Chromosome Variation and Mutations

These flashcards cover essential concepts related to chromosome variation and mutations, including types of mutations, their effects, and implications in genetics.

What is the P generation in plant breeding?

The initial generation of a breeding experiment.

What are the genomes of Einkorn wheat?

Genome AA (2n = 14).

What is the genome configuration of modern bread wheat?

Genome A, B, D (6n = 42).

What causes aneuploidy?

Deletion of a centromere, Robertsonian translocation, nondisjunction.

What is the significance of karyotyping?

To visualize large-scale chromosome mutations by arranging chromosomes according to size.

What does 'polyploidy' refer to?

The presence of more than two sets of chromosomes.

What can result from unequal crossing over during meiosis?

Duplications and deletions of genes.

How are deletions visualized during prophase I pairing?

By formation of a deletion loop.

What is pseudodominance?

When a recessive phenotype is expressed due to deletion of the dominant allele.

What is the difference between paracentric and pericentric inversions?

Paracentric does not involve the centromere, while pericentric does.

What is a consequence of chromosome duplications?

Abnormal phenotypes due to unbalanced gene dosage.

What is an example of a chromosomal disorder due to deletion?

Cri-du-chat syndrome.

What occurs during a translocation?

A segment of a chromosome moves to a nonhomologous chromosome.

What type of chromosome mutation involves breaking and reattachment in nonhomologous chromosomes?

Translocation.

What does 'monosomy' refer to?

Loss of a single chromosome (2n - 1).

What is the result of Robertsonian translocation?

Formation of a metacentric chromosome.

How does aging affect the incidence of aneuploidy in humans?

Increased maternal age leads to higher risks of aneuploidy.

What is 'haploinsufficiency'?

When a single copy of a gene is not enough for a wild-type phenotype.

What chromosome configuration leads to Down syndrome?

Trisomy 21.

In humans, which chromosome is affected in familial Down syndrome due to a translocation?

Chromosomes 14 and 21.

What is a primary cause of primary Down syndrome?

Random nondisjunction during egg formation.

What is 'autopolyploidy'?

Polyploidy from a single species.

What is 'allopolyploidy'?

Polyploidy from two different species.

What is a critical effect of gene duplication in evolutionary biology?

One gene maintains its original function while the duplicate may evolve new functions.

What facilitates the fertility of sterile hybrids in plants?

Nondisjunction that doubles chromosome numbers.

What type of translocation involves an exchange between nonhomologous chromosomes?

Reciprocal translocation.

What happens to a chromosome lacking a centromere during meiosis?

It is usually lost.

What is the outcome of nondisjunction during meiosis I?

It can produce gametes with aneuploidy.

What do inversions cause during meiosis?

Difficulty in chromosome alignment, leading to abnormal gametes.

How does karyotyping aid in detecting chromosome variations?

By visualizing chromosomal arrangements and mutations.

What is evidenced by the presence of a dicentric chromosome?

Crossing over in an individual with a paracentric inversion.

What can produce an autotriploid organism?

Nondisjunction in meiosis leading to a triploid gamete.

What is a common trait of many interspecies hybrids in animals?

They tend to be sterile.

What can occur due to chromosomal rearrangements in humans?

Various disorders and symptoms based on specific mutations.

What type of inversion leads to nonviable recombinant gametes due to missing genes?

Paracentric inversion.

What influences the incidence of trisomy syndromes?

Frequency of chromosomal abnormalities decreases from chromosome 8 to chromosome 21.

How can you identify aneuploidy?

Changes in the number of individual chromosomes.

How many chromosomes are typically present in a trisomic individual?

One additional chromosome compared to a diploid organism.

What defines gene duplications during meiosis?

They can affect developmental processes and lead to abnormal phenotypes.

What are the structural alterations referred to as 'chromosome rearrangements'?

Changes in chromosome structure like duplications or deletions.

What occurs in gene duplications that affects protein production?

Increased copy number of genes can disrupt developmental signaling.