Bio 110

microtubule

A cytoplasmic tubule made up of polymers of alpha- and beta-tubulin dimers. It is the structural component of cytoskeleton, cilia, and eukaryotic flagella.

organic catalyst

organic compound capable of initiating or speeding up a chemical reaction.

pyruvic acid

organic liquid produced by the breakdown of carbohydrates and sugars during glycolysis, If oxygen is available, pyruvic acid is converted to acetyl coenzyme A that enters the energy-producing pathway, the Krebs cycle. If oxygen is lacking, pyruvic acid is converted to lactic acid.

hypertonic

Having a greater degree of tone or tension. Having a higher osmotic pressure in a fluid relative to another fluid. Of or pertaining to a solution (e.g. extracelllular fluid) with higher solute concentration compared with another. (see: hypotonic, isotonic). For example, if the extracellular fluid has greater amounts of solutes than the cytoplasm, the extracellular fluid is said to be hypertonic. Supplement A cell placed in a highly concentrated solution will result in the water molecules diffusing out of the cell. Eventually, the cell will shrink. It should be noted, however, that not all cells in a hypertonic solution will shrink. The cells have ways to circumvent hypertonicity (see osmoregulation).

nucleolus

The round granular structure within the nucleus of a cell, and composed of protein and RNA.

asters

microtubules and fibers that radiate out from the centrioles

hypotonic

refers to a solution with a comparatively lower concentration of solutes compared to another

anaphase

the stage of meiotic or mitotic cell division in which the chromosomes move away from one another to opposite poles of the spindle.

kinetic energy

energy due to the motion of an object

adenosine diphosphate or ATP

(1) A nucleotide made up of adenine, ribose, and two phosphate units; having a molecular formula: C10H15N5O10P2 (2) The product of ATP de-phosphorylation via ATPases to release energy; and can be converted to ATP by phosphorylation (addition of phosphate and energy) via ATP synthases to store energy. Supplement Adenosine diphosphate or ADP is the result when ATP loses one of its phosphate groups when the energy is released to power up many vital cellular processes.

c-3 plants

(1) A plant that utilizes the C3 carbon fixation pathway as the sole mechanism to convert CO2 into an organic compound (i.e. 3-phosphogylycerate). (2) A plant in which the CO2 is first fixed into a compound containing three carbon atoms before entering the Calvin cycle of photosynthesis.

glycocalyx

(1) The outer layer usually made up of bound polysaccharides on the cell surface and superficial layer of unbound proteoglycans and glycoproteins (2) Sugar coat surrounding the cell wall of bacterium, as bacterial capsule or slime layer in various bacterial cells

homeostasis

(1) The tendency of an organism or a cell to regulate its internal conditions, usually by a system of feedback controls, so as to stabilize health and functioning, regardless of the outside changing conditions (2) The ability of the body or a cell to seek and maintain a condition of equilibrium or stability within its internal environment when dealing with external changes

nadh

The reduced form of NAD

centrioles

the diffusion of hydrogen ions (protons) across the biological membrane via the ATP synthase (a transport protein) due to a proton gradient that forms on the other side of the membrane. The proton gradient forms when the hydrogen ions accumulate as they are forcibly moved to the other side of the membrane by carrier proteins while the electrons pass through the electron transport chain in the membrane. Since more hydrogen ions are on the other side they tend to move back across the membrane via the ATP synthase. As they flow through energy is released which is then used to convert ADP to ATP (by a process called phosphorylation).

c-4 plants

(2) A plant in which the CO2 is first fixed into a compound containing four carbon atoms before entering the Calvin cycle of photosynthesis.

citric acid cycle (KREBS)

1) A cycle of reactions catalyzed by enzymes in which pyruvate derived from nutrients and converted to Acetyl Coenzyme A is completely oxidized and broken down into carbon dioxide and water to produce high-energy phosphate compounds, which are the source of cellular energy. (2) One of the major metabolic pathways of cellular respiration, and involves a cyclic series of enzymatic reactions by which pyruvate converted into Acetyl Coenzyme A is completely oxidized to CO2 and hydrogen is removed from the carbon molecules, transferring the hydrogen atoms and electrons to electron-carrier molecules (e.g. NADH and FADH2) as well as the metabolic energy to high energy bonds (e.g. ATP).

