Cell Structure and Organelles Quiz

Cell Structure

Basic unit of life.
Composed of cytoplasm, organelles, and a plasma membrane.
Two main types: prokaryotic (simple, no nucleus) and eukaryotic (complex, with nucleus).
Major components:
- Nucleus: Contains genetic material.
- Cytoplasm: Gel-like fluid where organelles are suspended.
- Plasma Membrane: Semi-permeable barrier regulating substance entry and exit.

Cell Organelles

Specialized structures within a cell, each with specific functions:
- Mitochondria: Powerhouse of the cell; produces energy (ATP) through respiration.
- Ribosomes: Synthesize proteins; can be free-floating or attached to the endoplasmic reticulum.
- Endoplasmic Reticulum (ER):
  - Rough ER: Studded with ribosomes; involved in protein synthesis and processing.
  - Smooth ER: Lacks ribosomes; involved in lipid synthesis and detoxification.
- Golgi Apparatus: Modifies, sorts, and packages proteins and lipids for secretion or delivery to organelles.
- Lysosomes: Contain digestive enzymes; break down waste materials and cellular debris.
- Peroxisomes: Involved in lipid metabolism and detoxification.
- Cytoskeleton: Provides structural support, cell shape, and aids in movement.

Cell Division

Process by which a parent cell divides into two or more daughter cells.
Types:
- Mitosis: Division of somatic cells, resulting in two identical diploid cells.
  - Stages: Prophase, Metaphase, Anaphase, Telophase, and Cytokinesis.
- Meiosis: Division of germ cells leading to four non-identical haploid cells; involves two rounds of division (Meiosis I and II).
Importance: Growth, repair, and reproduction.

Cell Membrane Transport

Mechanisms by which substances move across the cell membrane:
- Passive Transport: Movement without energy; includes diffusion, osmosis, and facilitated diffusion.
- Active Transport: Movement requiring energy (ATP); moves substances against their concentration gradient.
- Endocytosis: Process of engulfing substances into the cell through vesicles.
- Exocytosis: Process of expelling substances from the cell via vesicle fusion with the plasma membrane.

Cell Function

Cells perform various functions essential for life:
- Energy production: Metabolism and ATP generation in mitochondria.
- Protein synthesis: Ribosomes translate genetic information into proteins.
- Communication: Cells communicate via signaling molecules and receptors.
- Homeostasis: Maintaining internal balance despite external changes.
- Reproduction: Cells reproduce through mitosis or meiosis to ensure continuity of life.
- Transport: Regulation of materials in and out of cells for nutrient uptake and waste elimination.

Cell Structure

Cells are the fundamental units of life, comprising cytoplasm, organelles, and a plasma membrane.
Two primary cell types exist: prokaryotic (simple, no nucleus) and eukaryotic (complex, contains a nucleus).
Key components include:
- Nucleus: Houses genetic material (DNA).
- Cytoplasm: A viscous fluid where organelles are suspended.
- Plasma Membrane: A semi-permeable barrier that regulates the movement of substances in and out of the cell.

Cell Organelles

Organelles are specialized structures within cells, each fulfilling distinct roles:
- Mitochondria: Known as the powerhouse; generates ATP through cellular respiration.
- Ribosomes: Sites of protein synthesis; may be free or attached to the endoplasmic reticulum.
- Endoplasmic Reticulum (ER):
  - Rough ER: Covered with ribosomes; involved in protein synthesis and modification.
  - Smooth ER: Lacks ribosomes; functions in lipid synthesis and detoxification processes.
- Golgi Apparatus: Responsible for the modification, sorting, and packaging of proteins and lipids for secretion or delivery.
- Lysosomes: Contain enzymes that digest waste materials and cellular debris.
- Peroxisomes: Play a role in lipid metabolism and the detoxification of harmful substances.
- Cytoskeleton: Provides structural support and shape to the cell, facilitating movement.

