Biology Chapter on Reproduction and Chromosomes

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Questions and Answers

What happens to the membrane during cell division?

The growing membrane then divides the cell.

Which of the following statements about chromosomes is true?

Eukaryotic cells have less DNA than prokaryotic cells.

Chromosomes are visible only during cell division. (correct)

Each chromosome is made up of RNA.

Chromosomes do not duplicate before division.

The eukaryotic cell cycle consists of __ and M phase.

Interphase

What is the role of the mitotic spindle during mitosis?

To move chromosomes to the middle of the cell. (D) Signup and view all the answers

Cancer cells divide normally and do not form tumors.

False (B) Signup and view all the answers

What distinguishes diploid cells from haploid cells?

Diploid cells have two sets of chromosomes, while haploid cells have one set. Signup and view all the answers

The process that leads to genetic variation during meiosis is called __.

crossing over Signup and view all the answers

What might result from nondisjunction during meiosis?

An abnormal chromosome count. (D) Signup and view all the answers

What is a karyotype?

An ordered arrangement of images of a cell's chromosomes. Signup and view all the answers

What is asexual reproduction?

The creation of offspring by a single parent without sperm and egg (A) Signup and view all the answers

What is a chromosome?

A threadlike, gene-carrying structure found in the nucleus of a eukaryotic cell. Signup and view all the answers

What triggers the formation of a zygote?

The fusion of two haploid gametes (C) Signup and view all the answers

What does the term 'cell division' refer to?

The process where a cell divides into two daughter cells (C) Signup and view all the answers

Define cytokinesis.

The division of the cytoplasm to form two separate daughter cells. Signup and view all the answers

What is mitosis?

The division of a single nucleus into two genetically identical daughter nuclei. Signup and view all the answers

What is the purpose of meiosis?

To produce haploid gametes from diploid cells. Signup and view all the answers

The fertilized egg is known as a ______.

zygote Signup and view all the answers

What is a gamete?

A sex cell; haploid egg or sperm. Signup and view all the answers

A diploid cell contains only one set of chromosomes.

False (B) Signup and view all the answers

What characterizes Down syndrome?

Presence of an extra chromosome 21 (D) Signup and view all the answers

What is Turner syndrome?

A condition affecting females characterized by the absence of an X chromosome. Signup and view all the answers

What does nondisjunction refer to?

An accident of meiosis where homologous chromosomes or sister chromatids fail to separate. Signup and view all the answers

Cancer is essentially a disease of the ______.

cell cycle Signup and view all the answers

Study Notes

Asexual and Sexual Reproduction

Asexual reproduction involves a single parent creating offspring without gametes.
Sexual reproduction requires the fusion of two haploid gametes to form a diploid zygote, resulting in genetic diversity among offspring.

Chromosomes and Cell Division

Chromosomes are structures in eukaryotic cells consisting of DNA and proteins, visible during cell division.
Sister chromatids are identical copies of a duplicated chromosome, joined at the centromere.
Cell division involves mitosis and cytokinesis, allowing for organism growth and tissue repair.

The Cell Cycle

The cell cycle consists of interphase (G1, S, G2 phases) and the mitotic phase (M phase).
Interphase is when the cell grows and DNA is replicated.
Mitosis includes prophase, prometaphase, metaphase, anaphase, and telophase, where the nucleus divides, and chromosomes are distributed.

Cancer and Tumors

Cancer results from uncontrolled cell division, leading to tumor formation.
Benign tumors remain localized, while malignant tumors can invade other tissues and metastasize.
Different types of cancer include carcinoma (covering tissues), sarcoma (supportive tissues), and leukemia (blood-forming tissues).

Genetic Variation and Meiosis

Meiosis, necessary for gamete formation, consists of two divisions resulting in four haploid cells.
Homologous chromosomes, one from each parent, may undergo crossing over during meiosis, promoting genetic recombination.
Genetic variation is vital for evolution and adaption, with independent assortment and crossing over contributing to unique allele combinations.

Genetic Disorders

Nondisjunction during meiosis can lead to chromosomal disorders, such as Trisomy 21 (Down syndrome) characterized by various physical and cognitive abnormalities.
Klinefelter syndrome results from an extra X chromosome in males, leading to infertility.
Turner syndrome occurs in females with only one X chromosome, manifesting in growth delays and developmental issues.

Chromosomal Structure and Changes

Chromosomes can undergo breakage, leading to mutations such as deletions, duplications, inversions, and translocations, potentially causing genetic disorders or cancer.
A karyotype displays the number and appearance of chromosomes, useful for diagnosing genetic anomalies.

Key Terms in Cell Biology

Cleavage furrow: a sign of cytokinesis in animal cells.
Cell plate: forms in plant cells during cytokinesis.
Anchorage dependence: cells must attach to divide, crucial for normal growth.
Growth factor: proteins that stimulate cell division and play roles in cancer regulation.

Chromosomal Counts and Terms

Humans have a diploid number of 46 chromosomes (2n=46), with gametes being haploid (n=23).
The haploid number or combinations of chromosomes is critical in sexual reproduction.

These notes summarize fundamental concepts in cell biology relevant for understanding reproductive mechanisms, cell cycle dynamics, and genetic variability.### Chromosome Arrangement and Genetic Variation

Random arrangements of chromosome pairs during metaphase I of meiosis contribute to genetic diversity in gametes (sperm and eggs).
Homologous chromosomes may have different alleles at corresponding loci, resulting in variations in the inherited traits.

Chromosome Number and Disorders

A karyotype displays an ordered arrangement of chromosomes within a cell, allowing for visualization of chromosome number and structure.
Down syndrome results from an extra copy of chromosome 21, characterized by distinct phenotypic traits.
Nondisjunction is a process that leads to abnormal chromosome counts, occurring when homologous chromosomes fail to separate during meiosis II.
Nondisjunction can generate gametes with additional or missing sex chromosomes, potentially leading to various malfunctions, though these often do not impact overall survival.
Polyploidy arises from nondisjunction, resulting in organisms with more than two sets of chromosomes, which can affect species evolution.

Chromosome Breakage and Genetic Disorders

Chromosome breakage can cause rearrangements that may lead to genetic disorders or cancer, particularly when occurring in somatic cells.
Types of chromosomal rearrangements include:
- Deletions: segments of DNA lost from a chromosome.
- Duplications: segments of DNA duplicated, resulting in extra genetic material.
- Inversions: segments of DNA reversed within the chromosome.
- Translocations: segments of DNA moved to a different location, potentially disrupting gene function.

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Description

This quiz covers essential terms related to asexual reproduction and chromosomes. Understanding these concepts is crucial for grasping basic biological processes. Test your knowledge and comprehension of these fundamental topics.