Cell Cycle

Question 1

Mitosis definition

Answer 1

Cell division that results in two identical daughter cells from a single parent cell

Question 2

Mitosis consist of two things

Answer 2

1 nuclear division
2 cytokinesis
Definition of cytokinesis part of the cell division process during which the cytoplasm of a single eukaryotic cell divides into two daughter cells. Cytoplasmic division begins during or after the late stages of nuclear division in mitosis and meiosis

Question 3

In which type of cells does mitosis occurs exclusively

Answer 3

In eukaryotic cells
;;;; whose members are known as eukaryotes, is a diverse domain of organisms whose cells have a nucleus. All animals, plants, fungi, and many unicellular organisms, are eukaryotes. They belong to the group of organisms Eukaryota or Eukarya, which is one of the three domains of life;;;;;;

Question 4

Mention stages of mitosis

Answer 4

PMAT
Prophase
Metaphase
Anaphase
Telophase

Question 5

Events of prophase

Answer 5

Chormatid condense
Centromeres appear near the nucleus
Centromere consist of a pair of centrioles

Question 6

Events of metaphase

Answer 6

Nucleus disappear
Nuclear membrane disintegrate
Mitotic spindles appear
Centromeres migrate to both poles of the cell
Chromosomes align at the metaphase plate

Question 7

Anaphase events

Answer 7

Kinetochore : a point on the chromosome where the Mitotic spindle attach
Kinetochore shortening separating the chromatids
كل وحده بتحكي انا وبتقصير عشان تبعد عن التانيه .

Question 8

Telophase events

Answer 8

Chromtid deco dense
Mitotic spindles disappear
Nuclear membrane reformation
Followed by cytokinesis

Question 9

In which phase of cell cycle does cell division occur

Answer 9

In M phase mitosis and meiosis occur

Question 10

Cell cycle phases dna replication at which phase
Division
Growth

Answer 10

Question 11

Define meiosis

Answer 11

It’s a type of cell division that results in 4 haploid N non identical daughter cells from a single diploid parent cell
It occurs in germ cells , gonads , responsible about sexual differentiation

Question 12

Meiosis is responsible for production of which type of cells ; what about mitosis

Answer 12

Meiosis is responsible for germ cells production
M

Question 13

Meiosis involves 2 major events

Answer 13

1 reduction of genetic material reduction stage meiosis 1
2 2 successive nuclear division meiosis 2 which is similar to mitosis , each 1 n give 2n

Question 14

Meiosis 2 stages define them

Answer 14

Stage 1 meiosis , separation of two homologous chromosomes producing 2 haploid cells
Stage 2 as mitosis

Question 15

Stage 1 meiosis , prophase 1 main event

Answer 15

1 pairing of 2 homologous chromosome ( bivalent chromosomes )
2 CROSSINg over the genetic material between the 2 homologous chromosomes not the two sister chromatids
3 migration of centrosomes to both poles of the cell
Leptotene
Zygotone pairing stage
Pachytene crossing over stage
Diplotene
Diakinesis
Synchronous migration of centromere to opposite poles of the cell

Question 16

At which stage does crossing over occurs

Answer 16

In meiosis 1 prophase 1 in pachytene

Question 17

Meiosis 1 which is the reduction stage composed of

Answer 17

Question 18

At which stage of meiosis dose homologous chromosomes align

Answer 18

Alignment of the homologous chromosomes (tetrads)at the metaphase plate occur at the metaphase 1
Each pair is attached to a separate spindle fiber unlike mitosis which attached to double spindle fibers

Question 19

Dysjunction phase , is

Answer 19

Anaphase 1

Question 20

Where does crossing over of genetic material occur

Answer 20

At chiasmata , single or double at the near to each other chromosome that will cross over

Question 21

Meiosis

Answer 21

Question 22

Genetic transfer is based on

Answer 22

Manelian inheritance

Question 23

Law of segregation

Answer 23

States that each gamete receives only 1 allele for each gene

Question 24

Law of independent assortment 2nd law of mandelian

Answer 24

States that alleles of different genes assort independently of one another during gematogenesis

