| Term | Definition |
|---|
| isomers | molecules that have the same molecular formula but differ in their arrangement of these atoms. These differences can result in molecules that are very different in their biological activities. |
| functional groups | attach to the carbon skeleton have diverse properties. The behavior of organic molecules is dependent on the identity of their functional groups |
| Hydroxyl | -OH, helps dissolve molecules such as sugars; ex: alcohols such as ethanol and methanol |
| Carboxyl | -COOH, tend to ionize; source of H+ ions; ex: fatty acids and sugars |
| Carbonyl | <CO; ex: ketones and aldehydes such as sugars |
| Amino | -NH2; ex: amines such as amino acids |
| Phosphate | PO3, including ATP, DNA, and phospholipids |
| Sulfhydryl | -SH; found in some amino acids; forms disulfide bridges in proteins |
| monosaccharides | monomers of carbohydrates |
| starch | storage polysaccharide found in plants |
| primary structure | the unique sequence in which amino acids are joined |
| secondary structure (of a protein) | one of two three-dimensional shapes that are the result of hydrogen bonding: Alpha helix (coiled) or the Beta pleated sheet (accordion shape) |
| Tertiary structure | complex globular shape, due to interactions between R-groups, such as hydrophobic interactions, van der Waals interactions, hydrogen bonds, and disulfide bridges |
| Quaternary structure | the association of two or more polypeptide chains into one large protein. Hemoglobin is a globular protein with quaternary structure, as it is composed of four chains. |
| Macromolecules | proteins, lipids, nucleic acids, polysaccharides |
| lipids | hydrophobic; aren |
| fats | triglycerides; made up of a glycerol molecule and three fatty acid molecules |
| fatty acids | include hydrocarbon chains of variable length; chains are nonpolar and therefore hydrophobic |
| saturated fatty acids | have no double bonds bw C's; tend to pack solidly at room T, are linked to cardiovascular disease; are commonly produced by animals |
| Space-filling model of a phospholipid | Choline, phosphate, glycerol, fatty acids, hydrophilic head; hydrophobic tails |
| Unsaturated fatty acids | have some C=C; this results in kins; are commonly produced by plants |
| steroids | made up of four rings that are fused together; ex: cholesterol, estrogen, testosterone |
| proteins | monomers: amino acids |
| amino acids | contain a central C bonded to a carboxyl group, an amino group, a H atom, and an R group |
| Nucleotides | monomers of DNA and RNA: made up of nitrogenous base, pentose, phosphate group |
| cytoskeleton | reinforces cell's shape; functions in cell movement; components are made of proteins. Includes: Microfilaments, Intermediate filaments, Microtubules |
| microtubules (Tubulin polymers) | hollow tubes; functions: maintenance of cell shape; cell motility (as in cilia or flagella); chromosome movements in cell division; organelle movements |
| microfilaments | two intertwined strands of actin, each a polymer of actin subunits; functions: maintenance of cell shape, changes in celll shape, muscle contraction, cytoplasmic streaming, cell motility (as in pseudopodia); cell division (cleavage furrow formation) |
| Intermediate Filaments | Fibrous proteins supercolied into thicker cables; functions: maintenance of cell shape; anchorage of nucleus and certain other organelles; formation of nuclear lamina |
| extracellular matrix | main ingredients: glycoproteins secreted by the cells; ex: collagen forms strong fibers outside of the cells; |
| plasmodesmata | channels perforated in cell walls which allows cytosol to pass through and connects the chemical environments of adjacent cells |
| tight junctions | at ____, the plasma membranes of neighboring cells are very tightly pressed against each other, bound together by specific proteins; forming continuous seals around the cells, _____ prevent leakage of extracellular fluid across a layer of epithelial cells |
| desmosomes | fuction like rivets, fastening cells together into strong sheets; intermediate filaments made of sturdy keratin proteins anchor desmosomes into the cytoplasm. these attach muscle cells to each other in a muscle. |
