CH. 10 AP BIO

quiz - hailee

What is the significance of independent assortment in meiosis?

allows homologous chromosome pairs to separate randomly, leading to genetic variation in gametes.

How many combinations of chromosomes can be produced from a cell with three pairs of homologous chromosomes?

There are 2^3, or 8 possible combinations of maternal and paternal chromosomes.

What is the role of crossing-over in meiosis?

increases genetic variation by exchanging genetic material between nonsister chromatids.

What is the difference between asexual reproduction and sexual reproduction regarding genetic variation?

produces offspring that are genetically identical to the parent, while sexual reproduction introduces genetic variability.

What are the two main ways meiosis contributes to genetic variation?

Independent assortment and crossing-over during meiosis.

What is the chromosome number of the daughter cells produced by meiosis?

cells produced by meiosis are haploid, having half the chromosome number of the diploid parent cell.

How many different chromosome combinations are possible in human gametes?

There are 2^23, or 8,388,608 different combinations of chromosomes in human gametes.

What happens during prophase I of meiosis?

synapsis occurs, and crossing-over takes place between homologous chromosomes.

What is the outcome of meiosis II?

results in four haploid daughter cells, each genetically distinct from one another and from the parent cell.

What distinguishes metaphase I of meiosis from metaphase of mitosis?

homologous chromosomes are paired at the metaphase plate, while in mitosis, individual chromosomes align.

What is the result of cytokinesis following meiosis?

following meiosis results in four haploid daughter cells.

When does meiosis occur in humans?

occurs only in the reproductive organs and produces gametes.

What is the main function of mitosis compared to meiosis?

maintains the chromosome number in daughter cells, while meiosis reduces it by half.

What is the role of spindle fibers during meiosis?

are active in sorting and separating chromosomes during the meiotic divisions.

What occurs during anaphase I of meiosis?

homologous chromosomes separate and move toward opposite poles.

What is the difference in genetic identity between daughter cells produced by meiosis and mitosis?

Daughter cells from meiosis are genetically distinct, while those from mitosis are genetically identical to the parent cell.

What is the significance of bivalents during meiosis?

form during prophase I and allow for crossing-over, which increases genetic diversity.

What is the result of crossing-over during meiosis?

in chromatids that carry different combinations of alleles, enhancing genetic variation.

What are the phases of meiosis?

meiosis I and meiosis II, each with distinct stages.

What is the outcome of meiosis I?

results in two haploid cells, each containing half the original chromosome number.

How does meiosis differ in occurrence compared to mitosis?

Meiosis occurs only at specific times in the life cycle of sexually reproducing organisms, while mitosis occurs in all tissues for growth and repair.

What is the relationship between meiosis and genetic recombination?

Meiosis facilitates genetic recombination through independent assortment and crossing-over, leading to diverse offspring.

What happens to sister chromatids during meiosis II?

separate during meiosis II, resulting in haploid daughter cells.

What is the main difference between prophase I of meiosis and prophase of mitosis?

In prophase I of meiosis, homologous chromosomes pair up, while in prophase of mitosis, there is no pairing of chromosomes.

During which phase of meiosis do bivalents align at the metaphase plate?

Metaphase I.

What happens to homologous chromosomes during anaphase I of meiosis?

Homologues of each bivalent separate, and duplicated chromosomes move to opposite poles.

What is the result of telophase I in meiosis?

Two haploid daughter cells that are not identical to the parent cell.

How does metaphase II of meiosis differ from metaphase of mitosis?

In metaphase II, there is a haploid number of duplicated chromosomes at the metaphase plate, while in mitosis, there is a diploid number.

What is produced at the end of meiosis II?

Four haploid daughter cells that are not genetically identical.

What is nondisjunction?

is the failure of homologous chromosomes or sister chromatids to separate properly during cell division.

What are the potential outcomes of nondisjunction during meiosis?

It can result in gametes with an abnormal number of chromosomes, leading to conditions like trisomy or monosomy.

What is trisomy 21 also known as?

Down syndrome.

What are some characteristics of Down syndrome?

Short stature, flat face, stubby fingers, and an increased risk of developing leukemia.

How does maternal age affect the incidence of Down syndrome?

The chances of having a child with Down syndrome increase with maternal age, particularly after age 35.

What is a karyotype?

A visual display of an individual's chromosomes arranged by size, shape, and banding pattern.

