A2.2 Cell Structure Flashcards

This set covers IB Biology A2.2 Cell Structure concepts, including cell theory, microscopy techniques, organelle functions, differences between cell types, and HL-specific topics such as endosymbiosis and cell differentiation.

Cell Theory

The scientific theory stating that cells come from preexisting cells, living organisms are composed of cells as the smallest unit of life, and organisms consisting of only one cell carry out all functions in that cell.

Inductive Reasoning

A logical process that uses specific observations to form a general conclusion, such as developing the cell theory from examining biological tissues.

Deductive Reasoning

A logical process that uses a general premise to form a specific conclusion or generate predictions from theories.

Resolution

The ability of a microscope to distinguish two objects as separate from one another, defined as the shortest distance between two points that can be distinguished.

Iodine

A chemical stain used to identify starch, which it colors brown or blue-black.

Methylene Blue

A chemical stain used to identify cell nuclei and DNA.

Gram Stain

A staining technique that divides bacteria into Gram positive or Gram negative types based on the size and composition of the cell wall.

Magnification Formula

The calculation where Magnification = Measured length of image ÷ Actual length of object ($M = \frac{I}{A}$).

Electron Microscope

A device that uses electron beams focused by electromagnets to provide high resolving power ($0.001 \times 10^{-6} \text{m}$ or $1 \text{nm}$) and high magnification ($100,000 \times$ to $300,000 \times$).

Transmission Electron Microscope (TEM)

A type of electron microscope used to view cross-sections of objects.

Scanning Electron Microscope (SEM)

A type of electron microscope used to view the surface topography of objects.

Immunofluorescence

A technique used to visualize specific proteins or antigens by binding them to a specific antibody chemically attached to a fluorescent dye.

Freeze-fracture

An electron microscopic preparation technique involving rapid freezing of cells and fracturing them along lines of weakness, such as the center of membranes.

Cryogenic Electron Microscopy

A transmission electron microscopy technique used to determine the structure of molecules at near atomic-level resolution using low temperatures to freeze specimens.

Plasma Membrane

A phospholipid bilayer barrier that separates the cell interior from its surroundings and controls what enters and exits the cell.

Cytoplasm

A gel-like fluid substance, mainly water with dissolved solutes (cytosol), which serves as the site for most metabolic reactions.

Peptidoglycan

The primary molecular component of the cell wall in prokaryotes like Bacillus and Staphylococcus.

Nucleoid Region

The area in a prokaryotic cell containing a single circular, naked loop of DNA.

Pilus

A hair-like structure in some prokaryotes that enables the cell to attach to surfaces, swap DNA with other cells, or harpoon environmental DNA.

Flagellum

A long extension used for cell locomotion; it rotates in prokaryotes and bends laterally in eukaryotes.

Mitochondrion

A double-membrane organelle adapted for the production of ATP by aerobic cellular respiration.

Rough Endoplasmic Reticulum (rER)

A series of connected flattened membranous sacs with bound ribosomes that synthesize and transport polypeptides.

Smooth Endoplasmic Reticulum (sER)

A series of connected flattened membranous sacs that synthesize phospholipids and cholesterol for membrane repair and lack ribosomes.

Golgi Apparatus

An organelle consisting of stacked, flattened membranes that modifies, sorts, and packs proteins into vesicles for transport.

Lysosome

A single-membrane organelle containing enzymes used to digest large molecules, recycle cell components, or digest pathogens.

Chloroplast

An organelle in plant cells and algae adapted for photosynthesis, containing light-absorbing pigments such as chlorophyll.

Cytoskeleton

A network of microtubules, actin filaments, and intermediate filaments that helps cells maintain shape and enables movement.

Centrioles

Paired cylindrical organelles composed of microtubules arranged in nine groups of three; they arrange the mitotic spindle during cell division.

Homeostasis

The process by which organisms maintain a stable internal environment despite changes in the external environment.

Metabolism

The sum of all chemical reactions in a cell, including exergonic catabolic reactions and endergonic anabolic reactions.

Saprotrophs

Organisms, such as most fungi, that secrete digestive enzymes into their environment and absorb nutrients after external digestion.

Cellulose

The primary structural molecule that composes the cell walls of plants.

Chitin

The molecule that composes the cell walls of fungi.

Aseptate Fungal Hyphae

An atypical eukaryotic structure where hyphae are not separated by septa, forming large multinucleate cells with continuous cytoplasm.

Endosymbiotic Theory

The theory that eukaryotic organelles like mitochondria and chloroplasts originated from small prokaryotic cells being engulfed by larger host cells.

Stem Cells

Undifferentiated cells capable of endlessly reproducing and differentiating into specialized cells based on different patterns of gene expression.

Meristematic Tissue

Undifferentiated plant tissue capable of endlessly reproducing and contributing to primary and secondary growth.