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Questions and Answers
What is one of the key principles of cell theory?
What is one of the key principles of cell theory?
Which of the following statements is correct regarding the diversity of human cells?
Which of the following statements is correct regarding the diversity of human cells?
What distinguishes prokaryotic cells from eukaryotic cells?
What distinguishes prokaryotic cells from eukaryotic cells?
Which part of the cell is primarily responsible for maintaining homeostasis?
Which part of the cell is primarily responsible for maintaining homeostasis?
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What is a role of stem cells according to the stem cell theory?
What is a role of stem cells according to the stem cell theory?
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Which of the following is NOT a type of human cell?
Which of the following is NOT a type of human cell?
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Which statement accurately captures a common feature shared by most human cells?
Which statement accurately captures a common feature shared by most human cells?
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How many estimated cells does an adult human body contain?
How many estimated cells does an adult human body contain?
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Which type of cells are responsible for forming the placenta and umbilical cord during embryonic development?
Which type of cells are responsible for forming the placenta and umbilical cord during embryonic development?
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What role do stem cells play in adult organisms?
What role do stem cells play in adult organisms?
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Which cells are generated from a single totipotent cell?
Which cells are generated from a single totipotent cell?
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What are the germ layers that stem cells can differentiate into?
What are the germ layers that stem cells can differentiate into?
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Which phrase best describes the potency of totipotent stem cells?
Which phrase best describes the potency of totipotent stem cells?
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What characteristic distinguishes embryonic stem cells from adult stem cells?
What characteristic distinguishes embryonic stem cells from adult stem cells?
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What type of stem cells are primarily involved in differentiation during early embryonic development?
What type of stem cells are primarily involved in differentiation during early embryonic development?
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Which type of cell specializes in information gathering and control of body functions?
Which type of cell specializes in information gathering and control of body functions?
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Which factor will decrease the rate of diffusion most significantly?
Which factor will decrease the rate of diffusion most significantly?
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What is required for facilitated diffusion to occur?
What is required for facilitated diffusion to occur?
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In which situation would the rate of diffusion be the fastest?
In which situation would the rate of diffusion be the fastest?
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What determines if a solute can cross the lipid bilayer by simple diffusion?
What determines if a solute can cross the lipid bilayer by simple diffusion?
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What significantly influences the time it takes for diffusion to occur?
What significantly influences the time it takes for diffusion to occur?
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What type of substances typically utilize facilitated diffusion to cross the plasma membrane?
What type of substances typically utilize facilitated diffusion to cross the plasma membrane?
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Which statement about ion channels is accurate?
Which statement about ion channels is accurate?
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If the surface area of a membrane is decreased, how will this impact diffusion?
If the surface area of a membrane is decreased, how will this impact diffusion?
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What characterizes a gated ion channel?
What characterizes a gated ion channel?
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What distinguishes ligand-gated channels from other types of gated channels?
What distinguishes ligand-gated channels from other types of gated channels?
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Which statement best describes carrier-mediated facilitated diffusion?
Which statement best describes carrier-mediated facilitated diffusion?
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Which of the following substances is commonly transported by carrier-mediated facilitated diffusion?
Which of the following substances is commonly transported by carrier-mediated facilitated diffusion?
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What happens to the glucose transporter during the transport of glucose?
What happens to the glucose transporter during the transport of glucose?
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In the context of voltage-gated channels, what does the term 'voltage' refer to?
In the context of voltage-gated channels, what does the term 'voltage' refer to?
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Which ions are known to use specific protein channels for diffusion into and out of cells?
Which ions are known to use specific protein channels for diffusion into and out of cells?
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What feature do mechanically gated channels possess?
What feature do mechanically gated channels possess?
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Which of the following types of stem cells can differentiate into nearly all cell types derived from the three germ layers?
Which of the following types of stem cells can differentiate into nearly all cell types derived from the three germ layers?
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Which type of stem cell can only differentiate into a limited number of cell types closely related to one another?
Which type of stem cell can only differentiate into a limited number of cell types closely related to one another?
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What characterizes unipotent stem cells from other stem cells?
What characterizes unipotent stem cells from other stem cells?
