BIO 222 Chapter 2: Chromosomes and Reproduction

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Questions and Answers

List several characteristics that bacteria and archaea have in common and that distinguish them from eukaryotes.

Bacteria and archaea are prokaryotes. They differ from eukaryotes in that they have no nucleus, a single circular chromosomal genome (usually), and a smaller amount of DNA.

A virus is considered to be a prokaryote.

False

Which of the following is NOT a characteristic of prokaryotes?

Membrane-bound organelles (correct)

Single circular chromosome

Smaller amount of DNA compared to eukaryotes

Unicellular

Which of the following is NOT a feature of eukaryotic chromosomes?

Circular structure Signup and view all the answers

What is the function of kinetochores in eukaryotic chromosomes?

To attach to spindle microtubules Signup and view all the answers

During which phase of the cell cycle does DNA replication occur?

S phase Signup and view all the answers

Which of the following is a key transition point in the cell cycle, regulated by specific proteins that ensure the cell is ready to proceed to the next stage?

G1/S checkpoint Signup and view all the answers

What is the main process that occurs during the M phase of the cell cycle?

Nuclear division and cell division Signup and view all the answers

During which stage of mitosis do sister chromatids separate and migrate towards opposite poles?

Anaphase Signup and view all the answers

The spindle microtubules, which are composed of tubulin subunits, play a crucial role in aligning chromosomes during mitosis.

True Signup and view all the answers

What is the primary consequence of meiosis I?

Reduction of the chromosome number by half Signup and view all the answers

During which stage of meiosis does crossing over occur, a process that generates genetic variation?

Prophase I Signup and view all the answers

What is the significance of the random alignment of homologous chromosome pairs during metaphase I?

Contributes to genetic variation in gametes Signup and view all the answers

Which of the following events takes place during meiosis II but not in meiosis I?

Separation of sister chromatids Signup and view all the answers

Explain two major consequences of meiosis.

Meiosis produces four daughter cells from each original cell. However, the number of chromosomes in these daughter cells is reduced by half. The newly formed cells from meiosis are also genetically different from one another and from the parental cell. Signup and view all the answers

Which structure is diploid?

Microsporocyte Signup and view all the answers

What is the difference between spermatogenesis and oogenesis?

Spermatogenesis is the production of sperm cells in males, while oogenesis is the production of egg cells in females. Signup and view all the answers

What is the ploidy level of the zygote?

Diploid Signup and view all the answers

How does shugosin affect sister chromatids in meiosis I and meiosis II?

During anaphase I, shugoshin protects cohesin at the centromeres from the action of separase, preventing the separation of sister chromatids. However, during anaphase II, shugoshin breaks down, and cohesin at the centomeres is cleaved by separase, allowing the sister chromatids to separate. Signup and view all the answers

Which of the following processes is involved in the production of both sperm cells and egg cells?

Meiosis Signup and view all the answers

Study Notes

Chapter 2: Chromosomes and Cellular Reproduction

The chapter covers prokaryotic and eukaryotic cells, cell reproduction, and sexual reproduction.
A prokaryotic cell lacks a nucleus and membrane-bound organelles. Its DNA is circular and not complexed with histones. Prokaryotes include bacteria and archaea.
Eukaryotic cells contain a nucleus and membrane-bound organelles. Their DNA is linear and complexed with histones to form chromosomes.
Prokaryotic cell division is simple division, separating replicated circular chromosomes from the origin of replication. It has a high rate of replication
Eukaryotic cell replication involves homologous pairs, chromosome structure, and the cell cycle.

Eukaryotic Chromosomes

Homologous pairs: Diploid cells carry two sets of genetic information, with each set having similar chromosomes. Humans have 23 pairs.
Chromosome structure: At times, a chromosome consists of one chromatid, and at others, it consists of two sister chromatids. The centromere is the attachment point for spindle microtubules. The telomeres are the stable ends of chromosomes. Different types of chromosomes include submetacentric, metacentric, telocentric, and acrocentric.
Cell cycle: The cell grows, replicates DNA, and divides. Key transition points are the checkpoints: G1/S, G2/M. The cell cycle includes phases like G0, G1, S, G2, Mitosis (prophase, prometaphase, metaphase, anaphase, telophase), and Cytokinesis.

Prokaryotic Cell Reproduction

Simple division: Prokaryotic cells divide by separating replicated circular chromosomes from an origin of replication. The process happens at a high rate.

Eukaryotic Cell Replication

Cell cycle phases: G1: growth and development; S: DNA synthesis; G2: preparation for cell division. The cell cycle also includes mitosis (prophase, prometaphase, metaphase, anaphase, telophase) and cytokinesis. Mitosis is the active division of the nucleus and cytokinesis is the division of the cytoplasm. Multiple checkpoints regulate progression through the cell cycle
Genetic consequences of the cell cycle: The cycle produces two cells genetically identical to each other and to the original cell. Each new cell has a full complement of chromosomes.
The process occurs at a high rate of replication.
The mitosis phases are discussed as prophase, metaphase, anaphase, and telophase.
The mitosis separation of sister chromatids and homologous chromosomes involves an important protein: Cohesin.
Two types of cell divisions are covered: Mitosis (used for growth and repair in somatic cells) and Meiosis (used to produce gametes).

Meiosis

Meiosis: The production of haploid gametes. Meiotic events include interphase (DNA synthesis and chromosome replication), Meiosis I (separation of homologous chromosome pairs), and Meiosis II (separation of sister chromatids). Each meiosis cycle has four phases: prophase, metaphase, anaphase, telophase. Interkinesis is an intermediate phase between meiosis 1 and 2
Crossing over: Crossing over of chromosome segments takes place during prophase I; this is the first mechanism of generating genetic variation.
Genetic variation: The random alignment of homologous chromosome pairs in meiosis I and crossing over in prophase I create genetic variation in gametes. Genetic variation ensures diversity.
Interkinesis: An intermediate phase occurring between meiosis 1 and 2
Meiosis: Meiosis has been described as a haploid cell division which results in four cells from a single cell

Meiosis in the Life Cycle of Animals and Plants

Spermatogenesis: Male gamete production.
Oogenesis: Female gamete production.
Gametes are haploid reproductive cells.
Meiosis in plants: Plants often have different life cycles than animals in which the stages alternate between a single-celled haploid form and a multicellular diploid form. These terms are sporophyte (diploid form) and gametophyte (haploid form

Viruses

Viruses lack both prokaryotic or eukaryotic characteristics and are surrounded by an outer protein coat that encompasses the nucleic acid.

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Description

This quiz covers essential concepts in Chapter 2, focusing on chromosomes, cellular reproduction, and the differences between prokaryotic and eukaryotic cells. Understand the structures and processes involved in cell division and the significance of homologous pairs in genetic information.