Module 1: Cell and Cell Membrane

Nucleus

Control centre for the cell — controls protein synthesis.

Contains genetic material and is the blueprint for the activity of all cells

Surrounded by the nuclear envelope (nuclear pores allow selective transport of molecules in and out.

Endoplasmic Reticulum (ER)

A cell organelle that assists in the synthesis and processing of proteins and lipids. It exists in two forms: rough, with ribosomes for protein synthesis, and smooth, for lipid synthesis and detoxification.

Rough Endoplasmic Reticulum

A type of endoplasmic reticulum that is studded with ribosomes on its cytoplasmic surface, primarily involved in the synthesis and processing of proteins.

Smooth Endoplasmic Reticulum

A type of endoplasmic reticulum that has no ribosomes attached and looks smooth under the microscope. It has specialised functions depending on the kind of cell including lipid synthesis, detoxification of drugs and poisons, and storage of calcium ions.

Golgi apparatus

A cell organelle responsible for modifying, sorting, and packaging proteins and lipids for secretion or delivery to other organelles. It plays a key role in processing molecules synthesized in the endoplasmic reticulum.

Lysosomes

Organelles that contain digestive enzymes to break down waste materials and cellular debris, aiding in cellular cleanup and recycling.

Peroxisomes

Organelles that contain enzymes to break down fatty acids and detoxify harmful substances, playing a crucial role in cellular metabolism.

Mitochondria

Organelles known as the powerhouse of the cell, responsible for producing ATP through aerobic respiration. The mitochondria takes nutrients from the food we eat, combines it with oxygen to make energy releasing CO2 and H2O as a bi-product.

Adenosine Triphosphate (ATP)

The primary energy currency of the cell, ATP stores and transfers energy for various cellular processes. It consists of three phosphate groups. When hydrolyzed, it releases energy that powers cellular activities. ADP is formed after ATP donates one phosphate group.

Hydrophobic

Hates water and tends to avoid contact with it.

Hydrophilic

Loves water and tends to interact with it.

Passive Transport

The movement of molecules across the cell membrane without the use of energy, typically following their concentration gradient.

Active Transport

The process of moving molecules across the cell membrane using energy (usually in the form of ATP), often against their concentration gradient (from high concentration to low concentration)

Concentration Gradient

Differences in concentration across two areas. The concentration gradient influences the direction of movement for molecules during diffusion and is crucial for processes like passive and active transport. The greater the difference, the greater the concentration gradient.

Diffusion

The process of movement of molecules from an area of high concentration to an area of low concentration until equilibrium is reached.

Osmosis

The process of movement of water molecules across a semipermeable membrane from an area of low solute concentration (low osmolarity) to an area of high solute concentration (high osmolarity), until equilibrium is achieved. It controls the balance of water and solutes in cells.

Tonicity

The effect that a solution has on cell size and shape due to water movement (osmosis). Tonicity describes whether a solution is isotonic, hypertonic, or hypotonic relative to the cell's internal environment.

Isotonic solution

A solution that has the same solute concentration as another solution, resulting in no net movement of water across the cell membrane. Cells remain unchanged in size and shape in isotonic conditions.

Hypotonic solution

A solution that has a lower osmolarity than another solution, leading to water movement into the cell. This can cause the cell to swell and potentially burst.

Hypertonic solution

A solution that has a higher osmolarity than another solution, resulting in water movement out of the cell. This can cause the cell to shrink or crenate.

Primary active transport

Directly uses energy from breakdown of ATP to transport molecules against their concentration gradient across a membrane.

Secondary active transport

Uses energy stored in ion concentration gradients created by primary active transport. It indirectly uses ATP. Secondary active transporters always move more than one molecule at a time.

Na+-K+ pump

A membrane protein that actively transports sodium ions out of the cell and potassium ions into the cell, utilizing ATP for energy — against their concentration gradient

Endocytosis

The process by which cells engulf substances from outside their membrane, incorporating them into vesicles to bring them into the cell. This process allows for the uptake of large molecules or particles.

Exocytosis

The process by which cells expel substances in vesicles, fusing with the plasma membrane to release their contents outside the cell.