Translocations. A translocation occurs when a piece of one chromosome breaks off and attaches to another chromosome. This type of rearrangement is described as balanced if no genetic material is gained or lost in the cell.
What occurs when a section of one chromosome changes places with a section of its homologous chromosome?
Recombination occurs when two molecules of DNA exchange pieces of their genetic material with each other. One of the most notable examples of recombination takes place during meiosis (specifically, during prophase I), when homologous chromosomes line up in pairs and swap segments of DNA.
What is it called when homologous chromosomes switch parts?
Crossing over is a process that happens between homologous chromosomes in order to increase genetic diversity. During crossing over, part of one chromosome is exchanged with another. The result is a hybrid chromosome with a unique pattern of genetic material.
Which change in chromosome structure involves the transfer of one section of a chromosome to a non homologous chromosome?
A translocation occurs when a segment of a chromosome dissociates and reattaches to a different, nonhomologous chromosome.
What is it called when a section of a chromosome is lost during meiosis?
An umbrella term for a gain or loss of chromosome is aneuploidy. Chromosome abnormalities often occur during cell division (meiosis and mitosis). There are two main groups of chromosome abnormalities — numeric and structural.
During which phase of prophase 1 of meiosis crossing over does occur?
In the fourth phase of prophase I, diplotene (from the Greek for “twofold”), crossing-over is completed. Homologous chromosomes retain a full set of genetic information; however, the homologous chromosomes are now of mixed maternal and paternal descent.
What cell is formed after meiosis 1?
However, Meiosis I begins with one diploid parent cell and ends with two haploid daughter cells, halving the number of chromosomes in each cell. Meiosis II starts with two haploid parent cells and ends with four haploid daughter cells, maintaining the number of chromosomes in each cell.
What is the name for the sites of crossing over in a chromosome?
The structure that results is a cross-strand exchange, also known as a Holliday junction. The contact between two chromatids that will soon undergo crossing-over is known as a chiasma.
What is the definition of metaphase 1?
Metaphase I is the second stage in meiosis I. … At metaphase I, the homologous chromosomes move to the center of the cell and orient themselves along an equatorial plane, forming the so-called metaphase plate.
What is crossing over and its types?
Crossing Over on the Chromosomes: Mechanisms, Kinds, Factors and Significance! Crossing over is the process of exchange of genetic material or segments between non-sister chromatids of two homologous chromosomes. Crossing over occurs due to the interchange of sections of homologous chromosomes.
When one base is replaced with a different base this is called?
Substitution is a type of mutation where one base pair is replaced by a different base pair. The term also refers to the replacement of one amino acid in a protein with a different amino acid.
What is Interchromosomal and Intrachromosomal?
Intrachromosomal translocations involve the movement of a chromosomal segment from one location in the chromosome to another. … Interchromosomal translocations involve the movement of a chromosomal segment(s) between chromosomes.
What is Philadelphia chromosome?
Philadelphia chromosome (Ph): The chromosome abnormality that causes chronic myeloid leukemia (CML). Abbreviated as the Ph chromosome.
What is deletion?
Deletion is a type of mutation involving the loss of genetic material. It can be small, involving a single missing DNA base pair, or large, involving a piece of a chromosome.
What causes deletion?
Deletions can be caused by errors in chromosomal crossover during meiosis, which causes several serious genetic diseases. Deletions that do not occur in multiples of three bases can cause a frameshift by changing the 3-nucleotide protein reading frame of the genetic sequence.
What is a Nondisjunction quizlet?
Nondisjunction refers to the failure of pairs of chromosomes or sister chromatids to separate during meiosis or mitosis.