CH 8 (2) Transposable Elements and Aneuploidy in Genetics

These flashcards cover key vocabulary and concepts related to transposable elements, aneuploidy, and their implications in genetics.

Transposable Elements (TEs)

Movable genetic elements that can move themselves or copies within a genome.

LINEs

Long interspersed elements, a type of retrotransposon that encodes an RNA-binding protein and reverse transcriptase.

SINEs

Short interspersed elements, another type of retrotransposon that relies on LINE-encoded proteins for mobility.

HERVs

Human endogenous retroviruses, LTR-type retrotransposons that may encode viral coat proteins.

Aneuploidy

The loss or gain of one or more chromosomes, leading to an abnormal number of chromosomes.

Monosomy

Aneuploid condition where one chromosome is missing from the normal diploid number.

Trisomy

Aneuploid condition where there is one extra chromosome beyond the normal diploid number.

Tetrasomy

Aneuploid condition with four copies of a particular chromosome.

Nondisjunction

The failure of chromosomes to segregate normally during cell division.

Deleterious effects of aneuploidy

Most autosomal aneuploidies and trisomies are lethal, often resulting in fetal death.

Trisomy 21

Down syndrome, the most frequently observed autosomal trisomy, typically resulting from maternal nondisjunction.

X-inactivation

The process by which one of the two X chromosomes in females is inactivated, leading to dosage compensation.

Klinefelter syndrome

A condition in XXY individuals where some X-linked genes are expressed at double the normal level.

Turner syndrome

A condition in XO individuals, often leading to sterility due to reduced dosage of X-linked genes.

Polyploidy

A condition where an organism has more than two complete sets of chromosomes.

Euploid

Organisms that have complete sets of chromosomes.

Triploids

Organisms that have three complete sets of chromosomes.

Tetraploids

Organisms that have four complete sets of chromosomes.

Allopolyploid

Hybrids with chromosome sets from distinct but related species.

Amphidiploid

A type of allopolyploid that has two diploid genomes from different parent species.

Gene relocation due to transposition

The process where transposable elements can relocate genes, potentially leading to altered function.

Inverted repeats (IRs)

Sequences found at each end of most DNA transposons that are recognized by transposase.

Transposase

An enzyme that recognizes IRs and facilitates the movement of transposable elements.

Copia TE

A transposable element identified in Drosophila that is used for studying transposition mechanisms.

Mosaic organisms

Organisms with cells of differing genotypes, often arising from aneuploidy.

Spontaneous chromosomal rearrangements

Chromosomal changes that can occur due to the presence and activity of transposable elements.

Unequal crossing over

A genetic event that can lead to duplications or deletions in chromosomes, influenced by transposable elements.

Gag and env genes

Genes found in HERVs encoding retroviral coat proteins, contributing to their structure.

Fetal death and miscarriage

Common outcomes associated with autosomal aneuploidies in humans.

Chromosomal abnormalities

Changes in chromosome structure or number that can lead to genetic disorders.

Maternal meiosis I

The stage during which nondisjunction often occurs, leading to trisomy conditions.

Genomic target site

Specific location in the genome where transposable elements can insert after movement.

Reverse transcriptase

An enzyme used by retrotransposons to synthesize cDNA from RNA, crucial for their movement.

Detection of transposable elements

Methods such as in situ hybridization to locate specific TEs in genomic studies.

Human genome transposable elements

TEs such as LINEs and SINEs that have been identified as significant components of the human genome.