so scoring cannot be done more beginning (Poehlman And
Sleeper 1995). Use mark cytology in The formation of genetic maps is
usually based on displaying chromosome structure. Mark cytology rarely
used in mapping genetic.
Mapping genetic (genetic mapping) useful For show position gene And
feature order other on genome. Link genetic ( genetic linkage) that is
trend alleles at two or more loci of a chromosome bundle (chromatin) to
segregate together.
Genetic links can be detected automatically statistics with analysis of
associations between two or more traits that are expressions gene on
locus Which involved. There is two phase Which happen between two
locus Which adrift :
1. The coupled phase (cis or coupling ) occurs when two genes are in the
same direction influence the same one (the bait dominant) interrelated.
2. Opposite phases (trans or repulsion ), occur if two genes are in the same
direction influence different which are related.
3. Linkage occurs when two genes are close together on the same
chromosome. Like gene Which located near, Which get along in a way
independent Which called link gene. Linked genes are transmitted
together with the same gametes. if two genes far apart on the same
chromosome, they tend to associate together independent and the same
get away to gametes the same one or different.
Physical mapping is a molecular biology technique for examine DNA molecules
directly with the framework to construct a map which shows the sequence
position including genes. regular genetic mapping has relatively poor resolution
and tends to be inaccurate. to perfect it physical mapping is required if the map
is to be used in sequencing genome. mapping physique generated by that
method find position order certain on DNA molecule chromosome. important
technique :
1. Restrictions mapping
2. Fluorescent in there hybridization (FISH)
3. Sequence tagged site (STS) mapping
Mapping genetic based on principle that gene (mark or locus) segregate through
recombination chromosome during process meiosis So allows breeders to carry
out gene segregation analysis in individuals his elders Gen or mark DNA Which
close by (tightly-linked markers) inherited together from Elder to his progeny
with frequency Which more tall compared to genes that are located far from
each other. Genotypes of both parents and the heterozygous (recombinant)
genotype will be inherited as a result of crossing between second Elder. So can
calculated fraction recombination in count distance genetic in between mark
DNA Which mapped. Fraction recombination converted using a function
(mapping function) in known map units with centiMorgan (cM). Recombination
frequency value between two markers The smaller it shows the closeness of the
location of the two markers on a chromosome. Markers or genes are said to be
linked if they have a lower recombination frequency value from 50%, If on 50%
so considered No adrift One The same other. Amount mark used in constructing
genetic maps that will define groups constructable link. DNA markers with large
numbers will be very help in success construction map genetic with density tall.
