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Flashcards in Chapter 8 Deck (47)
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1
Q

chromosome mutation

A

Difference from the wild type in the number or structure of one or more chromosomes; often affects many genes and has large phenotypic effects.

2
Q

chromosome rearrangement

A

Change from the wild type in the structure of one or more chromosomes.

3
Q

chromosome duplication

A

Mutation that doubles a segment of a chromosome.

4
Q

tandem duplication

A

Chromosome rearrangement in which a duplicated chromosome segment is adjacent to the original segment.

5
Q

displaced duplication

A

Chromosome rearrangement in which the duplicated segment is some distance from the original segment, either on the same chromosome or on a different one.

6
Q

reverse duplication

A

Duplication of a chromosome segment in which the sequence of the duplicated segment is inverted relative to the sequence of the original segment.

7
Q

segmental duplication

A

Regions larger than 1000 bp that are almost identical in sequence in eukaryotic genomes.

8
Q

chromosome deletion

A

Loss of a chromosome segment.

9
Q

pseudo dominance

A

Expression of a normally recessive allele owing to a deletion on the homologous chromosome.

10
Q

haploinsufficient gene

A

Must be present in two copies for normal function. If one copy of the gene is missing, a mutant phenotype is produced.

11
Q

chromosome inversion

A

Rearrangement in which a segment of a chromosome has been inverted 180 degrees.

12
Q

paracentric inversion

A

Chromosome inversion that does not include the centromere in the inverted region.

13
Q

pericentric inversion

A

Chromosome inversion that includes the centromere in the inverted region.

14
Q

position effect

A

Dependence of the expression of a gene on the gene’s location in the genome.

15
Q

dicentric chromatid

A

Chromatid that has two centromeres; produced when crossing over takes place within a paracentric inversion. The two centromeres of the dicentric chromatid are frequently pulled toward opposite poles in mitosis or meiosis, breaking the chromosome.

16
Q

acentric chromatid

A

Lacks a centromere; produced when crossing over takes place within a paracentric inversion. The acentric chromatid does not attach to a spindle fiber and does not segregate in meiosis or mitosis; so it is usually lost after one or more rounds of cell division.

17
Q

dicentric bridge

A

Structure produced when the two centromeres of a dicentric chromatid are pulled toward opposite poles, stretching the dicentric chromosome across the center of the nucleus. Eventually, the dicentric bridge breaks as the two centromeres are pulled apart.

18
Q

translocation

A

Movement of a chromosome segment to a non-homologous chromosome or to a region within the same chromosome. Also, movement of a ribosome along mRNA in the course of translation.

19
Q

nonreciprocal translocation

A

Movement of a chromosome segment to a non-homologous chromosome or region without any (or with unequal) reciprocal exchange of segments.

20
Q

reciprocal translocation

A

Reciprocal exchange of segments between two non-homologous chromosomes.

21
Q

Robertsonian Translocation

A

Translocation in which the long arms of two acrocentric chromosomes become joined to a common centromere, resulting in a chromosome with two long arms and usually another chromosome with two short arms.

22
Q

alternate segregation

A

Type of segregation that takes place in a heterozygote for a translocation. If the original, nontranslocated chromosomes are N1 and N2 and the chromosomes containing the translocated segments are T1 and T2, then alternate segregation takes place when N1 and N2 move toward one pole and T1 and T2 move toward the opposite pole.

23
Q

adjacent 1 segregation

A

Type of segregation that takes place in a heterozygote for a translocation. If the original, nontranslocated chromosomes are N1 and N2 and the chromosomes containing the translocated segments are T1 and T2, then adjacent-1 segregation takes place when N1 and T2 move toward one pole and T1 and N2 move toward the opposite pole.

24
Q

adjacent 2 segregation

A

Type of segregation that takes place in a heterozygote for a translocation. If the original, nontranslocated chromosomes are N1 and N2 and the chromosomes containing the translocated segments are T1 and T2, then adjacent-2 segregation takes place when N1 and T1 move toward one pole and T2 and N2 move toward the opposite pole.

25
Q

fragile site

A

Constriction or gap that appears at a particular location on a chromosome when cells are cultured under special conditions. One fragile site on the human X chromosome is associated with intellectual disability (fragile-X syndrome) and results from an expanding trinucleotide repeat.

26
Q

fragile x syndrome

A

A form of X-linked intellectual disability that appears primarily in males; results from an increase in the number of repeats of a CGG trinucleotide.

27
Q

copy-number variation

A

Difference among individual organisms in the number of copies of any large DNA sequence (larger than 1000 bp).

28
Q

aneuploidy

A

Change from the wild type in the number of chromosomes; most often an increase or decrease of one or two chromosomes.

29
Q

polyploidy

A

Possession of more than two haploid sets of chromosomes.

30
Q

nullisomy

A

Absence of both chromosomes of a homologous pair (2n − 2).

31
Q

monosomy

A

Absence of one of the chromosomes of a homologous pair.

32
Q

trisomy

A

Presence of an additional copy of a chromosome (2n + 1).

33
Q

tetrasomy

A

Presence of two extra copies of a chromosome (2n + 2).

34
Q

Down Syndrome (trisomy 21)

A

Characterized by variable degrees of intellectual disability, characteristic facial features, some retardation of growth and development, and an increased incidence of heart defects, leukemia, and other abnormalities; caused by the duplication of all or part of chromosome 21.

35
Q

primary down syndrome

A

Caused by the presence of three copies of chromosome 21.

36
Q

familial down syndrome

A

Caused by a Robertsonian translocation in which the long arm of chromosome 21 is translocated to another chromosome; tends to run in families.

37
Q

translocation carrier

A

Individual organism heterozygous for a chromosome translocation.

38
Q

Edward Syndrome (trisomy 18)

A

Characterized by severe intellectual disability, low-set ears, a short neck, deformed feet, clenched fingers, heart problems, and other disabilities; results from the presence of three copies of chromosome 18.

39
Q

Patau Syndrome (trisomy 13)

A

Characterized by severe intellectual disability, a small head, sloping forehead, small eyes, cleft lip and palate, extra fingers and toes, and other disabilities; results from the presence of three copies of chromosome 13.

40
Q

trisomy 8

A

Presence of three copies of chromosome 8; in humans, results in intellectual disability, contracted fingers and toes, low-set malformed ears, and a prominent forehead.

41
Q

uniparental disomy

A

Inheritance of both chromosomes of a homologous pair from a single parent.

42
Q

mosaicism

A

Condition in which regions of tissue within a single individual have different chromosome constitutions.

43
Q

gynandromorph

A

Individual organism that is a mosaic for the sex chromosomes, possessing tissues with different sex-chromosome constitutions.

44
Q

autopolyploidy

A

Condition in which all the sets of chromsomes of a polyploid individual possessing more than two haploid sets are derived from a single species.

45
Q

allopolyploidy

A

Condition in which the sets of chromosomes of a polyploid individual possessing more than two haploid sets are derived from two or more species.

46
Q

unbalanced gametes

A

Gamete that has a variable number of chromosomes; some chromosomes may be missing and others may be present in more than one copy.

47
Q

amphidiploidy

A

Type of allopolyploidy in which two different diploid genomes are combined such that every chromosome has one and only one homologous partner and the genome is functionally diploid.