Module 1- cell structure and diversity Flashcards
Active transport
The movement of a substance across a cell membrane against its concentration
or electrochemical gradient, mediated by specific transport proteins and
requiring an expenditure of energy.
ATP
Adenosine Triphosphate: An adenine-containing nucleoside triphosphate that
releases free energy when its phosphate bonds are hydrolyzed (broken by
chemical reactions).
Aerobic respiration
A catabolic pathway for organic molecules, using oxygen O2 as the final electron acceptor in an electron transport chain and ultimately producing ATP (as well as carbon dioxide and water).
This is the most efficient catabolic pathway and is carried out in most eukaryotic cells and many prokaryotic organisms.
Amino Acid
An organic molecule serving as the monomer of polypeptides. The building blocks of proteins and macromolecules that carry out biological processes.
Archaea
One of two taxonomic prokaryotic domains having archaeal rRNA sequences, the other being Bacteria
Bacteria
Prokaryotic microorganisms typically having cell walls of peptidoglycan.
Biomolecule
A molecule or ion that is involved in the biological processes (e.g. cell division, development) of living organisms.
Carbohydrate
A sugar (monosaccharide), double sugar (disaccharide) or polysaccharide (multiple bonded sugar molecules)
Calvin Cycle
The second of two major stages in photosynthesis (following the light reactions) involving the fixation of atmospheric carbon dioxide and reduction of the fixed carbon into carbohydrate
Cell
A fundamental part of the living system, cells are the smallest collection of matter that perform all activities required for life. All organisms are made up of cells
Cellular respiration
The catabolic pathways of aerobic and anaerobic respiration, which break down organic molecules and use an electron transport chain for the production of ATP
Cellulose
A structural polysaccharide of plant cell walls, consisting of glucose monomers (identical bonded molecules) joined by b glycosidic linkages (a type of bond joining carbohydrate molecules to another group).
Central vacuole
A large membrane-enclosed organelle present in many plant cells; helps maintain turgor pressure of the plant cell, plays a limited storage role, and is also capable of a lysosome-like function in intracellular digestion
Chemiosmosis
An energy coupling mechanism that uses stored energy to drive cellular work, such as ATP synthesis.
Chloroplasts
An organelle found in plants and photosynthetic protists (eukaryotic organism that is not an animal, plant or fungi). Absorbing sunlight for use in photosynthesis.
Chromosome
A cellular structure consisting of one DNA molecule and associated protein
molecules
Chromatin
The complex of DNA and proteins making up eukaryotic chromosomes.
When the cell is not dividing, chromatin exists in its dispersed form, as a mass of very long, thin fibres that are not visible with a light microscope.
Citric acid cycle
A chemical cycle which oxidises acetyl CoA to carbon dioxide, completing the metabolic breakdown of glucose. Occurs within the mitochondrion in eukaryotic cells and in the cytosol of prokaryotes; together with pyruvate oxidation, the second major stage in cellular respiration. Sometimes called the Krebs cycle.
Collagen
A glycoprotein in the extracellular matrix of animal cells that forms strong fibres found extensively in connective tissue and bone
Constitutive secretion
In relation to secretory pathways, constitutive is defined as continuous.(occurring all the time) and is not influenced by external factors or signals.
Co-transport
The coupling of the “downhill” diffusion of one substance to the “uphill” transport of another against its own concentration gradient.
Covalent bond
A type of strong chemical bond in which two atoms share one or more pairs of valence (electrons in the outermost shell) electrons.
Cytoplasm
The contents of the cell bounded by the plasma membrane, excluding the nucleus.
Cytosol
The semifluid portion of the cytoplasm
Cytoskeleton
A network of microtubules, microfilaments, and intermediate filaments that extend through the cytoplasm to serve a variety of functions (mechanical, transport, signalling).
