Genetic Factors and Disorders

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Questions and Answers

What does the term 'euploid' refer to in genetic terminology?

Any exact multiple of n chromosomes (correct)

The condition of having only one chromosome set

Having an imbalance in chromosome numbers

Possessing more than two complete sets of chromosomes

Which term describes the condition of having an addition or subtraction of one or more chromosomes?

Polyploid

Tetraploid

Aneuploid (correct)

Euploid

What occurs during the process of synapsis in Meiosis I?

Homologous chromosomes pair lengthwise (correct)

Chromosomes are replicated

Sister chromatids separate

The nuclear envelope disappears

Crossing over during meiosis involves which of the following?

Interchange of chromatid segments between homologous chromosomes Signup and view all the answers

Which of the following statements is true regarding polyploidy?

It describes having more than two complete sets of chromosomes Signup and view all the answers

How do external factors like diet and chemical exposure relate to genetic disorders?

They play a role in increasing the risk of genetic disorders. Signup and view all the answers

What is a chromosomal characteristic of diploid organisms?

They contain two complete sets of chromosomes. Signup and view all the answers

The interchanging segments during crossing over during Meiosis I lead to what outcome?

Enhanced genetic diversity among offspring Signup and view all the answers

What is the result of meiotic nondisjunction?

The formation of gametes with abnormal chromosome numbers Signup and view all the answers

In which phase do chromosomes align at the centromere during meiosis II?

Metaphase II Signup and view all the answers

What primarily happens during Anaphase II of meiosis?

Chromatids divide at the centromeres Signup and view all the answers

What could lead to the formation of a trisomy condition?

The addition of a single extra chromosome during meiosis Signup and view all the answers

At which stage of meiosis II does the nucleoli and nuclear envelope disappear?

Prophase II Signup and view all the answers

Which factor is associated with an increased incidence of chromosomal abnormalities?

Maternal age over 35 years Signup and view all the answers

What characterizes the end result of meiosis II?

Four haploid cells Signup and view all the answers

What key event occurs during telophase II?

The formation of the nuclear envelope and nucleoli Signup and view all the answers

What occurs during anaphase in meiotic nondisjunction?

Sister chromatids fail to separate Signup and view all the answers

What is the primary outcome of mitotic nondisjunction?

Mosaicism in chromosome numbers Signup and view all the answers

What is the role of meiosis in maintaining chromosome number?

Reduces the chromosome number from diploid to haploid Signup and view all the answers

What type of chromosomal alteration results from chromosomal translocations?

Creation of fusion genes Signup and view all the answers

How does meiosis contribute to genetic diversity?

By random assortment of chromosomes Signup and view all the answers

What is a key characteristic of balanced chromosomal translocations?

No missing or extra genetic material Signup and view all the answers

What may result from early cell divisions involving mitotic nondisjunction?

Whole organism having abnormal chromosome number Signup and view all the answers

The reduction in chromosome number during meiosis leads to what significant outcome?

Production of haploid gametes Signup and view all the answers

Study Notes

Genetic Disorders

Disorders can arise from single gene mutations or complex gene mutations.
Risk factors for genetic disorders include diet, chemical exposure, and medication.

Chromosomal Abnormalities

Numerical Abnormalities

Euploid: an exact multiple of n, e.g., diploid (2n), triploid (3n).
Polyploid: condition of possessing more than two complete sets of chromosomes.
Aneuploid: an addition or subtraction of individual chromosomes, not a complete set.
- Monosomy (2n-1): loss of one chromosome.
- Trisomy (2n+1): addition of a single chromosome.

Causes of Chromosomal Abnormalities

Meiotic nondisjunction: failure of homologous pairs or sister chromatids to separate during meiosis.
- Can occur in either the first or second meiotic division.
- Incidence increases in women over age 35.
Mitotic nondisjunction: occurs during anaphase when sister chromatids fail to separate, leading to mosaicism.
- Mosaicism results in cells with varying chromosome numbers, some abnormal and some normal.
Chromosomal translocations: transfer of a portion of one chromosome to a nonhomologous chromosome, leading to a fusion gene.
- Can be balanced (no missing or extra genetic information) or unbalanced.

Phases of Meiosis II

Similar in process to mitosis; results in four haploid cells (n) from the two cells formed in meiosis I.
Prophase II: spindle fibers reform, nucleoli and nuclear envelope disappear.
Metaphase II: chromosomes align at the centromere.
Anaphase II: chromatids divide at the centromeres, moving to opposite poles.
Telophase II: formation of four haploid cells, each with half the number of original homologous pairs.

Significance of Meiosis

Maintains the constancy of chromosome number across generations by reducing diploid to haploid.
Allows for random assortment of maternal and paternal chromosomes in gametes.

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Description

Explore how genetic mutations, both single and complex, contribute to the development of various disorders. This quiz delves into the interplay of genetic factors with environmental influences like diet, chemical exposure, and medication.