Lecture_21_Chromosome_Rearrangement

What are chromosome rearrangements?

Changes in the structure of chromosomes that can involve breaking and rejoining DNA strands.

What is required for a chromosomal rearrangement to occur?

A double-stranded DNA break.

What is the difference between balanced and imbalanced chromosomal rearrangements?

Balanced rearrangements do not result in loss or gain of genetic information, while imbalanced rearrangements result in either loss or gain of genetic material.

What happens to genetic information during inversions?

Genetic information is rearranged; it is not lost or gained, just flipped around.

What is a paracentric inversion?

An inversion that does not involve the centromere.

What is a pericentric inversion?

An inversion that includes the centromere.

What is the significance of a centromere in chromosome arrangements?

A centromere is essential for recovering genetic information; if it is not present, genetic information may be lost.

What is an acentric fragment?

A fragment of chromosome that lacks a centromere, making it impossible to separate it during cell division.

What is a dicentric bridge?

A structure formed when two centromeres are present on a chromosome resulting from a chromosomal rearrangement.

What is pseudodominance?

Expression of a normally recessive allele due to the absence of a dominant allele to cover it up.

How do translocations affect genetic information?

Translocations move genetic material from one chromosome to another without changing the total amount of genetic information.

What is alternate segregation in the context of translocations?

A form of chromosome segregation during meiosis that results in viable gametes.

What does adjacent segregation in translocations lead to?

Nonviable gametes due to genetic imbalance.

What is the result of a deletion in a chromosome?

Loss of genetic information, which can affect the phenotype depending on how much is lost.

How do duplications affect genes?

Duplications increase the amount of genetic material, potentially leading to an imbalance and affecting the phenotype.

What is a Robertsonian translocation?

A type of chromosomal rearrangement where two acrocentric chromosomes fuse at their centromeres, which can lead to conditions such as Down syndrome.