D2.1-2.1.8
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Questions and Answers

What occurs before DNA replication in the cell cycle?

  • The cell prepares for nuclear division. (correct)
  • Cohesin begins to break down.
  • The DNA condenses into chromosomes.
  • Single chromatids are produced.

What structure holds the identical DNA molecules together after replication?

  • Cohesin loops (correct)
  • Nuclear envelope
  • Telomeres
  • Centromeres

During which phase are the cohesin loops cut?

  • Anaphase (correct)
  • Telophase
  • Metaphase
  • Prophase

What is the condition of DNA before it is replicated?

<p>It exists as long single molecules. (A)</p> Signup and view all the answers

What is a false hypothesis regarding the behavior of chromatids during division?

<p>A single centromere holds the chromatids together. (C)</p> Signup and view all the answers

What is the process called by which a mother cell produces new cells?

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

Which statement accurately reflects the theory of cell generation?

<p>New cells are produced from pre-existing cells. (A)</p> Signup and view all the answers

What happens to the mother cell during cell division?

<p>It disappears as an entity. (A)</p> Signup and view all the answers

From what did all cells in a person's body originate?

<p>The division of a zygote. (A)</p> Signup and view all the answers

Which component is NOT a direct ancestor of the cells in our bodies today?

<p>Cells in unrelated species (D)</p> Signup and view all the answers

What does the continuity of life imply about human cells?

<p>They can be traced back to the earliest cells on Earth. (C)</p> Signup and view all the answers

Which statement best describes the significance of cell division in living organisms?

<p>It is crucial for maintenance, growth, and reproduction. (C)</p> Signup and view all the answers

Which organization is attempting to create new living cells from lifeless components?

<p>BaSyC (D)</p> Signup and view all the answers

What occurs at the end of prophase regarding the nuclear membrane?

<p>It breaks down. (D)</p> Signup and view all the answers

Which structure grows microtubules towards the end of prophase?

<p>Microtubule organizing centres (MTOCs) (B)</p> Signup and view all the answers

During metaphase, what is the role of spindle microtubules?

<p>They align chromosomes on the equator. (D)</p> Signup and view all the answers

What is tested during metaphase to ensure proper attachment?

<p>The tension of the spindle microtubules (D)</p> Signup and view all the answers

What type of structure do the microtubules form during prophase?

<p>Spindle-shaped array (C)</p> Signup and view all the answers

What happens to sister chromatids during metaphase?

<p>They stay attached to each other. (A)</p> Signup and view all the answers

Which of the following structures directly interact with the chromosomes during metaphase?

<p>Kinetochore spindle microtubules (A)</p> Signup and view all the answers

What is the primary function of microtubules during the metaphase stage of mitosis?

<p>To facilitate chromosome alignment (D)</p> Signup and view all the answers

What prevents chromosomes from being pulled to either pole during the late stages of metaphase?

<p>Cohesin loops (C)</p> Signup and view all the answers

At what stage are chromosomes aligned at the equator of the cell?

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

Which structure is responsible for pulling chromosomes to the poles during anaphase?

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

What happens to the cohesin loops during anaphase?

<p>They are cut (A)</p> Signup and view all the answers

What initiates the movement of chromosomes towards the poles in anaphase?

<p>Kinetochore shortening (C)</p> Signup and view all the answers

By the end of which phase are chromosomes no longer held together by cohesin?

<p>Anaphase (D)</p> Signup and view all the answers

What stabilizes the chromosomes at the equator during metaphase?

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

What defines the formation of genetically identical chromosomes in anaphase?

<p>Separation of sister chromatids (D)</p> Signup and view all the answers

What happens to chromosomes during interphase?

<p>They are dispersed and decondensed. (C)</p> Signup and view all the answers

What is a key event that occurs during telophase?

<p>Chromosomes are dispersed into the nucleus. (B)</p> Signup and view all the answers

What primarily occurs in the cytoplasm during interphase?

<p>The cell grows and metabolically prepares for mitosis. (A)</p> Signup and view all the answers

What occurs immediately after cytokinesis?

<p>The cell starts interphase, doubling in size. (C)</p> Signup and view all the answers

What is the state of genes in decondensed chromosomes?