Desmosome
A type of intercellular junction in animal cells, functioning as a rivet, fastening cells together
DNA
Deoxyribonucleic Acid: A nucleic acid molecule, composed of two chains which form a double stranded helix, each chain is made up of four chemical
building blocks called nucleotides. DNA carries the genetic instructions for all cellular processes (growth, development, function and reproduction).
Domain
A taxonomic category above the kingdom level. The three domains of life are Archaea, Bacteria and Eukarya.
Electron acceptor
An oxidizing agent that accepts electrons transferred from another compound.
Electron transport chain
A sequence of electron carrier molecules (membrane proteins) that shuttle electrons down a series of redox reactions that release energy used to make ATP
Electrochemical gradient
The diffusion gradient of an ion / molecule
Endocytosis
Cellular uptake of biological molecules and particulate matter via formation of vesicles from the plasma membrane.
Endomembrane system
The collection of membranes inside and surrounding a eukaryotic cell that performs metabolic functions and regulates protein traffic. This system includes, the plasma membrane and membrane-enclosed organelles like; the
nuclear envelope, endoplasmic reticulum, the Golgi apparatus, lysosomes, vesicles, and the central vacuole.
Endoplasmic
reticulum
An extensive membranous network in eukaryotic cells composed of ribosome-studded (rough) and ribosome-free (smooth) regions.
Endosymbiosis
A relationship between two species in which one organism lives inside the cell or cells of another organism
Endosymbiont theory
The theory that mitochondria and plastids, including chloroplasts, originated as prokaryotic cells were engulfed by a host cell. The engulfed cell and its host cell
then evolved into a single organism
Enzymes
A macromolecule that serves as a catalyst in chemical reactions, increasing the reaction without being consumed.
Eukaryote
An organism with a membrane-enclosed nucleus and organelles. Typical size range 10-100 mm
Euchromatin
The less condensed form of eukaryotic chromatin that is available for transcription
Exocytosis
The cellular secretion of biological molecules by the fusion of vesicles containing them with the plasma membrane.
Extracellular matrix
ECM: The meshwork surrounding animal cells, consisting of glycoproteins, polysaccharides, and proteoglycans synthesised and secreted by cells.
Facilitated diffusion
The passage of molecules or ions down their electrochemical gradient across a biological membrane with the assistance of specific proteins, requiring no energy expenditure
Fermentation
A catabolic process that makes a limited amount of ATP from glucose (or other organic molecules) without an electron transport chain and that produces a characteristic end product, such as ethyl alcohol or lactic acid.
Fungi
Eukaryotic organisms that have cell walls and obtain food from other organisms.
Gap junction
A type of intercellular junction in animal cells, consisting of proteins surrounding a pore that allows the passage of materials between cells
Glycoproteins
A protein with one or more covalently attached carbohydrates
Golgi apparatus
An organelle in eukaryotic cells consisting of stacks of flat membranous sacs that modify, store and route products of the endoplasmic reticulum and synthesise some products, notably non-cellulose carbohydrates.
Hemicellulose
Heterogeneous group of polysaccharides deposited along with cellulose in the cell walls of plants and fungi to provide added strength.
Heterochromatin
Eukaryotic chromatin that remains highly compacted during interphase and is generally not transcribed.
Histone
A small protein with a high proportion of positively charged amino acids that binds to the negatively charged DNA and plays a key role in chromatin structure
Hydrolysis
A chemical reaction that breaks bonds between two molecules by the addition of water; functions in disassembly of polymers to monomers.
Hydrophilic
Having an affinity for water (easily dissolvable).
Hydrophobic
Having no affinity for water; tending to coalesce (combine) and form droplets in water
Integrin
In animal cells, a transmembrane receptor protein interconnecting the extracellular matrix and cytoskeleton.
Intermediate filaments
A component of the cytoskeleton that includes filaments intermediate in size between microtubules and microfilaments.
Ion channel
A transmembrane protein channel that allows a specific ion to diffuse across the membrane down its concentration or electrochemical gradient.
