Subject: Zoology (Cell Biology and Histology)
Paper Code: ZOODSM-151T
Exam: FYUG Even Semester Exam, 2024
Answer any ten of the following questions (All solved for full coverage):
According to cell theory, a cell is the basic structural, functional, and biological unit of all living organisms
. It is the smallest unit of life that can replicate independently.Facilitated transport is a type of passive transport where molecules move across the cell membrane through specific transmembrane integral proteins without the expenditure of cellular energy
.| Prokaryotic Cell | Eukaryotic Cell |
|---|---|
| Lacks a membrane-bound nucleus. | Has a true membrane-bound nucleus. |
| Membrane-bound organelles are absent. | Membrane-bound organelles (e.g., mitochondria) are present. |
Mitochondria are called the powerhouse of the cell because they are the primary sites of ATP (Adenosine Triphosphate) production through cellular respiration
.Microtubules are hollow, microscopic cylinders made of tubulin protein that form part of the cytoskeleton and play key roles in maintaining cell shape and facilitating cell division
.A nucleosome is the basic structural unit of DNA packaging in eukaryotes, consisting of a segment of DNA wound around a core of eight histone proteins
.The cell cycle is an ordered series of events involving cell growth and DNA replication that produces two new daughter cells
.It is a type of simple epithelium that appears layered (stratified) because the nuclei are at different levels, even though every cell is attached to the basement membrane
.The Haversian system (or osteon) is the fundamental functional unit of compact bone, consisting of concentric layers of bone tissue surrounding a central canal containing blood vessels and nerves
.Glial cells (neuroglia) are non-neuronal cells in the nervous system that provide support, nutrition, and protection for neurons
.A neuromuscular junction is a chemical synapse formed by the contact between a motor neuron and a muscle fiber, allowing the transmission of nerve impulses to cause muscle contraction
.Answer any five of the following questions (All solved for full coverage):
The fluid-mosaic model, proposed by Singer and Nicolson, describes the plasma membrane as a fluid lipid bilayer with embedded "mosaic" proteins
.Functions: Acts as a selective barrier, facilitates cell signaling, and provides structural support.
Tight Junctions: Specialized connections where the membranes of adjacent cells are pressed tightly against each other, sealed by specific proteins (claudins and occludins)
. They prevent the leakage of extracellular fluid.Gap Junctions: Channels (connexons) that connect the cytoplasm of adjacent cells, allowing the passage of ions and small molecules
. They facilitate rapid chemical and electrical communication between cells, such as in cardiac muscle.The ER is a network of membranous tubules and sacs called cisternae
.The nucleus is the control center of the cell, enclosed by a double-membrane nuclear envelope containing nuclear pores
. It contains nucleoplasm and chromatin (genetic material).Functions: Stores genetic information, controls gene expression, and regulates cell division
.Functions of Nucleolus: The nucleolus is the site of ribosomal RNA (rRNA) synthesis and the assembly of ribosomal subunits
.Cytoskeleton: A network of protein fibers (microtubules, microfilaments, and intermediate filaments) that provides structural support and facilitates cell motility
.Microfilament Structure: Composed of two intertwined strands of the protein actin
.Functions: Maintaining cell shape, muscle contraction (with myosin), and amoeboid movement
.G1 Checkpoint: The primary point at which the cell must choose whether or not to divide
. It checks for cell size, nutrients, growth factors, and DNA damage.Epithelial Tissue: A tissue composed of closely packed cells that covers body surfaces and lines internal organs
.Simple Epithelial Tissue: Consists of a single layer of cells
. Types include:Adipocytes: Specialized fat cells that store energy as lipids
.Three Types of Cartilage:
Functions: Provides structural support, cushions joints, and acts as a precursor for bone formation
.A myelinated neuron consists of a cell body, dendrites, and an axon covered by a fatty myelin sheath produced by Schwann cells
. The gaps in the sheath are called Nodes of Ranvier.Functions: Saltatory conduction of nerve impulses (increases speed)
.Types based on Polarity: Unipolar (one process), Bipolar (two processes), and Multipolar (multiple processes)
.Synapse: A junction between two neurons where information is transmitted
.Differences:
Chemical Synapse Structure: Consists of a presynaptic terminal (containing vesicles), a synaptic cleft, and a postsynaptic membrane (containing receptors)
.