Biology: The Fundamental Unit of Life

Vocabulary flashcards covering the discovery of cells, cell theory, membrane transport processes, and the structure and function of cell organelles based on the provided lecture notes.

Robert Hooke

The scientist who observed thin slices of cork in $1665$ and called the little compartments 'cells'.

Cell

A Latin word meaning 'a little room', representing the basic structural and functional units that living things consist of.

Leeuwenhoek

The scientist who, in $1674$, used an improved microscope to discover free-living cells in pond water for the first time.

Robert Brown

The scientist who discovered the nucleus in the cell in $1831$.

Purkinje

The scientist who coined the term 'protoplasm' in $1839$ for the fluid substance of the cell.

Cell Theory

The theory presented by Schleiden ($1838$) and Schwann ($1839$) stating that all plants and animals are composed of cells and that the cell is the basic unit of life.

Virchow

The biologist who expanded the cell theory in $1855$ by suggesting that all cells arise from pre-existing cells.

Unicellular organisms

Organisms that consist of a single cell that constitutes the whole organism, such as Amoeba, Chlamydomonas, Paramoecium, and bacteria.

Multicellular organisms

Organisms, such as some fungi, plants, and animals, where many cells group together to form various body parts and assume different functions.

Plasma Membrane

The flexible outermost covering of the cell made of lipids and proteins that separates the cell contents from the external environment.

Selectively permeable membrane

A property of the cell membrane that allows it to permit the entry and exit of some materials while preventing the movement of others.

Diffusion

The process involving the spontaneous movement of substances like $CO_2$ or $O_2$ from a region of high concentration to a region of low concentration.

Osmosis

The net diffusion of water molecules through a selectively permeable membrane toward a higher solute concentration.

Hypotonic solution

A solution where the medium surrounding the cell has a higher water concentration than the cell, causing the cell to gain water and swell.

Isotonic solution

A solution where the medium has exactly the same water concentration as the cell, resulting in no net movement of water.

Hypertonic solution

A solution where the medium has a lower concentration of water than the cell, causing the cell to lose water and shrink.

Endocytosis

The process by which the flexibility of the cell membrane enables the cell to engulf food and other material from its external environment, as seen in Amoeba.

Cell Wall

A rigid outer covering located outside the plasma membrane in plant cells, mainly composed of cellulose.

Plasmolysis

The phenomenon where a living plant cell loses water through osmosis, resulting in the shrinkage or contraction of cell contents away from the cell wall.

Nucleus

A large, darkly coloured, spherical or oval structure in a cell that has a double-layered nuclear membrane and contains genetic material.

Chromosomes

Rod-shaped structures visible during cell division that contain information for inheritance in the form of DNA and protein.

DNA

Deoxyribo Nucleic Acid; the molecules that contain the information necessary for constructing and organising cells.

Genes

The functional segments of DNA molecules.

Chromatin material

An entangled mass of thread-like structures present in the nucleus of a cell that is not dividing.

Nucleoid

An undefined nuclear region in some organisms like bacteria that contains only nucleic acids due to the absence of a nuclear membrane.

Prokaryotes

Organisms whose cells lack a nuclear membrane and most membrane-bound cytoplasmic organelles.

Eukaryotes

Organisms with cells that have a nuclear membrane as well as membrane-enclosed organelles.

Cytoplasm

The fluid content inside the plasma membrane that contains specialized cell organelles.

Endoplasmic Reticulum (ER)

A large network of membrane-bound tubes and sheets that serves as a channel for transport and a surface for biochemical activities.

Ribosomes

Particles attached to the RER or present in the cell that serve as the sites of protein manufacture.

Membrane biogenesis

The process of building the cell membrane using proteins and lipids manufactured by the endoplasmic reticulum.

Golgi apparatus

A system of membrane-bound vesicles (cisterns) involved in storage, modification, and packaging of cell products.

Lysosomes

Membrane-bound sacs filled with digestive enzymes, known as 'suicide bags' because they may digest their own cell if it gets damaged.

Mitochondria

Organelles known as the 'powerhouses of the cell' that release energy in the form of ATP molecules.

ATP

Adenosine triphosphate; the molecules known as the energy currency of the cell.

Plastids

Organelles present only in plant cells, classified into chromoplasts (coloured) and leucoplasts (white or colourless).

Chloroplasts

Chromoplasts containing the pigment chlorophyll, which are essential for photosynthesis in plants.

Vacuoles

Storage sacs for solid or liquid contents, which are very large in plant cells to provide turgidity and rigidity.

Mitosis

The process of cell division for growth where one mother cell divides to form two identical daughter cells with the same number of chromosomes.

Meiosis

The process of cell division that involves two divisions to produce four new cells with half the number of chromosomes, used to form gametes.