Question 25

Mitosis

Answer 25

Question 26

Dysjunction

Answer 26

Question 27

Deference between meiosis metaphase 1 and Mitosis metaphase and anaphase

Answer 27

Mitosis and metaphase 2 [centrosomes does so]plit 2 at each pole In prophase centrosomes doesn’t split one only on each side

Question 28

Mention the two types of structural abnormalities

Answer 28

1 Aneuploidy ; change in the number of cell chromosomes Down syndrome trisomy 21 Edward syndrome trisomy 18 Patau syndrome trisomy 13 Turner syndrome monosomy x 2 structural Deletion Translocation Duplication Insertion Inversion

Question 29

Which one of the structural chromosomal abnormalities form ring chromosome

Answer 29

Deletion

Question 30

Mosaics definition

Answer 30

Presence of 2 or more genetically different cell lines derived from a single zygote

Question 31

Types of mosaics

Answer 31

Gamete mosaics Somatic mosaicism as down turner

Question 32

Explain mosaicism

Answer 32

Question 33

Mosaicism in down and turner syndrome

Answer 33

Question 34

Trisomies occur due to

Answer 34

1 dysjunction at meiosis 1 >70% 2 dysjunction at meiosis 2 3 mosaicism < 5%

Question 35

Relation between trisomies and maternal age

Answer 35

Risk of trisomies a increase with increased maternal age

Question 36

Relation between the no of extra chromosomes in trisomies and the probability of learning disabilities if the individual survives

Answer 36

The greater the no of extra chromosomes the greater the probability for learning difficulties

Question 37

Down syndrome is

Answer 37

Trisomy 21

Question 38

Prevelance of Down syndrome

Answer 38

1: 700

Question 39

When is the higher incidence of Down syndrome And what the percentage that will go for spontaneous pregnancy loss

Answer 39

Higher incidence at conception . 80 % will go for spontaneous pregnancy loss .

Question 40

Down syndrome occurs due to

Answer 40

1 primary trisomy 21 occurs in 95% due to non dysfunction at meiosis 85 % maternal 15 % paternal . 2. Robertsonian Translocation mutation , ch( 14;21) 3 % 3 , mosaicism 1 %

Question 41

Features of Down syndrome

Answer 41

1 - increase Nt 2- dysmorphic features ( small ears. Flat facial profile , upslanting palpebral fissures , brachycephaly ) 3 - conductive hearing loss 4 - GI abnormalities ( duodenal atresia , hirsrchprung disease , imperforate anus ) 5- cardiac abnormalities AV canal defect 6- hypotonia

Question 42

Down syndrome are at increased risk to develop

Answer 42

1 ) hypothyroidism Alzheimer’s AML and ALL Celiac disease

Question 43

Risk at maternal age 25

Answer 43

1: 1500

Question 44

Risk at maternal age of Down syndrome 30

Answer 44

1: 900

Question 45

Down syndrome risk in maternal age 35

Answer 45

1:350

Question 46

Down syndrome risk at maternal age 40

Answer 46

1:100

Question 47

Risk for Down syndrome at age 45

Answer 47

1:30

Question 48

Risk for Down syndrome at age 50

Answer 48

1:11

Question 49

Cut off for invasive screening for Down syndrome

Answer 49

1:250 ( 40 )

Question 50

Edward syndrome incidence

Answer 50

1: 3000 live births Trisomy 18

Question 51

Male:female ration for Edward syndrome

Answer 51

1;2

Question 52

Features for Edward syndrome

Answer 52

1 musculoskeletal defects limb defect , overlapping fingers , rockerbottom foot 2 facial defects ; microganthia , cleft lip , palate 3 cvs defects vsd ads pda 4 abdominal defects diaphragmatic hernia , exomphalus , inguinal hernia renal malformation 5 IUGR Increased NT فتحات بكل مكان وقصير واصابعه فوق بعض ورجله متل الكره

Question 53

Mortality rate in Edward syndrome at 1 month 2 month 1 year

Answer 53

1 moth 30% 2nd month 50% 1 year 90 %

Question 54

% of Edward syndrome that can be detected by US at 18-20 weeks

Answer 54

90%

Question 55

Patau syndrome incidence

Answer 55

Trisomy 13 . 1:5000 of all live births . Increased risk with increased maternal age .