endoplasmic reticulum

1) A membrane-bounded organelle that occurs as labyrinthine, interconnected flattened sacs or tubules that is connected to the nuclear membrane, runs through the cytoplasm, and may well extend into the cell membrane.

ribosome

1) A minute particle composed of protein and ribonucleic acid (RNA) that serves as the site of protein synthesis. (2) A molecule consisting of two subunits that fit together and work as one to build proteins according to the genetic sequence held within the messenger RNA (mRNA). Using the mRNA as a template, the ribosome traverses each codon, pairing it with the appropriate amino acid. This is done through interacting with transfer RNA (tRNA) containing a complementary anticodon on one end and the appropriate amino acid on the other. (3) A sphere-shaped structure found in the cytoplasm of prokaryotic and eukaryotic cells. Some ribosomes occur freely in the cytosol whereas others are attached to the nuclear membrane or to the endoplasmic reticulum (ER) giving the latter a rough appearance, hence, the name rough ER or rER. Supplement Ribosomes of prokaryotes (e.g. bacteria) are smaller than most of the ribosomes of eukaryotes (e.g. plants and animals). However, the plastids and mitochondria in eukaryotes have smaller ribosomes similar to those in prokaryotes - a possible indication of the evolutionary origin of these organelles.

glycolysis

1) The initial metabolic pathway of cellular respiration in which a series of reactions happening in the cytosol results in the conversion of a monosaccharide, often glucose, into pyruvic acid, and the concomitant production of a relatively small amount of high-energy molecules, such as ATP. (2) The cellular degradation of the simple sugar, glucose, to yield ATP as an energy source.

diffusion

1. The passive movement of molecules or particles along a concentration gradient, or from regions of higher to regions of lower concentration.

vesicle

A bubble-like membranous structure that stores and transports cellular products, and digests metabolic wastes within the cell; an intracellular membranous sac that is separated from the cytosol by at least one lipid bilayer.

autotroph

A organism capable of making nutritive organic molecules from inorganic sources via photosynthesis (involving light energy) or chemosynthesis (involving chemical energy).

nadp

A coenzyme that occurs in many living cells and functions as an electron acceptor like NAD but reacts with different metabolites

chromatin

A complex of nucleic acids (e.g. DNA or RNA) and proteins (histones), which condenses to form a chromosome during cell division. In eukaryotic cells, it is found within the cell nucleus whereas in prokaryotic cells, it is found within the nucleoid. Its functions are to package DNA into a smaller volume to fit in the cell, strengthen the DNA to allow mitosis and meiosis, and to serve as a mechanism to control expression.

calvin-benson cycle

A cyclical series of biochemical reactions that occur in the stroma of chloroplasts during photosynthesis. It includes the light-independent reactions such as carbon fixation, reduction reactions and ribulose 1,5-diphosphate (RuDP) whereby sugars and starch are ultimately produced. Supplement At this stage of photosynthesis, the energy released from ATP produced during light reactions is used to drive the conversion of carbon dioxide and other compounds into an organic molecule (e.g. glucose). In C3 plants, the Calvin-Benson cycle is used directly to fix carbon dioxide. In C4 plants and CAM plants, a different carbon fixation precedes Calvin-Benson cycle.

meiosis

A form of cell division happening in sexually reproducing organisms by which two consecutive nuclear divisions (meiosis I and meiosis II) occur without the chromosomal replication in between, leading to the production of four haploid gametes (sex cells), each containing one of every pair of homologous chromosomes (that is, with the maternal and paternal chromosomes being distributed randomly between the cells).

facilitative transport

A form of passive transport in which materials are moved across the plasma membrane by a transport protein down their concentration gradient ; hence, it does not require energy.

cleavage furrow

A groove formed from the cell membrane in a dividing cell as the contractile ring tightens.

