Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

CELLULAR BASIS OF MEDICINE > CYTOGENETICS 1 > Flashcards

CYTOGENETICS 1 Flashcards

1
Q

WHAT DO CHROMOSOMAL ABNORMALITIES OCCUR IN?

A

– perinatal deaths, mentally retarded, patients with inborn defects, infertile couples (repeated
spontaneous abortions, sterility) and infertile men

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

HOW BIG IS THE PROPORTION OF ABORTIONS CAUSED BY CHROMOSOMAL ABNORMALITIES?

A

-> 30% spontaneous
-> 50% of early abortions between 8-15 weeks, most of the zygotes are lost before recognition of pregnancy - results in strong menstruation

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

WHAT PERCENTAGE OF LIVE BORN BABIES HAVE CHROMOSOMAL ABNORMALTIES?

A

0.6%

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

WHAT ARE THE CONGENITAL NUMERICAL CHROMOSOMAL ABNORMALITIES?

A

aneuploidy
polyploidy

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

WHAT ARE THE STRUCTURAL CHROMOSOMAL ABNORMALITIES?

A

balanced
unbalanced

-> difference between them both is that in unbalanced there are genes missing or genes added, while in balanced there is no addition of missing genes - they are just rearranged

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

DEFINE ANEUPLOIDY

A

one chromosome missing or in addition
-trisomy 2n+1
-monosomy 2n-1

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

DEFINE POLYPLOIDY

A

multiplication of haploid set
-> lethal – abortion, if children are born, they will die soon after birth,
-triploidy 3n
-tetraploidy 4n

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

NAME THE 3 TYPE OF BALANCED CHROMOSOMAL ABNORMALITIES

A

-Inversion / insertion
-Reciprocal translocation
-Robertsonian translocation

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

NAME THE 5 TYPE OF UNBALANCED CHROMOSOMAL ABNORMALITIES

A

-Deletion
-Duplication
-Ring chromosome
-Dicentric chromosome
-Isochromosome

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

HOW ARE ACCQUIRED CHROMOSOMAL ABNORMALITIES FORMED?

A

via mutagens (clastogenes) and time
-> not all genes form mutations
-> chromatid and chromosome breaks, chromatid exchanges, chromosome exchanges, rings, translocations, dicetrics

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

DEFINE MOSAIC

A
  • 2 or more cell lines with different karyotypes
  • origin from one cell during mitotic division of zygote
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

DEFINE CHIMAERA

A
  • formed by the fusion of 2 zygotes
  • fertilization of egg and polar body each by sperm with different gonosome
    -karyotype 46,XX/46,XY
    -origin from 2 cell lines / zygotes
    -very rare
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

DISCUSS DISPERMY

A

-possible way of triploidy
-most common way of triploidy
-lethal
-egg + 2 sperm
-23 + 23 + 23 = 69 chromosomes
-additional set of chromosomes from father -> partial mole

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

DIPLOID OVUM + HAPLOID SPERM

A
  • possible way of triploidy
  • 46+23 = 69 chromosomes
  • nonmolar product
  • lethal
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

DISCUSS HAPLOID OVUM AND DIPLOID SPERM

A
  • possible way of triploidy
  • 23+46 = 69 chromosomes
  • additional set of chromosomes from father -> partial mole
  • lethal
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

WHAT IS A COMPLETE MOLE?

A
  • formed by the fertilization of an enucleated (no nucleus) egg, only paternal genome (duplicates → 46 chromosomes)
  • A hydatiform complete mole is caused by a single sperm (90% of the time) or two (10% of the time) sperm combining with an egg which has lost its DNA. In the first case, the sperm then reduplicates, forming a “complete” 46 chromosome set
17
Q

EXPLAIN TETRAPLOIDY

A
  • formed by endoreduplication → division of chromosomes without division of cell (in mitosis)
  • 92 chromosomes
  • formed post-zygotically
18
Q

GIVE AN EXAMPLE OF PARTHENOGENESIS IN HUMANS

A

OVARIAN TERATOMA
- duplication of chromosome and division of unfertilized ovum (diploid)
- benign tumor which my have teeth and hair
- only maternal genome

19
Q

EXPLAIN NONDISJUNCTION IN MEIOSIS

A

-M1: undivided homologous chromosomes → disomic gametes
-M2: undivided sister chromatids → nullisomic gamete

→ fertilization → monosomy/trisomy

20
Q

EXPLAIN NONDISJUNCTION IN MITOSIS

A

undivided chromatid into daughter cell resulting in a mosaic

21
Q

WHAT ARE THE CAUSES OF NONDISJUNCTION?

A

nondisjunction of 21 occurs 4x more often in oogenesis than spermatogenesis and at the same time 4x more often in M1 than M2
- internal causes – individual risk of individual chromosomes to nondisjunction; increases with age of women above 35 and men above 50
- in women above 35 – error in M1 – aging of egg, dysfunction of mitotic spindle, changes in intracellular environment (due to decrease of hormonal function) and accumulation of mutagens during women’s life
- error in M2 – delayed fertilization due to over matured egg
- external causes – external mutagens - not main factors of nondisjunction

22
Q

EXPLAIN THE ORIGIN OF MOSAICS FROM TRISOMIC GAMETES

A
  • loss of chromosome from trisomic gamete by anaphase lag
  • monosomy can form → if healthy cell loses a chromosome, there are 45 left
23
Q

NAME AND EXPLAIN 3 CONSEQUENCES OF CHROMOSOMAL ABNORMALITIES

A

MONOSOMY X = only monosomy is compatible with life, but 99% of X monosomies are aborted

