Cell Structure and Function

Cells are the basic units of life, composed of:
- Plasma membrane (phospholipid bilayer)
- Cytoplasm ( jelly-like substance)
- Genetic material (DNA or RNA)
- Organelles (specialized structures)

Semi-permeable, allowing certain substances to pass through
Functions:
- Regulates what enters and leaves the cell
- Maintains cell shape
- Provides mechanical support

Nucleus:
- Contains most of the cell's genetic material (DNA)
- Controls cell growth and reproduction
Mitochondria:
- Generate energy for the cell through cellular respiration
- Convert glucose into ATP
Endoplasmic Reticulum (ER):
- Involved in protein synthesis and transport
- Rough ER: has ribosomes attached, smooth ER: no ribosomes
Ribosomes:
- Site of protein synthesis
- Found throughout the cytoplasm, attached to ER
Lysosomes:
- Contain digestive enzymes, break down and recycle cellular waste
- Maintain cellular homeostasis

Metabolism:
- Catabolism: breakdown of molecules to release energy
- Anabolism: synthesis of molecules to store energy
Cell signaling:
- Communication between cells through signaling molecules
- Regulates various cellular processes, such as growth and division
Cell division:
- Mitosis: division of somatic cells, producing two identical daughter cells
- Meiosis: division of gametes (sex cells), producing four non-identical daughter cells

Passive transport:
- Diffusion: movement of molecules from high to low concentration
- Osmosis: movement of water molecules through a selectively permeable membrane
Active transport:
- Requires energy, moving molecules against their concentration gradient
- Types: carrier proteins, pumps, and vesicle transport

Nucleus contains most of the cell's genetic material (DNA) and controls cell growth and reproduction
Mitochondria generate energy for the cell through cellular respiration, converting glucose into ATP
Endoplasmic Reticulum (ER) is involved in protein synthesis and transport, with rough ER having ribosomes attached and smooth ER having no ribosomes
Ribosomes are the site of protein synthesis and are found throughout the cytoplasm, attached to ER
Lysosomes contain digestive enzymes, breaking down and recycling cellular waste to maintain cellular homeostasis

Metabolism involves catabolism (breakdown of molecules to release energy) and anabolism (synthesis of molecules to store energy)
Cell signaling involves communication between cells through signaling molecules, regulating cellular processes like growth and division
Cell division includes mitosis (division of somatic cells, producing two identical daughter cells) and meiosis (division of gametes, producing four non-identical daughter cells)

Passive transport includes diffusion (movement of molecules from high to low concentration) and osmosis (movement of water molecules through a selectively permeable membrane)
Active transport requires energy, moving molecules against their concentration gradient
Types of active transport include carrier proteins, pumps, and vesicle transport

Plasma membrane is semi-permeable, regulating molecule movement in and out of the cell.
Cytoplasm is a jelly-like substance where metabolic reactions occur.
Cytoskeleton provides structural support, shape, and movement to the cell via protein filaments.
Organelles are specialized structures within the cell, including:
- Nucleus, containing genetic material (DNA), regulating cell growth and division.
- Mitochondria, generating energy through cellular respiration.
- Endoplasmic Reticulum (ER), involved in protein synthesis, transport, and storage.
- Ribosomes, the site of protein synthesis.
- Lysosomes, containing digestive enzymes for breaking down and recycling cellular waste and foreign substances.

Passive transport occurs without energy input, moving molecules from high to low concentration.
Diffusion is the random movement of molecules from high to low concentration.
Osmosis is the movement of water molecules from high to low concentration through a selectively permeable membrane.
Active transport requires energy input, moving molecules from low to high concentration.
Carrier proteins use ATP energy to transport molecules across the membrane.
Pumps use ATP energy to transport molecules against their concentration gradient.

Mitosis is the process of cell division, resulting in two daughter cells with the same number of chromosomes as the parent cell.
Interphase involves cell growth and DNA replication.
Prophase includes chromatin condensation and nuclear envelope breakdown.
Metaphase involves chromosomes lining up at the cell center.
Anaphase involves sister chromatids separating and moving to opposite poles.
Telophase involves nuclear envelope reformation and chromosome uncoiling.
Meiosis is the process of cell division, resulting in four daughter cells with half the number of chromosomes as the parent cell, involved in gamete production.

Signal transduction pathways are a series of molecular events that allow cells to respond to stimuli.
Receptors are proteins on the cell surface that bind to signaling molecules.
Signaling molecules include hormones, neurotransmitters, or growth factors that trigger a response.
Second messengers relay the signal from the receptor to the target molecule.