Exam #2 - chapter 3-6 Flashcards

Question

vesicles

Answer 1

transport molecules to destination

Answer 2

- membrane-bounded digestive vesicles - arise from golgi apparatus - enzymes catalyze breakdown of macromolecules - destory cells or foregin matter that the cell has engulfed by phagocytosis

Answer 3

variety of enzyme-bearing, membrane-enclosed vesicles **Peroxisomes** - contain enzymes involved in the oxidation of fatty acids - H₂O₂ produced as by-product – rendered harmless by catalase

Answer 4

membrane bounded structures in plants and animals 3 different types of vacuoles: 1. Central vacuole in plant cells 2. Contractile vacuole of some protists 3. Storage vacuoles

Answer 5

- found in all types of eukaryotic cells - bound by membranes -- Outer membrane -- Intermembrane space -- Inner membrane has cristae -- Matrix have their own DNA adn their own ribosomes

Answer 6

- Organelles present in cells of plants and some other eukaryotes - Contain chlorophyll for photosynthesis - Surrounded by 2 membranes - Thylakoids are membranous sacs within the inner membrane **Grana:** are stacks of thylakoids - Have their own DNA

Answer 7

One cell, a prokaryote, was engulfed by and became part of another cell, which was the precursor of modern eukaryotes - Mitochondria and chloroplasts

Answer 8

Network of protein fibers found in all eukaryotic cells - Supports the shape of the cell - Keeps organelles in fixed locations **Dynamic system** – constantly forming and disassembling

Answer 9

**Microfilaments (actin filaments) ** - 2 protein chains loosley twined together waith each part being largest of the cytoskeletal **Microtubules** - Largest of the cytoskeletal elements - Hollow tubes **Intermediate filaments ** - Between the size of actin filaments and microtubules

Answer 10

Region surrounding centrioles in almost all animal cells Microtubule-organizing center - Can nucleate the assembly of microtubules Animal cells and most protists have centrioles – pair of organelles Plants and fungi lack centrioles

Answer 11

- Actin and microtubules are important for movement within cells. - Movement often requires the use of ATP - Some cells crawl using actin microfilaments to “push” the cell membrane forward

Answer 12

9 + 2 arrangement of microtubules Not like prokaryotic flagella Microtubules move past each other and this leads to undulation of the flagella Surrounded by the plasma member with cytoplasm inside Cilia are shorter and more numerous

Answer 13

* secrete an elaborate mixture of glycoproteins into the space around them * form a protective layer over the cell surface * integrins link ECM to cell's cytoskeleton * animal cells lack cell walls*

Answer 14

most tissue-specific cell surface markers

Answer 15

recognition of "self" and "nonself" cells by the immune system

Answer 16

1. Tight Junction 2. Adhesive Junction 3. Communicating Junction

Answer 17

allows direct communication of molecules between adjacent plant cells

Answer 18

* phospholipids arranged in a bilayer * globular proteins inserted in the lipid bilayer * **Fluid Mosiac Model**: mosaic of proteins floats in or on the fluid lipid bilayer like boats on a pond

Answer 19

1. phospholipid bilayer 2. transmembrane proteins 3. interior protein network 4. cell surface markers

Answer 20

both TEM and SEM are used to study membranes

Answer 21

structure: - glycerol - 2 fatty acids - phosphate group spontaneously forms a bilayer (fatty acids on the inside, phosphate on both surfaces)

Answer 22

* saturated fatty acids make the membrane less fluid than unsaturated fatty acids * warm temps make the membrane more fluid than cold temps * lipid conpositiion of the ER membrane, golgi stack, & plasma membrane are distinct

Answer 23

1. Transporters 2. Enzymes 3. Cell-surface receptors 4. Cell-surface identity markers 5. Cell-to-cell adhesion proteins 6. Attachments to the cytoskeleton

Answer 24

anchoring molecules attach membrane protein to surface

Answer 25

1. Nonpolar regions that insert into the internal portion of the lipid bilayer 2. Chemical bonding domains that link directly to proteins

Answer 26

* span the lipid bilayer (transmembrane proteins) * Transmembrane domain

Answer 27

Extensive nonpolar regions within a transmembrane protein can create a pore through the membrane

Answer 28

the movement of molecules through the membrane in which: - No energy is required - Molecules move in response to a concentration gradient

Answer 29

* the movement of molecules from high concentration to low concentration * will continue until the concentration is the same in all regions

Answer 30

Major barrier to crossing a biological membrane is the hydrophobic interior that repels polar molecules but not nonpolar molecules

Answer 31

* Molecules that cannot cross membrane easily may move through proteins * Move from higher to lower concentration **Channel proteins**: Hydrophilic channel when open **Carrier proteins**: Bind specifically to molecules they assist * Membrane is selectively permeable

Answer 32

* Allow the passage of ions * **Gated channels:** open or close in response to stimulus (chemical or electrical) **3 conditions determine direction: **- Relative concentration on either side of membrane - Voltage differences across membrane - Gated channels – channel open or closed

Answer 33

net diffusion of water across a membrane toward a higher solute concentration * cytoplasm of the cell is an aqueous solution - water is a **solvent** - dissolved substances are **solutes**

Answer 34

* **Hypotonic** solution has a lower solute concentration * **Hypertonic** solution has a higher solute concentration * **Isotonic** solution has the same concentration *** aquaporins facilitate osmosis**

Answer 35

- some cells use extrusion in which water is ejected thru contractile vacuoles - isomotic regulation involves keeping cells isotonic with their environment - plant cells use turgor pressure to push cell membrane to cell wall

