Cell Biology

trocket52's version from 2015-10-22 01:55

Section 1

Question Answer
The Cell MembraneHolds in the internal contents of the cell & regulates what gets into & out of the cell
Phospholipid Bilayer (membrane structure)The basic structure is 2 layers of phospholipids. It is a flexible structure and is described as the fluid mosaic model
Cholesterol An integral part of the cell membrane. This keeps the cell membrane flexible bc although certain materials (gases) diffuse readily across the plasma membrane, other materials do not.
Membrane ProteinsAssociated w/ the membrane. Some are on the outside, some inside, and some are transmembrane (which go all the way across)
Membrane Protein Functions1. Acting as receptors 2. Acting as channels for ions & other materials to cross the membrane 3. Signaling across the membrane

Section 2

Question Answer
Diffusion (passive movement across membranes)Refers to the tendency of molecules to spread from areas of high concentration to areas of low concentration in order to reach equal concentration throughout. The process is driven by the concentration gradient.
Osmosis (passive movement across membranes)Has to do w/ the movement of water across cell membranes.
Isotonic (passive movement across membranes)Equal salt concentrations inside & outside of the cell
Hypotonic (passive movement across membranes)Salt concentrations outside the cell are less than those inside the cell
Hypertonic (passive movement across membranes)Salt concentrations outside the cell are greater than those inside the cell
Hypotonic (conditions)H2O moves into the cell to reduce the internal salt concentration inside. The cell will swell & may eventually burst
Hypertonic (conditions)H2O moves out of the cell to increase the internal salt concentration. The cell will shrink

Section 3

Question Answer
Active TransportInvolves transmembrane proteins acting as "pumps". ATP is required bc it's used for bringing materials into the cell or "pumping out" materials such as ions to maintain unequal conc. (such as the conc. of K+ and Na+ inside & outside the neurons)
EndocytosisBringing something into the cell across the membrane
Receptor-Mediated Endocytosis A method that allows the cell to bring in specific materials that it needs. The molecule binds to a receptor on the surface of the cell. Triggers the receptor & the material bound to it to be brought in through the cell membrane to the inside of the cell
PhagocytosisCell engulfs solid material (e.g.: white blood cell ingesting a bacteria). Brings it in through the cell membrane & breaks it down
PinocytosisCells engulf and bring in liquid material
ExocytosisSomething from the inside of the cell is released to the outside (the opposite of endocytosis)

Section 4

Question Answer
CytoplasmThe fluid or gel inside the cell (cytosol) & the organelles
Ribosome structurevery small. Made of 2 circular subunits. Found free in the cytoplasm or attached to the rough endoplasmic reticulum
Ribosome functionMaking protein
Endoplasmic Reticulum (ER) (Structure)A "stack" of folded interconnected membranes. Start at the edge of the nuclear membrane
ER Function (rough) covered with ribosomes. Makes protein
ER Function (smooth)Makes lipids
Golgi Apparatus (structure)A series of stacked, folded membranes (similar to but smaller than the ER)
Golgi Apparatus (function)1. Adding sugars to molecules & 2. Packaging material for movement to another part of the cell or release from the cell. The material is placed in a vesicle and then moved elsewhere within the cell or released by exocytosis
Lysosomes (structure)Small, rounded, membrane-bounded structures
Lysosomes (function)Contains digestive enzymes & other molecules. Break down things ingested by the cell
VacuolesA membrane-bound "bubble" within a cell that stores something
Mitochondria (structure)Kidney shaped. Contain highly infolded internal membranes called cristae
Cristae These are sites for metabolic enzymes to attach & function
Mitochondria (function)Production of ATP (cellular energy)
ChloroplastsSpecialized structure for carrying out photosynthesis. Contain chlorophyll & membrane systems including the thylakoid membranes
Cytoskeleton (structure)A group of different protein strands. Microtubules, microfilaments, & intermediate filaments
Cytoskeleton (function)1. Intermediate filaments are the internal "skeleton" providing structure for the cell. 2. Microtubules of tubulin for movement of materials from place to place within the cell. 3. Microfilaments of actin & myosin for movement of the cell itself.
Nuclear membrane (Nucleus)A membrane that surrounds the chromosomes. In it are nuclear pores. Small holes which allow material to pass from the nucleus to the cytoplasm
Chromosome (Nucleus) A strand of DNA & protein (chromatin). The DNA exists in a highly coiled state. Supercoiled. The proteins (histones) pack the DNA into a small space and are involved in controlling gene expression

