Biology Chapter 7 Section 3 Quiz

Questions and Answers

What does the term 'section summary' refer to in relation to chromosomes?

The number, size, shape, and banding pattern of chromosomes make them easily identifiable in a karyogram and allow for the assessment of many chromosomal abnormalities.

The genotype XXY corresponds to:

Klinefelter syndrome (correct)

Jacob syndrome

Triplo-X

Turner syndrome

Abnormalities in the number of X chromosomes tend to be milder than those in autosomes because of ______.

Nonhomologous recombination

X inactivation (correct)

Synapsis

Deletions

Aneuploidies are deleterious for the individual because of what phenomenon?

Gene dosage Signup and view all the answers

What can be hypothesized about chromosomes 21 and 18 based on their survivability in trisomies?

Chromosome 21 may be a smaller chromosome with fewer unbalanced gene products compared to chromosome 18, which may carry genes whose products are more sensitive to dosage differences. Signup and view all the answers

What is an aneuploid?

An individual with an error in chromosome number, including deletions and duplications of chromosome segments. Signup and view all the answers

What is an autosome?

Any of the non-sex chromosomes. Signup and view all the answers

What is meant by chromosome inversion?

The detachment, 180° rotation, and reinsertion of a chromosome arm. Signup and view all the answers

What characterizes an euploid?

An individual with the appropriate number of chromosomes for their species. Signup and view all the answers

What is a karyogram?

The photographic image of a karyotype. Signup and view all the answers

What does a karyotype represent?

The number and appearance of an individual's chromosomes, including size, banding patterns, and centromere position. Signup and view all the answers

What is monosomy?

An otherwise diploid genotype in which one chromosome is missing. Signup and view all the answers

What does nondisjunction refer to?

The failure of synapsed homologs to completely separate and migrate to separate poles during the first cell division of meiosis. Signup and view all the answers

What characterizes a polyploid?

An individual with an incorrect number of chromosome sets. Signup and view all the answers

What does translocation describe in genetics?

The process by which one segment of a chromosome dissociates and reattaches to a different, nonhomologous chromosome. Signup and view all the answers

What is trisomy?

An otherwise diploid genotype in which one entire chromosome is duplicated. Signup and view all the answers

What does X inactivation entail?

The condensation of X chromosomes into Barr bodies during embryonic development in females to compensate for the double genetic dose. Signup and view all the answers

Study Notes

Chromosomal Abnormalities

Chromosomes are identifiable through number, size, shape, and banding patterns in a karyogram, aiding in detecting chromosomal abnormalities.
Aneuploidies, or chromosomal number disorders, are usually lethal to embryos; however, some trisomic conditions are viable.
X inactivation leads to milder effects of sex chromosome abnormalities compared to autosomal abnormalities.
Chromosome abnormalities can include deletions, duplications, inversions, or translocations, each potentially causing negative developmental outcomes or mortality.
Inversions and translocations during meiosis I can lead to reduced fertility due to nondisjunction, where chromosomes fail to separate properly.

Specific Conditions

The genotype XXY corresponds to Klinefelter syndrome, a condition affecting males.
Abnormalities in the number of X chromosomes are less severe due to X inactivation, which balances gene dosage effects.

Gene Dosage Toxicity

Aneuploidies negatively impact individuals largely due to gene dosage imbalances; an excess of genes can disrupt developmental processes.
Survival differences between trisomy 21 and trisomy 18 suggest that the number of genes on the chromosomes affects viability. Chromosome 21 is smaller, possibly resulting in fewer unbalanced gene products.

Terminology

Aneuploid: an individual with a chromosomal number error, including segment duplications or deletions.
Autosomes are non-sex chromosomes, in contrast to sex chromosomes.
Chromosome inversion occurs when a chromosome arm detaches, rotates 180 degrees, and reattaches.
Euploid individuals have the proper chromosome number for their species.
A karyogram is a photographic representation of chromosomes.
A karyotype defines the total number and visual appearance of chromosomes in an individual, including size and banding.
Monosomy refers to a diploid genotype missing one chromosome.
Nondisjunction is the failure of homologous chromosomes to separate during meiosis, leading to chromosomal irregularities.
Polyploid describes individuals with an abnormal number of chromosome sets.
Translocation involves the movement of one chromosome segment to a different, nonhomologous chromosome.
Trisomy is characterized by having one duplicated chromosome in what would otherwise be a diploid set.
X inactivation refers to the process where one X chromosome in females condenses into a Barr body during early development to equalize gene dosage.

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Description

Test your knowledge on chromosomal analysis and abnormalities with this quiz based on Chapter 7, Section 3 of the biology textbook. Explore key concepts such as karyograms, aneuploidies, and the effects of sex chromosome aberrations.