Biology Chapter 10: Mitosis and Cell Division
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Questions and Answers

What is the primary function of the centrosome during mitosis?

  • To form the cell membrane
  • To replicate DNA
  • To generate energy for cell division
  • To organize the cell's microtubules (correct)

Centrioles are essential for the formation of the mitotic spindle in all types of cells.

False (B)

What structure is formed from a radial array of short microtubules extending from each centrosome?

Aster

What is the first stage of the cell division process?

<p>A two-celled embryo (A)</p> Signup and view all the answers

The protein that subunits of spindle microtubules incorporate is called ______.

<p>tubulin</p> Signup and view all the answers

Match the structures to their functions related to the mitotic spindle:

<p>Kinetochore = Attaches to microtubules to help in chromosome movement Centrosome = Organizes microtubules and forms spindles Nonkinetochore microtubules = Overlaps at the metaphase plate Aster = Extends from the centrosome and helps stabilize the spindle</p> Signup and view all the answers

Cell division is necessary only for reproduction.

<p>False (B)</p> Signup and view all the answers

What happens to spindle microtubules during mitosis?

<p>They can both elongate and shorten (B)</p> Signup and view all the answers

What continuously makes new blood cells in your body?

<p>dividing cells in the bone marrow</p> Signup and view all the answers

A typical human cell has about ____ meters of DNA.

<p>2</p> Signup and view all the answers

Sister chromatids each have a kinetochore during mitosis.

<p>True (A)</p> Signup and view all the answers

Match the following terms with their descriptions:

<p>Genome = Genetic information of a cell Amoeba = Single-celled eukaryote Eukaryotic cell = Contains multiple DNA molecules Cell division = Process of renewing and repairing cells</p> Signup and view all the answers

During which phases of mitosis do the centrosomes move apart?

<p>Prophase and prometaphase</p> Signup and view all the answers

Which of the following describes the DNA in a prokaryotic genome?

<p>Is often a single DNA molecule (B)</p> Signup and view all the answers

Each new cell produced during cell division is an individual organism in asexual reproduction.

<p>True (A)</p> Signup and view all the answers

What must happen before a cell can divide?

<p>The cell must replicate its DNA.</p> Signup and view all the answers

What enzyme is responsible for cleaving the cohesin of each chromosome during metaphase?

<p>Separase (A)</p> Signup and view all the answers

Kinetochore microtubules shorten at the pole end during anaphase.

<p>True (A)</p> Signup and view all the answers

What is the general mechanism by which motor proteins enable the movement of chromosomes toward the poles during mitosis?

<p>Motor proteins walk chromosomes along microtubules and depolymerize at the kinetochore ends.</p> Signup and view all the answers

The mechanism by which microtubules depolymerize at the _____ end after passing motor proteins is known as the 'Pac-man' mechanism.

<p>kinetochore</p> Signup and view all the answers

Match the following features with their corresponding roles in mitosis:

<p>Separase = Cleave cohesin Motor proteins = Facilitate chromosome movement Kinetochore microtubules = Connect chromosomes to spindle poles Spindle poles = Pull chromosomes apart</p> Signup and view all the answers

What experimental method was used to determine the behavior of kinetochore microtubules during anaphase?

<p>Fluorescent dye labeling (D)</p> Signup and view all the answers

The consensus among researchers is that only one mechanism is responsible for chromosome movement during mitosis.

<p>False (B)</p> Signup and view all the answers

What does the term 'reeled in' refer to in the context of chromosome movement?

<p>It refers to the process where motor proteins at the spindle poles draw chromosomes toward the poles.</p> Signup and view all the answers

What is the phase where most human cells are located?

<p>G0 Phase (B)</p> Signup and view all the answers

Mature nerve cells and muscle cells continuously divide throughout a human's life.

<p>False (B)</p> Signup and view all the answers

What role does MPF play in the cell cycle?

