Brainscape's Knowledge GenomeTM

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


See full index

Genetics > Cytogenetics > Flashcards

Cytogenetics Flashcards

You may prefer our related Brainscape-certified flashcards:
Biology 101 flashcards
0
Q

Aneuploidy

A

Monosomy: loss of a chromosome. Not compatible with life (except monosomy X/TURNER SYNDROME)
-kleinfelter syndrome (47, XXY)

Trisomy: presence of an additional chromosome.

  • trisomy 21 (Down syndrome )
  • trisomy 18 (Edward syndrome)
  • trisomy 13 (Patau syndrome)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
1
Q

Euploidy (polyploidy) (number of chromosomes is in multiples of 23)

A

Triploidy: contain three copies of each chromosome (69). Not compatible with life
-observed in abortus (69, XXY)

Tetrapoidy: contain 4 copies of each chromosome (92). Lethal

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

-trisomy 21 (Down syndrome ), 47, XY, +21

A

Increase maternal age, increases risk of neurotic nondisjunction during oogenesis
-most common is meiosis 1 nondisjunction

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

trisomy 18 (Edward syndrome), 47, XY, +18

A

Nondisjunction during oogenesis.

Features:

  • clenched fist, overlapping of fingers
  • rocker bottom feet
  • congenital heart defects
  • low-set ears, micrognathia
  • microcephaly
  • Intellectual disability
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Triscomy 13 (Patau syndrome)

A

Nondisjunction during oogenesis

Features:

  • polydactyly
  • cleft lip and palate
  • microphthalamia
  • microcephaly
  • intellectual disability
  • cardiac anomalies
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Turner syndrome (45, X)

A

Nondisjunction during meiosis (x chromosome monosomy)

  • short stature
  • webbed neck, cystic hygroma at birth(neck swelling)
  • Gonadal dysgenesis
  • streak ovaries
  • primary amenorrhea

Other cells are 46, XX and 47 XXX (indicate mitotic nondisjunction during embryogenesis)

Cells with 45 X; have no Barr body (inactivated X-chromosome)

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

Kleinefelter syndrome (47, XXY)

A

Nondisjunction during meiosis I or II in mom or nondisjunction in meiosis I in dad (XYY)

  • testicular atrophy
  • Gynecomastia
  • female distribution of hair
  • infertility 7
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Tripoidy (3*23=69 chromosomes)

A

Observed in abortus

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

Tetraploidy

A

In cancer

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

5 Common Chromosomal Syndromes caused by nondisjunction

A 
Trisomy 21
Trisomy 18
Trisomy 13 (Patau)
Monosomy X
47, XXY
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Structural chromosomal Abnormalities

  • Balanced
  • Unbalanced
A
  • Balanced (No loss or gain of genetic material)
  • Unbalanced (gain or loss of genetic material)
Translocation
-Reciprocal
-Robertsonian
Deletions
Inversions
Ring chromosomes
Isochromosome
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Reciprocal Translocation

A

Exchange of genetic material between non-homologous chromosomes
-chromosome 2 and 8- balanced reciprocal translocation

In somatic cells:

  • transformation to cancer occurs
  • may have no effect ( silent)

In germline:
-may cause spontaneous abortion in carriers

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

Reciprocal Translocation in SOMATIC CELLS

A
  • activation of an oncogene–>cancer
  • Philadelphia chromosome t(9;22)–>activation of ABL protooncogene in hematopoietic cells–>results in chronic myelogenous leukemia
  • t(8;14)–>Burkitt’s lymphoma
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Robertsonian Translocation

A

Occurs between acrocentric chromosomes
-chromosome 13, 14, 15, 21, 22

Fusion of the long arms of the two chromosomes.

Effects during meiosis

Alternate segregation can result in

  • Normal Gamete
  • Gamete with derivative chromosome, that results in a Robertsonian translocation carrier on fertilization

Adjacent Segregation results in trisomy of the respective chromosome on fertilization.

  • Trisomy 14 does not survive
  • Accounts for 2-5% of children with Down syndrome mainly due to adjacent segregation
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Segregation at meiosis

A

Alternate segregation

Adjacent I segregation

Adjacent II segregation

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Microdeletion Syndrome

A

Large deletions >4Mb

  • Wolf-Hirschhorn (4p-), Cri du Chat (5p-)-test with FISH
  • may be detected by classical cytogenetic
Small Deletions (microdeletions) <4 Mb
-FISH, Array CGH
16
Q

Wolf-Hirschhorn Syndrome

A
  • Deletion of chr 4p
  • Facial anomalies widely spaced eyes, prominent nose, abnormal iris
  • Cardiac anomalies
  • Intellectual and developmental delay
17
Q

Wilms’ tumor, Aniridia, genitourinary malformations, and retardation of growth and development (WAGR) Syndrome

A

Small-microdeletions

18
Q

Deletions in Chromosome 15 (15q11)

A

Prader-Willi syndrome (Paternal deletion)

  • hypotonia
  • initial failure to thrive
  • Distinctive facial features
  • Developmental delay
  • hypogonadism
  • eating disorder
Angelman Syndrome (happy puppet)-maternal deletion
-hypotonia'
-seizures
-lack of speech
severe developmental delay
-lack
19
Q

Inversions

A

Pericentric: involves centromere

Paracentric: does not involve centromere

Usually balanced and no clinical problems in carriers
-result in a change in the banding pattern of the chromosome and can be identified by Karyotype analysis

Note: Chromosome with acentric (no centromere) and dicentric (2 centromere on one chromosome) are not viable.

Carriers maybe asymptomatic, but they have a high risk of spontaneous abortion.

20
Q

Isochromosomes

A
  • Loss of one arm of a chromosome, and duplication of the other arm.
  • X isochromosome: long arms of the X chromsome join form an isochromosome
  • Typically results in chromosomal and gene dosage imbalance
  • Isochromosome is typically inactivated

e.g. some turner syndrome children

21
Q

Ring Chromosomes

A

chromosome loses genetic material at the terminal portions and the ends fuse to form a ring like structure

Genetics (10 decks)

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