Exam 4 Cell Bio Flashcards
sugars
A substance made of carbon, hydrogen, and oxygen with the general formula (CH2O)n. A carbohydrate or saccharide. The “sugar” of everyday use is sucrose, a sweet-tasting disaccharide made of glucose and fructose
monosaccharides
any of the class of sugars (e.g., glucose) that cannot be hydrolyzed to give a simpler sugar
disaccharides
any of a class of sugars whose molecules contain two monosaccharide residues
oligosaccharides
a carbohydrate whose molecules are composed of a relatively small number of monosaccharide units
D-form molecules
a specific configuration of a chiral molecule, indicating that when viewed in a standard projection (like a Fischer projection), the functional group on the chiral carbon furthest from the molecule’s reference point is positioned on the right side
L-form molecules
a specific spatial arrangement of atoms within a molecule, particularly in the context of organic chemistry, where it indicates one of two mirror-image enantiomers, with the “L” signifying the “left-handed” configuration
Optical isomers
each of two or more forms of a compound which have the same structure but are mirror images of each other and typically differ in optical activity
Carbohydrates
any of a large group of organic compounds that includes sugars, starch, and cellulose, containing hydrogen and oxygen in the same ratio as water (2:1) and used as structural materials and for energy storage within living tissues
glycosidic bonds
Monosaccharides linked by covalent bonds to form larger carbohydrates
polysaccharides
a carbohydrate (e.g. starch, cellulose, or glycogen) whose molecules consist of a number of sugar molecules bonded together
monomers
a molecule that can be bonded to other identical molecules to form a polymer
condensation reaction
a reaction in which two molecules combine to form a larger molecule, producing a small molecule such as H2O as a byproduct
Energetically unfavorable
hydrolysis reaction
any chemical reaction in which a molecule of water breaks one or more chemical bonds
energetically favorable
cellulose
an insoluble substance which is the main constituent of plant cell walls and of vegetable fibers such as cotton. It is a polysaccharide consisting of chains of glucose monomers
chitin
a fibrous substance consisting of polysaccharides and forming the major constituent in the exoskeleton of arthropods and the cell walls of fungi
glycoproteins
a protein with sugar molecules attached to it
fatty acid
Molecule that consists of a carboxylic acid attached to a long hydrocarbon chain. Used as a major source of energy during metabolism and as a starting point for the synthesis of phospholipids
amphipathic
having both hydrophilic and hydrophobic parts
alpha linkages
formed when the OH group on the carbon-1 of the first glucose is below the ring plane
beta linkages
formed when the OH group on the carbon-1 is above the ring plane
glycogen
a substance made of up many connected glucose molecules deposited in bodily tissues that act as a store of carbohydrates. It is a polysaccharide which forms glucose on hydrolysis
Branched polymer composed exclusively of glucose units used to store energy in animal cells. Granules of this material are especially abundant in liver and muscle cells
glycogen phosphorylase
an enzyme that breaks down glycogen into glucose that exists in inactive and active forms, with its activation regulated by various hormones and signaling molecules
glycogen synthase
an enzyme that catalyzes the conversion of glucose into glycogen, a storage form of glucose
pectin
a soluble gelatinous polysaccharide that is present in ripe fruits
primary cell wall
the cellulose-containing layer laid down by cells that are dividing and growing
secondary cell wall
a structure found in many plant cells, located between the primary cell wall and the plasma membrane which provides mechanical support
cellulose microfibrils
elongated structures in plant cell walls composed of cellulose chains arranged in a highly organized, crystalline fashion
lignin
a complex organic polymer deposited in the cell walls of many plants, making them rigid and woody
connective tissues
Tissue that supports, protects, and gives structure to other tissues and organs in the body
Also stores fat, helps move nutrients and other substances between tissues and organs, and helps repair damaged tissue
enzymes
a protein that catalyzes a specific chemical reaction
catalysis
Substance that accelerates a chemical reaction by lowering its activation energy; enzymes perform this role in cells.
metabolism
The sum total of the chemical reactions that take place in the cells of a living organism
catabolism
Set of enzyme-catalyzed reactions by which complex molecules are degraded to simpler ones with release of energy; intermediates in these reactions are sometimes called catabolites
anabolic
Set of metabolic pathways by which large molecules are made from smaller ones
biosynthesis
An enzyme-catalyzed process by which complex molecules are formed from simpler substances by living cells; also called anabolism.
