Questions and Answers
Who was the first person to use the term 'cell'?
Prokaryotic cells contain membrane-bound organelles.
False
What is the main function of the mitochondria?
production of energy in the form of ATP
Eukaryotic cells have a membrane-bound ______ and several other membrane-bound subcellular organelles.
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Match the cell life cycle stages with their descriptions:
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Study Notes
Cell Biochemistry
- Explores molecular mechanisms of normal cellular processes and diseases.
- All higher living organisms, including humans, are made up of cells.
Cell Types
- Two major classes: Prokaryotes and Eukaryotes.
- Prokaryotes: no membrane-bound nucleus, no subcellular organelles, only infoldings of the plasma membrane called mesosomes.
- Eukaryotes: have a membrane-bound nucleus and membrane-bound subcellular organelles.
Cell Theory
- A cell is the basic structural and functional unit of living organisms.
- The activity of an organism depends on the collective activities of its cells.
- The principle of complementarity states that the activities of cells are dictated by their structure, which determines function.
Eukaryotic Cell vs. Prokaryotic Cell
- Eukaryotes:
- DNA is found in the nucleus of the cell.
- Contain membrane-bound organelles (e.g., mitochondria, endoplasmic reticulum, and Golgi complex).
- Cell division involves mitosis.
- Prokaryotes:
- DNA is not enclosed within a membrane.
- Lack membrane-enclosed organelles.
- Usually divide by binary fission.
Molecular Composition of Cell
- Water accounts for about 70-75% of the cell's weight.
- Organic compounds (nucleic acids, proteins, polysaccharides, and lipids) account for 25-30% of the cell's weight.
- Proteins account for 10-20% of the cell's weight.
- Inorganic compounds account for the rest of the cell's weight.
Eukaryotic Cell Components
- Plasma membrane:
- Structure: phospholipid bilayer containing cholesterol and proteins, and some carbohydrates.
- Functions: acts as a physical barrier, regulates material movement, and functions in cell communication.
- Nucleus:
- Structure: enclosed within a double membrane called the nuclear envelope, contains nucleolus.
- Function: contains DNA that serves as the genetic material for directing protein synthesis.
- Cytoplasm:
- Structure: contains organelles and provides support for organelles.
- Function: responsible for various cellular processes.
- Mitochondria:
- Structure: double-membrane-bound organelles containing a circular strand of DNA.
- Function: responsible for the production of energy in the form of ATP.
- Lysosomes:
- Structure: spherical-shaped membrane-bound organelles formed from the Golgi apparatus.
- Function: digest microbes or materials by the cell.
- Endoplasmic reticulum:
- Structure: extensive interconnected membrane network.
- Function: modifies, transports, and stores proteins produced by attached ribosomes.
- Golgi apparatus:
- Structure: series of several elongated, flattened sac-like membranous structures.
- Function: modifies, packages, and sorts materials, and transports them in vesicles.
- Peroxisomes:
- Structure: similar to lysosomes.
- Function: contains enzymes involved in the metabolism of hydrogen peroxide.
- Cytoskeleton:
- Structure: organized network of protein filaments.
- Function: maintains integral structural support and organization of cells.
Cell Membrane Transport
- Passive transport:
- Diffusion: movement of a substance from an area of higher concentration to an area of lower concentration.
- Facilitated diffusion: requires a protein carrier.
- Osmosis: diffusion of water across a selectively permeable membrane.
- Active transport:
- Uses energy (ATP) provided by the cell.
- Example: sodium-potassium activated ATPase (sodium pump).
- Exocytosis and endocytosis:
- Exocytosis: bulk movement of substances out of the cell by fusion of secretory vesicles with the plasma membrane.
- Endocytosis: bulk movement of substances into the cell by vesicles forming at the plasma membrane.
Cell Life Cycle
- Interphase:
- Longer phase of the cell cycle where the cell is active and preparing for cell division.
- DNA molecule is duplicated exactly in a process called DNA replication.
- Cell division:
- Mitosis consists of four stages: prophase, metaphase, anaphase, and telophase.
- Result: two daughter nuclei, each identical to the mother nucleus.
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Description
Explore the basics of cell biology, including molecular mechanisms, cell types, and cell theory. Learn about prokaryotes and eukaryotes, and the fundamental principles of cellular structure and function.