Chapter 8 Part 1 Flashcards

Question

Dicentric Chromatid

Answer 1

Chromatid that has two centromeres; produced when crossing over takes place within a paracentric inversion

Answer 2

Chromatid that lacks a centromere; produced when crossing over takes place within a paracentric inversion

Answer 3

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

Answer 4

1. The heterozygous chromosomes -- homologous pairs or homologs -- posses one wild type -- the correct sequence -- and one chromosome with a paracentric inversion 2. In prophase I, an inversion loop forms when a single crossing over occurs within the inverted region 3. This results in an unusual structure...where two chromosomes form with four chromatids and two centromeres...and one chromosome that lacks a centromere --> formation of dicentric chromatids 4. In anaphase I, the centromeres separate stretching the dicentric chromatid, which breaks...the chromosome lacking a centromere is lost into the cytoplasm 5. The two gametes contain non-recombinant chromosomes one wild type -- normal and one with inversion...the other two contain recombinant chromosomes that are missing some genes; these gamester will not produce viable offspring

Answer 5

1. The heterozygote possesses one wild-type chromosome and one chromosome with a pericentric inversion 2. In prophase I, an inversion loop forms...if crossing over takes place within the inverted region...two of the resulting chromatids have too many copies of some genes and no copies of others 3. Unlike in paracentric, we still have two chromosomes each with two chromatids and one centromere 4. The chromosomes separate in Anaphase I, and than later in Anaphase II 5. Four gametes are produced: - Normal non recombinant gamete - Nonviable recombinant gametes X 2 - Nonrecombinanat gamete with pericentric inversion

Answer 6

Movement of a chromosomes segment to a non homologous chromosome or chromosomal region without any -- or with unequal -- reciprocal exchange of segments AB*CDEFG and MN*OPQRS AB*CDG and MN*OPEFQRS

Answer 7

Reciprocal exchange of segments between two non homologous chromosomes AB*CDEFG and MN*OPQRS AB*CDQRS and MN*OPEFG

Answer 8

1. They can physically link genes that were formerly located on different chromosomes...these new linkage relations may affect gene expression -- a position effect -- as genes translocated to new position effect, as genes translocated to new locations may come under the control of different sequences or other genes that affect their expression 2. Second, chromosome breaks that bring about translocations may take place within a gene and disrupt its function -- Ex. Neurofibromatosis, a genetic disease characterized by numerous fibrous tumours of the skin and nervous tissue, results from an autosomal dominant mutation.

Answer 9

The long arms of two afrocentric chromosomes become joined to a common centromere, generating a metacentric chromosome with two long arms and another chromosome with two very short arms -- some causes of Down syndrome disorder -- the short arm is a fragment that often fails to segregate and is lost

Answer 10

Alternate Segregation N1,N2 || T1,T2.

Answer 11

Adjacent-1 Segregation and Adjacent-2 Segregation missing genes or too many genes occur on the gene Adjacent-2 gametes are rare because homologous chromosomes with adjacent centromere do not segregate Adjacent-1 gametes are often found too...but they produce 50% viable and 50% non-viable offspring

Answer 12

Type of segregation that takes place in a heterozygote for a translocation: If the original, non-translocated 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 towards the opposite pole

Answer 13

One translocated and one non-translocated chromosomes separate... ***Homologous chromosomes segregate in Meiosis I

Answer 14

One translocated and one non-translocated chromosomes separate... ***Homologous chromosomes DO NOT segregate in Meiosis II

Answer 15

1. An individual heterozygous for the reciprocal translocation possesses one normal copy of each chromosome and one translocated copy 2. Because each chromosome has sections that are homologous to two other chromosomes, a cross like configuration forms in prophase I of meiosis 3. In anaphase I, the chromosomes separate in three different ways 4. Alternate Segregation 5. Adjacent-1 and Adjacent-2 Segregation

Answer 16

Sites that develop constrictions or gaps when the cells are grown in culture and that are prone to breakage under entrain conditions Ex. Common health condition as a result is fragile-X syndrome