The Fundamental Unit of Life: Cell

Flashcards covering cell biology concepts

Cell

The structural and functional unit of life

Robert Hooke

First discovered cells in 1665 using a simple microscope; observed cellulae in cork

Leeuwenhoek

First discovered living cells in 1674

Robert Brown

Discovered the nucleus in the cell in 1831

Purkinje

Coined the term 'protoplasm' for the fluid substance of the cell in 1839

Schleiden

Proposed that all plants are composed of cells in 1838

Schwann

Proposed that animal cells are composed of cells in 1839

Virchow

Proposed that all cells arise from pre-existing cells in 1855

Osmosis

The movement of water molecules through a selectively permeable membrane

Hypotonic Solution

Solution with a lower amount of solute than solvent; causes cells to swell

Isotonic Solution

Solution with an equal amount of solute and solvent; no net movement of water

Hypertonic Solution

Solution with a lesser amount of solvent than solute; causes cells to shrink

Plasma Membrane / Cell Membrane

The outermost covering of the cell that separates its contents from its external environment

Selectively Permeable Membrane

The plasma membrane allows or permits the entry and exit of particular materials in and out of the cell.

Diffusion

The process where substances like carbon dioxide or oxygen can move across the cell membrane.

Endocytosis

The flexibility of the cell membrane to engulf in food and other material from its external environment

Endocytosis

Movement of substance from outside to inside the cell

Exocytosis

Movement of substance from inside to outside the cell

Cell Wall

An additional rigid outer covering present in plant cells

Plasmolysis

A living plant cell loses water through osmosis, leading to shrinkage or contraction of the cell content away from the cell wall

Cell Wall Permeability

Allow the cell of plants, fungi, and bacteria to withstand very dilute (hypotonic) external media without bursting.

Nuclear Membrane

A double-layered covering around the nucleus with pores for material transfer

Chromosomes

Rod-shaped structures containing chromosomes, visible when the cell is about to divide

Prokaryotes

Organisms whose cells lack a defined nuclear membrane and other cytoplasmic organelles

Nucleoid

The nuclear region in prokaryotic cells, lacking a nuclear membrane; contains only nucleic acid

Chromosomes

Contain information for inheritance of features from one generation to the next in the form of DNA

Genes

Functional segments of DNA

Nucleus

Plays a central role in cellular reproduction, development, and determining the cell's form and function

Eukaryotic Cells

Cells where the nuclear region is well-defined and surrounded by a nuclear membrane

Cytoplasm

The fluid content inside the plasma membrane, containing cell organelles

Endoplasmic Reticulum (ER)

A large network of membrane-bound tubes and sheets within the cell

Rough Endoplasmic Reticulum (RER)

ER that looks rough under a microscope because of ribosomes attached to it; involved in protein synthesis.

Smooth Endoplasmic Reticulum (SER)

ER that looks smooth as it doesn't have ribosomes attached; involved in the synthesis of lipids and fat molecules

Biogenesis

The synthesis of protein, lipids, and fat molecules; used in building the cell membrane

Smooth Endoplasmic Reticulum (SER)

Plays a crucial role in detoxifying many poisons and drugs

Golgi Apparatus

A system of membrane-bound vesicles (flattened sacs) arranged approximately parallel to each other in stacks (cisterns)

Function of Golgi Apparatus

Storage, modification, and packaging of products; also involved in the formation of lysosomes

Lysosomes

Membrane-bound sacs filled with digestive enzymes; act as a waste disposal system

Function of Lysosomes

Keeps the cell clean by digesting foreign material and worn-out cell organelles

Cell Damage and Lysosomes

Lysosomes may burst and enzymes digest their own cell; known as "suicide bags" of the cell.

Mitochondria

Known as the "powerhouses" of the cell; have two membrane coverings

ATP

Adenosine triphosphate; the energy currency of the cell

Plastids

Can be chromoplasts (colored), chloroplasts (having chlorophyll), or leucoplasts (colorless)

Chloroplasts

Important for photosynthesis

Stroma

The internal organization of the chloroplast, with numerous membrane layers embedded in a material

Vacuoles

Storage sacs for solid or liquid content

Function of Vacuoles

Provide turgidity and rigidity to the cell; store important substances and may expel excess water and waste

Cell Division

The process of cell division for reproduction, growth, and repair

Mitosis

Cell division where the number of chromosomes in daughter cells remains the same

Meiosis

Cell division where the number of chromosomes in daughter cells is halved