Genetics- Chapter 2: Mitosis & Meiosis

What are homologous chromosomes?

Similar but not identical chromosomes that carry genes for the same inherited characteristics.

What is the diploid number of chromosomes in humans?

46 chromosomes, which are arranged in 23 homologous pairs.

What is the role of mitosis in cell division?

Mitosis partitions chromosomes into two dividing cells, each containing the same number of chromosomes as the parent cell.

What is meiosis?

A process that creates haploid gametes or spores, reducing the diploid number of chromosomes by half.

How do chromosomes behave during non-divisional phases?

Chromosomes uncoil into a diffuse network known as chromatin within the nucleus.

What are sister chromatids?

Identical copies of a chromosome, connected by a centromere.

What is a karyotype?

A visual representation that illustrates the physical appearance of an organism's homologous chromosome pairs.

What is the difference between mitosis and meiosis?

Mitosis produces two identical daughter cells, while meiosis results in four genetically diverse haploid cells.

What is biparental inheritance?

Inheritance from two parents, providing two copies of each gene in diploid organisms.

What structures are involved in chromosome migration during metaphase?

Kinetochore proteins bind to spindle fibers, allowing chromosome migration to the metaphase plate.

What happens during anaphase in mitosis?

Sister chromatids separate and move toward opposite poles of the cell.

What is cytokinesis?

The division of the cytoplasm, resulting in two new daughter cells.

What occurs during prophase of mitosis?

Centrioles divide and move to establish poles, while the nuclear envelope breaks down and chromosomes condense.

What is the significance of crossing over in meiosis?

It increases genetic variation by allowing the exchange of genetic material between nonsister chromatids.

How many haploid gametes are produced from one primary spermatocyte?

Four haploid spermatids are produced from one primary spermatocyte.

What are the substages of prophase I in meiosis?

Leptonema, Zygonema, Pachynema, Diplonema, Diakinesis.

What is the result of nondisjunction during anaphase?

It may lead to an abnormal number of chromosomes in the daughter cells.

What determines the maximum shortness of chromosomes during metaphase I?

The terminal chiasmata hold nonsister chromatids together.

What is the function of shugoshin protein?

It protects cohesin from being degraded during anaphase.

What do the terms monads and dyads refer to in meiosis?

Monads are single chromosomes after separation; dyads are pairs of sister chromatids before separation.

What is the outcome of meiosis II?

Cytokinesis results in four haploid cells, each with one member from each pair of homologous chromosomes.

What types of cells are produced by spermatogenesis?

Spermatogenesis results in the production of male gametes (sperm).

How does oogenesis differ from spermatogenesis?

Oogenesis produces only one ovum from the primary oocyte, while spermatogenesis produces four sperm.

Define centromere.

A constricted region on a chromosome that plays a key role during cell division.

What is the role of motor proteins in anaphase?

Motor proteins help in the movement of daughter chromosomes to opposite poles using ATP.

What is chromatin?

The diffuse form of chromosomes that uncoil during nondivisional phases.

What are alleles?

Different versions of the same gene that may be carried by homologous chromosomes.

Which cells undergo meiosis to produce gametes?

Germ cells undergo meiosis to produce haploid gametes.

What happens to chromosomes during telophase?

Chromosomes uncoil, and the nuclear envelope reforms around each set of chromosomes.

What is the main function of the meiotic spindle?

The meiotic spindle separates homologous chromosomes and sister chromatids during meiosis.

What is the end result of meiosis?

The formation of four genetically varied haploid gametes.

What is a synapsis?

The pairing of homologous chromosomes during prophase I of meiosis.

How many stages are there in mitosis?

Five distinct stages: prophase, prometaphase, metaphase, anaphase, and telophase.

What is the function of cohesin in cell division?

Cohesin holds sister chromatids together until they are separated during anaphase.

What is the role of cyclin proteins in cell cycle regulation?

Cyclin proteins regulate the activity of cyclin-dependent kinases (CDKs) in the cell cycle.