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What type of stem cell division is characterized by one daughter cell remaining a stem cell while the other becomes a differentiated cell?
What type of stem cell division is characterized by one daughter cell remaining a stem cell while the other becomes a differentiated cell?
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What is the characteristic of oligopotent stem cells?
What is the characteristic of oligopotent stem cells?
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Which statement best describes totipotent stem cells?
Which statement best describes totipotent stem cells?
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What distinguishes pluripotent stem cells from multipotent stem cells?
What distinguishes pluripotent stem cells from multipotent stem cells?
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What is the primary role of stem cells in the body?
What is the primary role of stem cells in the body?
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Which of the following is NOT a characteristic of all cell types?
Which of the following is NOT a characteristic of all cell types?
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How do prokaryotic cells differ from eukaryotic cells?
How do prokaryotic cells differ from eukaryotic cells?
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What primarily composes the cell walls of bacterial cells?
What primarily composes the cell walls of bacterial cells?
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Which type of cells can be found in the hierarchy of hemopoietic differentiation?
Which type of cells can be found in the hierarchy of hemopoietic differentiation?
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What is true about symmetric stem cell division?
What is true about symmetric stem cell division?
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What is the main function of tonicity in cellular processes?
What is the main function of tonicity in cellular processes?
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Which of the following correctly describes primary active transport?
Which of the following correctly describes primary active transport?
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What role does the Na+/K+-ATPase transporter play in cells?
What role does the Na+/K+-ATPase transporter play in cells?
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Which of the following statements about secondary active transport is true?
Which of the following statements about secondary active transport is true?
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Which of the following is NOT a major primary active-transport protein in cells?
Which of the following is NOT a major primary active-transport protein in cells?
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What initiates the cycle of the Na+/K+-ATPase pump?
What initiates the cycle of the Na+/K+-ATPase pump?
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What happens after K+ binds to the pump protein during the Na+/K+-ATPase cycle?
What happens after K+ binds to the pump protein during the Na+/K+-ATPase cycle?
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Which of the following is primarily responsible for the shape change in the Na+/K+-ATPase pump during transport?
Which of the following is primarily responsible for the shape change in the Na+/K+-ATPase pump during transport?
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Study Notes
MPharm Programme - Cell Science
- Course title: Cell Science - Introduction to Cellular Structure 1 & 2
- Lecturer: Dr Praveen Bhugra
- Course code: PHA115
Learning Objectives
- Students will be able to explain cell theory in detail
- Students will be able to detail stem cells
- Students will be able to differentiate between prokaryotic and eukaryotic cells
- Students will be able to differentiate between plant cell, animal cell and bacteria
- Students will be able to explain the structure and function of the three main parts of a cell (plasma membrane, cytoplasm & nucleus)
Cells Theory
- Cells are the building blocks of all plants and animals
- All cells come from the division of pre-existing cells
- Cells are the smallest units that perform all vital physiological functions.
- Each cell maintains homeostasis at the cellular level
Cells in the human body
- All body parts are made up of cells
- An estimated 3.72 x 10^13 cells in the human body
- There is no such thing as a typical cell
- The human body has many different types of cells - over 200 + 20 different organelles
- Chemical and structural features are shared by most cells
Diversity of Human Cells
- Adult humans consist of more than 200 different types of cells
- These types include nerve, muscle, skin, blood (red, monocytes, lymphocytes), bone, and cartilage cells
- Cells essential for embryonic development but not incorporated into the embryo's body include extra-embryonic tissues, placenta, and umbilical cord.