Ligand
A molecule that binds specifically to another molecule, usually a larger one.
Ligand-gated channels
A trans-membrane protein containing a pore that opens or closes as it changes shape in response to a signalling molecule (ligand), allowing or blocking the flow of specific ions
Lignin
A strong polymer embedded in the cellulose matrix of the secondary cell wall of vascular plants that provides structural support in terrestrial species.
Lipid
Any of a group of large hydrophobic biological molecules, including fats, phospholipids, and steroids, that mix poorly, if at all, with water
Lysosome
A membrane-enclosed sac of hydrolytic enzymes found in the cytoplasm of animal cells and some protists
Macromolecule
A very large molecule formed by the joining of smaller molecules. Polysaccharides, nucleic acids and proteins are common examples of polymeric macromolecules. Lipids are examples of non-polymeric macromolecules.
Membrane
Membranes are microscopic layers of lipids and proteins that provide the boundaries between the cell and its surrounding environment, or between cellular compartments (organelles). Cell membranes are composed of a bilayer of phospholipids containing many different types proteins and provide a semi-permeable barrier for the movement of fluids and solutes.
Microscopy
A technical field of using microscopes to view objects that cannot be seen by the naked eye
Microfilaments
A cable composed of actin proteins in the cytoplasm of almost every eukaryotic cell
Microtubules
A hollow rod composed of tubulin proteins that makes up part of the cytoskeleton in all eukaryotic cells and is found in cilia and flagella
Mitochondrion
An organelle found in large numbers in most eukaryotic cells that serves as the site of cellular respiration and energy production; using oxygen to break down organic molecules and synthesise ATP
Monomer
The subunit molecule that serves as the building block of a polymer
(macromolecule).
Mutation
A change in the nucleotide sequence of an organism’s DNA, or in the DNA
or RNA of a virus
Nuclear envelope
In a eukaryotic cell, the double membrane that surrounds the nucleus,
perforated with pores that regulate traffic with the cytoplasm. The outer
membrane is continuous with the endoplasmic reticulum.
Nuclear lamina
A netlike array of protein filaments that lines the inner surface of the nuclear
envelope and help maintain the shape of the nucleus.
Nuclear pore
Small opening in the nuclear envelope through which molecules enter and
exit the nucleus, lined by an intricate protein structure
Nucleic acid
A blueprint for proteins and cellular activity consisting of many nucleotide
monomers (a molecule that can bond with identical molecules to create a
polymer). DNA and RNA are the two types of nucleic acids.
Nucleotides
The building block of a nucleic acid, consisting of a five carbon sugar covalently
bonded to a nitrogenous base and one to three phosphate groups
Nucleus
The organelle of a eukaryotic cell that contains the genetic material in the
form of chromosomes, made up of chromatin.
Organelle
Any of several structures - usually membrane-enclosed - with specialized
functions, suspended in the cytoplasm of eukaryotic cells.
Organism
An individual living thing, consisting of one or more cells.
Osmosis
The diffusion of free water across a selectively permeable membrane.
Oxidative
phosphorylation
The production of ATP using energy derived from reactions in the electron
transport chain; the third major stage of cellular respiration.
Passive transport
The simple diffusion of a substance across a biological membrane with no
energy expenditure.
Pectin
Branched polysaccharides, found in plant cell walls, where they form a matrix
in which cellulose microfibrils are added.
Peptidoglycan
A type of polymer in bacterial cell walls consisting of modified sugars crosslinked by short polypeptides.
Photosynthesis
The conversion of light energy to chemical energy that is stored in sugars
or other organic compounds. This occurs in plants, algae and certain
prokaryotes
Phagocytosis
A type of endocytosis in which large particulate substances or small organisms
are taken up “cellular eating” by a cell. Carried out by some protists and
certain immune cells in animals.
Pinocytosis
A type of endocytosis in which the cell ingests “cellular drinking” extracellular
fluids and its dissolved solutes.