| gap junctions | provide cytoplasmic channels from one cell to an adjacent cell and in this way are similar in their function to the plasmodesmata in plants; consists of membrane proteins that surround a pore through which ions, sugars, amino acids, and other small molecules may pass; they are necessary for communication between cells in many types of tissues, including heart muscle, and in animal embryos |
| glycoproteins | secretory proteins that have carbohydrates covalently bonded to them |
| glycoproteins | proteins attached to membrane carbohydrates |
| active transport | substances are moved against their concentration gradient- from the side where they are less concentrated to the side where they are more concentrated. This type of transport requires energy, usually in the form of ATP; ex: sodium-potassium pump |
| hypertonic solution | cell will lose water to its surroundings, more solutes in the water around the cell, hence the mvmt of water to the higher concentration of solutes |
| hypotonic solution | water will enter the cell faster than it leaves; fewer solutes in the water around the cell, hence the mvmt of water into the cell where solutes are more heavily concentrated |
| integral proteins | completely embedded in the membrane, some of which are transmembrane proteins that span the membrane completely |
| eukaryotes | internal membranes, nucleus |
| nucleus | surrounded by a double membrane: the nuclear envelope; continuous with the rough endoplasmic reticulum; contains nuclear pores that control what may enter or leave the nucleus |
| ribosomes | sites of protein syntheis in the cell |
| smooth ER | three primary functions: synthesis of lipids, metabolism of carbohydrates, and detoxification of drugs and poisons |
| rough ER | ribosomes associated with ___ synthesize proteins generally secreted by the cell |
| Golgi apparatus | postal system: proteins from the transport vesicles are modified, stored, and shipped |
| peroxisomes | single-membrane-bound compartments in the cell responsible for various metabolic functions that involve the transfer of hydrogen from compounds to oxygen, producing H2O2. Break down fatty acids to be sent to mitochondria for fuel and detoxify alcohol by transferring H from the poison to the oxygen |
| microtubules | made up of protein tubulin; the largest of the cytoskeleton fibers; shape and support the cell and also serve as tracks along which organelles equipped with motor molecules can move. They also separate chromosomes during mitosis and meiosis (forming the spindle) and are the structural components of cilia and flagella (found primarily in animal cells) |
| microfilaments | composed of the protein actin; much smaller than microtubules, microfilaments function in smaller scale support. When coupled with the motor molecule myosin, microfilaments can be involved with movement. Examples include ameboid movement, cytoplasmic streaming, and contraction of muscle cells |
| intermediate filaments | slightly larger than microfliaments and smaller than microtubules; more permanent fixtures in teh cell, where they are important in maintaining the shape of the cell and fixing the position of certain organelles |
| centrosome | region located near the nucleus, from which microtubules grow. ___ contain centrioles in animal cells |
| lysosome | membrane-bround sacs of hydrolytic enzymes that digest large molecules, including proteins, polysaccharides, fats, and nucleic acids. They have digestive enzymes that break down macromolecules to organic molnomers; the digestive or hydrolytic enzymes work best in the acidic environment found in lysosomes |
| ECM | situated just external to plasma membrane; it is composed of glycoproteins secreted by the cell (most prominent of which is collagen). The ECM greatly strengthens tissues and serves as a conduit for transmitting external stimuli into the cell, which can turn genes on and modify biochemical activity. |
| fluid mosaic model | describes cell membranes as fluid, with proteins embedded in or associated with the phospholipid bilayer |
| cell cycle | life of a cell from the time it is formed from a dividing parent cell until its own division into two cells |
| mitosis | division of the cell's nucleus |
| cytokinesis | division of the cell's cytoplasm |
| G1 phase | the cell grows while carrying out cell functions unique to its cell type |
| S phase | the cell continues to carry out its unique functions but does one other important process--it duplicates its chromosomes |