Answer 36

* Requires energy – ATP is used directly or indirectly to fuel active transport * Moves substances from low to high concentration * Requires the use of highly selective carrier proteins

Answer 37

**uniporters:** move 1 molecule at a time **symporters:** moves 2 molecules in the same direction **antiporters:** move 2 molecules in opposite directions

Answer 38

* direct use of ATP for active transport * low internal Na⁺ and high K⁺ concentration * uses antiporter to move 3 Na⁺ out of the cell and 2 K⁺ into the cell

Answer 39

* indirect use of ATP * uses the energy released to supply energy to active transport of a different molecule * symporter is used * Glucose-Na⁺ symporter captures the energy from Na⁺ diffusion to mvoe glucose against the concentration gradient

Answer 40

move material in opposite directions

Answer 41

* movement of substances into the cell * phagocytosis: cell takes in particulate matter * pinocytosis: cell taken in only fluid * requires energy

Answer 42

* movement of substances out of the cell * used in plants to export cell wall material * used in animals to secrete hormones, neurotransmitters, digestive enzymes * requires energy

Answer 43

* branch of chem and physics concerned with energy changes * cells are governed by the laws of chem and physics

Answer 44

2 states: **1. Kinetic:** energy in motion **2. Potential:** stored energy many forms: mechanical, heat, sound, electric current, light, or radioactivity heat is the most convenient way of measuring energy 1 calorie = 4.2 joule 1 Calorie = 1,000 calories = 1 kcal

Answer 45

oxidation: atom or molecule loses an electron reduction: atom or molecule gains an electron, higher level of E than oxidized form | OIL RIG

Answer 46

* energy cannot be created nor distroyed * can only change from one form to another * total amt of energy in the universe remians constant * during conversion, energy is lost as heat

Answer 47

* entropy (disorder) is continuously increasing * E transformations proceed spontaneously to convert matter from a more orded/less stable to less ordered/more stable

Answer 48

* the amout of energy available to break/form bonds * G= gibbs free energy = energy available to do work * H = enthalpy, energy in molecules chemical bonds * T = absolute temp * S = entropy, unavilable energy

Answer 49

ΔG = change in free energy +ΔG: - products have more free energy - not spontaneous, requires input of energy - endergonic - ΔG: - products have less free energy than reactants - spontaneous - exergonic

Answer 50

* extra energy required to destablilize existing bonds and initiate a chemial rxn * exergonic rxn's rate depends on activation energy * rate can be increased by: 1. Increasing energy of reacting molecules (heating) 2. Lowering activation energy

Answer 51

substances that influence chemical bonds in a way that lowers activation energy

Answer 52

* all life gets energy from the sun * every organism is dependent on a very tiny amt of energy we get from the sun * stored as potential E in chemical bonds

Answer 53

* adenosine triphosphate * Chief “currency” all cells use Composed of: - Ribose – 5 carbon sugar - Adenine Chain of 3 phosphates: - Key to energy storage - Bonds are unstable - ADP – 2 phosphates - AMP – 1 phosphate – lowest energy form

Answer 54

ATP hydolysis drive endergonic rxns - couplet reactions results in net -ΔG - ATP not suitable for long term energy storage - ATP -> ADP = 7.3 kcal/mole ATP -> AMP = 10.3 kcal/mole *between 1-2 billon ATP's per minute

Answer 55

* most enzymes are protein - some RNA * shape of enzyme stabilizes a temporary association between substrates * enzyme not changed or consumed in rxn

Answer 56

* Pockets or clefts for substrate binding * Forms enzyme-substrate complex * Precise fit of substrate into active site * Applies stress to distort particular bond to lower activation energy - Induced fit

Answer 57

2 kinds: 1. intramolecular catalysis: catalyze rxn on RNA molecule itself 2. intermolecular catalysis: RNA acts on another molecule *important in ribosomoes

Answer 58

subunits work together to form molecular machine - Product can be delivered easily to next enzyme - Unwanted side reactions prevented - All reactions can be controlled as a unit

Answer 59

* rate of enzyme-catalyzed reaction depends on concentractions of substrate and enzyme * any chemical or physical condition that affects the enzyme's shape can change rate of: - optimum temp - optimum pH

Answer 60

substance that binds to enzyme and decreases its activity

Answer 61

**competitive inhibitor:** competes with substrate for active site **noncompetitive inhibitor:** binds to enzyme at a site other than active site - causes shape change that makes enzyme unable to bind substrate

Answer 62

ATP hydrolysis drivers endergonic reactions - not suitable for long term energy

Answer 63

amount of energy needed to start a reaction

Answer 64

- 5 carbon sugar ribose -adenine - chain of 3 phosphates

Answer 65

enzymes exist in active and inactive forms - most noncompetitive inhibitors bind to allosteric site (chemical switch on and off)

Answer 66

Bids to allosteric site and reduces enzyme activity

Answer 67

binds to allosteric site and increases enzyme activity

Answer 68

-metal ions that are found in the active site participating directly in catalysis

Answer 69

- nonprotein organic cofactor molecule

Answer 70

- expend energy to build up molecules

Answer 71

- harvest energy by breaking down molecules (cats love to tear apart)

Answer 72

reactions occur in a sequence, product of one reaction is the substrate for the next

Answer 73

shuts down pathway so raw materials and energy are not wasted - end product of pathway bind to an allosteric site on enzyme that catalyses

Exam #2 - chapter 3-6 Flashcards

Exam #2 Material (98 cards)