Cell Structure and Organelles

Plasma membrane: semi-permeable, regulates what enters/leaves cell
Cytoplasm: jelly-like substance inside cell membrane, site of metabolic reactions
Nucleus: control center, contains DNA
Mitochondria: energy-producing organelles
Endoplasmic reticulum (ER): transport and synthesis of proteins and lipids
Ribosomes: site of protein synthesis
Lysosomes: contain digestive enzymes, break down waste
Golgi apparatus: modify and package proteins and lipids for transport
Cytoskeleton: provides structural support and shape

Phospholipid bilayer: hydrophobic tails face inward, hydrophilic heads face outward
Selective permeability: allows certain molecules to pass through
Transport mechanisms:
- Passive transport: diffusion, osmosis
- Active transport: requires energy, carrier proteins

Mitosis: process of cell division, resulting in two identical daughter cells
- Interphase: cell grows, replicates DNA
- Prophase: chromosomes condense, nuclear envelope breaks down
- Metaphase: chromosomes align at center of cell
- Anaphase: sister chromatids separate
- Telophase: nuclear envelope reforms
- Cytokinesis: cytoplasm divides
Meiosis: process of gamete formation, resulting in four non-identical daughter cells

Passive transport:
- Diffusion: molecules move from high to low concentration
- Osmosis: water moves from high to low concentration
- Facilitated diffusion: uses carrier proteins to facilitate transport
Active transport:
- Pump: uses energy to transport molecules against concentration gradient
- Vesicle transport: uses vesicles to transport molecules

Signal transduction pathways: series of molecular interactions that transmit signals
Receptors: proteins that bind to signaling molecules
Signaling molecules: hormones, neurotransmitters, growth factors
Response: cellular response to signal, e.g. gene expression, muscle contraction

Photosynthesis: process by which cells convert light energy into chemical energy
Cellular respiration: process by which cells generate energy from glucose
- Glycolysis: breakdown of glucose into pyruvate
- Citric acid cycle: breakdown of pyruvate into ATP, NADH, FADH2
- Oxidative phosphorylation: generation of ATP from NADH and FADH2
Fermentation: process by which cells generate energy in absence of oxygen

Gene expression: process by which cells convert DNA into functional products
- Transcription: synthesis of RNA from DNA
- Translation: synthesis of protein from RNA
Cellular differentiation: process by which cells become specialized
Apoptosis: programmed cell death, important for development and tissue homeostasis

Plasma membrane is semi-permeable and regulates what enters and leaves the cell.
Cytoplasm is a jelly-like substance inside the cell membrane where metabolic reactions occur.
The nucleus is the control center of the cell containing DNA.
Mitochondria are energy-producing organelles.
Endoplasmic reticulum (ER) is responsible for the transport and synthesis of proteins and lipids.
Ribosomes are the site of protein synthesis.
Lysosomes contain digestive enzymes and break down waste.
Golgi apparatus modifies and packages proteins and lipids for transport.
Cytoskeleton provides structural support and shape to the cell.

Phospholipid bilayer forms the cell membrane with hydrophobic tails facing inward and hydrophilic heads facing outward.
Cell membrane has selective permeability, allowing certain molecules to pass through.
There are two types of transport mechanisms: passive transport and active transport.
Passive transport includes diffusion and osmosis.
Active transport requires energy and involves carrier proteins.

Mitosis is the process of cell division resulting in two identical daughter cells.
Interphase involves cell growth and DNA replication.
Prophase involves chromosome condensation and the breakdown of the nuclear envelope.
Metaphase involves the alignment of chromosomes at the center of the cell.
Anaphase involves the separation of sister chromatids.
Telophase involves the reformation of the nuclear envelope.
Cytokinesis involves the division of the cytoplasm.
Meiosis is the process of gamete formation resulting in four non-identical daughter cells.

Passive transport involves the movement of molecules from high to low concentration.
Diffusion is the movement of molecules from high to low concentration.
Osmosis is the movement of water from high to low concentration.
Facilitated diffusion uses carrier proteins to facilitate transport.
Active transport uses energy to transport molecules against their concentration gradient.
Pump is a type of active transport that uses energy to transport molecules.
Vesicle transport uses vesicles to transport molecules.

Signal transduction pathways are a series of molecular interactions that transmit signals.
Receptors are proteins that bind to signaling molecules.
Signaling molecules include hormones, neurotransmitters, and growth factors.
Response is the cellular response to a signal, such as gene expression or muscle contraction.

Photosynthesis is the process by which cells convert light energy into chemical energy.
Cellular respiration is the process by which cells generate energy from glucose.
Glycolysis is the breakdown of glucose into pyruvate.
Citric acid cycle is the breakdown of pyruvate into ATP, NADH, and FADH2.
Oxidative phosphorylation is the generation of ATP from NADH and FADH2.
Fermentation is the process by which cells generate energy in the absence of oxygen.

Gene expression is the process by which cells convert DNA into functional products.
Transcription is the synthesis of RNA from DNA.
Translation is the synthesis of protein from RNA.
Cellular differentiation is the process by which cells become specialized.
Apoptosis is programmed cell death, important for development and tissue homeostasis.