- These cells all derive from a single totipotent cell, the zygote
Diversity of Human Cells Examples
- Epithelial cells are cells that form linings or transport gases
- Fibroblasts connect body parts
- Erythrocytes are red blood cells
- Nerve cells gather information and control body functions
- Muscle cells move organs
- Macrophages fight disease
- Fat cells store nutrients
- Sperm is cells of reproduction
Stem Cells
- Stem cells are undifferentiated biological cells that can differentiate into specialized cells and divide further through mitosis to produce more stem cells
- In mammals, there are two broad types of stem cells:
- Embryonic stem cells which are isolated from the inner cell mass of blastocysts
- Adult stem cells which are found in various tissues
- In a developing embryo, stem cells can differentiate into all the specialized cells - ectoderm, endoderm, and mesoderm. These layers give rise to all the body tissues and organs
Stem cells potency
- Totipotent stem cells can differentiate into embryonic and extraembryonic cell types and form a complete, viable organism
- These cells result from an egg and sperm cell fusion
- Pluripotent stem cells are descendants of totipotent cells and can differentiate into nearly all cell types derived from any of the three germ layers
- Multipotent stem cells differentiate into a number of cell types, but only those in a related family (e.g. lymphoid or myeloid stem cells),
- Unipotent cells can produce only one cell type and have the property of self-renewal, which distinguishes them from non-stem cells
Stem cell division and differentiation
- Steps in stem cell division and differentiation
- Symmetric division of a stem cell produces two identical stem cells
- Asymmetric division of a stem cell produces one stem cell and one progenitor cell that can differentiate
- Progenitor cells divide and differentiate into specialized cells
Potential uses of stem cells
- Potential therapeutic applications:
- Stroke
- Traumatic Brain Injury
- Learning defects
- Alzheimer's Disease
- Parkinson's Disease, and more.
- Bone marrow transplantation
- Spinal cord injury
- Osteoarthritis and rheumatoid arthritis.
- Crohn's disease
- Potential uses include treating muscle dystrophy, diabetes, and many types of cancer.
Stem cell potency and source development
- Totipotent embryonic stem cells can become an entire organism
- Human embryonic stem cells = harmonic
- Pluripotent embryonic stem cells can become an entire organism
- Some give rise to blood cells
- Multipotent stem cells can become many cells of one type
- Example adult bone marrow, skin, and deciduous teeth (baby teeth)
Hierarchy of haematopoiesis differentiation
- Diagram showing lineage of differentiation A lineage diagram illustrating stem cells leading to progenitor cells and mature cells
- Illustrates haemopoiesis, the process that gives rise to blood cells and platelets
Characteristics of all cell types
- All types of cells have a surrounding membrane, protoplasm, organelles and a control centre with DNA
- Two major categories of cells include prokaryotic and eukaryotic
Prokaryotic Cells
- Lack a nucleus or membrane-bound organelles
- Simplest cell type
- Single circular chromosome
- Nucleoid region (central)
- Surrounded by cell membrane and a cell wall (peptidoglycan)
- Contain ribosomes in their cytoplasm to make proteins
- Examples: Bacteria
Prokaryotic Cells (Bacteria)
-
Cell walls protect the cell and maintain cell shape
-
Bacterial cell walls are composed of peptidoglycan
-
Archaean cell walls lack peptidoglycan
-
Flagella are present in some prokaryotic cells and are used for locomotion and rotary motion
-
Gram-positive bacteria: thick peptidoglycan layer, stains purple, high susceptibility to penicillin.
-
Gram-negative bacteria: thinner peptidoglycan layer, stains pink, low susceptibility to penicillin
Eukaryotic Cells
- Possess a membrane-bound nucleus
- More complex than prokaryotic cells in structure
- Organelles and the endomembrane system compartmentalize many cellular functions
- Contain a cytoskeleton for support and maintaining cellular structures
- Examples include fungi, protozoa, plant cells and animal cells
Eukaryotic cells - Animal cell
- Typical size of 1/100mm
- Two main parts: nucleus and cytoplasm
- Nucleus = DNA storage
- Cytoplasm = fluid inside the cell that contains organelles
Eukaryotic cells - Plant cell
- 40 times bigger than animal cells
- Main parts: nucleus and cytoplasm
- Plant cell wall = cellulose
- Vacuole
- Chloroplast
Cell Structure
- Three main parts:
- Plasma membrane
- Cytoplasm: cytosol + organelles
- Nucleus
Plasma Membrane
- Major structural element in cells
- Phospholipid bilayer
- Cholesterol
- Proteins (integral and peripheral)
- Attached carbohydrates (glycolipids and glycoproteins)
Plasma Membrane (Functions)
- Barrier between inside and outside of the cell
- Controls entry of materials (transport)
- Receives chemical and mechanical signals
- Transmits signals between intracellular and extracellular spaces
Plasma Membrane (Phospholipids)
- Amphipathic
- Non-polar fatty acid chains are in the middle
- Polar regions oriented toward the water in the extracellular fluid and cytosol
Plasma Membrane (Cholesterol)
- Intracellular membranes have less cholesterol
- Associates with membrane phospholipids and proteins
- Forms organized clusters that pinch off portions of the plasma membrane to form vesicles
Plasma Membrane (Glycolipids)
- Forms a polar "head", tails are nonpolar
- Located on the extracellular surface of the membrane.
