Genetics: Synapsis & Crossing-Over in Meiosis

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Questions and Answers

What happens during crossing over in meiosis?

Pieces of chromosomes or genes are exchanged (correct)

Sister chromatids separate and move apart

Chromosomes align along the equator of the cell

Homologous chromosomes Condense and become invisible

What is the main difference between metaphase I and metaphase II?

Number of lines along which chromosomes align (correct)

Appearance of centrioles and spindle fibers

Number of chromosomes aligned

Disappearance of nuclear membrane

What process occurs during anaphase I?

Cytokinesis divides the cell into two daughter cells

Chromosomes condense and become visible

Sister chromatids separate and move apart

Chromosomes separate and move apart to opposite poles (correct)

Which stage of meiosis is similar to mitosis?

Meiosis II Signup and view all the answers

What happens during telophase I?

Chromosomes become uncondensed and invisible Signup and view all the answers

What is the result of crossing over?

Genetic recombination in the offspring Signup and view all the answers

What is the number of haploid daughter cells produced at the end of meiosis?

4 Signup and view all the answers

What happens during metaphase II?

Chromosomes align along the equator in one line Signup and view all the answers

What occurs during the S phase of the cell cycle?

DNA replication Signup and view all the answers

What is the result of mitosis?

Two genetically identical daughter cells Signup and view all the answers

During which stage of mitosis do chromosomes become attached to spindle fibers?

Metaphase Signup and view all the answers

What occurs during cytokinesis?

Separation of cytoplasm and organelles into two cells Signup and view all the answers

During which stage of mitosis do chromosomes become visible?

Prophase Signup and view all the answers

What is the purpose of the G1 phase of the cell cycle?

Cell growth and protein synthesis Signup and view all the answers

What happens to the nuclear membrane during prophase?

It disappears Signup and view all the answers

What is the result of the G2 phase of the cell cycle?

Significant protein synthesis Signup and view all the answers

What is the main difference between meiosis and mitosis?

Meiosis is a type of reduction division, while mitosis is a type of equational division. Signup and view all the answers

During which stage of meiosis do homologous chromosomes come together to form a tetrad?

Prophase I Signup and view all the answers

What is the result of crossing over during meiosis?

Increased genetic variation in the offspring. Signup and view all the answers

What is the purpose of meiosis?

To produce gametes with a unique combination of genetic traits. Signup and view all the answers

During which stage of meiosis do the sister chromatids separate?

Anaphase II Signup and view all the answers

What is the number of chromosomes in the daughter cells produced during meiosis?

Haploid (1n) Signup and view all the answers

During which stage of meiosis do the chromosomes align at the center of the cell?

Metaphase I Signup and view all the answers

What is the term for the process by which a single cell divides twice to produce four cells with half the number of chromosomes?

Meiosis Signup and view all the answers

Study Notes

Meiosis

Meiosis occurs in eukaryotic life cycles involving sexual reproduction
It's the process by which a single cell divides twice to produce four cells with half the number of chromosomes (gametes)
Original cell is diploid (2n), and four daughter cells produced are haploid (1n)
Meiosis is also called Reduction-division

Interphase

Similar to mitosis interphase, chromosomes replicate (S phase)
Each duplicated chromosome consists of two identical sister chromatids attached at their centromeres

Meiosis I

Prophase I: chromosomes condense and become visible, centrioles move to opposite sides of the nucleus and become attached via spindle fibers, nuclear membrane disappears
Synapsis occurs: homologous chromosomes come together to form a tetrad
Crossing over occurs, creating variation (diversity) in the offspring's traits
Metaphase I: homologous pairs of chromosomes align along the middle (equator) of the cell in two lines
Anaphase I: chromosomes separate and move apart to opposite poles of the cell
Telophase I: chromosomes become uncondensed and invisible, centrioles and spindle fibers disappear, nuclear membrane appears, and cytokinesis divides the cell into two haploid daughter cells

Meiosis II

No interphase II (no more DNA replication), Meiosis II is similar to mitosis
Prophase II: chromosomes condense and become visible, centrioles move to opposite sides of the nucleus and become attached via spindle fibers, nuclear membrane disappears
Metaphase II: chromosomes align along the equator of the cell in one line
Anaphase II: sister chromatids separate and move apart to opposite poles of the cell
Telophase II: chromosomes become uncondensed and invisible, centrioles and spindle fibers disappear, nuclear membrane appears, and cytokinesis divides the cell into two haploid daughter cells

Synapsis and Crossing-Over

Synapsis: homologous chromosomes come together to form a tetrad
Crossing over: pieces of chromosomes or genes are exchanged, producing genetic recombination in the offspring

Mitosis

Mitosis is the asexual process by which a eukaryotic cell (somatic cell) divides into two daughter cells containing roughly equal shares of cellular components and genetically identical to each other and to their parent cell
Cell cycle: Interphase, Mitotic (M) phase, Prophase, Metaphase, Anaphase, Telophase, and Cytokinesis
Mitosis is essential for growth, development, and tissue repair in multicellular organisms

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Description

Learn about the process of synapsis and crossing-over in meiosis, including the formation of chiasmata and the exchange of genes, resulting in genetic recombination in offspring.