<p>MPF promotes mitosis by phosphorylating various proteins.</p> Signup and view all the answers

Cyclin combines with ______ to produce MPF.

<p>Cdk</p> Signup and view all the answers

What event does the M checkpoint prevent if chromosomes are not properly attached?

<p>Cell division (C)</p> Signup and view all the answers

Cyclin is ______ during anaphase, which terminates the M phase.

<p>degraded</p> Signup and view all the answers

What triggers liver cells to leave the G0 phase?

<p>External cues such as growth factors during injury.</p> Signup and view all the answers

What is the role of nonkinetochore microtubules during anaphase?

<p>To elongate the cell (C)</p> Signup and view all the answers

During anaphase, the region of overlap between nonkinetochore microtubules increases.

<p>False (B)</p> Signup and view all the answers

What process occurs in animal cells for cytokinesis?

<p>Cleavage</p> Signup and view all the answers

The first sign of cleavage during cytokinesis is the appearance of a _____ furrow.

<p>cleavage</p> Signup and view all the answers

Which of the following statements about kinetochore microtubules is true?

<p>They facilitate the release of tubulin subunits. (C)</p> Signup and view all the answers

Motor proteins attached to microtubules provide the energy required for cell elongation during anaphase.

<p>True (A)</p> Signup and view all the answers

Match the following components with their functions during anaphase:

<p>Nonkinetochore microtubules = Push apart spindle poles Contractile ring = Causes the formation of cleavage furrow Kinetochore microtubules = Shorten to move chromosomes Myosin = Interacts with actin microfilaments</p> Signup and view all the answers

Cytokinesis typically begins during _____ or telophase.

<p>anaphase</p> Signup and view all the answers

What is the primary method of cell division in bacteria?

<p>Binary fission (B)</p> Signup and view all the answers

Eukaryotes evolved first before prokaryotes on Earth.

<p>False (B)</p> Signup and view all the answers

What is the role of the actin-like protein in bacterial cell division?

<p>It helps in the movement of the chromosome during cell division.</p> Signup and view all the answers

The process by which bacterial cells separate into two daughter cells is called _____ fission.

<p>binary</p> Signup and view all the answers

During bacterial cell division, chromosomes replicate at the:

<p>Origin of replication (B)</p> Signup and view all the answers

Chloroplasts are involved in the process of binary fission.

<p>False (B)</p> Signup and view all the answers

What evolutionary relationship exists between bacterial division and mitosis?

<p>Mitosis may have evolved from simpler prokaryotic mechanisms like binary fission.</p> Signup and view all the answers

Flashcards

Cell division

The process by which a single cell divides into two daughter cells. This is a fundamental process for life, enabling growth, development, and repair in multicellular organisms and reproduction in single-celled organisms.

Asexual reproduction

A type of cell division that produces two daughter cells genetically identical to the parent cell. It's essential for growth, development, and repair in multicellular organisms, and for reproduction in single-celled organisms.

Genome

The genetic material of a cell, typically composed of DNA molecules.

DNA length in a eukaryotic cell

The total length of DNA packed within a eukaryotic cell. It is significantly longer than the diameter of the cell, necessitating elaborate packaging mechanisms.

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What are Kinetochores?

Specialized structures made of proteins that assemble on specific sections of DNA at each centromere. They connect sister chromatids to the spindle microtubules during cell division.

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Meiosis

A specialized type of cell division in eukaryotes that produces gametes (eggs and sperm). It reduces the chromosome number from diploid to haploid, ensuring genetic diversity in offspring.

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Development

The process by which a fertilized egg divides into a multicellular organism.

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What are Nonkinetochore Microtubules?

Microtubules that extend from the centrosome and do not attach to the kinetochores. They overlap at the metaphase plate, contributing to the spindle's structure and pushing the poles apart.

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Cell differentiation

The process by which cells become specialized for specific functions. This involves turning on and off specific genes in a cell.

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What are Asters?

