genetic recombination - bimogeum.ucoz.com€¦ · genetic recombination genetic recombination ......
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Genetic Genetic
recombinationrecombination
Genetic Genetic
recombinationrecombination
Genetic recombinationGenetic recombinationGenetic recombinationGenetic recombination
Obtaining of new gene combinations by Obtaining of new gene combinations by
rearrangements in genetic materialrearrangements in genetic material::
Between two DNA moleculesBetween two DNA molecules
Between two different chromosomes Between two different chromosomes
Between two sets of chromosomesBetween two sets of chromosomes
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Biological importance of Biological importance of
recombinationrecombination
Biological importance of Biological importance of
recombinationrecombination
Genetic variabilityGenetic variability
Natural selectionNatural selection
Biologic evolutionBiologic evolution
Recombination and phenotype Recombination and phenotype
consequencesconsequences
Recombination and phenotype Recombination and phenotype
consequencesconsequences
Genetic polymorphismGenetic polymorphism
Normal phenotypic polymorphismNormal phenotypic polymorphism
Different reaction to environmentDifferent reaction to environment ((drugsdrugs, ,
foodfood, , toxinstoxins...)...)
Susceptibility to infectionsSusceptibility to infections
Predisposition to diseasesPredisposition to diseases ((cancerscancers, ,
diabetesdiabetes...)...)
Abnormal phenotypic polymorphismAbnormal phenotypic polymorphism
Types of recombinationTypes of recombinationTypes of recombinationTypes of recombination
GenomicGenomic –– betweenbetween andandgenomes genomes 23 c23 chhrsrs + 23 + 23 cchhrsrs = 46= 46
ChromosomalChromosomal
InterchromosomalInterchromosomal –– between nonbetween non--homologous chromosomeshomologous chromosomes;;
IntrachromosomalIntrachromosomal –– between between homologous homologous chromosomeschromosomes
Gene Gene –– between two alleles by between two alleles by gene fusiongene fusion
During
fertilisation
During
meiosis
During
meiosis
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????
What dose fertilization representsWhat dose fertilization represents??
Fusion of two sexual cells of different origin Fusion of two sexual cells of different origin
((haploid gametes; haploid gametes; 23 23 chrschrs) ) formation of formation of
zygotezygote ((diploid cell diploid cell 46 46 chrschrs).).
What does meiosis representsWhat does meiosis represents??
Formation of haploid cells called gametes Formation of haploid cells called gametes ((by by
reductionalreductional division a cell withdivision a cell with 46 46 chrschrs
makes haploid cells with 23 makes haploid cells with 23 chrschrs))
Passing of genetic material from parents to childrenPassing of genetic material from parents to children
Fertilization
Zigot
(2n)
Mitosis,
differentiation,
growing
Mitosis,
differentiation,
growing
Copil
(2n) Adulţi
(2n)
Meiosis
Sperm (n)
Egg (n)
Peculiarities of segregation of chromosomes in meiosis
during ovogenesis and spermatogenesis
OVOGENESISOVOGENESIS
SPERMATOGENESISSPERMATOGENESIS
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Mitosis Mitosis vs. vs. MeiosisMeiosisMitosis Mitosis vs. vs. MeiosisMeiosis
46 SC chrs46 SC chrs
46 BC chrs 46 BC chrs
46 SC
chrs
46 SC
chrs
Mitosis
Replication
Meiosis
Replication
23 BC
chrs
23 SC
chrs
23 SC
chrs
23 SC
chrs
23 SC
chrs
23 BC
chrsI
IISomatic cells
Sexual cells = gametes
MitosisMitosis MeiosisMeiosis
! Bivalents at equator
! BC Chrs to poles
! n=2c
! n=c
2n=4c
2n=2c 2n=2c
2n=2c
! MC Chrs to
poles
MIMI
AIAI
TITI
MIIMII
AIIAII
TIITII
MM
AA
TT
MeiosisMeiosisMeiosisMeiosis
I I division division –– reductionalreductional ((2n2n==4c4cn=n=2c2c)) Prophase Prophase II
Metaphase Metaphase I I
AnaphaseAnaphase II
Telophase Telophase II
II II Division Division –– equationalequational (n=(n=2c2cnn=c)=c) Prophase Prophase IIII
Metaphase Metaphase III I
AnaphaseAnaphase IIII
Telophase Telophase IIII
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Meiosis Meiosis I I –– reductionalreductionalMeiosis Meiosis I I –– reductionalreductional
Prophase Prophase II
Condensation of chromosomesCondensation of chromosomes
Formation of spindleFormation of spindle
!!! !!! Conjugation of homologous Conjugation of homologous chromosomes chromosomes bivalents bivalents
!!! !!! CrossingCrossing--overover intrachromosomalintrachromosomalrecombinationrecombination
There are 5 phasesThere are 5 phases: : L, P, Z, D, L, P, Z, D, DD
Prophase Prophase IIProphase Prophase II
LeptotenLeptoten ZigotenZigoten PahitenPahiten DiplotenDiploten DiachinezăDiachineză
Chromatin
condensation
!!! Conjugation
of homologous
chromosomes
!!! Crossing-
over
Pushing of
chromosomesChiasma
termination
Conjugation of homologous Conjugation of homologous
chromosomeschromosomes
Conjugation of homologous Conjugation of homologous
chromosomeschromosomes
Takes place during prophase ITakes place during prophase I
Synapses of homologous Synapses of homologous
chromosomeschromosomes
Ensured by Ensured by synaptonemalsynaptonemal complexcomplex
Importance Importance –– formation of bivalentsformation of bivalents
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SynaptonemalSynaptonemal complexcomplexSynaptonemalSynaptonemal complexcomplex
