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This presentation has been supported by the Erasmus

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Plus K2 Cooperation Partnerships.

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Innovation of the structure and content of study programs
in the field of animal

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genetic and 

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food resources management
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with the use of digitalization innovation.

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The European Commission

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Support for the production of this presentation
does not constitute

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an endorsement of the contents,
which reflects the views only of the authors.

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And the Commission cannot be held responsible for any use
which may be made of the information contained therein.


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Modul no. 1: Animal Genetics
Ewa Salamończyk from Siedlce University of Natural Sciences and Humanities, Faculty of Agrobioengineering and Animal Husbandry.

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Genetic linkage,
also known as genetic inheritance,

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refers to the transmission of traits
from one generation to another through genes.

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almost all

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genetic information

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is located in

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the chromosomes, located in the nucleus of the cell,

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the set of all chromosomes in the somatic cells

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of a given organism constitutes its karyotype.

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Each plant and animal species has a fixed

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and characteristic number of chromosomes.

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The normal pig karyotype
shown in the picture contains 38 chromosomes.

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Karyotype = autosomes + sex chromosomes

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Among all the chromosomes of a given species in the karyotype.

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two are responsible for the sex of the animal,
and we call them sex chromosomes.

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The sex chromosomes in the porcine karyotype are: XX sows and

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XY boars.

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Genes located

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on one chromosome
tend to be inherited together.

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We say that they are coupled
and this phenomenon is called coupling

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these genes   

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that are all

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on different chromosomes,

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unlinked genes

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Each

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chromosome contains

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a large number of genes that are located some distance apart
or close to each other.

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Those that are some distance away can move between homologous
chromosomes in the process of recombination

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during meiosis. 

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We call such genetic

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 connections loose.

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Those genes

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that are very close to each other
on the same chromosome are often inherited together.

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We call such a genetic link strong

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Genes can be linked in cis and trans

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The genes on homologous
chromosomes can be cis-linked

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when dominant alleles are on one chromosome or trans

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if the dominant alleles are on different chromosomes.

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Thus

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linked traits are traits

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whose genes

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have their locus on the same chromosome.

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These traits are inherited together, forming a linkage.

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Great.

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The number of linkage groups corresponds
to the number of homologous chromosome pairs in a cell.

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The external manifestation of linked traits

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is a reduction in the diversity of phenotypic forms
because the phenomenon of linkage restricts

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the number of types of gametes
produced by heterozygous individuals.

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Types of linked traits

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There are two types of coupling,

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absolute linkage
and relative linkage.

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Absolute linkage occurs
when there is no crossing over between the genes, 

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relative linkage occurs when there is crossing over between genes.

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Individuals with a recombined gene arrangement

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are produced in relation to the parental gene arrangement.

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Segregation of

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linked genes

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Crossing over - the phenomenon of exchange of genetic material

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between non sister chromatids of homologous chromosomes.

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It occurs during the prophase I of meiotic division,

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hence it is also called meiotic recombination.

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The resulting new forms are called recombinant.

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This phenomenon, which leads to the creation of new genetic forms,
is the main cause

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of genetic variability in a population and the basis

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for determining the linkage between any segments of DNA.

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The process occurs during the pre
phase of the first meiotic division or non sister chromatids

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during crossing over an unstable connection called
chiasma is formed

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between two chromatids oriented in the same direction

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as a result of completed crossing over,

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there can be a permanent exchange of chromosome segments
between homologous chromosomes,

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either closer to the telomere or between two chiasmata.

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This leads to the formation of recombinant gametes

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with a different allelic arrangement than the parental gametes.

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The process of crossing over is a random

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event and occurs at random locations.

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However, the randomness of this phenomenon
at a specific chromosomal location

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has a limiting effect
on the occurrence of crossing over nearby interference phenomenon.

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The chromatid that participated in the exchange acquires

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a combination of alleles
from both the paternal and maternal origins.

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Unlike the situation before crossing over,

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in that case the chromosome, and thus its chromatids,

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had a set of alleles from only one parent,
as dictated by the principle that within a pair of homologous

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chromosomes, one originates from the father
and the other from the mother.

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Non-sister chromatids
Sister 
chromatids
Crossing over in prophase I of meiosis

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Completed exchange in metaphase I of meiosis
Chromosomes in gametes

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Non-recombinant (parental)

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chromosomes
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Recombinant chromosomes

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Crossing over does not occur with a constant frequency.

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Crossing over is more likely to occur on long

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segments of the chromosome than on short segments.

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It more frequently occurs in meiosis 

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in females than in males.

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A form of gene cooperation is the phenomenon of pleiotropy occurs

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when one gene influences the development of several traits

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Pleiotropy can be true an apparent 

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True pleiotropy occurs
when a Pleiotropic Gene affects several distinct centers.

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Example: the gene for platinum color in foxes. 

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Platinum Foxes unlike standard colored individuals, are 

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less lively and more excitable

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individuals homozygous for this gene are not viable.

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Also for SNAP was given them to go
guano, sandstone and those richer.

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But in the case of apparent pleiotropy,

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a gene controls a specific trait that in turn influences

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depending on environmental influences
the variation of other traits.

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For example, the gene responsible for feather curliness 

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in poultry also affects, among others, the metabolic rate,

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heart function and digestive processes.

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However, these changes are a consequence of abnormal feathering,

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which does not protect the bird from excessive heat
loss.

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in the case of
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many traits,
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 genes from different illegal pairs
through their combined action

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result in the emergence of a new form of qualitative trait.

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The interaction between genes from different allele pairs

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in shaping the phenotype is called allelic interaction.

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Examples of Allelic interaction 

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Epistasis (the expression of one allele pair is dependent on the presence of another allele pair).

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Additive gene action 

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Multiple genes from different Lockie contribute to a single trait
resulting in varying degrees of expression

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Thank you for your attention.