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Questions and Answers
Which of the following best describes the significance of cell biology?
Which of the following best describes the significance of cell biology?
- It primarily deals with the historical aspects of cell discovery.
- It focuses solely on the classification of different types of cells.
- It is limited to the study of cells in plants and animals.
- It provides the foundation for understanding tissues, organs, and entire organisms. (correct)
What was Rudolf Virchow's major contribution to the cell theory?
What was Rudolf Virchow's major contribution to the cell theory?
- Stating that all cells come from pre-existing cells. (correct)
- Discovering the presence of DNA inside the cell.
- Proposing that all living things are made of cells.
- Observing 'cells' in cork slices using a microscope.
Which of the following is NOT a key tenet of the cell theory?
Which of the following is NOT a key tenet of the cell theory?
- Cells arise only by the division of pre-existing cells.
- Cells are the smallest unit of life.
- Cells can spontaneously generate from non-living matter. (correct)
- All organisms are composed of one or more cells.
What is the primary function of the plasma membrane in a human cell?
What is the primary function of the plasma membrane in a human cell?
Which of these transport mechanisms requires energy input by the cell?
Which of these transport mechanisms requires energy input by the cell?
Which component of the cytoskeleton is primarily responsible for cell motility?
Which component of the cytoskeleton is primarily responsible for cell motility?
Which of the following features distinguishes eukaryotic cells from prokaryotic cells?
Which of the following features distinguishes eukaryotic cells from prokaryotic cells?
What is the approximate water content in a typical human cell?
What is the approximate water content in a typical human cell?
A researcher is studying a cell that has the ability to divide indefinitely and differentiate into various specialized cells. Which type of cell is the researcher most likely studying?
A researcher is studying a cell that has the ability to divide indefinitely and differentiate into various specialized cells. Which type of cell is the researcher most likely studying?
Which of the characteristics below is NOT a criterion used for kingdom classification?
Which of the characteristics below is NOT a criterion used for kingdom classification?
A scientist is examining cells from an organism found in a hot spring. The cells lack a nucleus and have cell walls that do not contain peptidoglycan. To which kingdom does this organism likely belong?
A scientist is examining cells from an organism found in a hot spring. The cells lack a nucleus and have cell walls that do not contain peptidoglycan. To which kingdom does this organism likely belong?
If a cell is undergoing mitosis, what type of cell will be produced?
If a cell is undergoing mitosis, what type of cell will be produced?
Which of the following cell types would be most suitable for repairing damaged tissue in an adult?
Which of the following cell types would be most suitable for repairing damaged tissue in an adult?
Which of the following best describes the role of nucleic acids within cells?
Which of the following best describes the role of nucleic acids within cells?
What cellular process is directly responsible for the specialization of cells, allowing them to perform specific functions in the body?
What cellular process is directly responsible for the specialization of cells, allowing them to perform specific functions in the body?
A researcher observes a cell under a microscope and notes the absence of a defined nucleus. The cell is also observed to have a rigid cell wall composed of peptidoglycan. To which kingdom does this cell most likely belong?
A researcher observes a cell under a microscope and notes the absence of a defined nucleus. The cell is also observed to have a rigid cell wall composed of peptidoglycan. To which kingdom does this cell most likely belong?
Flashcards
Cytology
Cytology
The study of cell structure, function, and behavior.
Cell
Cell
The basic unit of life, fundamental to understanding tissues, organs, and organisms.
Cell Theory
Cell Theory
- All organisms are made of cells. 2. Cells arise from pre-existing cells. 3. Cells are the smallest unit of life.
Organelles
Organelles
Specialized structures within a cell that perform unique functions.
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Plasma Membrane
Plasma Membrane
A phospholipid bilayer that protects the cell and controls transport and signalling.
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Passive Transport
Passive Transport
Movement across the membrane without energy (diffusion, osmosis).
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Prokaryotic Cells
Prokaryotic Cells
Found in bacteria and archaea, lack a nucleus and membrane-bound organelles.
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Eukaryotic Cells
Eukaryotic Cells
Found in plants, animals, fungi, and protists, and contain membrane-bound organelles and a nucleus.
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Mitosis
Mitosis
Cell division that produces identical diploid cells for growth and repair.
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Meiosis
Meiosis
Cell division producing haploid gametes (sex cells) for reproduction.
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Karyotype
Karyotype
A display of chromosomes in a cell, arranged by size and shape.
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Stem Cells
Stem Cells
Unspecialized cells that can self-renew and differentiate into specialized cells.
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Stem Cell Differentiation
Stem Cell Differentiation
The process where stem cells become specialized cells with specific functions.
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Cell Differentiation
Cell Differentiation
The process by which unspecialized cells become specialized to perform specific functions.
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Protista
Protista
Eukaryotic, mostly unicellular organisms. Kingdom Classification
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Nutrition (in cells)
Nutrition (in cells)
Energy acquisition through absorption or photosynthesis.
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- Cytology, or cell biology, is the study of the structure, function, and behavior of cells
- Cells are the fundamental unit of life
- Understanding cells is the basis for understanding all tissues, organs, and organisms
- Cell biology explains cellular processes, like the cell cycle, division, and differentiation
- DNA is the universal genetic blueprint
The Cell Theory
- Robert Hooke observed individual "cells" in cork slices in the 1600's
- Theodor Schwann and Matthias Schleiden stated in 1839 that "all living things are made of cells"
- Rudolf Virchow stated in 1855 that "all cells come from pre-existing cells"
- All organisms are composed of one or more cells
- Cells arise only by the division of pre-existing cells
- Cells are the smallest unit of life
Cell Structure and Function
- Organelles are specialized subcellular structures performing unique functions
- Examples: Nucleus, mitochondria, ribosome, lysosome
- The plasma membrane has a phospholipid bilayer structure and is involved in protection, transport, and signaling.