electron transport chain

A group of compounds that pass electron from one to another via redox reactions coupled with the transfer of proton across a membrane to create a proton gradient that drives ATP synthesis. Supplement The major role of electron transport chain is to extract energy via redox reactions in cellular respiration and photosynthesis. In eukaryotes, the electron transport chain can be found in the inner mitochondrial membrane where it serves as the site of oxidative phosphorylation. It is also found in the thylakoid membrane of the chloroplast in photosynthetic organisms.

active transport

A kind of transport wherein ions or molecules move against a concentration gradient, which means movement in the direction opposite that of diffusion - or - movement from an area of lower concentration to an area of higher concentration. Hence, this process will require expenditure of energy, and the assistance of a type of protein called a carrier protein.

cell wall

A membrane of the cell that forms external to the cell membrane whose main role is to give cells rigidity, strength and protection against mechanical stress. It is found in cells of plants, bacteria, archaea, fungi, and algae. Animals and most protists do not have cell walls.

vacuole

A membrane-bound vesicle found in the cytoplasm of a cell whose function includes intracellular secretion, excretion, storage, and digestion.

fluid mosaic model

A model conceived by S.J. Singer and Garth Nicolson in 1972 to describe the structural features of biological membranes. The plasma membrane is described to be fluid because of its hydrophobic integral components such as lipids and membrane proteins that move laterally or sideways throughout the membrane. That means the membrane is not solid, but more like a 'fluid'. The membrane is depicted as mosaic because like a mosaic that is made up of many different parts the plasma membrane is composed of different kinds of macromolecules, such as integral proteins, peripheral proteins, glycoproteins, phospholipids, glycolipids, and in some cases cholesterol, lipoproteins. According to the model, the plasma membrane is a lipid bilayer (interspersed with proteins). It is so because of its phospholipid component that can fold in itself creating a double layer - or bilayer - when placed in a polar surrounding, like water. This structural feature of the membrane is essential to its functions, such as cellular transport and cell recognition.

homologous chromosomes

A pair of chromosomes having the same gene sequences, each derived from one parent.

CAM planta

A plant that utilizes the Crassulacean acid metabolism (CAM) as an adaptation for arid conditions. CO2 entering the stomata during the night is converted into organic acids, which release CO2 for the Calvin Cycle during the day, when the stomata are closed.

endocytosis

A process in which cell takes in materials from the outside by engulfing and fusing them with its plasma membrane. Supplement Most of the extracellular materials that the cells absorb are large polar molecules (e.g. proteins and hormones) that cannot pass through the hydrophobic plasma membrane by simple diffusion. There are two types of endocytosis, called phagocytosis, which literally means cell-eating, and pinocytosis, which literally means cell-drinking.

photon

A quantum unit of light energy. A quantum of electromagnetic radiation; an elementary particle that is its own antiparticle.A quantum of radiant energy with a visible [[wavelength.

cellular respiration

A series of metabolic processes that take place within a cell in which biochemical energy is harvested from organic substance (e.g. glucose) and stored as energy carriers (ATP) for use in energy-requiring activities of the cell. It consists of: (1) Glycolysis (2) Citric Acid cycle or Krebs Cycle (3) Oxidative phosphorylation The cell seems to "respire" in a way that it takes in molecular oxygen (as an electron acceptor) and releases carbon dioxide (as an end product), hence, the process is described to be aerobic. There are organisms that use other organic molecules as electron acceptors instead of oxygen. This type of respiration in which oxygen is not used as a final electron acceptor is referred to as anaerobic. In anaerobic respiration (respiration in absence of oxygen), pyruvate is not metabolized by cellular respiration but undergoes a process of fermentation. The pyruvate is not transported into the mitochondrion, but remains in the cytoplasm, where it is converted to waste products that may be removed from the cell. Cellular respiration is essential to both eukaryotic and prokaryotic cells since biochemical energy is produced to fuel many metabolic processes, such as biosynthesis, locomotion, transportation of molecules across membranes. The entire process occurs in the cytoplasm of prokaryotes and yields 38 atp. In eukaryotes, glycolysis occurs in the cytoplasm whereas the Krebs Cycle and oxidative phosphorylation occur in the mitochondria and yields 36 atp.

