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Questions and Answers
What is the primary function of ribosomes in eukaryotic cells?
Which organelle is responsible for energy production in eukaryotic cells?
What characteristic distinguishes plant cells from animal cells?
Which structure is noted to have a double membrane and internal stacks of flattened discs in plant cells?
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Which of the following components is NOT typically found in eukaryotic cells?
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What is a key limitation of electron microscopes compared to light microscopes?
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Which characteristic allows stem cells to maintain their population over time?
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Where in the human body can stem cells be predominantly found?
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How is the magnification of an image calculated?
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In which of the following locations would you NOT find stem cells in animals?
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Which statement accurately describes osmosis?
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What distinguishes primary active transport from secondary active transport?
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How can solutions be categorized based on solute concentration?
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Which process allows large or charged molecules to cross the cell membrane?
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Which of the following correctly defines a hypertonic solution?
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Which of the following functions is NOT integral to the survival of living things?
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Which structure is NOT common to all cells?
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In prokaryotic cells, what is the role of pili?
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What size are ribosomes in prokaryotic cells typically characterized as?
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Which of the following best differentiates animal cells from plant cells?
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Which of these is true regarding the cytoplasm in all cells?
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What characteristic is NOT typical for eukaryotic cells?
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Which of the following functions in living organisms is concerned with maintaining a stable internal environment?
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What is the primary function of haemopoietic stem cells in the bone marrow?
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How do membrane proteins contribute to the cell membrane's function?
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Which characteristic of the phospholipid bilayer restricts the passage of certain substances?
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What is the process by which particles move from an area of high concentration to an area of low concentration across the cell membrane?
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What role do the hydrophobic tails of phospholipids play in the structure of the cell membrane?
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Why are epidermal stem cells found in hair follicles considered for regenerative medicine?
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What property of the phospholipid bilayer allows for the spontaneous breaking and reforming of membranes?
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What condition is necessary for materials to move freely across the cell membrane?
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Study Notes
Seven Basic Functions of Living Things
- Metabolism: Chemical reactions are essential for survival.
- Reproduction: Living things produce offspring through sexual or asexual processes.
- Sensitivity: Living things respond to internal and external stimuli.
- Homeostasis: Maintaining a stable internal environment is crucial.
- Excretion: Removal of waste products is necessary.
- Nutrition: Exchange of materials and gases with the environment.
- Growth/Movement: Living things can move and change shape or size.
Four Common Structures in All Cells
- Plasma Membrane: An outer border that maintains an internal chemistry distinct from the exterior.
- Genetic Material: Coded instructions control internal cell activities.
- Ribosomes: Ribosomes translate coded cell instructions into functional elements.
- Cytoplasm: Internal fluid that serves as a medium for metabolic processes.
Prokaryotic Cells
- Genetic material resides in the nucleoid region of the cytoplasm.
- Ribosomes are small (70S) and responsible for protein synthesis.
- All prokaryotes possess a cell wall; some have an outer coating.
- Pili are hair-like extensions that aid in adhesion.
- Flagella are whip-like projections that enable movement.
Drawings of Prokaryotic Cells
- Genetic material should be represented as a loop.
- Pili and flagella extend from the cell wall.
- Ribosomes are depicted as filled dots labeled 70S.
- Flagella are thicker and longer than pili.
- Shape should reflect the specific type of bacteria.
Eukaryotic Organisms
- Cells contain a nucleus and numerous membrane-bound organelles.
- Exhibit a higher level of structural complexity.
- Four types: Animal, Plant, Fungi, and Protist.
Eukaryotic Cells
- Genetic material is housed within the nucleus, a double-membrane structure.
- Ribosomes are larger (80S).
- Share membrane-bound organelles: mitochondria, endoplasmic reticulum, Golgi apparatus, vesicles.
- Plant cells also possess chloroplasts and a large central vacuole.
Drawings of Eukaryotic Animal Cells
- Nucleus should be a double membrane structure with pores.
- ER network is connected membranes, while Golgi membranes are unconnected.
- Ribosomes are filled dots labeled 80S.