A radial array of short microtubules extending from each centrosome, contributing to the spindle's structure and helping position the chromosomes during cell division.

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What is the Centrosome?

A subcellular region containing material that organizes the cell's microtubules. It is crucial for spindle formation during cell division.

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Cell repair

The process by which cells replace damaged or worn-out cells. It's essential for maintaining tissue integrity and function.

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What are Kinetochore Microtubules?

Microtubules that attach to the kinetochores of chromosomes. They pull the chromosomes towards the poles during cell division.

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What is Polymerization?

The process by which microtubules grow longer by adding subunits of tubulin.

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What is Depolymerization?

The process by which microtubules shorten by losing subunits of tubulin.

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What is the Metaphase Plate?

The region midway between the two poles of the spindle where chromosomes align during metaphase.

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Bacterial Binary Fission

The process by which a single bacterial cell divides into two daughter cells.

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Origin of Replication

The starting point for chromosome replication in bacterial cells.

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Pinch Point

A region in the bacterial cell that helps pinch the plasma membrane inwards during cell division, leading to the separation of daughter cells.

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Bacterial Tubulin

A protein related to tubulin found in bacteria that assists in pinching the plasma membrane inward during division.

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Evolution of Mitosis

The evolutionary hypothesis that suggests the process of mitosis in eukaryotes evolved from simpler processes used by prokaryotes for reproduction.

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Variations in Cell Division

A variation of cell division that is seen in some organisms, showing that this process is not a single, rigid pathway.

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Actin-like Protein

The protein involved in bacterial chromosome movement during cell division.

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Evolution of Eukaryotic Cell Division

The evolution of eukaryotic cells with nuclear envelopes and larger genomes is thought to have contributed to the development of mitosis from the simpler binary fission process in bacteria.

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Anaphase

The process by which sister chromatids are separated during mitosis.

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Kinetochore

A protein complex that attaches to the centromere region of a chromosome, serving as a point of attachment for microtubules during cell division.

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Kinetochore microtubules

Microtubules that extend from the spindle poles and attach to kinetochores, playing a crucial role in separating sister chromatids during anaphase.

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Pac-man mechanism

A process where a motor protein on the kinetochore 'walks' the chromosome along the microtubule, while the microtubule depolymerizes at its kinetochore end.

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Reeling-in mechanism

A process where a motor protein at the spindle pole 'reels in' the chromosome, causing the microtubule to depolymerize at the pole end.

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Separase

The enzyme that cleaves the protein complex holding sister chromatids together, allowing them to separate during anaphase.

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Nonkinetochore microtubules

The two microtubules that extend from the spindle poles toward the equatorial plane of the cell, but don't attach to chromosomes.

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Anaphase mechanism

The general consensus is that both the 'Pac-man' and 'reeling-in' mechanisms are used during anaphase. The relative contribution of each mechanism can vary depending on cell types.

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What happens to nonkinetochore microtubules during anaphase?

The region of overlap between nonkinetochore microtubules from opposite poles shortens during anaphase, pushing the spindle poles apart and elongating the cell.

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How do nonkinetochore microtubules lengthen during anaphase?

During anaphase, microtubules lengthen somewhat by adding tubulin subunits to their overlapping ends, while simultaneously being pushed apart by motor proteins.

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How do kinetochore microtubules contribute to chromosome movement during anaphase?

The microtubules attached to kinetochores shorten at their kinetochore ends, pulling chromosomes towards the poles.

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What is a cleavage furrow?

A shallow groove in the cell surface near the old metaphase plate that forms during cytokinesis in animal cells.

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What is the contractile ring?

A contractile ring made of actin microfilaments and myosin molecules found on the cytoplasmic side of the cleavage furrow.

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How does the contractile ring contribute to cytokinesis?

The contractile ring contracts, pulling the cell membrane inward and ultimately dividing the cytoplasm into two daughter cells.

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What is cytokinesis?

The process of dividing the cytoplasm of a cell during cell division, typically occurring after nuclear division.