chromosome

A structure within the cell that bears the genetic material as a threadlike linear strand of DNA bonded to various proteins in the nucleus of eukaryotic cells, or as a circular strand of DNA (or RNA in some viruses) in the cytoplasm of prokaryotes and in the mitochondrion and chloroplast of certain eukaryotes.

reactant

A substance taking part in a chemical reaction.

microfilament

A thin, helical, single-stranded filament of the cytoskeleton found in the cytoplasm of eukaryotic cells, composed of actin subunits, and functions primarily in maintaining the structural integrity of a cell and cell movements.

stoma

A tiny pore in a plant leaf surrounded by a pair of guard cells that regulate its opening and closure, and serves as the site for gas exchange.

plant vacuole

A vacuole is a membrane-bound organelle which is present in all plant and fungal cells and some protist, animal[1] and bacterial cells.[2] Vacuoles are essentially enclosed compartments which are filled with water containing inorganic and organic molecules including enzymes in solution, though in certain cases they may contain solids which have been engulfed. Vacuoles are formed by the fusion of multiple membrane vesicles and are effectively just larger forms of these.[3] The organelle has no basic shape or size; its structure varies according to the needs of the cell.

Adenosine triphosphate or ATP

ATP is a nucleotide that contains a large amount of chemical energy stored in its high-energy phosphate bonds. It releases energy when it is broken down (hydrolyzed) into ADP (or Adenosine Diphosphate). The energy is used for many metabolic processes. Hence, ATP is considered as the universal energy currency for metabolism. ATP is produced via cellular respiration in the mitochondria and photosynthesis in chloroplasts.

nad

Abbreviation for nicotinamide adenine dinucleotide, a coenzyme involved in redox reactions Supplement In metabolic reactions, nicotinamide adenine dinucleotide may be oxidized, NAD+, or reduced, NADH.

fermentation

An anaerobic (without oxygen) cellular process in which organic foods are converted into simpler compounds, and chemical energy (ATP) is produced.

atpase

An enzyme that catalyzes the hydrolysis or decomposition of ATP into ADP and a free phosphate ion, thereby releasing energy for use in another biochemical reaction.

heterotroph

An organism that is unable to synthesize its own organic carbon-based compounds from inorganic sources, hence, feeds on organic matter produced by, or available in, other organisms.

autosome

Any chromosome not considered as a sex chromosome, or is not involved in sex determination. It occurs in pairs in somatic cells and singly in sex cells (gametes).

eukaryote

Any of the single-celled or multicellular organisms whose cell contains a distinct, membrane-bound nucleus. Supplement Organisms such as animals, plants, fungi, and protists are examples of eukaryotes because their cells are organized into compartmentalized structures called organelles, the nucleus in particular. The presence of a distinct nucleus encased within membranes differentiates the eukaryotes from the prokaryotes. The eukaryotes are also known for having cytoplasmic organelles apart from nucleus, such as mitochondria, chloroplasts and Golgi bodies. Eukaryotes often have unique flagella made of microtubules in a 9+2 arrangement.

chloroplast

Chlorophyll-containing plastid found within the cells of plants and other photosynthetic eukaryotes.

osmosis

Diffusion of a solvent (usually water molecules) through a semipermeable membrane from an area of low solute concentration to an area of high solute concentration.

ethanol

Ethanol, also called ethyl alcohol, pure alcohol, grain alcohol, or drinking alcohol, is a volatile, flammable, colorless liquid with the structural formula CH3CH2OH, often abbreviated as C2H5OH or C2H6O

cytoplasm

In eukaryotic cells, the cytoplasm is that part of the cell between the cell membrane and the nuclear envelope. It is the jelly-like substance in a cell that contains the cytosol, organelles, and inclusions, but not including the nucleus. In fact, the cytoplasm and the nucleus make up the protoplasm of a eukaryotic cell. In prokaryotic cells that do not have a well-defined nucleus, the cytoplasm is simply everything enclosed by the cell membrane. It therefore contains the cytosol, and all the other cellular components, including the chromosome in the nucleoid region.