<p>They are transcribed and translated into proteins. (B)</p> Signup and view all the answers

What occurs at the end of anaphase?

<p>Chromosomes reach the poles. (D)</p> Signup and view all the answers

What happens to the chromosomes during telophase?

<p>They spread out to form dispersed chromatin. (A)</p> Signup and view all the answers

What initiates cytokinesis during the mitotic process?

<p>The appearance of a cleavage furrow. (C)</p> Signup and view all the answers

What typically happens to daughter cells after completing mitosis?

<p>They enter interphase. (A)</p> Signup and view all the answers

Where does the nuclear membrane reform during telophase?

<p>Near the chromosomes at each pole. (C)</p> Signup and view all the answers

During which phase are chromosomes tightly grouped near the MTOC?

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

What is the primary characteristic of chromosomes at the conclusion of anaphase?

<p>They have reached the poles but have not decondensed. (A)</p> Signup and view all the answers

Which of the following statements is true concerning the events of cytogenesis?

<p>A furrow forms at the equator during cytokinesis. (A)</p> Signup and view all the answers

Flashcards

Cell Division

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

Mother Cell

The original cell that divides during cell division.

Daughter Cells

The new cells produced from the division of a mother cell.

Cell Theory

The theory that all new cells are produced from the division of pre-existing cells.

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Zygote

The first cell that forms when a sperm and an egg fuse.

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Cell Lineage

The process of tracing the origin of cells back through generations.

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Continuity of Life

The continuity of life from its early beginnings to present-day cells.

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Common Ancestry

The idea that all living organisms share a common ancestor.

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DNA replication

The process by which a cell replicates its DNA before dividing, ensuring each daughter cell receives a complete set of genetic information.

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Cohesin

A protein complex that holds together identical DNA molecules (chromatids) after replication, ensuring they stay connected until the start of anaphase.

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Anaphase

The stage of cell division (mitosis or meiosis) where sister chromatids separate to opposite poles of the cell, marking the end of DNA replication.

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Chromosomes

Long, linear molecules of DNA that carry genetic information within the nucleus of a cell.

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Sister chromatids

Pairs of identical DNA molecules that are produced during replication and remain connected by cohesin until anaphase.

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Spindle

A structure that extends from the poles of the cell during mitosis and meiosis, composed of microtubule fibers that attach to chromosomes and help separate them.

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Microtubule Organizing Center (MTOC)

A structure within a cell where microtubules originate during cell division, typically located near the poles of the cell.

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Kinetochore

The point on a chromosome where microtubules from the spindle attach.

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Metaphase Plate

During metaphase, the chromosomes line up at the center of the cell, forming a structure called the metaphase plate.

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Spindle Fibers

Microtubules are protein fibers that form the spindle fibers, a structure that helps to separate chromosomes during cell division. They attach to the kinetochore, a protein structure on the chromosome.

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Kinetochore Microtubules

Kinetochore microtubules are spindle fibers that attach to the kinetochore, a protein complex on the chromosome. These microtubules shorten during anaphase, pulling the chromosomes towards the poles.

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Chromosome Segregation

The process of separating the duplicated chromosomes in a parent cell into two daughter cells is called chromosome segregation. This ensures that each daughter cell receives a complete set of chromosomes.

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Microtubule Depolymerization

Microtubule depolymerization is the process of breaking down microtubules. It occurs during anaphase, where the kinetochore microtubules shorten, pulling the chromosomes to the poles of the cell.

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Centromere

The centromere is a constricted region on a chromosome where the sister chromatids are joined. It plays a crucial role in chromosome segregation during cell division.

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Telophase

The final stage of mitosis where the nuclear envelope reforms around the separated chromosomes, the chromosomes decondense, and the cell starts to divide its cytoplasm (cytokinesis).

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Cytokinesis

The process where the cytoplasm of a cell divides after mitosis or meiosis, creating two separate daughter cells.

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Pole

The region where the chromosomes are gathered at opposite poles of the cell during anaphase and telophase.

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Chromatids

The condensed and visible form of DNA during cell division. They are formed from two identical sister chromatids held together by cohesin.

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Chromosomes decondense

The process by which chromosomes unwind and spread out inside the nucleus after cell division, becoming less visible.

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What is Condensing?

