Biochemistry Unit 1: Introduction to The Cell

Flashcards covering the fundamentals of cell biology, including cell theory, organelle functions, differences between eukaryotic and prokaryotic cells, and laboratory techniques like microscopy and chromatography.

Cell

The basic structural, functional, and biological unit of life discovered by Robert Hooke in 1665.

Cella

The Latin word from which 'cell' is derived, meaning 'small room'.

Cell Theory

A theory developed by Mathias Jacob and Theodar Schwann stating that all organisms are composed of cells, all cells come from pre-existing cells, and cells contain hereditary information.

Unicellular Organism

An organism made up of just one single cell, such as Bacteria.

Multicellular Organism

An organism made up of many cells, such as animals.

Eukaryotic Cell

Cells which have a true nucleus, a nuclear membrane, well-defined chromosomes, and membrane-bound organelles.

Prokaryotic Cell

Cells whose nucleus is not distinct, DNA is not organized into chromosomes, and which lack most membrane-bound organelles.

Protoplasm

The collective term for the different substances that make up the cell.

Plasma Membrane

A thin, semi-permeable membrane of $7.5$ to $10\,nm$ thickness made of a phospholipid bilayer embedded with proteins ($55\%$ protein, $25\%$ phospholipids).

Cytoplasm

A clear gelatinous fluid (also called cytosol) that fills the cell, contains $90\%$ water, and serves as the seat for pathways like glycolysis.

Organelles

Well-organized, specialized structures within the cytoplasm that carry out vital cell functions.

Mitochondrion

The 'Powerhouse of the cell' that generates energy as Adenosine Triphosphate (ATP) and contains its own DNA.

Cristae

The folded and pleated inner membrane of the mitochondria that provides a large surface area for biochemical processes.

Matrix

The inner cavity of the mitochondria packed with enzymes for the citric acid cycle and fatty acid oxidation.

Porin

An intrinsic protein in the outer mitochondrial membrane that forms channels for solutes and metabolites with molecular weight less than $10,000$.

Endoplasmic Reticulum (ER)

A network of tubular and vascular structures extending from the nucleus to the plasma membrane.

Rough Endoplasmic Reticulum (RER)

A type of ER with ribosomes attached to its surface, involved in protein processing, folding, and sorting.

Smooth Endoplasmic Reticulum (SER)

A type of ER without ribosomes, involved in lipid synthesis, steroid hormone production, and detoxification of drugs.

Golgi Apparatus

A stack of membranous sacs that packs and sorts proteins into vesicles before they are sent to their destinations.

Ribosomes

Spherical organelles made of two subunits (large and small) that link amino acids together to serve as the site for protein synthesis.

Lysosomes

Organelles called 'suicidal bags' that contain hydrolytic enzymes (like protease and lipase) to digest macromolecules or damaged cell material.

Peroxisomes

Microbodies involved in the oxidation of substances and the decomposition of hydrogen peroxide ($H_2O_2$) into water and oxygen.

Microtubules

Long, hollow cylinders ($24\,nm$ diameter) made of $\alpha$-tubulin and $\beta$-tubulin that support the cytoskeleton and aid chromosome segregation.

Microfilaments

Small rod-like structures ($4$-$7\,nm$ diameter) made of the protein Actin that provide shape and help in cytokinesis.

Intermediate Filaments

Cytoskeletal elements ($8$-$12\,nm$ diameter) made of fibrous proteins like keratin that provide mechanical strength to withstand stress.

Centriole

A non-membrane bound cylindrical structure made of tubulin protein strands used in cell division and the formation of cilia and flagella.

Centrosome

A structure formed by two centrioles oriented at right angles to each other.

Vacuole

A membrane-enclosed fluid-filled sac used for waste removal, maintaining pH, and hydrostatic pressure.

Nucleus

The cell's information center that houses chromosomes and regulates gene expression and synthetic activity.

Nucleolus

A structure within the nucleus that synthesizes rRNA and assembles ribosomes.

Flagellum

A long, whip-like structure in prokaryotes used for locomotion.

Pili

Small hair-like structures on the surface of bacteria used for attachment.

Nucleoid

The region in a prokaryotic cell that contains the genetic material.

Plasmid

A small, double-stranded, circular DNA molecule found in bacteria that can replicate itself.

Microscopy

The technical field and science of using microscopes to view objects that cannot be seen with the unaided eye.

Electron Microscope

A microscope that uses a beam of electrons instead of light to illuminate specimens, providing high magnifying power.

Phase Contrast Microscope

A technique that converts phase shifts in light passing through transparent specimens into brightness changes to see unstained objects.

Ultraviolet Microscope

A microscope using quartz lenses and ultraviolet light ($180$-$400\,nm$) for higher resolution images.

Cell Fractionation

A technique of rupturing cells to separate components by size and density using centrifugal force.

Homogenate

An isotonic slurry formed by grinding cells, typically in $0.25\,molal$ sucrose solution at $0$-$4\,^{\circ}C$.

Gel Electrophoresis

A method of separating macromolecules (DNA, RNA, proteins) based on size and charge by passing them through agarose gel with an electric field.

Chromatography

A technique for separating a mixture by passing it through a medium with a stationary and mobile phase so components move at different rates.