AUTOSOMAL MONOSOMY = always lethal and aborted

AUTOSOMAL TRISOMY = some have a chance to be born (trisomies 21, 18, 13, mosaic 8)
-abortions also seen (trisomy 16)

24
Q

DOWN SYNDROME (TRISOMY 21)

A

-47 chromosomes
frequency of live births - 1/800 (but 75% foetuses are aborted)
- 95% cases with DS are free trisomies, 5% are translocation trisomies, which are formed by Robertsonian translocation
(fusion of long arms of both acrocentric chromosomes which then divide as one chromosome)
-carrier of Robertsonian translocation has no clinical symptoms
- 1% of patients with DS have a mosaic
- risk for child increases with the age of mother – 35yrs = 1/350, 40yrs = 1/100, 45y.o= 1/25
-> pregnancy of mother above 35 y.o. is an automatic risk = prenatal screening
-> for translocation form of DS, the age does not matter and they have 46 chromosomes
- phenotype of DS - face – abnormal slant of palpebral fissures, round face, flat nasal bridge, big tongue (does not fit in the mouth, that is why the mouth is constantly semi open)
o short fingers, short stature, mental retardation
o in free trisomy and translocation form the phenotype is the same
o often tumours (especially leukaemia) – trisomy cells are more prone to mutagens

25
Q

EDWARDS SYNDROME (TRISOMY 18)

A

do not live long, max. few months – 18. -Chromosome has a lot of genes that are necessary for survival
- frequency of live births - 1/5000
- symptoms – prolonged occipital part of skull, dysmorphic features of face, low set malformed ears, short sternum, abnormal overlapping fingers, severe malformations of heart or other organs, severe retardation of development

26
Q

PATAU SYNDROME (TRISOMY 13)

A

karyotype 47XX + 13 or 47XY + 13
- frequency of live births - 1/10 000
- 20% translocation form 13/13 or 13/14
- Clinical symptoms – dysmorphic features of face, microcephaly, polydactyly, cleft lip and palate, severe organ malformation (heart defect, CNS), severe retardation of development
- Death after a few weeks post birth - lots aborted before this

27
Q

TURNER SYNDROME (MONOSOMY X)

A

-45,X or mosaics
-1/5000 liveborn girls (but 99% fetuses are aborted)
-does not depend on age of mother
-patient with TS –> syndrome formed by postzygotic loss of X chromosome
-aborted fetuses –> formed by the fertilization of nullisomic gamete
-severe circulation complications
-if a mother has a daughter with TS, there is no increased risk for the next child
-in the case of 45, X there is a loss of paternal chromosome in 77% cases (delay of chromosome)
-karyotype with 46, X,i(Xq) is fertile – missing short arm of one chromosome, second X chromosome is normal
-> development of gonads is critically conditioned to the region on long arm q- in the loss of p arm there is no loss of genes which are involved in gonad development -> fertility is not affected
- karyotype with 46, X,i(Xp) has gonad dysgenesis
- karyotype with Y chromosome has a risk of malignant gonads
-Clinical symptoms - small stature, sterility, underdeveloped secondary sexual characteristics, amenorrhea, neck
webbing, low hair line, mostly normal intelligence, in new-borns oedema on foot

28
Q

KLINEFELTER SYNDROME

A

-most common karyotype of 47,XXY
-need at least 1Y and more than 1X
-47,XXY / 48,XXYY or 48,XXYY / 49,XXXXY / 46,XY/47,XXY
-frequency of live births in boys - 1/1000
- not only 47, XXY, but anything that has at least 1Y and at the same time more than 1X (so XXXY, XXYY, XXXXY etc.)
- in 1/3 cases it is due to the nondisjunction in M1 of father, 47% nondisjunction in M1 of mother (age dependent), 22% nondisjunction in M2 of mother
- the more X, the taller the stature and lower the IQ
- Clinical symptoms - sterility (azoospermia = no sperm in ejaculate), hypogonadism (atrophy of testes), secondary sexual characteristics of women (eunuchoid appearance)
- „Klinefelter is born as the last child in the family. “– a saying, because the risk of the syndrome increases with mothers age

29
Q

TRIPLE X SYNDROME

A

-47,XXX
-1/1000 women affected
-normal phenotype, fertile, risk of schizophrenia

30
Q

SYNDROME 2 Y

A

-47,XYY
-1/1000 men affected
-normal phenotype, tall, chance of increased aggression

31
Q

DO MEN CONTRIBUTE TO AN INCREASED RISK IN CHROMOSOMAL ABNORMALITIES?

A

yes if over the age of 50

32
Q

DOES AN INCREASE IN THE MOTHERS AGE INCREASE THE RISK OF LOSS OF CHROMOSOME IN ANAPHASE?

A

no it does not

33
Q

WHAT IS THE KARYOTYPE OF CHIMERAE?

A

46,XX/46,XY

34
Q

WHAT IS THE KARYOTYPE OF OVARIAN TERATOMA IN WOMEN?

A

46,XX

35
Q

WHAT ARE NOT COMPATIBLE WITH LIFE?

A

autosomal monosomies

36
Q

DOES AN INCREASE IN THE MOTHERS AGE INCREASE THE RISK OF ALL CHROMOSOMAL ABNORMALITIES?

A

no

37
Q

WHAT DOES A COMPLETE HYDRATIFORM MOLE CONTAIN?

A

paternal genome only

38
Q

WHAT IS THE PARTIAL MOLE DUE TO?

A

triploidy with an additional set of paternal chromosomes

39
Q

DOES AN INCREASE IN THE MOTHERS AGE INCREASE THE RISK OF NONDISJUNCTION?

A

yes

CELLULAR BASIS OF MEDICINE (32 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions