Cytogenetic Analysis (CHROMOSOME) Flashcards
humans inherit a ____ of genes (23 chromosomes) from each parent, X and y are exceptions.
haploid set
carried on the chromosomes in the form of the order or sequence of nucleotide bases in the DNA helix.
genetic information
the total genes found in a single individual.
human genome
The human genome consists of 2.9 billion nucleotide base pairs of DNA organized into ____
23 chromosomes.
Physically organized form of DNA in the nucleus of a cell.
CHROMOSOMES
Consist of DNA, histones, non-histone protein, RNA & polysaccharides.
CHROMOSOMES
It is very long continuous thread of DNA which contains many genes
CHROMOSOMES
From the Greek word “chroma” means color and “soma” means body due to its capacity to stain dyes.
CHROMOSOMES
“chroma” means
color
“soma” means
body
DNA wrapped in a histones
Chromatin
loosely wrapped DNA in a histones, less condensed and stained lighter.
Euchromatin
thread-like structure in the nucleus that carry genes.
chromosome
tightly coiled DNA in a histones, more condensed and stained darker.
heterochromatin
replicated copy of chromatin
chromatids
2 chromatids attached together by 1 centromere
sister chromatids
a protein where DNA is tightly bind. Helps DNA to condensed into chromosomes. (H1, H2A, H2B, H3, and H4 ).
Histones
Postively charged due to arginine and lysine.
Histones
consist of 8 units of histones. A repeating structural and functional unit of chromatin.
Nucleosome
help in tightly packing of DNA , it controls gene expression as well.
Histones
genes are easily expressed
Euchromatin
genes are not expressed
heterochromatin
chromosomes that are similar in terms of size and genetic material. From paternal and maternal chromosomes
Homologous
2 identical copies of the chromosomes.
Sister chromatids-
they are separated to become a full chromosome during?
mitosis
Basic parts of a chromosome
Centromere
Telomere
Long arm
Short arm
the central region of the chromosome.
Centromeres
the point of attachment of 2 sister chromatids and pulls it apart during mitosis.
Centromeres
the tips of chromosomes.
Telomere
protects the ends of chromosomes from damage and prevents the attachment of 2 sister chromatids.
Telomere
shorten as we age.
Telomere
the long arm of a chromosome.
q arm
short arm of the chromosome.
p arm-
are used in genetic mapping (finding the location of gene in a chromosome).
p and q arm
22 pairs (44)
Identical in both sexes.
AUTOSOMES
Contain the related information about phenotypic characteristics of a human.
AUTOSOMES
1 pair (X and Y)
X chromosome is larger then Y.
HETEROSOMES/ALLOSOMES
Types of chromosomes Based on centromere location
Metacentric
Submetacentric
Acrocentric
Telocentric
Helps in the determination of sex of the progeny.
HETEROSOMES/ALLOSOMES
centromere is at the center nearly equal in length arm.
Metacentric
Metacentric Chromosome affects what number?
1
3
16
19-20
centromere is little away from the center. Chromatids on 1 side is longer than the other
Submetacentric
Submetacentric Chromosome affects what number?
2
4, 5, 6, 7, 8, 9, 10, 11-12
17-18
X
centromere located closer at end of the chromatid. A small round structure attach to the end of shorter arm (satellite).
Acrocentric
Acrocentric Chromosome affects what number?
13, 14, 15
21-22
Y
centromere is located at end of chromatid producing only 1 arm.
Telocentric
Carry the genetic information for the development of sexual characteristics
Sex chromosomes
This allow the determination of male or female.
Sex chromosomes
Not present in human.
Telocentric
Sex is determined __ weeks after the fertilization.
10
Sex determining region on y chromosome
SRY gene
found only in the y chromosome
SRY gene
responsible for the development of male sexual characteristics.
SRY protein
It codes for the production of SRY protein responsible for the development of male sexual characteristics.
SRY gene
If the zygote inherit SRY gene it will become _____.
male
If the zygote does not inherit SRY gene it will become_____.
female
22 autosomes and X chromosome
Unfertilized egg (n)
22 autosomes and X chromosome
22 autosomes and y chromosome
Sperm cells (n)
Chromosomal abnormalities (Numerical abnormalities) Aneuploidy
Monosomy
Trisomy
Tetrasomy
Chromosomal abnormalities (Numerical abnormalities) Polyploidy
Triploidy
Tetraploidy
Chromosomal abnormalities (Structural abnormalities)
Translocation
Inversion
Duplication
Deletion
Ring chromosome
complete set of chromosomes (46)
Euploidy
extra or missing chromosome (> or < 46)
Aneuploidy
Absence of 1 pair of chromosome.
Addected: sex chromosome
Monosomy
(45 X)
Structural abnormalities
Infertility.
Turner syndrome
extra chromosome in a pair.
Affected: sex chromosome
Trisomy
(47XXY)
Breast enlargement
Less facial and body hair
Infertility
Klinefelter syndrome
extra chromosome in a pair.
Affected: autosomes
Trisomy
(trisomy 21)
Facial features
Learning problems
Birth defect
Down syndrome
(trisomy 18)
Microcephaly
Cleft palate
Neural tube defect
Low chance of survival
Edward syndrome
(trisomy 13)
Microcephaly
Polydactyly
Cleft palate
Heart defects
Patau syndrome
(48 XXXX)
Affects only female
Distinct facial features
Heart defects
Impaired learning ability
Tetrasomy X
more than 2 paired of chromosomes
Affected: all chromosomes
Polyploidy
(3n)
Total chromosome: 69
Miscarriage or less than 1 year of survival
Triploid syndrome
Total chromosome: 92
Miscarriage or death after birth
Tetra ploidy (4n)
Chromosomal aberration (altered structure) Types
Deletions
Duplications
Translocation
Inversion
Rings
missing or deleted portion of chromosome resulting to lost of genetic materials.
Deletions
Deletion of chromosome 5p
Cri du Chat (Cat cry syndrome)
a portion of a chromosome is transferred to another (non- homologous).
Translocation
a segment of chromosome is duplicated resulting to an extra genetic material this result improper functioning of the genes.
Duplications
Duplication of genetic material in chromosome 12 p arm.
Pallister Killian syndrome
Exchange of some parts between chromosome 8 and chromosome 21.
Acute myeloid leukemia (AML)
Types of translocation
Reciprocal
Robertsonian
non homologous chromosome exchange genetic material with each other.
Reciprocal
2 acrocentric chromosome joined together losing the p arms of both. Asymptomatic but can be passed to offspring leading to genetic disorders.
Robertsonian
apportion of chromosome is broken off, turn upside down, and reattached. Resulting to inverted genetic material.
Inversion
Types of Inversion
Paracentric
Pericentric
centromere is not involved, occur in one arm only
Paracentric
centromere in involved, occur in both arms.
Pericentric
inv (9).
Infertility
Pericentric inversion of chromosome 9
break in both ends of a chromosome resulting to fused together forming a ring.
Rings
Mental disability
Epilepsy
Short stature
Ring chromosome 14 syndrome
the complete set of chromosomes in a cell (somatic cell)
Karyotype
Normal karyotype in male and female
46 XY- male
46 XX – female
Karyo typing is also known as
nucleus typing
A cytogenetic technique for direct observation of chromosomes.
Karyotyping (nucleus typing)
To diagnose aneuploidy and chromosomal aberrations.
Karyotyping (nucleus typing)
For therapeutic monitoring of genetic diseases.
Karyotyping (nucleus typing)
Identification of possible carrier in the family
Karyotyping (nucleus typing)
Karyotyping specimens
Blood
Bone marrow
Amniotic fluid
Placental tissue
Determination of chromosomal abnormalities after exposure to environmental hazards.
Karyotyping (nucleus typing)
Individual chromosome is photograph, cut images then organized according to size.
Karyotyping
Arrangement of chromosomes
Karyotyping (nucleus typing)
Other technique used computer software that arrange chromosomes according to sizes and displayed in a monitor.
Karyotyping
Application of stain to chromosomes for direct observation.
Chromosome banding
A light and dark color (banding pattern) is observed along the chromosome after staining.
Chromosome banding
____ allows chromosome identification.
Staining
Types of chromosome banding
G-banding
R-banding
Q-banding
C-banding
NOR banding
The most common banding method in cytogenetics.
G-banding
Chromosome is treated with trypsin for digest proteins then stain with giemsa
G-banding
Produces an alternating banding pattern of Dark region and Light region
G-banding
Guanine-Cytosine rich bases
Dark Region
Adenine-Thymine rich bases
Light Region
Represents euchromatin.
DNA is loosely wrapped into nucleosomes.
Genes can be expressed.
G-C rich bases (Dark band)
Represents heterochromatin.
DNA is tightly wrapped into nucleosomes .
Genes can not be expressed.
A-T rich bases (light band)
Chromosome is heat denatured (87°C for 10 min, then cooling to 70°C).then stain with giemsa.
R-banding
Banding pattern
Dark region (A-T)
R-banding
Banding pattern
Light region (G-C)
R-banding
Observe under light microscope.
It is used to analyzed the telomeres since it stained light in G-banding
R-banding
Chromosome is denatured with alkali solution (barium hydroxide), then stain with giemsa.
C-banding
Stained with quinacrine mustard dye
Q- banding
Observe under light microscope.
Used to analyzed heterochromatin or centromere.
C-banding
Creates fluorescent when exposed to UV light.
Q- banding
Banding patter is similar with G-banding
Q- banding
Observed under fluorescent microscope.
Gives a high resolution of banding.
Q- banding
Not widely used due to expensive equipment.
Q- banding
NOR staining stands for
nucleolar organizing region
Stains the terminal region of acrocentric chromosomes responsible for the formation of nucleolus.
NOR staining
are code for the production of rRNA
NOR staining
Chromosomes are stained with silver nitrate stain
NOR staining
Gene address
Describe the location of specific genes along the chromosome.
Cytogenetic mapping
Identifies the specific location (locus) of gene in a chromosome.
Cytogenetic mapping
It is a combination of numbers and letters.
Cytogenetic mapping
G-banding pattern is used.
Cytogenetic mapping
Location of gene based on the
G- banding pattern.
occupies a specific position on a chromosomes.
a gene (DNA sequence)
indicates the chromosome number
autosomes (1-22)
sex chromosomes ( X &Y)
1st number
indicates short arm (p) or long arm (q).
Letter
indicates the region
2nd number
indicates band region
3rd number
decimal point indicates the sub region
4th number
located on the long arm of chromosome 1, region 2 band 3 sub-band 2.
Gene blue
long arm of chromosome 7 at region 1,band 3.
male with a deletion
long arm of chromosome 9
female with a deletion
between the short arms of chromosomes 5 and 17 and region 1, band 3, sub-band 3, and region 1, band 3, respectively.
male with translocation