Plasma Membrane (Protein)
- Integral and peripheral membrane proteins
- Integral proteins are closely associated with membrane lipids
- Peripheral proteins are not amphipathic
Plasma Membrane (Protein) - Functions
- Classify proteins by their position and function:
- Anchoring proteins
- Recognition proteins
- Enzymes
- Receptor proteins
- Carrier proteins
- Leak channels
- Gated channels
Plasma Membrane (Junctions)
- Cells can be physically joined by types of junctions:
- Desmosomes
- Tight junctions
- Gap junctions
- Integrate transmembrane proteins in the plasma membrane to link to specific proteins in the extracellular matrix
Cell Organelles
- Cytoskeleton
- Flagella, cilia, and centrioles
- Endoplasmic reticulum
- Golgi apparatus
- Mitochondrion
- Nucleus, nucleolus, nuclear envelope
- Vesicles (e.g., lysosome)
Cell Organelles (Cytoskeleton)
- Maintains cell shape and organelle positioning.
- Includes microfilaments, intermediate filaments, and microtubules
Cell Organelles (Centrosome)
- Composed of two centrioles
- Composed of microtubules, in 9 clusters of 3 (triplets)
- Pericentriolar material composed of tubulin that grows the mitotic spindle.
- Moves chromosomes during cell division
Cell Organelles (Cilia and Flagella)
- Specialized for motion
- Flagellum: Single tail-like structure on sperm, propels the sperm
- Cilia: Occur in groups, found in the respiratory system, moves mucus
Cell Organelles (Ribosomes)
- Made within the nucleus
- Sites of protein synthesis
- Consist of rRNA and proteins
- Can be attached to endoplasmic reticulum or free in cytosol
Cell Organelles (Endoplasmic Reticulum) (ER)
- Network of folded membranes
- Functions include synthesis and intracellular transport
- Rough ER is studded with ribosomes and is responsible for protein synthesis
- Smooth ER lacks ribosomes and has functions such as lipid synthesis, detoxification, and storage/release of calcium ions
Cell Organelles (Golgi Complex)
- Flattened membranes or cisterns
- Modifies proteins and glycoproteins
- Packages and exports protein or stored in lysosomes
Cell Organelles (Lysosomes)
- Spherical or oval structures
- Contains digestive enzymes for digestion of worn-out parts of the cell
- Tay-Sachs disease (hereditary disorder) - a missing lysosomal enzyme leads to nerve destruction
Cell Organelles (Peroxisomes)
- Moderately dense oval bodies enclosed by a single membrane
- Consume molecular oxygen to remove hydrogen from organic molecules
- Abundant in liver for detoxification
Cell Organelles (Proteasomes)
- Tiny barrel-shaped structure containing proteases
- Digest unneeded or faulty proteins
- Examples include the accumulation of faulty proteins in those with Alzheimer's Disease or Parkinson's
Cell Organelles (Mitochondria)
- Sausage-shaped with many folded membranes (cristae) and a liquid matrix containing enzymes.
- Have some DNA and ribosomes (can make proteins) - Major site of ATP production, O₂ utilization and CO₂ formation Contains enzymes active in Kreb's cycle and oxidative phosphorylation
Nucleus
- Round or oval structure surrounded by a nuclear envelope with nuclear pores.
- Contains nucleolus (makes ribosomes).
- DNA/proteins form a fine network known as chromatin
Nucleus - Characteristics
- The most prominent structure in the nucleus is the nucleolus (small dense region without membrane).
