PRE FI LEC 2: CHROMOSOME Flashcards
1
Q
- Study of inheritance in relation to the structure and function of chromosomes
- Deals with the cytological and molecular basis of heredity, variation, variation, mutation, morphogenesis, etc.
A
CYTOGENETICS
2
Q
- consists primarily of DNA & proteins with a small amount of RNA
A
CHROMOSOME
3
Q
ESSENTIAL PART OF A CHROMOSOME
A
- TELOMERE
- ORIGIN OF REPLICATION SITES
- CENTROMERE
4
Q
- consist of highly repetitive DNA sequences
A
Heterochromatin (dark)
5
Q
- contains many protein and coding sequences
A
Euchromatin (light)
6
Q
CLASSIFICATION AND CENTROMERE POSITION
- GROUP A
- LARGE METACENTRIC
A
CHROMOSOMES 1,2
7
Q
CLASSIFICATION AND CENTROMERE POSITION
- GROUP A
- LARGE SUBMETACENTRIC
A
CHROMOSOME 3
8
Q
CLASSIFICATION AND CENTROMERE POSITION
- GROUP B
- LARGE SUBMETACENTRIC
A
CHROMOSOMES 4,5
9
Q
CLASSIFICATION AND CENTROMERE POSITION
- GROUP C
- MEDIUM - SIZED SUBMETACENTRIC
A
CHROMOSOMES 6-12, X
10
Q
CLASSIFICATION AND CENTROMERE POSITION
- GROUP D
- MEDIUM - SIZED ACROCENTRIC WITH SATELLITES
A
CHROMOSOMES 13-15
11
Q
CLASSIFICATION AND CENTROMERE POSITION
- GROUP E
- SHORT METACENTRIC
A
CHROMOSOME 16
12
Q
CLASSIFICATION AND CENTROMERE POSITION
- GROUP E
- SHORT SUBMETACENTRIC
A
CHROMOSOME 17,18
13
Q
CLASSIFICATION AND CENTROMERE POSITION
- GROUP F
- SHORT METACENTRIC
A
19, 20
14
Q
CLASSIFICATION AND CENTROMERE POSITION
- GROUP G
- SHORT ACROCENTRIC WITH SATELLITES
A
CHROMOSOME 21, 22
15
Q
CLASSIFICATION AND CENTROMERE POSITION
- GROUP E
- SHORT ACROCENTRIC
A
Y
16
Q
- chromosome chart
- displays chromosomes in pairs by size and by physical landmarks that appear during mitotic metaphase, when DNA coils tightly
- 24 human chromosomes types
- chromosome 1 - 22
- X and Y chromosome
A
KARYOTYPE
17
Q
Chromosomes contain
A
- TELOCENTRIC
- ACROCENTRIC
- SUBMETACENTRIC
- METACENTRIC
18
Q
USES OF KARYOTYPE
A
- IDENTIFY GENETIC ABERRATIONS, DIAGNOSE, AND CLASSIFICATION OF ORGANISMS
- REVEALS THE EFFECTS OF ENVIRONMENTAL TOXINS
19
Q
what animal species is the human’s closest revolutionary relative according to karyotype analysis?
