Transcript research methods

METHODS OF RESEARCH
INTO HUMAN GENETICS
Výukový materiál GE 02 - 56
Tvůrce: Mgr. Šárka Vopěnková
Tvůrce anglické verze: ThMgr. Ing. Jiří Foller
Projekt: S anglickým jazykem do dalších předmětů
Registrační číslo: CZ.1.07/1.1.36/03.0005
Tento projekt je spolufinancován ESF a SR ČR
2014
RESEARCH METHODS
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human genetics differs from genetics of plants,
fungi, animals and bacteria:
moral a ethic reasons
human has in life a very small number of
descendants
phenotype is in a very big measure influenced by
the external environment (social conditions) polygenic features
generation period of a person is very long
geneticist can observe maximally only 4
generations
human genome is very complex
RESEARCH METHODS
specific observational methods:
1. research into family trees – genealogic
method
2. research into twins – gemellological method
3. methods of population genetics
4. research into karyotypes
5. biochemical and molecular-genetic methods
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RESEARCH METHODS
research into family trees – genealogic
method :
 based on arrangement of family trees
 generation period of human = 20 – 25 let >
maximally observed 4 generations
 by monogenic features can be detected:
 feature conditioned by a dominant /
recessive allele
 feature is on autosome / gonosome
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RESEARCH METHODS
result of research:
 determination of probability of
occurrence of the disease by the
descendants
 principal method by the diagnosis of
hereditary diseases
 used international symbols
 > e.g.. proband
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RESEARCH METHODS
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research into twins:
a) twins originate from only one egg fertilized by
one sperm
100 % accordance of genome
monozygotic twins MZ
identical sex
b) twins originate by fertilization of two eggs by two
sperms
50% accordance of genome
dizygotic twins DZ
identical or different sex
RESEARCH METHODS
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monozygotic twins: MZ
phenotype variations are consequence of the nonhereditary component of variability
by means of the phenotype accordance and
differences by MZ and DZ twins can be determined
the mass of influence of hereditary and nonhereditary component of variability
disease with a high heritability > hereditary disease,
can be predicted
disease with a high heritability > better curable
RESEARCH METHODS
research into karyotypes:
 cytogenetic research of chromosomes
 in the nucleus 23 pairs of chromosomes
 220 pairs of autosomes + 1 pair of
gonosomes
 according to Denver nomenclature > in 7
groups A to G in agreement with their
size and placing of centromeres
RESEARCH METHODS
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biochemical and molecular-genetic
many diseases caused by mutations
defect alleles are mostly recessive
ill people are also recessive heterozygotes
> autosomal recessive heredity
these diseases are caused by mutations of
structural genes = molecular diseases
e.g.: phenylketonuria, galactosemia a albinism
RESEARCH METHODS
handicapped child from its birth up
to 15 years of age - special diet
 organized a wide recapture of
new born babies on the base of a
simple biochemical examination
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GENETIC PREVENTION AND COUNSELLING
DNA diagnostics:
 molecular-genetic method
 used in prenatal diagnostics
 e.g. Sickle-cell anaemia - disease:
 stricken only homozygotes ( SS) foe
defect allele S
 they have got erythrocytes of sickle
shape
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RESEARCH METHODS
a big research project HGP
 deals with mapping of human genome
 started in 1990
 by 2000 -2003 read the sequence of
human genome
 human has got 30 000 genes
 98,5 % genes have a non-coding
sequence
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RESEARCH METHODS
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genetic counselling:
an important part of preventive medicine
medicine genetics department – hospitals:
specification of diagnosis
determination of risk of disabled children in a
high-risk family
interruption
essential principle of genetic counselling:
guarantee of free (both) parents´ decision !!!
RESEARCH METHODS
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eugenics:
science struggling for improvement of biological and
mental quality of human population
most effective reduction possibility of birth disabled
humans
most effective reduction possibility of transmission
indisposed alleles into following generations
hardly solvable contradiction:
frequency of defect alleles in the populations
increases thanks to medicine (individuals with serious
hereditary diseases are saved)
WORKSHEET
Internationally given symbols, from which
are created genealogical tables (family trees).
FILL IN THE SCHEMA
SOURCES
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CHALUPOVÁ-KARLOVSKÁ, Vlastimila. Obecná biologie:
středoškolská učebnice : evoluce, biologie buňky, genetika : s 558
řešenými testovými otázkami. 2., opr. vyd. Olomouc: Nakladatelství
Olomouc, 2010, 206 s. ISBN 978-80-7182-282-0