- Mitochondria are sausage-shaped with highly folded inner membranes.
- Peroxisomes, lysosomes, and secretory vesicles have similar appearances.
Drawings of Plant Cells
- A large central vacuole occupies significant space.
- Cell wall made of cellulose is a thicker external line.
- Chloroplasts are double-membrane structures with internal stacks of flattened discs.
Microscopes
- Scientific instruments used to visualize objects too small for the naked eye.
- Two main types: Light and Electron.
Light Microscopes
- Use glass lenses to bend light and magnify images.
- Employ visible light and lenses to magnify mounted specimens.
- Include ocular and objective lenses.
Electron Microscopes
- Provide much higher magnification and resolution than light microscopes.
- Cannot view living specimens in natural color.
Calculating Magnification
- Formula: Magnification = Image size ÷ Actual size
- Image size and actual size must be in the same units.
Stem Cells
- Undifferentiated cells capable of dividing and differentiating into various cell types.
- Found in plants and animals.
- Plant stem cells are located in meristems (root and shoot tips).
- Animal stem cells are found in embryos, adult tissues (bone marrow, blood cells), and cord blood.
- Used in treating diseases like leukemia, lymphoma, and diabetes.
Stem Cell Characteristics
- Self-renewal: Continuous division and replication.
- Potency: Capacity to differentiate into specific cell types.
Stem Cell Niches
- Locations where stem cells reside, including bone marrow, hair follicles, heart, intestines, and brain.
- Bone marrow: Haemopoietic stem cells give rise to different blood cell types.
- Hair follicles: Contain epidermal stem cells involved in hair growth and wound repair.
Cell Membrane
- Encloses the cell, separating internal components from the external environment.
- Controls internal conditions and maintains homeostasis.
- Semi-permeable: Allows only certain materials to cross.
- Selective: Regulates the passage of materials that cannot freely cross.
Cell Membrane Components
-
Phospholipid bilayer: Forms a barrier to certain materials.
- Hydrophobic core limits permeability to large and charged substances.
-
Membrane proteins: Embedded within the phospholipid bilayer, acting as transport points for large and charged substances.
- Enable the transport of hydrophilic materials according to need.
Phospholipids
- Composed of a polar head (glycerol and phosphate) and two non-polar tails (fatty acid chains).
- Hydrophilic (water-loving) head region faces outwards.
- Hydrophobic (water-repelling) tail region faces inwards.
- Spontaneously arrange into a bilayer.
Phospholipid Bilayer Properties
- Held together by weak hydrophobic interactions between tails.
- Restricts the passage of many substances.
- Individual phospholipids move within the bilayer, contributing to fluidity and flexibility.
- Allows for spontaneous breaking and reforming of membranes.
Movement Across Biological Membranes
-
Passive transport: Movement along a concentration gradient (high to low).
- Simple diffusion: Movement of small or lipophilic molecules across the bilayer.
- Osmosis: Movement of water molecules through the bilayer.
- Facilitated diffusion: Movement of large or charged molecules via transmembrane proteins.
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Active transport: Movement against a concentration gradient (low to high).
- Primary active transport: Uses ATP hydrolysis to move a molecule against its gradient.
- Secondary active transport: Couples movement of one molecule against its gradient to another molecule moving down an electrochemical gradient.
Osmosis
- Special form of simple diffusion involving the movement of free water molecules.
- Water acts as a solvent, dissolving polar or charged molecules to create a solution.
- Water, being small enough to move between phospholipids, facilitates this movement.
- The net movement of water goes from a region of low solute concentration to a region of high solute concentration.
- Solutions can be categorized as hypertonic, hypotonic, or isotonic based on their relative solute concentrations.
- Hypertonic: Higher solute concentration.
- Hypotonic: Lower solute concentration.
- Isotonic: Equivalent solute concentrations.
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Description
Explore the seven essential functions of living things and learn about the common structures found in all cells. This quiz covers key concepts such as metabolism, reproduction, and the unique features of prokaryotic cells. Test your knowledge on the building blocks of life!