A
BONOBO or formerly known as the PYGMY CHIMPANZEE (PAN PANISCUS)
20
Q
DETECTING CHROMOSOMES
A
- DIRECT VISUALIZATION OF CHROMOSOMES
- INDIRECT DETECTION OF EXTRA CHROMOSOMES
21
Q
DIRECT VISUALIZATION OF CHROMOSOMES
- 2 technologies that provide images of chromosomes from a fetus
A
- AMNIOCENTESIS
- CHORIONIC VILLUS SAMPLING
22
Q
DIRECT VISUALIZATION OF CHROMOSOMES
- 1st fetal karyotype (1966)
- procedure: obtains a sample of AMNIOTIC FLUID from the UTERUS with a needle passed through the women’s abdominal wall
- most common chromosomal abnormality detected is TRISOMY
- performed between 14 & 16 weeks gestation
A
AMNIOCENTESIS
23
Q
DIRECT VISUALIZATION OF CHROMOSOMES
- during 10th through 12th week of pregnancy
- procedure: A needle/catheter is inserted either through the cervix/abdomen and guided to placenta to obtain cells from the chorionic villi tissue
- tests for inborn errors of metabolism (iEM) are not possible
A
CHORIONIC VILLUS SAMPLNG
24
Q
- can be used to examine chromosomes
- saliva and cheek scrapings include WBCs and epithelial cells, which are commonly used as the source of DNA in a clinical setting
A
ANY CELL OTHER THAN A MATURE RBC
25
C. Preparing cells and chromosomes
- counting of chromosomes:
________________ is used to arrest cells during cell division
COLCHICINE
26
C. Preparing cells and chromosomes
- Untangling chromosomes:
Washing WBCs in a ______________
SALT SOLUTION (HYPOTONIC)
27
C. Preparing cells and chromosomes
- 1ST Karyotypes used _____ to stain chromosomes a uniform color
DYES
28
FIRST CHROMOSOMAL ABNORMALITIES DESCRIBED IN 1959:
- extra chromosome 21
DOWN SYNDROME
29
FIRST CHROMOSOMAL ABNORMALITIES DESCRIBED IN 1959:
- female with only 1 X chromosome
TURNER SYNDROME (X0 SYNDROME)
30
FIRST CHROMOSOMAL ABNORMALITIES DESCRIBED IN 1959:
- male with an extra X chromosome
KLINEFELTER SYNDROME (XXY SYNDROME)
31
1967
- material missing from chromosome 4 (belongs to chromosome 4 of B group)
B-GROUP CHROMOSOME DISORDER
32
1970s
- new stains created banding patterns unique to each chromosomes such as _______________________
GIEMSA STAINS creates G BANDS
33
1970s:
- introduced to highlight individual gametes
FLUORESCENCE IN SITU HYBRIDIZATION (FISH)
34
- Based on chromosome banding
- graphical representation that displays chromosome information
- schematic chromosome map
IDEOGRAM
35
- symbols to describe the type of aberration, such as deletion or translocation; numbers corresponds to specific bands
CHROMOSOMAL SHORTHAND
36
CHROMOSOMAL SHORTHAND
Abbreviation: 46, XY
Meaning: ?
NORMAL MALE
37
CHROMOSOMAL SHORTHAND
Abbreviation: 46, XX
Meaning: ?
NORMAL FEMALE
38
CHROMOSOMAL SHORTHAND
Abbreviation: 45, X
Meaning: ?
TURNER SYNDROME (FEMALE)
39
CHROMOSOMAL SHORTHAND
Abbreviation: 47, XXY
Meaning: ?
KLINEFELTER SYNDROME (MALE)
40
CHROMOSOMAL SHORTHAND
Abbreviation: 47, XYY
Meaning: ?
JACOBS SYNDROME (MALE)
41
CHROMOSOMAL SHORTHAND
Abbreviation: 46, XY, del (7q)
Meaning: ?
A MALE MISSING PART OF THE LONG ARM OF CHROMOSOME 7
42
CHROMOSOMAL SHORTHAND
Abbreviation: 47, XX, +21
Meaning: ?
A FEMALE WITH TRISOMY 21 DOWN SYNDROME
43
CHROMOSOMAL SHORTHAND
Abbreviation: 46, XY, t, (7, 9), (p21, 1, q34,1)
Meaning: ?
A MALE WITH TRANSLOCATION BETWEEN THE SHORT ARM OF CHROMOSOME 7 AT BAND 21, 1 AND THE LONG ARM OF CHROMOSOME 9 AT BAND 34, 1
44
CHROMOSOMAL SHORTHAND
Abbreviation: 48, XXYY
Meaning: ?
A MALE WITH AN EXTRA X AND Y CHROMOSOME
45
- COMPUTERIZED representation of an individual's/ organism's complete set of chromosomes
- it shows copy number variants (repeats) and is color-coded to represent chromosomes that have exchanged parts
- involves capturing, analyzing, and displaying the chromosomes in a standardized format using specialized software
DIGITAL KARYOTYPE
46
- measures or detect characteristics that is associated with havInG
chromosomal abnormality
- used as screening tests to identify individuals at elevated risks (do not provide diagnostic)
INDIRECT DETECTION OF CHROMOSOMES
47
INDIRECT DETECTION OF CHROMOSOMES
- biochemical whose levels in the blood are within a certain range in a pregnant woman carrying a fetus with normal number of chromosomes, but may lie outside that range in fetuses whose cells have an extra copy of a certain chromosomes
MATERNAL SERUM MARKERS
48
MATERNAL SERUM MARKERS
_________________ value indicates how far an individual results deviate from the normal range of concentration of each marker
MULTIPLE OF MEDIANS (MoM)
49
_________ = level of biomarker is 2x as high or 2x as low as the average in a normal pregnancy (elevated risk)
MoM ABOVE 2.0
50
INDIRECT DETECTION OF CHROMOSOMES
- testing of the fetal DNA in the woman's bloodstream ( 20% of those small pieces of DNA came from the placenta)
- done 10 weeks into the pregnancy or later
- first versions detected trisomies 13, 18, and 21
- removes the focus on maternal age
- so sensitive
- complete fetal exomes and genomes can also be sequenced
CELL - FREE FETAL DNA TESTING
51
C. ATYPICAL CHROMOSoME NUMBER
- the number of chromosomes in a somatic cell is 46
true or false?
FALSE, the number of chromosomes in a somatic cell is NOT 46
52
C. ATYPICAL CHROMOSoME NUMBER
- EXTRA SETS of chromosomes in a cell
- Triploid
common among flowering plants and in some insects
POLYPLOIDY
53
- individual whose cells have 3 copies of each chromosome (3N , for 3 sets of chromosomes)
TRIPLOID
54
- 2/3 of all triploids result from fertilization of an oocyte by _____
- 17% spontaneous abortion
2 sperm
55
C. ATYPICAL CHROMOSoME NUMBER
- MISSING a single chromosome (monosomy) or having an extra chromosome (trisomy)
ANEUPLOIDY
56
most are spontaneously aborted & intellectual disability is concern
AUTOSOMAL ANEUPLOIDY
57
milder symptoms
SEX CHROMOSOME ANEUPLOIDY
58
a chromosome pair fails to separate at anaphase of either 1st or 2nd meiotic division
NONDISJUNCTION
59
- having extra or missing autosome
- most cease developing long before birth
-most frequently seen extra autosomes in newborns are chromosomes 21 (trisomy 21/DOWN), 18, (trisomy 18/EDWARD), & 13 (trisomy 13/PATAU)
AUTOSOMAL ANEUPLOIDY
60
- most common autosomal aneuploidy among liveborns
- 1st described by John Langdon Haydon Down in 1866 & referred to it as " MONGOLIAN IDIOCY" due to epicanthal folds and flat face
- genes near the tip of the long arm of the chromosome contribute most of the abnormalities
- Genome editing: mechanism of X inactivation to "turn off" the extra chromosome
- 90% are due to nondisjunction during meiosis I in the female
TRISOMY 21 (DOWN SYNDROME)
61
1959: ________________ identified the presence of an extra chromosome in individuals with down syndrome
JEROME LEJEUNE
62
Likelihood of giving birth to a child with trisomy 21 increases dramatically with the _________:
- the older the woman, the longer oocytes have been arrested on the brink of completing meiosis
- females have a pool of immature aneuploidy oocytes resulting from spindle abnormalities
AGE OF THE MOTHER
63
TRISOMY 21 is 1st described by______________ in 1866 & referred to it as " MONGOLIAN IDIOCY" due to epicanthal folds and flat face
JOHN LANGDON HAYDON DOWN
64
- described by John Edwards in 1960
- most do not survive to be born, but few have lived into young adulthood
- great physical & intellectual disabilities, with developmental skills stalled at the 6-month level
- nondisjunction in meiosis II of the oocyte
TRISOMY 18 (EDWARDS SYNDROME)
65
TRISOMY 18 (EDWARDS SYNDROME)
MAJOR ABNORMALITIES:
- HEART DEFECTS
- DISPLACED LIVER
- GROWTH RETARDATION
- ODDLY CLENCHED FISTS
66
TRISOMY 18 (EDWARDS SYNDROME)
MILDER SIGNS:
- OVERLAPPING FINGERS
- NARROW AND FLAT SKULL (MICROCEPHALY)
- LOW - SET EARS
- SMALL MOUTH
- UNUSUAL FINGERPRINTS
- "ROCKER-BOTTOM" FEET
67
TRISOMY 18 is described by ________________ in 1960
JOHN EDWARDS
68
- described by Dr, Klaus Patau in 1960
-mostly affected individuals do not survive to be born, but few have lived into young adulthood
- MOST STRIKING SIGN: FUSION OF THE DEVELOPING EYES (more common is a small or absent eye
TRISOMY 13 (PATAU SYNDROME)
69
TRISOMY 13 (PATAU SYNDROME)
MAJOR ABNORMALITIES:
- AFFECT THE HEART, BRAIN, KIDNEYS, FACE & LIMBS
- THERE MAY BE PRESENCE OF EXTRA FINGERS
70
TRISOMY 13 (PATAU SYNDROME)
ULTRASOUND EXAMINATION:
- EXTRA SPLEEN
- ATYPICAL LIVER
- ROTATED INTESTINES
- ABNORMAL PANCREAS
71
- having extra or missing sex chromosomes
- FEMALE: X0 SYNDROME, TRIPLO-X SYNDROME
- MALE: XXY SYNDROME, XXYY SYNDROME, XYY SYNDROME
SEX CHROMOSOME ANEUPLOIDS
72
- 45, X
- 1938: HENRY TURNER observed young women with the condition; physicians assumed this was caused by hormonal insufficiency
1954: cells from turner patients do not have a BARR BODY
1959: only 1 X chromosome; missing only a part of an X chromosome, mosaics (only some cells missing an X chromosome)
- 99% of X0 fetuses are NOT BORN
- Syndrome affects in 1 in 2,500 female births
X0 SYNDROME (TURNER SYNDROME)
73
X0 SYNDROME
At birth:
PUFFY HANDS AND FEET CAUSED BY IMPAIRED LYMPH FLOW
74
X0 SYNDROME
ADULTS:
- OSTEOPOROSIS
- TYPE 1&2 DIABETES
- COLON CANCER
75
- 47, XXX
- 1st identified in 1995 by Dr. Patricia Jacobs & her colleagues
- 1 in every 1,000 females
- tall structure and menstrual irregularities
- rarely intellectual disabled, but they to be less intelligent than their siblings
- behavioral problems (ADHD or symptoms of autism spectrum disorder) & psychological problems (depression & anxiety)
- lack of symptoms: protective effect f X inactivation
TRISOMY X (TRIPLO-X SYNDROME)
76
- 47, XXY
- 1st described by Dr. Harry Klinefelter in 1942 & his colleagues
- 1 in every 500 males has the extra X chromosomes
- severely affected MEN: underdeveloped sexually, have very long arms & legs, large hands & feet, & may develop breast issues (gynecomastia)
- slow to learn but are not intellectually disabled
- most common genetic or chromosomal cause of male infertility
XXY SYNDROME (KLINEFELTER SYNDROME)
77
- 48, XXYY
- previously been described as a variant of Klinefelter syndrome, however the medical and neurodevelopmental features are complex
- 1 in 17, 000 newborn boys
- tend to develop foot and leg ulcers
- adolescent & teen years: ADHD, OCD, ASD, & learning disabilities; low testosterone level, delayed development of secondary sexual characteristics, & undescended testes
- ADULTS: infertile
XXYY SYNDROME
78
- 47, XYY
- 1st described by Dr. Avery Sandberg & colleagues in 1961 and became more widely publicized in 1965 when Dr. Patricia Jacobs & colleagues suggested a link between XYY syndrome, intellectual disability and criminal behavior
- 1 in 1,000 males & 96% may be very tall and have acne
- problems with speech and understanding language are subtle
- nondisjunction in the male, producing a sperm with 2 Y chromosomes that fertilizes an X-bearing oocyte
XYY SYNDROME (JACOBS SYNDROME)
79
- The individual chromo have extra, missing or rearranged genetic material
ATYPICAL CHROMOSOME STRUCTURE
80
ATYPICAL CHROMOSOME STRUCTURE
- Missing & extra DNA sequences
- Often arise de novo(neither of the parents has abnormalities)
- Uses COMPARATIVE GENOMIC HYBRIDIZATION:
used to detect microdeletions and microduplications
- Helps diagnose autism
DELETIONS AND DUPLICATION
81
used to detect microdeletions and microduplications
COMPARATIVE GENOMIC HYBRIDIZATION
82
ATYPICAL CHROMOSOME STRUCTURE
- Different (nonhomologous) chromosome exchange or combine parts
- Types:
a) Robertsonian translocation
b) Reciprocal translocation Philadelphia chromosome
c) Insertional translocation
TRANSLOCATIONS
83
TYPES OF TRANSLOCATION
- some cases in Down syndrome
a) Robertsonian translocation
b) Reciprocal translocation Philadelphia chromosome
c) Insertional translocation
Robertsonian translocation
84
TYPES OF TRANSLOCATION
- when 2 chromosomes exchange parts
a) Robertsonian translocation
b) Reciprocal translocation Philadelphia chromosome
c) Insertional translocation
Reciprocal translocation Philadelphia chromosome
85
TYPES OF TRANSLOCATION
- rare type
- Parts of chromosomes insert to other parts of
chromosomes
a) Robertsonian translocation
b) Reciprocal translocation Philadelphia chromosome
c) Insertional translocation
Insertional translocation
86
Person with large translocation is called
____________ : HAS 45 CHROMOSOMES not 46
translocation carrier
87
used technique to highlight chromosomes.