| interphase | 90% of the cell cycle; consists of G1, S, and G2 phases |
| Prophase | 1) the chromatin becomes more tightly coiled into discrete chromosomes. 2) the nucleoli disappear; 3) the mitotic spindle (consisting of microtubules extending from the two centrosomes) begins to form in the cytoplasm |
| Prometaphase | 1) The nuclear envelope begins to fragment, allowing the microtubules to attach to the chromosomes. 2) The two chromatids of each chromosome are held together by protien kinetochores in the centromere region 3) The microtubules will atach to the kinetochores. |
| Metaphase | 1) The microtubules move the chromosomes to the metaphase plate at the equator of the cell. The microtubule complex is referred to as the spindle. 2) The centrioles have migrated to opposite poles in the cell, riding along on the developing spindle |
| Anaphase | 1) Sister chromatids begin to separate, pulled apart by motor molecules interacting with kinetochore microtubules. 2) The cell elongates, as the nonkinetochore microtubules ratchet apart, again with the help of motor molecules. 3) By the end of anaphase, the opposite ends of the cell both contain complete and equal sets of chromosomes. |
| Telophase | 1) The nuclear envelopes re-form around the sets of chromosomes located at opposite ends of the cell. 2) The chromatin fiber of the chromosomes becomes less condensed; 3) Cytokinesis begins, during which the cytoplasm of the cell is divided. |
| cleavage furrow | when cytokinesis begins, a ____ forms that eventually divides the cytoplasm, in animal cells |
| cell plate | in plant cells, a ____ forms that divides the cytoplasm. |
| Major cell checkpoints | G1 phase checkpoint, G2phase checkpoint, and M phase checkpoint |
| G1 phase checkpoint | gives the cell the go ahead at the checkpoint, it usually completes the whole cell cycle and divides; if it does not receive the go-ahead signa, it enders a nondividing phase called Go phase. |
| Kinases | ___ are the protein enzymes that control the cell cycle. They exist in the cells at all times, but ar active only when they are connected to cyclin proteins. They are called cyclin-dependent kinases (Cdk). Specific kinases give the go-ahead signals at the G1 and G2 checkpoints |
| cyclin molecules | combine with Cdk molecules producing enough molecules of MPF to pass the G2 checkpoint and initiate the go-ahead signals at the G1 and G2 checkpoints. |
| How does a cell stop division? | During anaphase, MPF switches itself off by starting a process that leads to the destruction of cyclin molcules. Without cyclin moleules Cdk molecules become inactive, bringing mitosis to a close. |
| viruses | Smaller than ribosomes, the tiniest ___ are about 20 nm across |
| virus | A nucleic acid surrounded by a protein coat; the genomes can be double or single-stranded DNA or RNA |
| capsid | a protein shell that surrounds the genetic material. |
| bacteriophages | they are viruses that infect bacterial cells |
| lytic cycle | The ____ ends in the death of the host cell by rupturing it. IN this cycle, a bacteriophage injects its DNA into a host cell and takes over theh host cell |
| What is the lysogenic cycle? | In the lysogenic cycle the bacteriophage's DNA becomes incorporated into the host cell's DNA and is replicated along with the host cell's genome. The viral DNA is known as prophage. Under certain conditions, the prophage will enter the lytic cycle, described above. |
| retroviruses | RNA viruses that use the enzyme reverse transcriptase to transcribe DNA from an RNA template. The new DNA then permanently integrates into a chromosome in the nucleus of an animal cell. The host transcribes the viral DNA into RNA that may be used to synthesize viral proteins or may be released from the host cell to infect more cells |
| Restriction enzymes | these are used to cut strands of DNA at specific locations (called restriction sites). They are derived from bacteria. |
| sticky end | When a DNA molecule is cut by restriction enzymes, which will have at least one single-stranded end, called a _____. ______ can form hydrogen bonds with complementary single-stranded pieces of DNA. These unions can be sealed with the enzyme DNA ligase. |
| cloning vector | plasmid (usually bacterial) that will carry the DNA sequence to be cloned. |
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