Cell Structure and Function Flashcards
Prokaryotic Cells
Structurally simple, metabolically diverse cells that lack membrane-bound nucleus; include domains bacteria and archaea
Eukaryotic Cells
Possess membrane-bound nucleus, have a higher complexity than prokaryotes due to presence of multiple organelles; includes kingdoms protista, animalia, fungi, and plantae
Cell Theory
All organisms are made up of basic living units called cells, and all cells come from previously existing cells
Surface-area-to-volume ratio
Dividing a large cube into smaller cubes provides more surface area per volume. A higher surface area to volume ratio increases the efficiency of transporting materials into and out of the cell.
Plasma membrane
Consists of phospholipid bilayer embedded with protein molecules. The boundary that separates the living contents of the cells from the surrounding environment. Regulates the entrance and exit of molecules into and out of the cytoplasm.
Cytoplasm
Semi-fluid medium inside the cells, composed of water, salts, and dissolved organic molecules.
Flagella
Long, thin protein extensions that rotate like a propeller, allowing bacteria to move rapidly in a fluid medium.
Fimbriae
Short appendages (hair-like bristles) that help bacteria attach to an appropriate surface. Often increase the ability of pathogenic bacteria to cause disease.
Nucleoid
A region within the cytoplasm of Prokaryotic cells that contains a single chromosome (loop of DNA associated with proteins). Nucleoid is not surrounded by a membrane.
Plasmids
Small accessory rings of DNA in Prokaryotic cells, located within the cytoplasm and contain small amounts of genetic information. May be moved from one prokaryote to another.
Key Bacterial cell features
Capsule, cell wall, plasma membrane, nucleoid, ribosomes, and flagella and/or fimbriae.
Cell Walls (Eukaryotic)
Not present in animal/some protist cells. Walls of plants/algae composed of cellulose, which forms fibrils that lie at right angles to one another for added strength. Walls of some fungi composed of cellulose and chitin. Support and protect the cell.
Organelle
Membrane-bound well-defined sub-cellular structures within a cell that perform a particular function.
Nucleus
Made up of nuclear envelope, nucleoplasm, chromatin, and nucleoli. Stores genetic information, synthesizes DNA and RNA.
Ribosomes
Made up of protein and RNA in two subunits - “large and small.” Protein synthesis. Can be found individually in the cytoplasm or in groups called polyribosomes. Can also be found attached to the endoplasmic reticulum.
Rough Endoplasmic Reticulum (RER)
Network of folded membranes studded with ribosomes. Folding, modification, and transport of proteins for export or associated with membranes.
Smooth Endoplasmic Reticulum (SER)
Network of folded membranes having no ribosomes. Lipid and carbohydrate synthesis in some cells; detoxification of chemicals.
Golgi Apparatus
Stack of small, membranous sacs. Processing, packaging, and distribution of proteins and lipids.
Lysosomes (animal cells only)
membranous vesicle produced by Golgi apparatus containing digestive enzymes. Intracellular digestion; recycling of cellular components.
Vacuoles and vesicles
Membranous sacs of various sizes. Storage of substances. Vacuoles are larger than vesicles. Plant vacuoles are larger than animal - filled with watery fluid to support cell shape.
Peroxisomes
Membranous vesicle containing specific enzymes. Breakdown of fatty acids produces hydrogen peroxide (toxic), but also contain catalase, which breaks down H2O2 into water.
Mitochondria
Inner membrane (cristae) bound by an outer membrane; cellular respiration. Power plants of the cell. Provided by the mother during reproduction.
Chloroplasts (plant cells and some protists)
membranous grana bound by two membranes; photosynthesis.
Cytoskeleton
Microtubules, intermediate filaments, actin filaments. Shape of cell and movement of its parts.
Cilia and flagella (cilia rare in plant cells)
Made of microtubules - arranged in cylinders of nine microtubule doublets arranged in a circle around two central microtubules. Movement of cell.
Chromatin
Substance within the nucleus consisting of DNA and associated proteins. Present during most of a cell’s lifetime.
Chromosomes
Coiled and condensed structures created from chromatin when a cell undergoes cell division. Humans contain 46 chromosomes.
Nucleoplasm
Semifluid medium housing chromosomes.
Nucleolus
Region within the nucleus where ribosomal RNA is produced. rRNA joins with other proteins to form the subunits of ribosomes
Nuclear envelope
Double membrane separating the cytoplasm from the nucleus, continuous with the endoplasmic reticulum. disappears during cellular division.
Nuclear pores
Openings in the nuclear envelope approx. 100nm that permit the bidirectional transport of proteins and ribosomal subunits.
The Endomembrane system
Consists of the nuclear envelope, the endoplasmic reticulum, the Golgi apparatus, and several vesicles. The transportation and product-processing section of the cell. System compartmentalizes the cell to restrict particular enzymatic reaction to specific regions.
Autophagy
When parts of the cell are digested by its own lysosomes (ex: finger webbing)
Chloroplasts
Organelle specializing in converting energy into a form the cell can use. Uses solar energy to synthesize carbohydrates, broken down by mitochondria, converted to ATP. Green from pigment chlorophyll.
Cellular respiration
Process by which the chemical energy of carbohydrates is converted into ATP. Process completed in the mitochondria in Eukaryotic cells.
Carbohydrate+oxygen->carbon dioxide+water+energy
Photosynthesis
Process by which chloroplasts use solar energy to synthesize carbohydrates.
solar energy+carbon dioxide+water->carbohydrate+oxygen
Stroma
Fluid-filled space bounded by two membranes within a chloroplast. Contains a single circular DNA molecule plus ribosomes.
Thylakoids
Interconnected flattened sacs within the stroma. Stacked thylakoids are called grana. There can be hundreds of grana within a single chloroplast.
Chlorophyll
Located in the thylakoid membranes of grana, captures solar energy needed to enable chloroplasts to produce carbohydrates.
Matrix
Inner fluid-filled space of the mitochondria. Contains ribosomes and enzyme products that break down carbohydrates to release energy for ATP.
Cristae
Formed by invagination of the mitochondrial inner membrane. Provide much greater surface area to accommodate protein complexes that produce ATP.
Actin
Part of cell cytoskeleton. Long, extremely thin, flexible fibers that occur in bundles or meshlike networks, about 7nm in diameter.
Motor molecules
Proteins that can attach, detach, and reattach further along the filament by interacting with actin filaments to produce movement.
Intermediate filaments
8-11 nm in diameter. Between actin and microtubules. Ropelike assembly of fibrous polypeptides.
Microtubules
Small, hollow cylinders about 25 nm in diameter. Made of globular protein tubulin.
Centrosome
Main microtubule organization center, they control the assembly of microtubules. Microtubules radiate from the centrosome - cell shape and tracks for organelles to move.
Centrioles
Short cylinders of microtubules surrounding hollow center. In animal cells, 2 centrioles lie at right angles to each other, and replicate before a cell divides.
Endosymbiotic Theory
Theory that first cells were prokaryotes, but that chloroplasts and mitochondria arose from prokaryotes that were engulfed by a cell but not digested (“in” “living together”)