Arises de novo on oocytes or sperms
FISH (FLUORESCENCE IN SITU HYBRIDIZATION)
88
ATYPICAL CHROMOSOME STRUCTURE
- Inverted sequence of chromosomes
- Occurs when there are two breaks in 1 chromosome
TYPES:
- Paracentric inversion
- Pericentric inversion
INVERSION
89
TYPES OF INVERSION:
- Inversion DOES NOT include centromere
Paracentric inversion
90
TYPES OF INVERSION:
- Inversion INCLUDES the centromere
Pericentric inversion
91
ATYPICAL CHROMOSOME STRUCTURE
- Results of another meiotic error that leads to
UNBALANCED GENETIC MATERIAL
- Forms during division
- Known for chromosome 12 & 21 for the long arms of X & Y
ISOCHROMOSOMES
92
ATYPICAL CHROMOSOME STRUCTURE
- Shaped like rings
- May arise when telomeres are lost, leaving sticky ends that adhere
- Exposure to radiation forms ring
- Do not affect health, but few can
RING CHROMOSOMES
93
ATYPICAL CHROMOSOME STRUCTURE
- Inheriting two chromosomes or chromosome segments from one parent
- 2 bodies from 1 parent
Cause:
- NONDISJUNCTION of the same chromosome in
sperm
- Trisomy is followed by CHROMOSOME LOSS
UNIPARENTAL DISOMY (UPD)
94
unequal chromosome division
NONDISJUNCTION
95
EXAMPLES OF UPD
- Prader-Willi syndrome
- Angelman syndrome
- a baby inherits both copies of a section of chromosomes 15 from mother
- inherits both copies from father instead mother
- Unusual case of cystic fibrosis
- Doubles part of 1 parents contribution
- Baby inherits the allele in double dose
96
Chromosomes contain
Has centromeres in one end
Telomere DNA sequence is at the tip
A. TELOCENTRIC
B. ACROCENTRIC
C. SUBMETACENTRIC
D. METACENTRIC
TELOCENTRIC
97
Chromosomes contain
- mid centromere
- P short arm and q long arm
A. TELOCENTRIC
B. ACROCENTRIC
C. SUBMETACENTRIC
D. METACENTRIC
SUBMETACENTRIC
98
Chromosomes contain
- centromere near at the end
A. TELOCENTRIC
B. ACROCENTRIC
C. SUBMETACENTRIC
D. METACENTRIC
ACROCENTRIC
99
Chromosomes contain
- has equal sized arm
A. TELOCENTRIC
B. ACROCENTRIC
C. SUBMETACENTRIC
D. METACENTRIC
METACENTRIC
100
RING CHROMOSOME SYNDROME
- Microcephaly; triangular forehead; closely spaced, slanted, protruding eyes; arched brows; small jaw; congenital heart defects; abnormal male genitalia; intellectual disability
CHROMOSOME 9
101
RING CHROMOSOME SYNDROME
- Microcephaly, small eyes, developmental delay, underdevelopment of certain brain parts, difficulty feeding, unusual hands and feet, small or closed anus, abnormal genitals, heart defects, abnormal kidneys
CHROMOSOME 13
102
RING CHROMOSOME SYNDROME
- Microcephaly, puffy hands and feet, seizures, delayed speech and motor skills, recurrent infections, intellectual disability
CHROMOSOME 14
103
RING CHROMOSOME SYNDROME
- Microcephaly, short stature, seizures, intellectual disability
CHROMOSOME 20
104
RING CHROMOSOME SYNDROME
- Microcephaly, wide nose, large ears and eyes, floppiness (HYPOTONIA), delayed speech and language, autistic behaviors, learning disabilities
CHROMOSOME 22
