Cell Theory - Foundations of Biology

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Questions and Answers

Which postulate of cell theory states that all cells arise from preexisting cells?

All organisms are composed of one or more cells.

Cells are the smallest and basic units.

Cells can spontaneously generate.

All cells arise only from previously existing cells. (correct)

What type of microscope would you use to examine the internal structure of a cell with high clarity?

Light Compact Microscope (LCM)

Scanning Tunneling Microscope (STM)

Compound Light Microscope (CLM)

Electron Microscope (EMS) (correct)

Which of the following characteristics of life is associated with the concept of maintaining stable internal conditions?

Reproduction

Adaptations evolve over time

Development

Homeostasis (correct)

Who is credited with the discovery of cells through observing cork?

Robert Hooke Signup and view all the answers

Which of the following is NOT a characteristic of living organisms according to the foundation of biology?

Reproduces asexually only Signup and view all the answers

What is the primary limitation of a Light Compact Microscope (LCM)?

It provides lower resolution than electron microscopes. Signup and view all the answers

Which of the following is considered an organelle?

Nucleus Signup and view all the answers

What is the primary function of flagella?

Locomotion Signup and view all the answers

Which of the following correctly describes cilia?

Shorter and more numerous than flagella Signup and view all the answers

What are pseudopods primarily used for?

Capturing prey and movement Signup and view all the answers

What distinguishes microvilli from villi?

Microvilli are smaller and increase absorption surface area Signup and view all the answers

What role does the extracellular matrix (ECM) play in the body?

It provides structure and support to cells Signup and view all the answers

Which type of modification occurs between apical and basal surfaces?

Lateral Modification Signup and view all the answers

What is a significant function of villi in the intestines?

Increase surface area for nutrient absorption Signup and view all the answers

What happens during the metaphase checkpoint?

Cells ensure that all chromosomes are attached to the centrosome. Signup and view all the answers

What is the meaning of the term 'pseudopod'?

False foot Signup and view all the answers

What key event occurs during anaphase?

Sister chromatids are separated to opposite sides of the cell. Signup and view all the answers

Which of the following processes is NOT part of the synthesis phase?

Preparation of cell division. Signup and view all the answers

What is the role of centrosomes during mitosis?

To organize microtubules for the mitotic spindle. Signup and view all the answers

Which statement regarding apoptosis is accurate?

Apoptosis is a form of programmed cell death. Signup and view all the answers

In telophase, which of the following occurs?

Nuclear membrane reforms around the chromosomes. Signup and view all the answers

What happens to sister chromatids after they are separated?

They are now referred to as chromosomes. Signup and view all the answers

Which of the following describes the Gap 2 phase in the cell cycle?

Preparation for mitosis and synthesis of proteins occurs. Signup and view all the answers

What is the result of the fusion of haploid gametes during fertilization?

Formation of one diploid zygote Signup and view all the answers

What type of cells do spermatogonia produce through mitotic division?

Primary spermatocytes Signup and view all the answers

What is the chromosome composition of primary spermatocytes?

46 chromosomes Signup and view all the answers

Where does the maturation of sperm cells occur?

In the lumen of seminiferous tubules Signup and view all the answers

What is the purpose of meiosis I in spermatogenesis?

To reduce the chromosome number by half Signup and view all the answers

What stage follows the differentiation of spermatogonia?

Formation of primary spermatocytes Signup and view all the answers

What would happen if sex cells contained the full set of chromosomes?

Zygotes would have extra genetic material Signup and view all the answers

What is the final phase of sperm cell production in the seminiferous tubules?

Sperm maturation Signup and view all the answers

What is produced during meiosis?

Four genetically different gametes Signup and view all the answers

During which phase of the cell cycle does DNA replication occur?

Interphase Signup and view all the answers

What happens to the nuclear membrane during prophase of mitosis?

It disintegrates Signup and view all the answers

Which of the following statements about homologous pairs is TRUE?

They consist of two chromosomes of the same type but possibly different alleles Signup and view all the answers

What is the main purpose of cytokinesis?

To separate the cytoplasm into two daughter cells Signup and view all the answers

What is a characteristic feature of metaphase in mitosis?

Chromosomes align at the cell's equator Signup and view all the answers

Which checkpoint is NOT typically associated with the cell cycle?

P checkpoint Signup and view all the answers

How many chromosomes are present in the daughter cells produced by mitosis if the parent cell is diploid (2n)?

2n chromosomes Signup and view all the answers

Study Notes

Multicellular (Eukaryotes)

Organisms are characterized by reproduction, development, evolution, response to stimuli, homeostasis, and energy requirements.
Protozoan cells are considered the first living cells, according to the cell theory established by Schleiden and Schwann.

Postulates of Cell Theory

All organisms consist of one or more cells.
Cells are the basic units of structure and function in organisms.
Cells can only arise from existing cells through cell division.

History of Cell Discovery

Robert Hooke discovered cells in 1665 while examining cork under a microscope.

Microscopes

Zacharias Jansen invented the microscope in the late 1600s, enabling observation of small objects.
Micrograph: Image produced by a microscope.
Magnification: Measure of the optical instrument's ability.
Resolution: The clarity of an image.
Types of microscopes include Light Compact Microscopes (LCM) and Electron Microscopes (EMS).

Cell Organelles

Organelles, or “little organs,” are specialized structures within cells, each with distinct functions.
Non-membrane-bound structures, like flagella, assist in cell locomotion.
Cilia are shorter, more numerous, and function similarly to flagella but are primarily used for movement and sensory detection.
Pseudopodia are temporary extensions of the cytoplasm used for locomotion and capturing prey.
Villi and microvilli increase absorptive surface area in epithelial cells.

Extracellular Matrix (ECM)

The ECM is a network of proteins and molecules surrounding cells, supporting structure and communication.

Types of Cell Modification

Apical, lateral, and basal modifications facilitate diverse cellular functions.

Cell Division

The cell cycle includes Interphase (DNA replication), M Phase (cell division), and Cytokinesis (separation of the parent cell).
Mitosis produces two identical diploid cells (2n) from a parent cell.

Mitotic Phases

Prophase: Chromosomes condense and become visible; nuclear envelope breaks down.
Metaphase: Chromosomes align at the cell's equator; checkpoints ensure attachment to the mitotic spindle.
Anaphase: Sister chromatids separate to opposite sides of the cell.
Telophase: Chromosomes decondense; nuclear membrane reforms.

Apoptosis

Apoptosis refers to programmed cell death, ensuring proper cell turnover.

Importance of Haploid Gametes

Gametes (sperm and egg) combine to form a diploid zygote, maintaining genetic stability.
Spermatogenesis occurs in the testes, starting from spermatogonia, which proliferate to form primary spermatocytes through mitosis.

Gamete Formation

Primary spermatocytes undergo meiosis I, reducing the chromosome count.
Mature sperm cells are released into seminiferous tubules for further maturation.

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Description

Test your knowledge on the foundational concepts of cell theory, including the characteristics of multicellular eukaryotes and the key postulates laid out by scientists such as Schleiden and Schwann. Explore topics such as reproduction, adaptation, and homeostasis in living organisms.