- Transport across the plasma membrane can be passive (diffusion, osmosis) or active (pumps, endocytosis)
- The cytoskeleton provides shape, support, and motility and is composed of actin filaments and microtubules
- Cells are made of 85% water
- Cells include organic molecules like proteins, lipids, carbohydrates and nucleic acids
- Cells include inorganic substances like minerals and ions
Types of Cells
- Prokaryotic Cells:
- Found in bacteria and archaea
- They have no nucleus and contain circular DNA
- Ribosomes are smaller and cell walls are made of peptidoglycan
- Eukaryotic Cells:
- Found in plants, animals, fungi, and protists
- Contain membrane-bound organelles and linear chromosomes and are larger in size
Cell Characteristic Comparison
| Feature | Eukaryotic Cells | Prokaryotic Cells |
|---|---|---|
| Size | Larger (10-100 μm) | Smaller (0.1-5 μm) |
| Nucleus | Present, membrane-bound nucleus | Absent; DNA is in the nucleoid region |
| DNA Structure | Linear chromosomes with histones | Circular DNA without histones |
| Organelles | Membrane-bound organelles | No membrane-bound organelles |
| Cell Division | Mitosis and meiosis | Binary fission |
| Reproduction | Sexual reproduction | Asexual reproduction |
| Ribosomes | Larger (80S) | Smaller (70S) |
| Cell Wall | Cellulose or chitin (plants and fungi) | Peptidoglycan (most) |
| Metabolic Pathways | More complex | Simpler pathways |
| Examples | Animals, plants, fungi | Bacteria, archaea |
| Genetic Material | DNA enclosed in nucleus | DNA floats in Cytoplasm |
| Motility Structure | Complex (flagella, cilia) | Simple flagella (if present) |
Cell Division
- Mitosis produces identical diploid cells for growth and repair
- Meiosis produces haploid gametes for reproduction
- Human body cells have 46 chromosomes arranged in 23 pairs of autosomes and 1 pair of sex chromosomes
Stem Cells
- Stem cells are unspecialized cells with the ability to self-renew and differentiate
- Types of Stem Cells:
- Embryonic Stem Cells: Found in early embryos, capable of forming any cell type.
- Adult Stem Cells: Found throughout the body, for repair and maintenance.
- Induced Pluripotent Stem Cells (iPS): Programmed to act like embryonic stem cells
- Stem Cell Differentiation is when they specialize into distinct cell types with specific functions, guided by signals they receive.
- Key Properties of Stem Cells:
- Self-Renewal:divide and maintain themselves over time.
- Unspecialized: They can become specialized cells.
- Signal-Dependent: Stem cells differentiate upon receiving signals
Cell Differentiation
- Is when unspecialized cells become specialized to perform specific functions
- All human cells are derived from the zygote (fertilized egg).
- The zygote divides and differentiates into over 220 specialized cell types
- Differentiation allows cells to acquire unique functions
Kingdom Classification
- Criteria for Classification:
- Cell Type (Prokaryotic vs. Eukaryotic)
- Cell Number (Unicellular vs. Multicellular)
- Feeding Type (Autotrophic vs. Heterotrophic)
- Kingdom examples:
- Eubacteria: Prokaryotic, peptidoglycan cell walls.
- Archaebacteria: Prokaryotic, live in extreme conditions.
- Protista: Eukaryotic, mostly unicellular.
- Fungi: Eukaryotic, multicellular, heterotrophic.
Kingdom Characteristics
| Kingdom | Cell Type | Cell Number | Characteristics | Cell Wall |
|---|---|---|---|---|
| Eubacteria | Prokaryotic | Unicellular | Autotrophic/Heterotrophic, Asexual Repr., Live everywhere | Present (peptidoglycan) |
| Archaebacteria | Prokaryotic | Unicellular | Autotrophic/Heterotrophic, Live in extreme conditions | Present (no peptidoglycan) |
| Protista | Eukaryotic | Multi/Unicellular | Asexual/Sexual, Auto/Heterotrophic | Absent |
| Fungi | Eukaryotic | Mostly Multicellular | Heterotrophic | Present |
| Plantae | Eukaryotic | Multicellular | Autotrophic (photosynthesis) - cellulose | Present (cellulose) |
| Animalia | Eukaryotic | Multicellular | Heterotrophic - no cell wall | Absent |
Chemical Composition of Cells
- Proteins: Act as enzymes, structural components, and transporters
- Lipids: Used for energy storage, signaling molecules, and membrane components
- Carbohydrates: Act as energy sources and structural polymers
- Nucleic Acids: Includes DNA (genetic material) and RNA (protein synthesis)
Functionality of Life in Cells
- Nutrition: Acquisition of energy via absorption or photosynthesis
- Metabolism: Chemical reactions, such as respiration
- Growth: Increase in size or cell number
- Response: Reacting to stimuli around the cell
- Excretion: Removal of metabolic waste
- Homeostasis: Maintaining internal balance
- Reproduction: Hereditary information is transferred
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