| Term |
 |
|
| Meaning |
|
|
| eukaryote kingdoms |
Plantae, Animalia, Fungi, Protista |
| nucleus |
contain & protect DNA, transcription, partial assembly of ribosomes |
| mitochondria |
houses Kreb's cycle, oxidative phosphorylation |
| ribosomes |
synthesize proteins |
| RER |
synthesis and modification of secretory, membrane-bound, organelle proteins |
| SER |
detoxification and glycogen breakdown in liver, steroid synthesis in gonads |
| Golgi |
modification & sorting of protein, some synthesis |
| lysosomes |
contain acid hydrolases which digest various substances |
| peroxisomes |
metabolize lipids and toxins using peroxide |
| In the nucleus... |
... replication, transcription, and splicing occur. |
| Telomerase is necessary... |
... because otherwise RNA primers at the 5'-most end cannot be replaced by DNA. |
| heterochromatin |
Densely packed chromatin that generally contain silent genes |
| euchromatin |
Loosely packed chromatin that contain accessible genes. |
| nuclear matrix |
(i.e., nuclear scaffold) A mesh of protein believed to confer structural support to the nucleus. |
| nucleolus |
Not membrane-enclosed, contains DNA loops, RNA polymerases, rRNA, unassembled protein components of the ribosome. Site of transcription of only rRNA (by RNA pol I) |
| nuclear envelope |
Consists of double lipid bilayer, nuclear pores ("porin" proteins). |
| The lumen of the ER... |
... is contiguous with the space between the nuclear double lipid bilayer. |
| The nuclear envelope... |
... lets proteins under 60kD to diffuse freely and keeps larger proteins out. Larger proteins may pass with a nuclear localization sequence, a peptide extension of the protein. |
| mitochondria |
Consists of two membranes. Inner membrane is generally impermeable and is folded into a matrix called cristae. The outer membrane contain large pores and allows free diffusion. |
| Mitochondria... |
... contain their own plasmid genome that encodes rRNA, tRNA, and some mitochondrial proteins. Uses unique RNA/DNA polymerases, ribosomes, aminoacyl-tRNA synthetases. |
| Mitochondria... |
... are maternally inherited. Sperm only contributes genomic DNA. |
| The ER... |
... synthesizes proteins that have an N-terminal signal sequence recognized by SRP. Secreted proteins leave after cleavage of the signal sequence; integral proteins have internal signal sequences and are threaded through during translation. |
| The ER... |
... houses initial post-translational modifications, including limited glycosylation and disulfide linkage formation. |
| Golgi complex |
Consists of cis -> medial -> trans stacks. |
| constitutive secretory pathway |
Pathway starting from trans-Golgi stack directly to the plasma membrane. |
| regulated secretory pathway |
Pathway starting from trans-Golgi, to secretory vescicles under the plasma mebrane, to the plasma membrane. |
| Lysosome proteins... |
... are made in the ER and transported from the trans-Golgi stack. |
| autophagy |
Degradation of damaged organelles by lysosome. |
| crinophagy |
Digestion of unneeded secretory products by lysosome. |
| acid hydrolases |
Degrade things via hydrolysis in lysosomes. Activity is dependent on low pH (inactive in higher pHs). |
| Peroxisomes... |
... metabolize lipids and toxins using enzymes that produce hydrogen peroxide as a by-product. Peroxisomes separate oxygen radical by-products from the rest of the cell. |
| catalase |
Converts hydrogen peroxide into water and oxygen in peroxisomes. |
| lipids of eukaryotic membranes |
phospholipids, glycolipids, cholesterol |
| phospholipid |
Most abundant lipid. Amphipathic molecules. (Ex: phosphatidyl choline. Two fatty acid chains esterified to glycerol attached to phosphoryl choline group.) |
| glycolipid |
Amphipathic molecules with carbohydrate side chains. |
| Lipid bilayers are... |
... permeable to nonpolar molecules and have very hydrophobic interiors. |
| peripheral membrane proteins |
Associated with integral membrane proteins and not the membrane itself. |
| passive transport |
Membrane transport that does not require energy. |
| active transport |
Membrane transport that requires energy. |
| simple diffusion |
Diffusion of a solute without the use of a protein. |
| facilitated diffusion |
Movement of a solute down a gradient through a protein, where the membrane is intrinsically impermeable to the solute. |
| channels |
Selectively allow particular solutes to flow down their gradient. Can be gated, either by voltage or ligand. |
| carriers |
"Carry" solutes across membrane (not a simple channel). |
| uniport |
Carrier protein that transports one molecule at a time. |
| symport |
Carrier protein that transports two molecules at a time, in the same direction. |
| antiport |
Carrier protein that transports two molecules at a time, in opposite directions. |
| primary active transport |
Active transport that is coupled with ATP hydrolysis. |
| secondary active transport |
Active transport that is coupled with the flow of another ion down its electrochemical gradient. |
| Active transport can... |
... reverse. |
| phagocytosis |
Absorbtion of large matter for degradation in lysosomes. |
| pinocytosis |
Nonspecific uptake of small molecules and ECF. |
| receptor-mediated endocytosis |
Regulated endocytosis. |
| Microtubules... |
... are organized at the MTOC, which contains two centrioles. They radiate out to form an aster, which connect to chromosomes via (microtubular) polar fibers. Centrioles are not essential to mitosis, but the MTOC is. MTs also mediate vesicle transport. |
| Intermediate filaments... |
... are more permament than MTs or microfilaments. Involved in mechanical support. |
| Microfilaments... |
... are responsible for gross movements of the cell. |
| cell junction |
Consists of tight/occluding junctions (seal space between cells), desmosomes (hold cells together), gap junctions (allow flow of things between cells) |
| S phase |
Replication of genome between gap phases. |
| G1 phase |
First gap phase, between M phase and S phase. |
| G2 phase |
Second gap phase, between S phase and M phase. |
| interphase |
G1-S-G2 phases combined. |
| M phase |
Mitosis. Prophase-Metaphase-Anaphase-Telophase. |
| prophase |
Condensing of chromatin into chromosomes. Nucleolus, nucleus disappear. Spindle, kinetochore fibers appear, centriole pairs move to poles of cell. |
| metaphase |
Chromosomes line up at midline of cell, metaphase plate. Spindle fibers attached to centromeres. |
| anaphase |
Sister chromatid are pulled apart. |
| telophase |
Nuclear membrane forms, chromosomes decondense, nucleolus reappears. |
| During mitosis, the cell's ploidy is... |
... doubly diploid (2n x 2). |