nadph

NADPH is the reduced form of NADP+. NADP+ differs from NAD+ in the presence of an additional phosphate group

haploid cell

Of or pertaining to a condition in which there is only half of the complete set of chromosomes in somatic cells.

diploid

Of or pertaining to a diploid, that is a cell or an organism with two sets of chromosomes.

lysosome

Organelles containing a large range of digestive enzymes used primarily for digestion and removal of excess or worn-out organelles, food particles, and engulfed viruses or bacteria. Supplement Their specific functions include digestion of macromolecules from phagocytosis, endocytosis, and autophagy, digestion of bacteria and other wa

isotonic

Pertaining to a solution that has the same tonicity as some other solution with which it is compared.

mitochondria

Spherical or rod-shaped organelles found within the cytoplasm of eukaryotic cells, and are referred to as the "powerhouse of the cell since they act as the site for the production of high-energy compounds (e.g. ATP), which are vital energy source for several cellular processes. Supplement They produce large amounts of energy through oxidative phosphorylation of organic molecules during cellular respiration. That is, they are capable of using glucose and oxygen to produce energy (and releasing carbon dioxide and water in the process) for use in many metabolic processes. Thus, it is not surprising to find several mitochondria in high energy-requiring cells, such as muscle cells. They are semi-autonomous, self-reproducing organelles because they contain their own genome. In fact, their DNA has become an important tool in tracking genetic histories since their genetic material is present in only one copy, and does not recombine in reproduction. According to the endosymbiotic theory, mitochondria might have been the remnants of early bacteria engulfed by ancient eukaryotic cells a billion years ago that might have evolved and become energy-yielding structures within eukaryotic cells at present.

plasma membrane

The cell's outer membrane made up of a two layers of phospholipids with embedded proteins. It separates the contents of the cell from its outside environment, and it regulates what enters and exits the cell.

granum

The collective term for the stack of thylakoids within the chloroplast of plant cells. The granum contains the light harvesting system composed of chlorophyll and phospholipids.

cytokinesis

The division of the cytoplasm and the plasma membrane following the division of the nucleus resulting into two cells, each having its own nucleus and cytoplasm surrounded by a plasma membrane.

nuclear envelope

The double-layered membrane that envelopes the nucleus of a eukaryotic cell, separating the contents of the nucleus from the (cytoplasm).

chlorophyll

The green pigment found in the chloroplasts of higher plants and in cells of photosynthetic microorganisms (e.g. photosynthetic bacteria), which is primarily involved in absorbing light energy for photosynthesis.

cristae

The infoldings or inward projections of the inner membrane of the mitochondrion, which are studded with proteins and increase the surface area for chemical reactions to occur like cellular respiration.

nucleus

The large, membrane-bounded organelle that contains the genetic material, in the form of multiple linear DNA molecules organized into structures called chromosomes. In biology, the major functions of nucleus are to maintain the integrity of DNA and to control cellular activities such as metabolism, growth, and reproduction by regulating gene expression. It has three main components: the nucleolus, the chromatin and the nuclear envelope. The nuclear envelope has nuclear pores to control the movement of molecules between the nucleoplasm and the cytoplasm.

cytoskeleton

The lattice or internal framework of a cell composed of protein filaments and microtubules in the cytoplasm, and has a role in controlling cell shape, maintaining intracellular organization, and in cell movement.

passive transport

The movement of a chemical substance across a cell membrane without expenditure of energy by the cell, as in diffusion.

turgor pressure

The pressure exerted by water inside the cell against the cell wall.

carbon fixation

The process by The process by which photosynthetic organisms such as plants turn inorganic carbon (usually carbon dioxide) into organic compounds (us. Carbohydrates). which photosynthetic organisms such as plants turn inorganic carbon (usually carbon dioxide) into organic compounds (us. Carbohydrates).

exocytosis

The process in which the cell releases materials to the outside by discharging them as membrane-bounded vesicles passing through the cell membrane.