ScaffoldRecombination
nodules
Chromatin of
paternal sister
chromatids
Chromatin of
maternal sister
chromatids
CrossingCrossing--overoverCrossingCrossing--overover
Takes place during prophase ITakes place during prophase I
Exchange of fragments between Exchange of fragments between
homologous chromosomes homologous chromosomes
intrachromosomalintrachromosomal recombinationrecombination
Determined by Determined by synaptonemalsynaptonemal complexcomplex
Importance Importance –– genetic variabilitygenetic variability
Crossover
gametes
Non-crossover
gametes
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Molecular mechanism of Molecular mechanism of
crossingcrossing--overover
Molecular mechanism of Molecular mechanism of
crossingcrossing--overover
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Metaphase Metaphase IIMetaphase Metaphase II
Bivalents at equatorBivalents at equator
!!! !!! Random orientation of chromosomes to Random orientation of chromosomes to
polespoles
or
Important
Anaphase Anaphase IIAnaphase Anaphase II Disjunction of homologous chromosomesDisjunction of homologous chromosomes
Migration of BC chromosomes to poles Migration of BC chromosomes to poles ((nnchromosomes to each poleschromosomes to each poles))
!!! !!! Independent combination of nonIndependent combination of non--homologous chromosomes homologous chromosomes = = interchromosomalinterchromosomal recombinationrecombination 22nn
combinationcombination
or or or
AbC aBc ABC abc Abc aBC ABc abC
InterchromosomalInterchromosomal recombinationrecombinationInterchromosomalInterchromosomal recombinationrecombination
Takes place during anaphase ITakes place during anaphase I
Between nonBetween non--homologous maternal and homologous maternal and
paternal chromosomespaternal chromosomes
Random separation of nonRandom separation of non--homologous homologous
chromosomeschromosomes
Importance Importance genetic variability of genetic variability of
gametesgametes
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Telophase Telophase IITelophase Telophase II
Reorganization of two nucleiReorganization of two nuclei (n=(n=2c2c))
CitokinesisCitokinesis
Two gametocytes (haploid, Two gametocytes (haploid,
chromosomes BC)chromosomes BC) !!! !!! Reduction of Reduction of
number of chromosomesnumber of chromosomes
2n=4c
n=2c
n=2c
InterkinesisInterkinesisInterkinesisInterkinesis
Preparation to second division Preparation to second division ((meiosismeiosis II)II)
Meiosis Meiosis II II –– equationalequational divisiondivisionMeiosis Meiosis II II –– equationalequational divisiondivision
Prophase Prophase IIII
Formation of spindleFormation of spindle
Maturation of Maturation of kinetocoreskinetocores
andand
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Metaphase Metaphase IIIIMetaphase Metaphase IIII
At equator SC chromosomesAt equator SC chromosomes
andand
AnaphaseAnaphase IIIIAnaphaseAnaphase IIII
Longitudinal cleavage of centromereLongitudinal cleavage of centromere
Disjunction of chromatidsDisjunction of chromatids
Migration of SC chromosomes Migration of SC chromosomes (n=c (n=c cchhrsrs))
andand
TelophaseTelophase IIIITelophaseTelophase IIII
Reorganization of nuclear envelopes and Reorganization of nuclear envelopes and formation of haploid nucleiformation of haploid nuclei ((n=c)n=c)
CytokinesisCytokinesis
4 haploid gametes4 haploid gametes
2n=4c
n=2c
n=2c
n=c
n=c
n=c
n=c
I div
II div
II div
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Biological importance of meiosisBiological importance of meiosisBiological importance of meiosisBiological importance of meiosis
Maturing of gametesMaturing of gametes
Genetic recombinationGenetic recombination
Multiplication of gametesMultiplication of gametes
2n=4c
n=2c
n=2c
n=c
n=c
n=c
n=c
I div
II div
II div
Ovogenesis Spermatogenesis
Ovogonia Spermatogonia
1st ovocyte1st spermatocyte
2nd ovocyte 2nd spermatocytes
Polar body
Polar bodies
Spermatides
Spermatozoons
Spermatozoons
Zygote
Egg
Replication Replication
Meiosis I (reductional) Meiosis I (reductional)
Meiosis II (equational) Meiosis II (equational)
Fecundation)
Formation of
sperms
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Molecular biologyMolecular biologyMolecular biologyMolecular biology
Theoretic support for other subjectsTheoretic support for other subjects
Genetics Genetics
HistologyHistology
BiochemistryBiochemistry
PhysiologyPhysiology
Understanding of molecular and cellular Understanding of molecular and cellular
organization of human organismorganization of human organism
Knowledge of material support of heredity Knowledge of material support of heredity and variabilityand variability
Knowledge of material support of Knowledge of material support of human human pathologypathology
Knowledge of Knowledge of methods of diagnostic at methods of diagnostic at molecular levelmolecular level
Knowledge of Knowledge of bases of modern bases of modern biotechnologiesbiotechnologies
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Quality of DNAQuality of DNAQuality of DNAQuality of DNA
Quality and quantity of Quality and quantity of
cellular and extracellular cellular and extracellular
proteinsproteins
Quality and life lengthQuality and life length
Knowledge Knowledge ------ key of success key of success
for modern medicinefor modern medicine