oxidation
Removal of electrons from an atom, as occurs during the addition of oxygen to a carbon atom or when a hydrogen is removed from a carbon atom; can also refer to a partial shift of electrons between atoms linked by a covalent bond.
reduction
Addition of electrons to an atom, as occurs during the addition of hydrogen to a carbon atom or the removal of oxygen from it; can also refer to a partial shift of electrons between atoms linked by a covalent bond.
free energy, G
Energy that can be harnessed to do work, such as driving a chemical reaction.
free-energy change, ΔG
in a chemical reaction, the difference in free energy between reactant and product molecules. A large negative value of ΔG indicates that the reaction has a strong tendency to occur. (See also standard free-energy change)
activation energy
The energy that must be acquired by a molecule to undergo a chemical reaction.
substrates
A molecule on which an enzyme acts to catalyze a chemical reaction.
equilibrium
State in which the forward and reverse rates of a chemical reaction are equal so that no net chemical change occurs.
ATP
Activated carrier that serves as the principal carrier of energy in cells; a nucleoside triphosphate composed of adenine, ribose, and three phosphate groups. (See Figure 2–26.)
ADP
Nucleoside diphosphate produced by hydrolysis of the terminal phosphate of ATP
coupled reaction
Linked pair of chemical reactions in which free energy released by one reaction serves to drive the other reaction.
ATP to ADP is an exergonic reaction that can provide energy for endergonic reactions
hydrolysis reactions
a reaction in which one molecule breaks apart to form multiple smaller molecules
activated carrier
A small molecule that stores energy or chemical groups in covalent bonds that can be donated to many different metabolic reactions. Examples include ATP, acetyl CoA, and NADH.
NADH
Activated carrier of electrons that is widely used in the energy-producing breakdown of sugar molecules
NADPH
Activated carrier closely related to NADH and used as an electron donor in biosynthetic pathways. In the process it is oxidized to NADP+.
acetyl CoA
Activated carrier that donates the carbon atoms in its readily transferable acetyl group to many metabolic reactions, including the citric acid cycle and fatty acid biosynthesis; the acetyl group is linked to coenzyme A (CoA) by a thioester bond that releases a large amount of energy when hydrolyzed.
NAD+
A molecule that accepts a hydride ion (H–) from a donor molecule, thereby producing the activated carrier NADH. Widely used in the energy-producing breakdown of sugar molecules. (See Figure 3–34.)
NADP+
Molecule that accepts a hydride ion (H–) from a donor molecule, thereby producing the activated carrier NADPH; widely used as an electron donor in biosynthetic pathways.
diffusion
Process by which molecules and small particles move from one location to another by random, thermally driven motion
cell respiration
Process by which cells harvest the energy stored in food molecules; usually accompanied by the uptake of O2 and the release of CO2.
three main stages:
glycolysis, the Krebs cycle/citric acid cycle, the electron transport chain
entropy
Thermodynamic quantity that measures the degree of disorder in a system.
photosynthesis
The process by which plants, algae, and some bacteria use the energy of sunlight to drive the synthesis of organic molecules from carbon dioxide and water.
thermodynamics
Branch of science that studies the relationship between work, heat, and other forms of energy.
equilibrium constant, K
For a reversible chemical reaction, the ratio of substrate to product when the rates of the forward and reverse reactions are equal
standard free-energy change, ΔG°
The free-energy change measured at a defined concentration, temperature, and pressure.
lipid
An organic molecule that is insoluble in water but dissolves readily in nonpolar organic solvents; typically contains long hydrocarbon chains or multiple rings. One class, the phospholipids, forms the structural basis for biological membranes
covalent bond
interatomic linkage that results from the sharing of an electron pair between two atoms
hydrogen bond
a weak bond between two molecules resulting from an electrostatic attraction between a proton in one molecule and an electronegative atom in the other
ionic bond
type of linkage formed from the electrostatic attraction between oppositely charged ions in a chemical compound
macromolecule
a molecule containing a very large number of atoms, such as a protein, nucleic acid, or synthetic polymer
noncovalent bond
chemical association that does not involve sharing electrons; singularly weak but can be a sum total strong
Ex: hydrogen bonds, Van der Waals attractions
substrate-level phosphorylation
Process by which ATP is formed by the transfer of a phosphate group from a substrate molecule to ADP; substrates that participate in this form of ATP synthesis must carry a phosphate group that is linked via a “high-energy” covalent bond.