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How does the spindle dissemble?

The disassembly of the spindle apparatus during cytokinesis by depolymerization of microtubules.

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Maturation Promoting Factor (MPF)

A protein complex composed of cyclin and cyclin-dependent kinase (Cdk), which triggers the transition from G2 to M phase of the cell cycle.

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Cyclin

A protein that combines with Cdk to form MPF (Maturation Promoting Factor), controlling the progression through the cell cycle.

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Cyclin-dependent Kinase (Cdk)

A protein that acts as a kinase (enzyme that adds phosphate groups), playing a key role in regulating the cell cycle by phosphorylating other proteins.

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M Checkpoint

A checkpoint in the cell cycle that ensures all chromosomes are properly attached to the spindle microtubules before anaphase begins.

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G0 Phase

A resting state where cells exit the cell cycle and are not actively dividing. Most cells in the human body are in this state.

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G2 Phase

The phase of the cell cycle where the cell grows and replicates its organelles and DNA in preparation for mitosis.

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Prophase

The phase of the cell cycle when replicated chromosomes condense, the nuclear envelope breaks down, and the spindle forms.

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Metaphase

The phase of the cell cycle where the replicated chromosomes align at the metaphase plate, ensuring equal distribution to daughter cells.

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Study Notes

Plant Diversity II: The Evolution of Seed Plants

  • Seed plants have key adaptations for life on land
  • Gymnosperms bear "naked" seeds, typically on cones
  • Angiosperms have flowers and fruits, for reproduction
  • Human welfare depends on seed plants for food, fuel, wood, and medicine

Seeds and Pollen Grains

  • Seeds are key adaptations for life on land
  • Seeds contain an embryo plus food supply and protection (seed coat)
  • Pollen grains are used to transfer sperm from the male part to the female part of a plant, eliminating the need for water
  • Reduced gametophytes are protected from the environment
  • Heterospory - seed plants have different types of spores - megaspores and microspores
  • Ovules - megasporangium, megaspore, and integument
  • Pollen grain contains the male gametophyte, which develops a pollen tube to carry sperm to the ovule
  • Fertilization produces the zygote and the ovule transforms into a seed.

Gymnosperms

  • Gymnosperms have naked seeds, typically on cones
  • Two types of sporangia - microsporangia and megasporangia
  • Megasporangia are found within ovules, which in turn are within an ovulate cone
  • Microspores develop into pollen grains, which are carried by wind to ovulate cones.
  • The male gametophyte produces sperm, and the female gametophyte produce eggs in the ovule.
  • Fertilization produces a zygote, and the ovule develops into a seed containing the embryo, food supply, and seed coat.
  • Important groups - Cycadophyta, Ginkgophyta, Gnetophyta, Coniferophyta

Angiosperms

  • Angiosperms have flowers and fruits (ovary matures into fruit)
  • Flowers have sepals, petals, stamens, and carpels
  • Sepals and petals are sterile floral organs; they protect flower parts and attract pollinators
  • Stamens produce pollen (male gametophytes)
  • Carpels produce ovules, which are located in the ovaries
  • Double fertilization (two sperm are needed): one fertilizes the egg producing a zygote, one fertilizes the central cell producing the endosperm
  • Ovules mature into seeds; the ovary develops into a fruit
  • Groups - basal angiosperms, monocots, and eudicots

Human Welfare Depends on Seed Plants

  • Seed plants are essential for food, fuel, wood, and medicine
  • Plant diversity is declining due to habitat destruction, and this loss has serious consequences for humans.
  • Tropical forests contain a large portion of Earth's plant diversity
  • Loss of forests impacts climate change, and threatens countless species of animals and plants.

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The Cell Cycle PDF

Description

Test your knowledge on the crucial processes of mitosis and cell division with this quiz. Explore key structures like centrosomes, spindle fibers, and the role of microtubules. Answer questions about the stages of mitosis and the organization of genetic material in cells.

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