What is Turner syndrome?

A condition caused by the presence of a single X chromosome (XO), resulting in a female phenotype.

What is Klinefelter syndrome?

A condition in males characterized by an extra X chromosome (XXY).

What is Swyer syndrome?

A condition where an individual with an XY karyotype develops as a female due to the deletion of the SRY gene.

What is de la Chapelle syndrome?

A condition where an individual with an XX karyotype develops as a male due to the presence of the SRY gene on the X chromosome.

Why are sex chromosome aneuploids more likely to survive than autosomal aneuploids?

Extra copies of sex chromosomes are better tolerated in humans than extra copies of autosomes.

What is the role of the SRY gene?

is critical for male genital development; its presence determines maleness.

What is the significance of the Gart gene in Down syndrome?

is associated with high levels of purines in the blood, which may contribute to intellectual disabilities.

What is the main outcome of meiosis?

The production of gametes with half the number of chromosomes, leading to genetic diversity.

How does meiosis contribute to genetic diversity?

Through processes like crossing over during prophase I and independent assortment during metaphase I.

What is the difference between haploid and diploid cells?

Haploid cells contain one set of chromosomes (n), while diploid cells contain two sets (2n).

What is the purpose of meiosis in sexual reproduction?

To produce gametes that can combine during fertilization to form a new organism.

What occurs during fertilization of abnormal gametes?

It can result in zygotes with abnormal chromosome numbers, leading to various genetic disorders.

What is the relationship between oogenesis and nondisjunction?

Nondisjunction during oogenesis can lead to eggs with an abnormal number of chromosomes.

What is the typical chromosome number in a human zygote?

46 chromosomes, or 23 pairs.

What is a Barr body?

An inactive mass formed from additional X chromosomes in females and males with extra X chromosomes.

What condition is characterized by having only one X chromosome?

Turner Syndrome.

What are some physical characteristics of Turner females?

Short stature, broad chest, widely spaced nipples, low posterior hairline, and neck webbing.

Can Turner syndrome individuals undergo puberty?

No, they do not undergo puberty or menstruate without hormone supplements.

What are common physical traits of males with Klinefelter Syndrome?

Underdeveloped testes and prostate gland, lack of facial hair, large hands and feet, and long arms and legs.

What is a poly-X female?

A female with more than two X chromosomes, sometimes referred to as a superfemale.

What are some characteristics of poly-X females?

They may be tall and thin, with some experiencing delayed motor and language development, but most do not have an intellectual disability.

What is a chromosomal deletion?

The loss of a chromosome segment due to a break in the chromosome.

What is a chromosomal duplication?

The presence of a chromosomal segment more than once within the same chromosome.

What is a chromosomal inversion?

A segment of a chromosome that breaks loose and rejoins in the reversed direction.

What is a chromosomal translocation?

The exchange of chromosome pieces between nonhomologous chromosomes.

What is Jacobs Syndrome?

A condition in males with an XYY karyotype, resulting from nondisjunction during spermatogenesis.

What are common traits of individuals with Jacobs Syndrome?

They are usually taller than average and may have speech and reading problems but are fertile.

What is Williams Syndrome?

A condition caused by the deletion of a small end piece of chromosome 7, leading to specific physical and cognitive traits.

What are some characteristics of individuals with Williams Syndrome?

They have turned-up noses, wide mouths, small chins, large ears, and exhibit excellent verbal and musical abilities.

What is Cri du chat syndrome?

A condition caused by the deletion of an end piece of chromosome 5, characterized by a small head and an infant's cry resembling that of a cat.

What is the effect of translocation on genetic material?

Individuals with both translocated chromosomes can be healthy, but those inheriting only one may have an unbalanced genetic material distribution.

What is the relationship between Down syndrome and translocations?

Some cases of Down syndrome are caused by an unbalanced translocation between chromosomes 21 and 14.

What are the potential outcomes of embryos with unbalanced translocations?

They usually result in miscarriage, but those born may have severe symptoms.

What is the significance of gene dosage compensation in sex chromosomes?

It explains why extra sex chromosomes are more easily tolerated than extra autosomes.

What is the role of testosterone therapy in Klinefelter Syndrome?

It may help increase muscle strength, sex drive, and concentration ability but does not reverse sterility.

What is the typical phenotype of females with three X chromosomes?

They have no distinctive phenotype aside from a tendency to be tall and thin.