ENDO PART 1

Question 1

Cytogeneticists use three things to tell chromosomes apart:

Answer 1

• Chromosome size
• The position of the centromere
• Characteristics banding patterns of alternating light and dark bands
(caused by staining the chromosomes with dyes)

Question 2

the representation of entire metaphase chromosomes in a cell, arranged in order of size.

Answer 2

KARYOTYPE

Question 3

the cytogenetic map location of a gene termed CFTR (cystic fibrosis transmembrane conductance regulator) is

Answer 3

7q31.2

Question 4

Are those in which a single copy of allele is enough for the trait to be expressed or shown in the phenotype of the person

Answer 4

Autosomal Dominant Traits

Question 5

Are those that are expressed in heterozygotes.

Answer 5

Dominant conditions

Question 6

Refers to the additional genes in cell’s mitochondria. Because mitochondria are almost exclusively passed from parent to child in the egg and not in the sperm, a hallmark of this is transmission from an affected woman to all of her children.

Answer 6

mitochondrial inheritance

Question 7

Works differently depending upon
wether the mother or father is the carrier of a gene that causes a disease or disorder.

Answer 7

X-linked dominant inheritance

Question 8

All daughters of an affected father will also be ____ but none of his sons will be ____ (unless the mother is also affected).

The mother of an affected son is son is also ______ (but not necessarily the other way around).

Answer 8

• affected; affected’

- affected

Question 9

X-linked recessive inheritance expressed in

Answer 9

(1) Males (who are necessarily hemizygous for the gene mutation because they have only one X chromosome); and
(2) Females who are homozygous for the gene mutation

Question 10

Nucleotide diversity is based on single mutations called

Answer 10

single nucleotide polymorphisms (SNPs)

Question 11

Most of these SNPs are ___ but some are ____ and influence phenotypic differences between humans through alleles.

Answer 11

neutral; functional

Question 12

In full sequences of an individual’s genome, the analysis of diploid sequences, has shown that ______ accounts for much more human genetic variation than single nucleotide diversity.

Answer 12

non-SNP variation

Question 13

This non-SNP variation includes copy number variation and results from

Answer 13

1) deletions,
2) inversions,
3) insertions,
4) duplications

Question 14

two basic categories of cytogenetically detectable variation:

Answer 14

(1) Numerical

(2) Structural changes

Question 15

Errors in division can give rise to chromosome complements that have greater than or less than 46 chromosomes.

Answer 15

Numerical Abnormalities

Question 16

Exact multiples of the haploid set of chromosomes is known as

Answer 16

euploidy

Question 17

Gain or less of one or a few chromosomes is known as

Answer 17

aneuploidy.

Question 18

The normal state of human cells, is a form of euploidy.

Answer 18

Diploidy

Question 19

May be due to the failure in gametogenesis of one of the meiotic divisions giving rise to a 2N gamete which, when fertilized by a haploid gamete from the other parent, produces a triploid zygote

Answer 19

Triploidy

Question 20

A 3N complement may be derived from dispermy, the fertilization of a haploid egg by two sperm, and this generally results in a

Answer 20

partial hydatidiform mole

Question 21

Is caused by a single (incidence is about 90%) or two (incidence is about 10%) sperm combining with an egg which has lost DNA.

Answer 21

Complete mole

Question 21

Is caused by a single (incidence is about 90%) or two (incidence is about 10%) sperm combining with an egg which has lost DNA.

Answer 21

Complete mole

Question 22

Usually a postmeiotic event and presents as a duplication of a diploid complement (xxxx or xxyy) most likely due to failure of an early mitotic cleavage division in the zygote

Answer 22

Tetraploidy,

Question 23

More common anomaly resulting in aneuploidy.

Answer 23

nonjudisjunctional errors

Question 24

Produce in early mitotic nondisjunction chromosome complement in all cells of the body, but a latter. An individual with two cell lines that differ only by a single
chromosome.

Answer 24

MOSAIC

Question 25

Is the most commonly detected trisomy in spontaneous abortus tissue but is not reported in liveborn individuals.

Answer 25

Trisomy 16

Question 26

Liveborn autosomal trisomies include chromosomes

Answer 26

13, 18, and 21

Question 27

The only viable monosomy is of the X chromosome

Answer 27

(45,X)

Question 28

In the case of monosomy, the rescue is accomplished by _____ of the single existing chromosome resulting in a chromosome complement with uniparental isodisomy for that chromosom

Answer 28

duplication

Question 29

Most trisomies are

Answer 29

nonviable

Question 30

But if one of the three chromosomes is lost, a disomy for that chromosome pair is ____.

Answer 30

reinstated

Question 31

Will result in heterodisomy, which is two homologous but heterozygous chromosomes (one grandmaternal and one grandpaternal)

Answer 31

first-division nondisjunction

Question 32

Will result in duplicate copies of a single chromosome, isodisomy.

Answer 32

second division error

Question 33

Rearrangements may be (1) ____, if all the chromosomal material is present and functional but simply arranged in a different conformation; or (2) _____, if there is loss and/or addition of some chromosomal material.

Answer 33

balanced; unbalanced

Question 34

Rearrangements usually are clinically benign, but may increase the risk of errors in meiosis resulting in chromosomal imbalances in fetuses or liveborn children.

Answer 34

Balanced

Question 35

Are generally associated with an abnormal clinical phenotype often including developmental delay and mental retardation.

Answer 35

Unbalanced

Question 36

Is the loss of a part of a chromosome and leads to partial monosomy of the chromosome involved.

Answer 36

deletion

Question 37

Is the presence of an additional copy of a chromosome segment, which leads to partial trisomy for that interstitial.

Answer 37

duplication

Question 38

Is a reversal of a chromosomal segment with respect to the normal gene arrangement and requires a minimum of two breaks in one chromosome

Answer 38

inversion

Question 39

Inversions are classifies as either (1) _____, the two breaks occur on the same side of the centromere (i.e. in the same arm); or (2) ____, the break occur on opposite sides of the centromere and the inversion involves both arms.

Answer 39

paracentric; pericentric

Question 40

The homologous chromosome pair and recombination occurs.

Answer 40

meiosis I

Question 41

Formed in order for an inverted chromosome to pair with its homolog

Answer 41

inversion loop

Question 42

is a chromosome whose arms have fused together to form a ring.

Answer 42

ring chromosome

Question 43

Where a ring formed by one copy of chromosome 20 is associated with epilepsy

Answer 43

ring chromosome 20 syndrom

Question 44

Ring chromosome syndrome are associated with mental retardation and dysmorphic facial features

Answer 44

14 and ring chromosome 13 syndrome

Question 45

ing chromosome ssociated with mental retardation, dwarfism, and microcephaly.

Answer 45

ring chromosome 15

Question 46

¾Ring formation of an X-chromosome cause

Answer 46

Turner syndrome

Question 47

A structural abnormality is indicated by the abbreviation of the:

Answer 47

1) abnormality followed by the
2) chromosome involved and
3) breakpoint on the chromosome

Question 48

Cytogenetic abnormalities may be found in apparently

Answer 48

1) normal individuals
2) patients with phenotypic anomalies
3) with a diagnosed genetic disorder.

Question 49

The most common chromosome abnormalities detected in prenatal testing are the

Answer 49

1) liveborn trisomies

2) sex chromosome aneuplodies.