The stage of cell division (mitosis or meiosis) when the replicated chromosomes condense into compact structures visible under a microscope.

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What is Telophase?

The final stage of mitosis or meiosis during which the replicated chromosomes reach opposite poles of the cell, the nuclear envelope reforms, and the cytoplasm divides, forming two daughter cells.

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What is Interphase?

The period between cell divisions when the cell grows, replicates its DNA, and carries out its normal metabolic functions. It's the longest stage of the cell cycle.

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What is Cytokinesis?

The process of dividing the cytoplasm of a cell during cell division, resulting in two daughter cells.

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What is decondensing?

The process of unwinding and relaxing the tightly packed chromosomes so genetic information can be copied (replicated).

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Study Notes

Cell Division in Living Organisms

  • All organisms need new cells for growth, maintenance, and reproduction.
  • This is achieved through cell division.
  • A mother cell divides into two daughter cells.
  • The mother cell is no longer a separate entity.
  • New cells are always created from pre-existing cells (strong evidence for this theory).
  • Our bodies are made of trillions of cells, each originating from the initial zygote.
  • The zygote is formed from the fusion of sperm and egg.
  • The origins of our cells can be traced back to earlier generations.
  • This demonstrates continuity of life from the earliest cells to the cells in our bodies today.

Cytokinesis in Animal Cells

  • Cytokinesis divides the cytoplasm during cell division.
  • It happens after nuclear division (mitosis in mother cells).
  • Cytoplasm and contents are divided between two daughter cells.
  • Animal cells form a cleavage furrow around the center.
  • Contractile proteins (actin and myosin) pull the plasma membrane inwards, pinching it apart.

Cytokinesis in Plant Cells

  • Plant cells use a different approach.
  • Microtubules form a scaffold at the equator.
  • Vesicles fuse to create a cell plate.
  • This develops into a new cell wall, separating the two cells.
  • The cell plate connects to existing plasma membranes to complete cell division.

Equal and Unequal Cytokinesis

  • Equal cytokinesis divides cytoplasm evenly. Happens in growing root tips.
  • Unequal cytokinesis divides cytoplasm unequally.
  • Resulting smaller cells can still function if they receive enough organelles.
  • Mitochondria, for instance, require pre-existing ones to be viable.

Budding in Yeast

  • Yeast reproduces asexually.
  • A small outgrowth (bud) forms on the mother cell.
  • Nuclei divide.
  • Bud receives a portion of cytoplasm.
  • Bud eventually separates from the mother cell, leaving a scar.

Oogenesis in Humans

  • One large oocyte and small polar bodies are produced in each meiotic cycle.
  • The large oocyte receives most of the cytoplasm, providing resources for the developing embryo.
  • The polar bodies eventually degenerate and are not involved in fertilization.

Mitosis and Meiosis in Eukaryotes

  • Mitosis creates genetically identical cells.
  • The diploid chromosome number is maintained.
  • Meiosis halves the chromosome number (from diploid to haploid).
  • Meiosis generates genetic variation for sexual reproduction.

DNA Replication for Mitosis and Meiosis

  • DNA replication is necessary before mitosis/meiosis.
  • It ensures that each daughter cell receives a complete set of genetic information.
  • Chromosomes, initially long strands of DNA, condense into visible structures during cell division.
  • Each chromosome duplicates (during interphase) and becomes two sister chromatids.
  • Cohesin loops hold chromatids together until anaphase.

Chromosome Condensation and Movement

  • Chromosomes condense to become easier to move during cell division (mitosis/meiosis).
  • Microtubules are used in the structure of the spindle which separates the chromosomes in mitosis/meiosis.
  • Kinetochores, protein structures on chromosomes, link chromosomes to microtubules.

Mitosis Phases

  • Mitosis is divided into interphase (preceding mitosis), prophase, metaphase, anaphase, and telophase.
  • Key events like chromosome condensation, alignment at the cell equator, separation of chromatids, and nuclear membrane reformation occur in each.

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D2.1.1-2.1.7 Cell Biology PDF

Description

This quiz covers key concepts related to the cell cycle and cell division, including DNA replication, the role of cohesin, and the processes involved in cell generation. Test your knowledge on crucial phases of cell division and the origins of cells within the human body.

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