SAMOSTATNÁ PRÁCE STUDENTŮ

Protocols for Practical Courses in Biology and Genetics
2nd semester, 1st week - REPETITION
p. 1
REVISION – SELECTED TASKS of summer semester: 1. Nondisjunction in Down, Turner and
Klinefelter syndromes, 2. Evaluation of karyotype with aberration, 3. Gene Linkage
WORK 1. Nondisjunction is the failure of chromosome distribution to daughter cells during the
meiosis. It can take place either in the 1st (nondisjunction of homologous chromosomes) or the 2nd
meiotic division (nondisjunction of sister chromatids). This way, from mother diploid (2n) cell arise
aneuploidy daughter cells/gametes with aberration from normal haploid number of chromosomes,
either (n-1) and/or (n+1).
Nondisjunction – here in protocol „only“ pp. 62-63/Tasks 3, 4 and 1 (Down and Klinefelter
syndrome). N.B.: Fill in all possibilities of the nondisjunction events leading to a particular
syndrome. This is asked in the text, exactly as in the final exam test ().
sub 3) Schedule of nondisjunction in Down syndrome (simple trisomy) in the meiosis I in the father
or in the mother
sub 4) Schedule of nondisjunction in Down syndrome (simple trisomy) in the meiosis II in one of the
parents (in the father or in the mother)
Chromatid nondisjunction
in meiotic division II.
Protocol ii01: REPETITION
Worked out by: …………………………………
Group:………………
Checked by:……………………………….
Protocols for Practical Courses in Biology and Genetics
2nd semester, 1st week - REPETITION
p. 2
sub 1) Schedule of nondisjunction in Klinefelter syndrome in paternal meiosis I (meiosis I in the
father)
sub 1) Schedule of nondisjunction in Klinefelter syndrome in maternal meiosis I (meiosis I in the
mother)
sub 1) Schedule of nondisjunction in Klinefelter syndrome in maternal meiosis II (meiosis II in the
mother)
Protocols for Practical Courses in Biology and Genetics
2nd semester, 1st week - REPETITION
p. 3
WORK 2. Evaluation of karyotype with aberration
a) Task 7a,b/ p. 65
Karyotype formula
(cytogenetic diagnosis):
Solution (syndrome):
The difference between cytogenetic and clinical diagnosis: Not all individuals expressing the
symptoms of a concrete syndrome have to have the same cytogenetic finding (formula, diagnosis). But
all individuals sharing the same cytogenetic diagnosis usually express the same complex phenotype
(syndrome, disease).
b) Task 13/ p. 71
Karyotype formula
– cytogenetic diagnosis
(acc. ISCN 2013):
Solution – clinical diagnosis:
c) segregation of chromosomes to gametes
in this individual
G A M E T ES
Gametes of
healthy wife
„Fate“ of zygotes:
Z Y G O T ES
Protocols for Practical Courses in Biology and Genetics
2nd semester, 1st week - REPETITION
p. 4
WORK 3. Gene linkage – Task 10/p. 93 (old ed. p. 104) – linkage in genealogy (nail-patella sy)
I
00
B0
II
B0
B0
B0
00
B0
A0
A0
A0
00
00
00
B0
00
00
B0
III
B0
B0
B0
Questions:
Answers:
a) Determine type of inheritance (AD, AR, GD,
AD (alely označme např. NPSmut a NPS+),
GR)?
b) does the linkage between both loci exist?
ano (pozn.: lokalizace dnes známa, 9q34),
c) draw the homologous chromosomes
u dědečka I/1 jsou 0 NPS+ / 0 NPS+ a u babičky I/2
(haplotypes) in both grandparents (I/1 and I/2):
jsou B NPSmut / 0 NPS+,
(choose in aid under the table)
d) Which of children have inherited
rekombinace je u synů II/5, II/8 a II/14 a vnučky
recombination? Assign correct haplotypes to
III/3,
them and assemble genotypes.
(choose in aid under the table)
e) the percentage of recombination between the
4/16 = 0,25, tj. 25 % rekombinací (pozn.: současné
genes (recombination fraction)?
odhady mapové vzdálenosti jsou 1,5 – 3 cM),
f) Can the pedigree admit the possibility of
ano – rekombinace u III/3 vznikla při meioze u
recombination during gametogenesis in males?
muže II/3.
Haplotypes (aid):
0
B
0
+
NPS
mut
NPS
B
mut
NPS
+
NPS