- Associated with DNA regions containing genes which code for the particular types of RNA that is used to build ribosomes.
- Contains DNA in 46 chromosomes, storing genetic material for protein synthesis and in the new cells formed during reproduction.
Comparison of Bacteria, Animal, and Plant Cells
| Feature | Bacteria | Animal | Plant |
|---|---|---|---|
| Cell wall | Present (protein and polysaccharide) | Absent | Present (cellulose) |
| Plasma membrane | Present | Present | Present |
| Flagella/cilia | Sometimes | Sometimes | Sperm of few species |
| Endoplasmic reticulum | Absent | Usually | Usually |
| Microtubules | Absent | Present | Present |
| Centrioles | Absent | Present | Absent |
| Golgi apparatus | Absent | Present | Present |
| Nucleus | Absent | Present | Present |
| Mitochondria | Absent | Present | Present |
| Chloroplasts | Absent | Absent | Present |
| Chromosomes | Single circular DNA | Multiple units, DNA with protein | Multiple units, DNA with protein |
| Ribosomes | Present | Present | Present |
| Lysosomes | Absent | Present | Present |
| Vacuoles | Absent | Present or small | Usually large, single vacuole in mature cells |
Cellular Processes 1&2
Learning Objectives
- Understand the different transport processes (passive and active) and transport in vesicles into and out of cells.
- Understand how substances are transported across membranes
- Apply the transport processes to the functioning of cells and the nervous system / neurotransmission
- Terminology: Body Fluid Pools*
- Intracellular Fluid (ICF) - Inside cells
- Extracellular Fluid (ECF) - Outside cells
- Interstitial fluid - ECF between cells
- Plasma - ECF within blood vessels
- Lymphatic fluid (lymph) - ECF in lymphatic vessels
- Cerebrospinal fluid - ECF in the brain and spinal cord
Terminology: Solutions
- Solvent: Liquid doing the dissolving (usually water)
- Solute: Dissolved material
- Concentration: Amount of solute in a given amount of solvent
- Concentration gradient: Difference in concentration between two areas.
Molecule movement across membranes
- Selective Permeability: the cell membrane allows some substances to cross while restricting others
- Concentration Gradient: a difference in the concentration of a substance across a membrane
- Electrical Gradient: a difference in electrical charge across a membrane (membrane potential).
- Electrochemical Gradient: Combined influence of concentration and electrical gradients on the movement of a molecule
Transport Methods (Passive)
- Simple Diffusion: Substances cross the membrane from high to low concentration.
- Facilitated Diffusion: Substances cross the membrane with the help of proteins (channels or carriers) from high to low concentration.
- Osmosis: Water movement across the membrane from high water concentration to low water concentration.
- Important: Osmolarity (total solute concentration) influences water concentration.
- Tonicity: The ability of a solution to cause a cell to gain or lose water (isotonic, hypertonic, hypotonic)
Transport Methods (Active)
- Active transport: Substances are moved across the membrane against their concentration gradient, requiring energy (ATP).
- Primary Active Transport: Directly uses ATP to move substances. Examples include Na+/K+-ATPase, Ca2+-ATPase, and H+/K+-ATPase.
- Secondary Active Transport: Uses the energy stored in an electrochemical gradient established by primary active transport to move other substances across the membrane.
- Symporters: Move substances in the same direction
- Antiporters: (or exchangers) Move substances in opposite directions
Vesicular Transport
-
Endocytosis: Brings substances into the cell.
- Receptor-mediated endocytosis: Selective uptake of specific substances bound to receptors on the cell surface
- Pinocytosis: ("cell drinking") Non-selective uptake of extracellular fluid.
- Phagocytosis: ("cell eating") Engulfing large particles like bacteria.
-
Exocytosis: Moves substances out of the cell.
Summary of Transport Processes
- Refer to details in the information above.
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Description
Test your knowledge on the key principles of cell theory and the various types of human cells. This quiz covers topics such as prokaryotic vs eukaryotic cells, the roles of stem cells, and their differentiation capabilities. Perfect for students looking to solidify their understanding of cellular biology.