Plasmodesmata
Open channels through the cell wall connecting the cytoplasm and plasma
membrane of adjacent plant cells, allowing water, small molecules and some
larger molecules to pass between cells.
Plastid
One of a family of closely related organelles, including chloroplasts and
chromoplasts. Found in the cells of photosynthetic eukaryotes.
Polarity
A lack of symmetry; structural differences in opposite ends of an organism
or structure, such as a root end and shoot end of a plant.
Polypeptide
A polymer of many amino acids linked together by peptide bonds (a covalent
bond between amino acids).
Polymer
A long molecule (macromolecule) consisting of many similar or identical
monomers bonded together through the process of a chemical reaction
called polymerization.
Polymeric
Term used to describe examples of or relating to a polymer, or having
properties of a polymer. e.g. a polymeric compound
Polysaccharides
A polymer of many monosaccharides, formed by dehydration reactions
Primary cell wall
Plant
In plants, a relatively thin and flexible layer that surrounds the plasma
membrane of a young cell.
Prokaryote
An organism with cells that lack a membrane-enclosed nucleus and organelles.
Typical size range 1-10 mm.
Protein
A biological macromolecule consisting of one or more polypeptides
Proteoglycans
A large molecule consisting of a small core protein with many carbohydrate
chains attached, found in the extracellular matrix of animal cells. A
proteoglycan may consist of up to 95% carbohydrate.
Protist
An informal term applied to any eukaryote that is not a plant, animal or
fungus. Most protists are unicellular, though some are colonial or multicellular
Receptor-mediated
endocytosis
Specialised type of endocytosis that enables a cell to acquire bulk quantities
of specific substances (macromolecules and peptide hormones)
Regulated secretion
In relation to secretory pathways, regulated is defined as occurring only in
response to stimulation via external factors and signals.
RNA
Ribonucleic Acid: A type of nucleic acid consisting of a polynucleotide made
up of nucleotide monomers, a ribose sugar and nitrogenous bases (adenine,
cytosine, guanine, uracil). Usually single-stranded; functions in protein
synthesis, in gene regulation, and as the genome for some viruses.
Ribosome
A complex of ribosomal RNA and protein molecules that functions as a site
of protein synthesis in the cytoplasm
Secretion
(1) The discharge of molecules synthesized by a cell. (2) The active transport
of wastes and certain other solutes (minor components of a solution) from
the body fluid into the filtrate in an excretory system
Secondary cell wall
Plant
In plant cells, a strong and durable matrix that is often deposited in several
laminated layers around the plasma membrane and provides protection and
support
Signal transduction
The linkage of a mechanism, chemical, or electromagnetic stimulus to a
specific cellular response
Simple diffusion
A passive transport process - using no energy investment - of the random
thermal motion of particles of liquids, gases, or solids. Diffusion results in the
net movement of a substance down its concentration gradient from a highly
concentrated region to the low concentrated region in order to spread out
into available space
Stroma
The dense fluid within the chloroplast containing ribosomes and DNA.
Involved in the synthesis of organic molecules from carbon dioxide and water
Synthesis
The production of an organic compound in a living thing, which can be aided
by enzymes
Thylakoid
A flattened, membranous sac inside the chloroplast comprising the thylakoid
membrane and thylakoid space. Their membranes contain molecular
“machinery” used to convert light energy to chemical energy
Tight junction
A type of intercellular junction between animal cells that prevents the leakage
of material through the space between cells
Turgor pressure
The force directed against the plant cell wall from the absorption of fluid
through the process of osmosis. This pressure results in the cells and tissues
to become rigid, providing plant structure.
Vacuole
A membrane-enclosed vesicle whose specialised function varies in different
kinds of cells.
Voltage-gated
channels
A specialised ion channel that opens and closes in response to changes in
membrane potential.
Vesicle
A membranous sac in the cytoplasm of eukaryotic cells.