oxidative phosphorylation
Membrane-based process in bacteria and mitochondria in which ATP formation is driven by the transfer of electrons derived from food molecules to molecular oxygen.
glycolysis (Embden–Meyerhof pathway)
Series of enzyme-catalyzed oxidation reactions in which sugars are partially degraded and their energy is captured by the activated carriers ATP and NADH. (Literally, “sugar splitting.”)
pyruvate
Three-carbon metabolite that is the end product of the glycolytic breakdown of glucose; provides a crucial link to the citric acid cycle and many biosynthetic pathways.
acetyl CoA
Activated carrier that donates the carbon atoms in its readily transferable acetyl group to many metabolic reactions, including the citric acid cycle and fatty acid biosynthesis; the acetyl group is linked to coenzyme A (CoA) by a thioester bond that releases a large amount of energy when hydrolyzed.
electron-transport chain
A series of membrane-embedded electron carrier molecules that facilitate the movement of electrons from a higher to a lower energy level, as in oxidative phosphorylation and photosynthesis.
fermentations
The breakdown of organic molecules without the involvement of molecular oxygen. This form of oxidation yields less energy than aerobic cell respiration.
fats
Type of lipid used by living cells to store metabolic energy. Mainly composed of triacylglycerols
control mechanisms
Three stages of catabolism
- Breakdown of large food molecules to simple subunits
- Glycolysis: Breakdown of simple subunits to acetyl CoA (limited ATP and NADH)
- Complete oxidation of acetyl CoA to CO2 and H2O (plentiful of ATP produced)
Starch
Polysaccharide composed exclusively of glucose units, used as an energy store in plant cells
feedback inhibition
Process whereby enzymes are either positively or negatively regulated in response to the levels of metabolites that are not their substrates.
a conformational change in an enzyme may occur so that an active enzyme becomes inactivated and vice versa
gluconeogenesis
Set of enzyme-catalyzed reactions by which glucose is synthesized from small organic molecules such as pyruvate, lactate, or amino acids; in effect, the reverse of glycolysis.
Glycogen structure
composed of two major bonds, which are alpha-1,4 and alpha-1,6 glycosidic bonds - making linear glucose chains and branching points, respectively, for storage in animals
Starch Structure
a simple linear polymer called amylose (polysaccharide chain that is made up of glucose monomers joined by ɑ (1,4) glycosidic linkage) and a more complex branched form called amylopectin for energy storage in plants
Cellulose structure
long polymer chains of glucose units connected by a beta linkages
They are layered closely together due to hydrogen bonds that provide rigidity and strength to the structure of plants
Delta G < 0
Exergonic
Spontaneous
Delta G > 0
Endergonic
Not spontaneous
Low blood sugar process
–When blood sugars are low, the pancreas releases the hormone glucagon into the blood stream
–Glucagon binds to liver cell receptors
–This triggers the liver to release stored glucose originally stored as glycogen into the blood
High blood sugar process
–When glucose levels are high, the pancreas releases the hormone insulin into the blood stream
–Insulin binds to cell insulin receptors
–This allows the transportation of glucose into cells
Isoenzymes
different forms of the same enzyme that have different amino acid sequences and are found in different tissues that catalyze the same chemical reaction
They may have:
–Different genes
–Different tissue expression
–Different developmental timing of expression
Summary of Glycolysis
- Energy investment as two ATP are used
- The cleavage of glucose from into two 3-carbon molecules
- Energy generation of two pyruvate, four ATP and two NADH
Isoenzyme example of Phosphofructokinase
PFK-L liver
PFK-M muscle
PFK-P platelets
Different enzymes that all phosphorylate fructose-6-phophate to form fructose-1,6-bisphosphate
Hereditary Fructose Intolerance
HFI is a recessive disorder where individuals with HFI lack a functional copy of Aldolase B
Aldolase catalyzes the conversion of fructose 1-6-diphosphate into two different molecules
