Cell Division and Mitosis

Flashcards about cell division and mitosis.

What occurs in cells just prior to cell division?

Growth, doubling of organelles, and DNA replication.

What are the three major stages of the cell cycle?

Interphase, Mitotic Stage, and Cytokinesis

What are the four stages of the division of the nucleus?

Prophase, Metaphase, Anaphase, and Telophase

What is cytokinesis?

Division of the cytoplasm and organelles.

What percentage of a cell's life is spent in the mitotic phase?

Approximately 10%

What are the three stages of Interphase?

Gap one, Synthesis, and Gap two

What is apoptosis?

Programmed cell death

Under what condition will a cell undergo apoptosis at the GAP one checkpoint?

The DNA has been damaged.

What is checked at the mitotic checkpoint in the GAP two phase?

That the DNA has replicated properly.

What is interphase?

A period of normal growth.

Under what condition will mitosis not continue at the mitotic checkpoint?

The chromosomes are not properly aligned.

What types of cells typically remain in the gap zero stage?

Nerve and muscle cells.

What is the gap zero stage?

A non-dividing state.

What occurs in the gap one phase?

Recovery from the previous division, duplication of organelles, growth in size, and accumulation of materials needed for DNA synthesis.

What occurs in the S stage of interphase?

Proteins associated with DNA are synthesized, and chromosomes enter with one chromatid and leave with two (sister chromatids).

What is a duplicated chromosome made of?

Two sister chromatids.

What is the state of DNA during interphase?

Loose and diffused, not compacted.

What are chromatin and chromosomes made of?

DNA plus histones.

Is chromatin loose or compacted DNA

Loose

Are chromosomes loose or compacted DNA?

Compacted.

What is the centromere?

Narrow waistband of the duplicated chromosome.

What does the cell do in preparation for division?

Synthesizing proteins, including microtubules.

What is the purpose of mitosis?

Growth and repair.

What is the result of mitosis?

Two genetically identical daughter cells.

What form does DNA take when it is loosely packed?

Chromatin.

What is the number of chromosomes in human cells?

46

What is the term for the total number of chromosomes (2n)?

Diploid number.

What is the term for the number of chromosomes in gametes (n or 1n)?

Haploid number.

What occurs as nuclear division is about to begin?

Fragmentation of the nuclear envelope, spindle assembly, and movement of centrosomes.

What are spindles made of?

Microtubules.

What is produced in the nucleolus?

Ribosomal RNA.

Why does DNA need to be replicated prior to cell division?

To replicate DNA so each daughter cell receives an exact copy.

What are the four phases of mitosis?

Prophase, Metaphase, Anaphase, and Telophase

What happens during interphase to prepare for cell division?

Organelles and cytoplasmic components replicate, DNA replicates and enzymes needed for cell division are produced.

What are the three major checkpoints in the cell cycle?

G1/S, G2/M and spindle checkpoints.

What is located just outside the nucleus that is the microtubule organizing center?

Centrosomes, which contain centrioles in animal cells.

What occurs during metaphase?

The chromosomes are aligned at the equator of the cell.

What is the difference between kinetochore and nonkinetic core microtubules?

Kinetochore microtubules attach to the kinetochores, while nonkinetic core microtubules do not connect to sister chromatids, and press against each other to elongate the cell.

What occurs during anaphase?

Sister chromatids separate at the centromere and become daughter chromosomes which are pulled to opposite poles.

What is the key difference during cytokinesis between animal and plant cells?

A cleavage furrow forms in animal cells, while a cell plate forms in plant cells.

What happens during telophase?

The spindle apparatus disappears, new nuclear envelopes form around the daughter chromosomes, and cytokinesis occurs.

How does cytokinesis occur in animal cells?

A contractile ring of actin filaments pinches the mother cell into two.

How does cytokinesis occur in plant cells?

Membranes form a cell plate that expands and secretes primary cell walls.

What are kinetochores?

Structures on sister chromatids where microtubules attach during cell division.

What is a cleavage furrow?

A groove in the cell membrane of animal cells where the cell pinches off during cytokinesis.

What is a cell plate?

A structure that forms in plant cells during cytokinesis, eventually forming the new cell wall.

What is the G1 checkpoint?

The point in the cell cycle where the cell assesses DNA integrity and environment before committing to cell division.

What is the G2 checkpoint?

The phase where the cell checks for successful DNA replication and prepares for mitosis.

What is the spindle checkpoint?

The checkpoint in mitosis where the cell ensures chromosomes are properly aligned before anaphase.

What is a kinase?

The enzyme responsible for adding phosphate groups to proteins, regulating the cell cycle.

What are cyclins?

Proteins that bind to kinases, activating them to control the cell cycle.

What is a cyclin-dependent kinase (Cdk)?

The complex formed by a cyclin and a kinase, which phosphorylates target proteins to control cell cycle progression.

What is cellular senescence?

A process where cells stop dividing, often due to DNA damage or other stress.