Cell Structure and Organelles

Study Notes

Phospholipid bilayer: a thin layer of lipid and protein molecules
Semi-permeable: allows certain substances to pass through while keeping others out
Functions:
- Regulates what enters and leaves the cell
- Provides structural support and maintains cell shape
- Acts as a barrier against external environment

Types:
- Nucleus: contains genetic material (DNA)
- Mitochondria: generates energy for the cell through cellular respiration
- Endoplasmic Reticulum (ER): synthesizes and transports proteins and lipids
- Ribosomes: site of protein synthesis
- Lysosomes: contains digestive enzymes to break down and recycle cellular waste
- Golgi Apparatus: processes and modifies proteins and lipids for transport
Functions:
- Carry out specific cellular tasks
- Collaborate to maintain cellular homeostasis

Types:
- Mitosis: somatic cell division resulting in two identical daughter cells
- Meiosis: reproductive cell division resulting in four non-identical daughter cells
Phases:
- Interphase: cell growth and preparation for division
- Prophase: condensation of chromosomes
- Metaphase: alignment of chromosomes at the cell equator
- Anaphase: separation of chromosomes
- Telophase: re-formation of nuclear envelope
- Cytokinesis: physical separation of daughter cells

Types:
- Autocrine signaling: cell signals itself
- Paracrine signaling: cell signals nearby cells
- Endocrine signaling: cell signals distant cells
Mechanisms:
- Ligand-receptor binding: activation of signal transduction pathways
- Signal transduction pathways: cascades of molecular interactions
Functions:
- Regulates cellular responses to environment and stimuli
- Coordinates cellular behavior and communication

Types:
- Passive transport: movement of molecules down concentration gradient
- Active transport: movement of molecules against concentration gradient
Mechanisms:
- Diffusion: spontaneous movement of molecules
- Osmosis: movement of water molecules through a selectively permeable membrane
- Facilitated diffusion: protein-mediated transport
- Active transport: energy-dependent transport
Functions:
- Maintains cellular homeostasis
- Regulates the exchange of materials between the cell and its environment

Composed of a phospholipid bilayer with embedded proteins, regulating what enters and leaves the cell
Semi-permeable, allowing certain substances to pass through while keeping others out
Maintains cell shape and provides structural support

Nucleus contains genetic material (DNA) and controls cell growth and reproduction
Mitochondria generates energy for the cell through cellular respiration
Endoplasmic Reticulum (ER) synthesizes and transports proteins and lipids
Ribosomes are the site of protein synthesis
Lysosomes contain digestive enzymes to break down and recycle cellular waste
Golgi Apparatus processes and modifies proteins and lipids for transport

Mitosis: somatic cell division resulting in two identical daughter cells
Meiosis: reproductive cell division resulting in four non-identical daughter cells
Phases of cell division:
- Interphase: cell growth and preparation for division
- Prophase: condensation of chromosomes
- Metaphase: alignment of chromosomes at the cell equator
- Anaphase: separation of chromosomes
- Telophase: re-formation of nuclear envelope
- Cytokinesis: physical separation of daughter cells

Autocrine signaling: cell signals itself
Paracrine signaling: cell signals nearby cells
Endocrine signaling: cell signals distant cells
Ligand-receptor binding activates signal transduction pathways
Signal transduction pathways: cascades of molecular interactions regulating cellular responses

Passive transport: movement of molecules down concentration gradient
Active transport: movement of molecules against concentration gradient
Mechanisms of transport:
- Diffusion: spontaneous movement of molecules
- Osmosis: movement of water molecules through a selectively permeable membrane
- Facilitated diffusion: protein-mediated transport
- Active transport: energy-dependent transport
Maintains cellular homeostasis and regulates the exchange of materials between the cell and its environment