A biological cell is the basic structural and functional unit of all living organisms. Cells are the building blocks of life, and they perform various essential functions necessary for the survival and functioning of living organisms. These functions include metabolism, growth, reproduction, and responding to their environment.
Cells can be classified into two main categories: prokaryotic and eukaryotic cells.
- Prokaryotic cells: These are simpler and smaller cells that lack a distinct membrane-bound nucleus. The genetic material in prokaryotic cells is present in the form of a single circular molecule of DNA located in the nucleoid region. Prokaryotic cells are found in organisms such as bacteria and archaea.
- Eukaryotic cells: These are more complex cells that have a true membrane-bound nucleus containing the genetic material (DNA). Eukaryotic cells are found in plants, animals, fungi, and protists. In addition to the nucleus, eukaryotic cells contain various other membrane-bound organelles, such as mitochondria, endoplasmic reticulum, Golgi apparatus, lysosomes, and others, which perform specific functions within the cell.
The main components of a typical eukaryotic cell include:
a. Cell Membrane: A semi-permeable membrane that surrounds the cell and regulates the movement of substances in and out of the cell.
b. Nucleus: The control center of the cell, containing the cell’s genetic material (DNA) and responsible for regulating cellular activities.
c. Cytoplasm: The gel-like substance that fills the cell and houses various organelles.
d. Mitochondria: Organelles responsible for producing energy (ATP) through cellular respiration.
e. Endoplasmic Reticulum (ER): A network of membranes involved in protein synthesis and lipid metabolism.
f. Golgi Apparatus: Involved in the modification, packaging, and transport of proteins and lipids.
g. Lysosomes: Organelles containing enzymes that break down waste materials and cellular debris.
h. Vacuoles: Membrane-bound sacs involved in storage, digestion, and waste removal.
Cells are highly specialized, and different types of cells have specific structures and functions that suit their roles in the body. They work together to form tissues, organs, and organ systems, enabling the organism to carry out complex life processes.
The study of cells and their structure and function is a fundamental aspect of biology and is known as cell biology or cytology. Understanding cell biology is crucial for advancing our knowledge of living organisms, health, and disease, and it plays a significant role in various scientific fields, including medicine, genetics, and biotechnology.
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Biological cell MCQs
Q1. Which organelle in the cell, other than the nucleus, contains DNA ?
(b) Golgi apparatus
Q2. How does the plant cell diﬀer from the animal cell?
(b) Cell wall
(c) Presence of protoplasm
(d) Cell nucleus
Q3. Which part of the animal cell is called power house?
(a) Cell wall
(d) Entire cell
Q4. Plasma membrane is built up of
(d) Both (a) and (b)
Q5. The cellular and molecular control of programmed cell death are known as :
Q6. What is the basic structural unit of all living organisms?
Q7. Which organelle is responsible for protein synthesis in the cell?
d) Golgi apparatus
Q8. What is the function of the cell membrane?
a) Provides structural support
b) Regulates the flow of nutrients
c) Controls cellular respiration
d) Stores genetic information
Q9. Which type of cells have a cell wall for structural support?
a) Animal cells
b) Plant cells
c) Both animal and plant cells
d) None of the above
Q10. What is the function of chloroplasts in plant cells?
a) Cellular respiration
c) DNA replication
d) Lipid synthesis
Q11. Which part of the cell is responsible for storing and processing genetic information?
a) Endoplasmic reticulum
d) Golgi apparatus
Q12. Which organelle contains digestive enzymes to break down waste materials in the cell?
Q13. What is the process by which cells divide and create identical copies of themselves called?
Q14. What is the function of the cell wall in plant cells?
a) Cellular respiration
c) Structural support and protection
d) Protein synthesis
Q15. Which organelle contains the cell’s genetic material in the form of DNA?
Q16. Which type of cells are found in multicellular organisms like humans?
a) Prokaryotic cells
b) Eukaryotic cells
c) Plant cells
d) Animal cells
Q17. What is the process by which cells release energy from glucose molecules?
c) Cellular respiration
d) Active transport
Q18. Which organelle is responsible for detoxifying harmful substances in the cell?
Q19. What is the function of the cell’s cilia and flagella?
a) Cell movement
b) Protein synthesis
Q20. Which type of cells have a rigid cell wall made of peptidoglycan?
a) Plant cells
b) Animal cells
c) Fungal cells
d) Bacterial cells
Q21. Which organelle is responsible for maintaining the cell’s shape and preventing it from bursting under osmotic pressure?
c) Cell membrane
d) Golgi apparatus
Q22. What is the process by which cells engulf large particles or even other cells to bring them into the cell?
What is a biological cell?
A biological cell is the smallest unit of life, serving as the fundamental building block of all living organisms. It can be either prokaryotic or eukaryotic, with prokaryotic cells lacking a nucleus and eukaryotic cells containing a distinct membrane-bound nucleus. Cells perform vital functions like metabolism, growth, and reproduction, and they work together to form tissues and organs in complex organisms.
How do cells reproduce?
Cell reproduction, or cell division, occurs through two main processes: mitosis and meiosis. Mitosis is the common form of cell division, producing genetically identical daughter cells for growth, repair, and asexual reproduction. Meiosis, on the other hand, is specific to sexual reproduction, resulting in the formation of gametes (sperm and egg cells) with half the normal chromosome number.
What are organelles in a cell?
Organelles are specialized structures within a eukaryotic cell that carry out specific functions. Some crucial organelles include the nucleus, responsible for housing DNA, mitochondria for energy production, endoplasmic reticulum for protein synthesis, and Golgi apparatus for protein modification and packaging. Lysosomes are involved in waste disposal, while vacuoles store various substances.
How do cells obtain energy?
Cells obtain energy through cellular respiration, a process that occurs in mitochondria. During cellular respiration, glucose and oxygen react to produce carbon dioxide, water, and adenosine triphosphate (ATP), the energy currency of cells. ATP is then utilized to power various cellular activities, allowing cells to carry out essential functions and maintain life.
How do cells communicate?
Cells communicate through complex signaling pathways, including chemical signals and receptor interactions. These signals can be local or long-distance, influencing cell behavior, growth, and development. Cell communication is vital for coordinating various processes in multicellular organisms, such as immune responses, tissue repair, and hormonal regulation. Defective cell communication can lead to various diseases and disorders.