Cell Cycle & Cancer
A cell increases in size, copies its DNA, and prepares for division. What three phases make up this part of the cell cycle?
G1, S, and G2 (interphase).
Chromosomes become visible as they condense, and the spindle begins forming. Identify the phase of mitosis.
Prophase. - The chromosomes condense and the mitotic spindle develops.
During which phase of meiosis does crossing over occur?
Meiosis 1: Prophase 1
A single-celled organism reproduces asexually and produces offspring genetically identical to itself, assuming no mutations. How many parents contributed genetic information?
One parent.
Which process produces two genetically identical daughter cells?
Mitosis
A cell has completed G1 and is about to copy its DNA. Which phase comes next?
S phase; DNA is replicated so daughter cells can receive complete genetic information.
A microscope image shows duplicated chromosomes lined up individually along the middle of a cell. Identify the mitosis phase.
Metaphase. - Chromosomes align at the metaphase plate.
When homologous chromosome pairs line up randomly at the middle of a cell, what is this called and in which phase does it happen in?
Independent assortment, which happens in Meiosis 1; Metaphase 1
A strawberry plant reproduces asexually through a runner. Its leaf cells contain 56 chromosomes. How many chromosomes should the new plant's leaf cells contain?
56 chromosomes.
Asexual reproduction normally preserves chromosome number.
Which process produces four haploid cells?
Meiosis
A cell has already copied its DNA but has not started mitosis. Which phase is it most likely in, and what is happening?
G2; the cell is preparing for mitosis.
A cell's sister chromatids are pulled toward opposite poles. Identify the phase and the structures responsible for their movement.
Anaphase; spindle fibers. - Sister chromatids separate during mitotic anaphase.
During anaphase I, what separates? How is this different from anaphase II?
Anaphase I separates homologous chromosomes; anaphase II separates sister chromatids.
Which type of cell division produces gametes for sexual reproduction?
Meiosis
How many rounds of division occur during mitosis and meiosis?
Mitosis-1, Meiosis- 2
A cell has finished nuclear division, but its cytoplasm has not divided. Which process must occur to separate the cell?
Cytokinesis.
Chromosomes reach opposite poles and two nuclear envelopes begin reforming. Identify the phase and explain what happens to the chromosomes.
Telophase; chromosomes begin to decondense. - New nuclei form around the chromosome sets.
A cell has reached telophase I and finishes cytokinesis. What two cells (haploid or diploid) form, and are their chromosomes still duplicated?
Two haploid cells with chromosomes that are still duplicated.
Homologous chromosomes have separated, but sister chromatids remain attached.
A plant reproduces asexually. Its parent has 30 chromosomes. How many will its offspring's corresponding body cells have?
30 chromosomes
A human body cell has 46 chromosomes. How many chromosomes are in a normal gamete?
23 chromosomes
A mutation disables a gene that normally prevents damaged cells from dividing. Predict what could happen if those cells continue through the cell cycle.
Uncontrolled cell division, potentially forming a tumor or developing into cancer.
A diploid skin cell has 18 chromosomes. It undergoes mitosis and cytokinesis. How many cells form, and how many chromosomes does each have?
Two daughter cells, each with 18 chromosomes.
Mitosis maintains the chromosome number and normally produces genetically identical daughter cells.
Two haploid cells begin meiosis II without copying DNA again. Describe what happens during prophase II, metaphase II, and telophase II.
Prophase II: spindles form; metaphase II: chromosomes line up individually; telophase II: nuclei reform around separated chromosomes.
Why does sexual reproduction produce greater genetic variation?
It combines genetic information from two gametes; meiosis also creates variation.
What separates during anaphase of mitosis versus anaphase I of meiosis?
Mitosis: sister chromatids; meiosis I: homologous chromosomes.