Questions and Answers
What is the main function of the plasma membrane?
What is the main component of the cell wall in plant cells?
What is the role of the nucleus in the cell?
What is the type of transport that requires the cell to use energy?
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What is the movement of molecules from a higher to a lower concentration without using energy?
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What is the site of many cellular processes like metabolism and protein synthesis?
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What is the term for the movement of water molecules across a selectively permeable membrane from higher to lower water concentration?
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What is the structure present outside the plasma membrane in plant cells, bacteria, and fungi?
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What is the primary function of the plasma membrane?
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Who is credited with the discovery of cells?
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What is the name of the theory that states that all living organisms are composed of cells?
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What is the function of the nucleus in a cell?
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What is the term for organisms that consist of only one cell?
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Who extended the cell theory by stating that new cells arise from the division of pre-existing cells?
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What is the term for the jelly-like substance inside the plasma membrane?
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What is the characteristic of cells in terms of their shape?
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Study Notes
Fundamental Unit of Life - The Cell
- Cells are the structural and functional units of life for all living organisms
- Living organisms are made up of cells, which carry out all the functions necessary for life
- Cells are the most basic units that make up the structure and carry out the functions of living things
- The discovery and understanding of cells has been a key development in biology
Discovery of Cells
- Robert Hooke was the first person to observe and describe cells in 1665 using a self-designed microscope
- Hooke observed and named the "cells" in a sample of cork bark
- Anthony van Leeuwenhoek later observed the first living cells under a microscope in 1674
Advances in Cell Theory
- Matthias Schleiden and Theodor Schwann proposed the cell theory in the 1830s:
- All plants are composed of cells
- All animals are composed of cells
- Rudolf Virchow later extended the cell theory, stating that new cells arise from the division of pre-existing cells (omnis cellula e cellula)
Diversity of Cells
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Cells can vary greatly in their:
- Number - from single-celled organisms to multicellular organisms with trillions of cells
- Shape - can be spherical, oval, rod-shaped, branched, spindle-shaped, etc.
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Single-celled organisms (unicellular) have only one cell
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Multicellular organisms have many cells of different types and functions### Cell Components and Structure
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Cells have various structural components that perform different functions
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The plasma membrane is the outermost boundary of the cell, made up of phospholipids and proteins
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The plasma membrane is selectively permeable, controlling the entry and exit of substances into and out of the cell
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The cytoplasm is the jelly-like substance inside the plasma membrane, containing various organelles
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The nucleus is the control center of the cell, containing the cell's DNA
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Other organelles like mitochondria, chloroplasts, Golgi bodies, etc. perform specialized functions within the cell
Plasma Membrane
- The plasma membrane is flexible and fluid in structure, following the fluid mosaic model proposed by Singer and Nicolson
- It is made up of phospholipids and proteins, which allow selective permeability
- The plasma membrane controls the movement of substances in and out of the cell
Cell Wall
- The cell wall is a non-living, rigid structure present outside the plasma membrane in plant cells, bacteria, and fungi
- It provides structural support and protection to the cell
- The cell wall is made of different materials in different organisms - cellulose in plants, peptidoglycan in bacteria, chitin in fungi
Nucleus
- The nucleus is the control center of the cell, containing the cell's DNA
- It regulates all cellular activities and is considered the "brain of the cell"
- The DNA in the nucleus stores the genetic information that guides the cell's functioning
Cytoplasm
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The cytoplasm is the jelly-like substance inside the plasma membrane, containing various organelles