Cell Division

Cell division is the process through which a parent cell divides, producing daughter cells.
Main types of cell division:
- Mitosis: Division of somatic cells, resulting in two genetically identical diploid cells.
  - Stages include Prophase, Metaphase, Anaphase, Telophase, and Cytokinesis.
- Meiosis: Division of germ cells, producing four non-identical haploid cells through two cycles (Meiosis I and II).
Cell division is crucial for growth, repair, and reproduction.

Cell Membrane Transport

Transport mechanisms regulate how substances cross the cell membrane:
- Passive Transport: Movement that occurs without energy usage, involving diffusion, osmosis, and facilitated diffusion.
- Active Transport: Requires energy (ATP) to move substances against their concentration gradient.
- Endocytosis: Involves the engulfing of substances into the cell through vesicles.
- Exocytosis: Expulsion of substances from the cell via vesicle fusion with the plasma membrane.

Cell Function

Cells engage in diverse functions vital for sustaining life:
- Energy Production: Mitochondria generate ATP through metabolic processes.
- Protein Synthesis: Ribosomes convert genetic code into proteins.
- Communication: Cells transmit signals using signaling molecules and receptors.
- Homeostasis: Cells maintain stable internal conditions despite external fluctuations.
- Reproduction: Cells divide via mitosis or meiosis to ensure species continuity.
- Transport: Cells regulate nutrient uptake and waste elimination to maintain equilibrium.

Cell Organelles

Nucleus: Houses DNA and acts as the control center for cellular activities.
Mitochondria: Known as the cell's powerhouse, responsible for ATP production through cellular respiration.
Ribosomes: Sites for protein synthesis; can exist either freely in the cytoplasm or embedded in the rough endoplasmic reticulum.
Endoplasmic Reticulum (ER):
- Rough ER: Characterized by ribosomes on its surface, plays a key role in protein synthesis and processing.
- Smooth ER: Lacks ribosomes and is involved in lipid synthesis and detoxification functions.
Golgi Apparatus: Functions in modifying, sorting, and packaging proteins and lipids for secretion or transfer to other organelles.
Lysosomes: Enzymatic sacs that digest waste and cellular debris.
Peroxisomes: Organelles that assist in lipid metabolism and the detoxification of harmful substances.
Cytoskeleton: A network providing structural support, essential for intracellular transport and facilitating cell division.

Cell Division

Mitosis: Results in two identical daughter cells; includes distinct phases:
- Prophase: Chromatin condenses into visible chromosomes; nuclear envelope dissolves.
- Metaphase: Chromosomes align along the cell's equator.
- Anaphase: Sister chromatids split and are pulled toward opposite poles of the cell.
- Telophase: Nuclear envelopes reform around the separated chromosomes; they begin to decondense.
Cytokinesis: The process where the cytoplasm divides, producing two distinct daughter cells.
Meiosis: Specialized division for producing gametes; results in four genetically varied cells.

Cell Structure

Plasma Membrane: Composed of a phospholipid bilayer; selectively permeable to regulate substance entry and exit.
Cytoplasm: Gel-like medium that surrounds organelles and contains cytosol.
Cell Wall: A rigid outer layer found in plant cells that provides structural support and protection; absent in animal cells.
Cilia/Flagella: Projections that assist in cell movement and sensory functions.

Cell Function

Metabolism: Encompasses the chemical reactions essential for maintaining life, including catabolic reactions (breaking down molecules) and anabolic reactions (building up molecules).
Reproduction: Cells reproduce via mitosis (asexual) or meiosis (sexual).
Response to Stimuli: Cells react to environmental changes through complex signaling pathways.
Homeostasis: The process of maintaining internal stability despite external fluctuations.

Cell Membrane Transport

Passive Transport: Movement of substances across membranes without energy usage, including:
- Diffusion: Movement from regions of high concentration to low.
- Facilitated Diffusion: Transport through specific protein channels.
- Osmosis: Water movement across a selectively permeable membrane.
Active Transport: Requires energy (ATP) to move substances against their concentration gradient.
Endocytosis: The cellular process of engulfing substances using vesicles.
Exocytosis: The mechanism of expelling substances from a cell through vesicles.