Cytogenetics (Chromosomal)

Question 1

What phase of mitosis are the Chromosomes most visible?

Answer 1

Metaphase

Question 2

What are the ends of chromosomes known as?

Answer 2

Telomeres

Question 3

The short arm of the chromosome is also know by which letter?

Answer 3

P

Question 4

The long arm of the chromosome is also known by which letter?

Answer 4

q

Question 5

Approximately how many genes and bands make up a karyotype?

Answer 5

550bands 30kGenes

Question 6

Is loss or gain of chromosomes worse?

Answer 6

Loss

Question 7

What is position effect?

Answer 7

Chromosome in new environment will function differently = different phenotype

Question 8

Is sex chromosome or autosome imbalance worse?

Answer 8

Autosome imbalance is more severe

Question 9

What does aneuploidy mean?

Answer 9

Gain or loss of chromosomes

Question 10

What is mosaicism in terms of karyotype/cells?

Answer 10

Some are diploid (normal) and some have aneuploidy!

Question 11

An increase in maternal age can increase the likelihood of what?

Answer 11

Aneuploidy

Question 12

An increase in paternal age can increase the likelihood of what?

Answer 12

Nothing (well no aneuploidy)

Question 13

In meiosis when are the chiasmata visible?

Answer 13

Metaphase I

Question 14

In meiosis when are the chromosomes separated?

Answer 14

Anaphase I

Question 15

What happens in meiosis II?

Answer 15

Mitotic division of the secondary gametocyte - Chromatids separate = mature sex cell produced

Question 16

What is non disjunction?

Answer 16

A meiotic error

Question 17

When does most non-disjunction occur (%) ?

Answer 17

Meiosis I (80-90%)

Question 18

In trisomy one you are at greater risk of what?

Answer 18

Leukaemia, hypothyroidism, alzheimers + more

Question 19

Which of males of females are usually infertile with trisomy 21?

Answer 19

Males

Question 20

What percentage of trisomy 21 foetus’s spontaneously abort?

Answer 20

75%

Question 21

What is the risk of trisomy 21 at a normal age?

Answer 21

1/700

Question 22

Trisomy 18 is called what? risk and spontaneous abortion stats?

Answer 22

Edward’s syndrome, 1/6000 95% spontaneous abortion

Question 23

Features of Edward’s syndrome

Answer 23

Short lifespan, microcephaly, sort sternum, low birth weight

Question 24

Most common organ abnormality in trisomy 18?

Answer 24

Congenital heart disease (90%

Question 25

Trisomy 13 stats?

Answer 25

Patau syndrome, 1/12000 (95% spont abort)

Question 26

features of trisomy 13?

Answer 26

Small eyes, cleft lip and palate, polydactyly-fingers flexed heart defects - severe retardation

Question 27

Why is trisomy 13, 18 and 21 more commonly seen than others?

Answer 27

Small chromosomes- others tend to be lethal although these do have high rates of abortion

Question 28

At what age do female ages start and remain at Meiosis I ?

Answer 28

5 months, suspended until puberty

Question 29

Karyotype of turner's syndrome?

Answer 29

45X (affects females)

Question 30

Fertility issues with turners syndrome?

Answer 30

Infertility, no ovarian function or puberty

Question 31

Lymphatic issue of Turner's?

Answer 31

Webbed neck, swollen feet

Question 32

Turner's syndrome causes what structural problems?

Answer 32

Coarction of aorta, and short stature

Question 33

What is a common reason for diagnosis of klinefleters?

Answer 33

Inferitlity or Agenesis of sperm!

Question 34

Stature of klinefelter's ?

Answer 34

Tall, long arms and legs!

Question 35

Klinefelter's has a high risk of what cancer due to what?

Answer 35

Due to gynaecomastia 20X risk of breast cancer

Question 36

What is Digyny?

Answer 36

A diploid egg

Question 37

Double maternal contribution gives what?

Answer 37

Big head!!

Question 38

Double paternal contribution?

Answer 38

Foeutus many abnormalities, cystic placenta

Question 39

contribution of dad = what and mum = what?

Answer 39

``` Mum = head Dad = Placenta ```

Question 40

Molar pregnancy is what?

Answer 40

Conception but not embryo!, only a placenta

Question 41

what is the consequence of mosaicism on phenotype?

Answer 41

Variable. possibly less lethality!

Question 42

Females are mosaic?

Answer 42

X inactivations

Question 43

13, 14, 15, 21 and 22 are known as what?

Answer 43

Acrocentric chromosomes

Question 44

P arms do or do not contain coding DNA?

Answer 44

Do not!

Question 45

Robertsonian translocation involves what?

Answer 45

Fusions of two Qarms no P arms have 45 chromosomes

Question 46

Inversion of chromosomes involves what?

Answer 46

Two breaks in chromosomes rotation etc

Question 47

2 breaks in one arms is knows as what?

Answer 47

Paracentric inversion

Question 48

2 breaks in different arms is what?

Answer 48

Pericentric! inversion

Question 49

unbalanced rearrangements are usually inherited?

Answer 49

No sporadic!

Question 50

Unbalance rearrangement more likely in which sex?

Answer 50

Males

Question 51

What types of deletion can occur?

Answer 51

Interstitial or terminal