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It is the site of many cellular processes like metabolism, protein synthesis, etc.### Transport and Osmosis
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Transport of substances across the cell membrane can be passive or active
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Passive transport involves movement of substances from higher to lower concentration without using energy
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Active transport requires the cell to use energy (ATP) to move substances against the concentration gradient
Passive Transport
- Diffusion - movement of molecules (solids, liquids, gases) from higher to lower concentration, no energy required
- Osmosis - movement of water molecules across a selectively permeable membrane from higher to lower water concentration
Osmosis
- Occurs when water molecules move from a region of higher water concentration (lower solute concentration) to a region of lower water concentration (higher solute concentration)
- Requires the cell membrane to be selectively permeable to allow water but not solute molecules to pass through
- Can be:
- Endosmosis - water moves into the cell, causing it to swell
- Exosmosis - water moves out of the cell, causing it to shrink
Hypotonic, Hypertonic, Isotonic Solutions
- Hypotonic solution has lower solute concentration than inside the cell, water moves in, cell swells
- Hypertonic solution has higher solute concentration than inside the cell, water moves out, cell shrinks
- Isotonic solution has equal solute concentration as inside the cell, no net movement of water
Fundamental Unit of Life - The Cell
- Cells are the structural and functional units of life for all living organisms
- They carry out all the functions necessary for life and are the most basic units that make up the structure and functions of living things
Discovery of Cells
- Robert Hooke was the first person to observe and describe cells in 1665 using a self-designed microscope
- He observed and named the "cells" in a sample of cork bark
- Anthony van Leeuwenhoek later observed the first living cells under a microscope in 1674
Advances in Cell Theory
- Matthias Schleiden and Theodor Schwann proposed the cell theory in the 1830s, stating that:
- All plants are composed of cells
- All animals are composed of cells
- Rudolf Virchow later extended the cell theory, stating that new cells arise from the division of pre-existing cells (omnis cellula e cellula)
Diversity of Cells
- Cells can vary greatly in their:
- Number, from single-celled organisms to multicellular organisms with trillions of cells
- Shape, such as spherical, oval, rod-shaped, branched, or spindle-shaped
- Single-celled organisms (unicellular) have only one cell
- Multicellular organisms have many cells of different types and functions
Cell Components and Structure
- The plasma membrane is the outermost boundary of the cell, made up of phospholipids and proteins, and is selectively permeable
- The cytoplasm is the jelly-like substance inside the plasma membrane, containing various organelles
- The nucleus is the control center of the cell, containing the cell's DNA and regulating all cellular activities
- Other organelles like mitochondria, chloroplasts, and Golgi bodies perform specialized functions within the cell
Plasma Membrane
- The plasma membrane is flexible and fluid in structure, following the fluid mosaic model
- It is made up of phospholipids and proteins, allowing selective permeability
- The plasma membrane controls the movement of substances in and out of the cell
Cell Wall
- The cell wall is a non-living, rigid structure present outside the plasma membrane in plant cells, bacteria, and fungi
- It provides structural support and protection to the cell
- The cell wall is made of different materials in different organisms, such as cellulose in plants, peptidoglycan in bacteria, and chitin in fungi
Nucleus
- The nucleus is the control center of the cell, containing the cell's DNA
- It regulates all cellular activities and is considered the "brain of the cell"
- The DNA in the nucleus stores the genetic information that guides the cell's functioning
Cytoplasm
- The cytoplasm is the jelly-like substance inside the plasma membrane, containing various organelles
- It is the site of many cellular processes like metabolism, protein synthesis, etc.
Transport and Osmosis
- Transport of substances across the cell membrane can be passive or active
- Passive transport involves movement of substances from higher to lower concentration without using energy
- Active transport requires the cell to use energy (ATP) to move substances against the concentration gradient
Passive Transport
- Diffusion is the movement of molecules from higher to lower concentration, without using energy
- Osmosis is the movement of water molecules across a selectively permeable membrane from higher to lower water concentration
Osmosis
- Occurs when water molecules move from a region of higher water concentration (lower solute concentration) to a region of lower water concentration (higher solute concentration)
- Requires the cell membrane to be selectively permeable to allow water but not solute molecules to pass through
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Description
Discover the basics of cells, the structural and functional units of life, and learn about their discovery and significance in biology.