Section 5

Question Answer
Mitosis (general concept)Occurs in body cells (known as somatic cells). It is the replication of the nucleus. Consists of series of phases
ProphaseThe cell prepares to divide: The nuclear membrane breaks down & the spindle apparatus forms
MetaphaseThe two sets of chromosomes line up in the middle of the cell
Anaphase The two sets of chromosomes move apart to opposite ends
Telophase The nucleus reforms & the spindle apparatus breaks down
InterphaseThe period between cell mitoses
The Cell CycleRefers to the various phases a cell goes through. Mitosis (M) is one of them. A cell spends most of its time in the growth (G) or DNA duplication (S) phases of the cell cycle.

Section 6

Question Answer
MeiosisOccurs in reproductive cells. Germ cells (sperm and egg). Normal body cells (somatic cells have 2 chromosomes in pairs. Condition referred to as diploid and indicated by 2n. (e.g.: 46)
HaploidThis is when meiosis results in the formation of germ cells which have single chromosomes. Indicated by 1n (e.g.: 23)
Cytokinesisreplication of the rest of the cell (remember mitosis is only the nucleus). Cytoplasm and organelles.

Section 7

Question Answer
Cell metabolismmetabolism is all the various biochemical reactions taking place in a cell. There are 2 broad categories
Anabolism (cell metabolism category) Building things up from smaller components or subunits
Catabolism (cell metabolism category)Breaking molecules down
EnzymesCarry out all the metabolic reactions in the cell
Catalyst Lower the energy needed for the reaction to happen. Each is specific for a single reaction & an repeat that reaction
SubstrateThe substance the enzyme acts upon. The binding is highly specific & depends on the shapes of the substrate & the enzyme's active site
Coenzyme Organic (e.g.: thiamine, riboflavin, niacin). What are commonly known as "vitamins"
Fat-soluble vitaminsA, E, D, & K vitamins; taking these vitamins in high amounts can lead to toxicity, as they are not excreted well
Water-soluble vitaminsC (also known as ascorbic acid) and the various B vitamins (e.g.: B1 thiamine, B2, riboflavin, B3 niacin, B6,B7,B12). The disease resulting from a deficiency in vitamin C is known as Scurvy.
CofactorsInorganic (e.g.: iron, zinc, magnesium). A mineral
Feedback inhibitionThe amount of product produced (the end-product) acts as a signal that will bind to and shut down the enzyme

Section 8

Question Answer
Aerobic RespirationThe most important pathway involves the breakdown of glucose to release energy.
GlycolysisFirst step in the process of aerobic respiration. Glucose (6 carbons) is broken into two 3-carbon acids (pyruvic acid). During this process, 2 ATPs are made & also some proton/electron pairs
Kreb's CycleAlso known as the citric acid cycle. The two 3 carbon molecules made in glycolysis will be completely broken & released as CO2 & 2 ATPs produced
Oxidative phosphorylation (Electron Transport)This is where the majority of the ATP is made. Transport molecules NAD & FAD carry proton/electron pairs to the cytochromes involved in the electron transport chain, where a chain of oxidation & reduction reactions take place, creating a proton gradient that is used to generate ATP. In the final step, a proton (H+) is added to the oxygen (that's why oxygen is needed) water is made as a waste product
Respiration of Proteins & LipidsAll other molecules: proteins lipids & other carbohydrates, are fed into some stage (either glycolysis or the Krebs cycle) of this pathway
Anaerobic RespirationProcess does not require O2. One way of doing this is to use a different terminal acceptor in place of oxygen (e.g.: using sulfur & producing H2S instead of H2O, or using carbon & producing CH4.)
Fermentation (type of anaerobic respiration)The process involves glycolysis & a few additional steps. It does not go on to the Krebs cycle & electron transport chain. This is a less efficient process than aerobic respiration. 2 ATPS is the result. Various organic end-products (such as alcohol or acetic acid) are formed