What is the haploid number for humans?

The haploid number for humans is 23 chromosomes.

What is the chromosomal configuration during metaphase?

Centromeres align on the metaphase plate.

Distinguish between spermatogenesis and oogenesis in terms of gamete production.

Spermatogenesis produces four viable sperm, while oogenesis produces one viable ovum and three polar bodies.

What are the centromere types based on their location on chromosomes?

Metacentric, submetacentric, acrocentric, and telocentric.

What occurs at the chiasma during meiosis?

Overlap between nonsister chromatids where crossing over can occur.

What is the difference between haploid and diploid cells?

Haploid cells contain one set of chromosomes; diploid cells contain two sets.

What is the importance of electron microscopy in studying chromosomes?

It has revealed the physical structure and organization of mitotic and meiotic chromosomes.

What defines the equatorial plane during prometaphase?

The metaphase plate where chromosomes align before separation.

How does cytokinesis differ in plant and animal cells?

In plant cells, a cell plate forms; in animal cells, a cleavage furrow constricts.

What is the role of antiparallel orientation in DNA strands?

It allows the complementary base pairing essential for DNA replication.

What is a dyad in the context of meiosis?

A dyad is a structure formed by two sister chromatids joined at a centromere.

What determines the centromere designation in a chromosome?

The position of the centromere relative to the chromosome arms.

Describe the state of chromosomes in interphase.

Chromosomes are not visible and exist as a diffuse form called chromatin.

What do we call the genetic material partitioned to daughter cells during karyokinesis?

Genetic material, consisting of replicated chromosomes, is divided during karyokinesis.

What role do kinases play in cell cycle regulation?

Kinases add phosphates to proteins to regulate cell cycle progression.

What is meant by sexual reproduction in diploid organisms?

A reproductive process that involves the fusion of haploid gametes to form a diploid zygote.

What happens during the reductional division of meiosis?

Homologous chromosomes are separated, reducing the chromosome number by half.

What is a tetrad in meiosis?

A structure formed when homologous chromosomes associate during prophase I.

How does mitosis ensure genetic continuity?

Mitosis produces daughter cells with identical genetic material to the parent cell.

What is the primary focus of meiotic cell division?

To produce genetically diverse haploid gametes for sexual reproduction.

What is the effect of mutations on the cell cycle?

Mutations can disrupt the regulatory mechanisms, potentially leading to uncontrolled cell division.

How does meiosis contribute to genetic diversity?

Through processes like crossing over and independent assortment of chromosomes.

What structure acts as the organizing center for spindle fibers during mitosis?

Centrosomes serve as organizing centers for spindle fibers.

What happens to the nuclear envelope during prophase?

It breaks down to allow the spindle fibers access to the chromosomes.

What are the characteristics of the S phase of interphase?

DNA synthesis occurs, resulting in the replication of chromosomes.

How does telophase conclude the process of mitosis?

Daughter chromosomes arrive at poles, and the nuclear envelope reforms.

What are the two main phases of the cell cycle?

Interphase and mitotic phase (mitosis).

What is the primary function of the spindle apparatus during mitosis?

To separate sister chromatids and ensure correct segregation into daughter cells.

What is the consequence of errors in the cell cycle?

Errors can lead to issues such as cancer or developmental abnormalities.

What are the characteristics of metaphase II in meiosis?

Chromosomes align at the metaphase plate as singles, and centromeres face opposite poles.

Define the term locus in genetics.

A specific location or position of a gene on a chromosome.

What is the major difference between meiosis I and meiosis II?

Meiosis I is a reductional division, while meiosis II is an equational division.

How does DNA synthesis occur in relation to the cell cycle?

DNA synthesis occurs in the S phase during interphase before cell division begins.

What occurs during leptonema of prophase I?

Chromosomes first become visible and appear as long, single threads.

How does crossing over enhance genetic diversity?

It allows the exchange of genetic material between homologous chromosomes.