Question 56

Patau syndrome features

Answer 56

Similar to Edward 1) midline defects : Hypertelorism Holoproscencephaly Cleft lip Cleft palate Scalp defect 2 ) post axial polydactyly 3) cardiac defect 4) renal malformations 5 ) IUGR 6) omphalocele

Question 57

Mortality rate at 1 month age in Patau syndrome

Answer 57

100%

Question 58

Hypertelorism is a feature of which syndrome and means >

Answer 58

Abnormally decreased distance between the eyes pataus

Question 59

Holoprosecephaly

Answer 59

Failure of the prosencephalon to develop into 2 hemispheres . Feauture of Patau s syndrome .

Question 60

Sex chromosome an aneuploidy. In female ration and male s

Answer 60

Males 1:400 Female 1 ; 600

Question 61

Mention two examples of sex chromosomes aneuploidy Chromosomes and incidence for each one

Answer 61

Turner syndrome so monosomy 1:2500 Klinefilter syndrome 47 XXY 1 : 1000

Question 62

Which syndrome have increased risk for developing gondalblastoma

Answer 62

Turner syndrome

Question 63

Turner syndrome features

Answer 63

10 features 1 short stature . 2 webbed neck . 3 shield shaped chest with wide space between nipples . 4 renal malformations horseshoe kidney . 5 gonadaldysgenesis , 6 coarcation of the aorta . 7 wide angle arms 8cystic hygroma 9 lymphedema 10 raised NT

Question 64

Intellectual status for turner syndrome

Answer 64

Normal intellectually

Question 65

Klinefelters syndrome chromosomes incidence

Answer 65

47 XXY 1:1000

Question 66

Features of Klinfilters syndrome

Answer 66

Tall Small testis with hypogonadism hypogonadrtrophic Infertility

Question 67

Lyon hypothesis

Answer 67

Barr body Which is inactivated X chromosome Happen when there is more than 2 X chromosome in a single cell .

Question 68

Lyon hypothesis ( when does inactivation of 1 X chromosome happen in female )

Answer 68

15-16 days gestation

Question 69

Define translocation

Answer 69

Is the exchange of 2 segment of chromosomes between 2 NON- HOMOLOGOUS chromosomes

Question 70

Mention the 2 types of translocation

Answer 70

1 balanced , genetic material didn’t change , even equalexchange of genetic material without loss or excess of genetic material . 2 unbalanced unqual exchange of genetic material resulting in excess or lost genetic material .

Question 71

Robertsonian translocation result from

Answer 71

Fusion of the long arms of the two acrocentric chromosome 14, 21

Question 72

mention three syndromes associated with chromosomal structural deletion abnormality’s

Answer 72

Digeorge syndrome velocardiofacial Prayer Willi syndrome Angleman syndrome

Question 73

Which syndromes result from deletion of ch22q11 ,

Answer 73

Digeorge

Question 74

Which syndrome results due to failure of 3rd and 4th pharyngeal pouches development

Answer 74

Digeorge syndrome

Question 75

Digeorge mean 2 feautures for each feautures CATCH_22

Answer 75

1 2 ——- ch 22q11 .2 2 glands absent thymus and PTH 2 consequences hyocalcemia , decreased T lymphocytes , decreased immunity Congenital heart defects Cleft lip palate 2Cs Auitism لحالها. .

Question 76

Angelman syndrome deletion paternal or maternal

Answer 76

Maternal deletion

Question 77

Angelman deletion at which chromosome

Answer 77

15q-11-13 Protein ligase E3A

Question 78

Features of angel man syndrome

Answer 78

Happy disposition Macroglossia Seizure Ataxia Learning difficulties.

Question 79

Prayer willi syndrome ch maternal or paternal

Answer 79

Paternal deletion 15 q-11-13

Question 80

Features of prayer willi syndrome

Answer 80

Obese Hypotonia Hypogonadism