mitosis

The process where a single cell divides resulting in generally two identical cells, each containing the same number of chromosomes and genetic content as that of the original cell.

light independent reaction

The series of biochemical reactions in photosynthesis that do not require light to proceed, and ultimately produce organic molecules from carbon dioxide. Supplement The energy released from ATP (produced during the light reactions) drives this metabolic pathway. It is described to be light-independent as it proceeds regardless of the amount of light available. The term is used in contrast to light-dependent reaction of photosynthesis that as the name implies depends on and requires light to take place

light dependent reaction

The series of biochemical reactions in photosynthesis that require light energy that is captured by light-absorbing pigments (such as chlorophyll) to be converted into chemical energy in the form of ATP and NADPH. Supplement The light-dependent reaction takes place on the thylakoid membranes of the chloroplast. It can be cyclic or non-cyclic. In cyclic reaction, when the electron is displaced from the photosystem, the electron is passed down the electron acceptor molecules and returns back to photosystem I, from where it was emitted. In the non-cyclic reaction, the photons are captured in the light-harvesting antenna complexes of photosystem II by chlorophyll and other accessory pigments.

photolysis

The splitting or decomposition of a chemical compound by means of light energy or photons. Supplement For example, the photolysis of water molecule in photosynthesis occurred under the influence of light. When photons are absorbed, it causes the hydrogen to bind to an acceptor, subsequently releasing the oxygen.

photosynthesis

The synthesis of complex organic material using carbon dioxide, water, inorganic salts, and light energy (from sunlight) captured by light-absorbing pigments, such as chlorophyll and other accessory pigments. Photosynthesis consists of light reactions and dark reactions. This process can be simplified in this equation: 6CO2+12H2O+energy=C6H12O6+6O2+6H2O. It means photosynthesis is a process in which carbon dioxide (CO2), water (H2O) and light energy are utilized to synthesize an energy-rich carbohydrate like glucose (C6H12O6) and to produce oxygen (O2) as a by-product.

chromatids

The two strands joined together by a single centromere, formed from the duplication of the chromosome during the early stages of cell division and then separate to become individual chromosomes during the late stages of cell division.

carrier-faciliated

Transport of substances across a biological membrane from an area of higher concentration to an area of lower concentration by means of a carrier molecule. Since the substances move along the direction of their concentration gradients, energy is not required.

lactic acid

a byproduct of anaerobic glucose metabolism.

cytochrome

a class of hemoprotein found in mitochondria that transport electron or protons(e.g. Hydrogen ions)(for instance during cell respiration or photosynthesis) cytochromes are found in the mitochondrial inner membrane of eukaryotes, in the chloroplasts of plants, in photosynthetic microorganisms, as well as in bacteria

homolog

a member of a homologous pair or series.

fad

a riboflavin-containing hydrogen Acceptor molecule in the krebs Cycle of plant respiration and a coenzyme of some oxidation-reduction enzymes.

interkinesis

a short resting period occurring between meiosis I and meiosis II

entropy

a thermodynamic quantity representing the unavailability of a system's thermal energy for conversion into mechanical work, often interpreted as the degree of disorder or randomness in the system. 2. lack of order or predictability; gradual decline into disorder.

glycoproteins

conjugated proteins containing one or more covalently linked carbohydrate residues. While technically describing conjugates in which the carbohydrate is less than 4 per cent by weight, the term is often used generically to include the mucoproteins and proteoglycans.

golgi apparatus

found in eukaryotes, packaging of molecules like proteins into vesicles for secretion, transport of lipids around the cell, and the creation of lysosomes

fadh

oxidized fad

photopigment

pigment involved in photosynthesis in plants. Includes chlorophyll, carotenoids and phycobilins

carotenoids

pigment molecules- usually yellow, orange,and red- that interact with chlorophylls to absorb light energy needed in photosynthesis

potential energy

y) energy due to position, it is stored energy which can be used to do work. The mechanical energy that a body has by virtue of its position; stored energy.A form of energy that has potential for a reaction, though at present is in a stored form. Glycogen has potential energy but is not readily usably by the body.