Quiz 3 Chap 5/6 Flashcards
how is NADH significant in the electron transport chain?
- NAD+ coenzyme is previously transferred electrons from organic compounds
- each NADH represents stored energy to make ATP, NADH electron carriers pass/donate electrons to compounds in the ETC
- carriers alternate reduced and oxidized states as they accept and donate electrons
how does the ETC work
- O2 pulls electrons down the chain, yielding energy for ATP in a series of redox reactions
- electrons are passed through many proteins (including cytochromes containing Fe) and drop in free energy as they go down the chain
- this causes proteins in the cristae to pump H+ (protons) from the matrix to the intermembrane space
significance of ETC being a series of small steps
ETC functions to break the large free-energy drop from food into smaller steps, releasing energy in manageable amounts
ETC structure
multi-protein complex in the cristae (inner membrane)
chemiosmosis
use of energy in a H+ (proton) gradient to drive cellular work
how is ATP made via chemiosmosis, and what is a proton-motive force?
- H+ moves back across the membrane via ATP synthase (turbine-like)
- energy from this H+ gradient causes phosphorylation of ADP to ATP
proton motive force – H+ gradent
significance of oxygen during ETC stage
electrons are passed to oxygen at the end of the chain to form H2O, chain can’t function without oxygen to accept them
flow of energy during cellular respiration
glucose - NADH - ETC - proton-motive force - ATP
how many ATP are produced during each stage of respiration (per glucose)
glycolysis - 2
citric acid cycle - 2 (1 per turn, 2 turns per glucose)
oxidative phosphorylation - 26-28
evolutionary significance of glycolysis
- occurs in nearly all organisms
- evolved in ancient prokaryotes before there was atmospheric oxygen
- glycolysis and citric acid cycle lead to many different catabolic/anabolic pathways
***fats and proteins can also be used for glycolysis, with additional steps before
structure of the plasma membrane
- selective permeability, some substances pass through more easily
- fluid mosaic model: fluid structure with a “mosaic” of various proteins embedded in it
- like jello, phospholipids and proteins can move within the bilayer
how does the plasma membrane change in response to temperature?
- at cool temps, membranes switch from fluid to solid (specific temp depends on type of lipids)
- membranes rich in unsat. fats more fluid
importance of membrane fluidity, how they maintain it
membranes must be a specific fluidity in order to function properly
- steroid-cholesterol restrains movement of phospholipids in warm temps and maintains fluidity by preventing tight packing in cool temps
peripheral vs intergral proteins
peripheral: bound to surface of membrane
integral: penetrate hydrophobic core
6 functions for membrane proteins
transport enzymatic activity signal transduction cell-cell recognition intercellular joining attachment to cytoskeleton and extracellular matrix
how do cells recognize each other?
specific molecules on the plasma membrane (glycolipids and glycoproteins)
- these are unique among species, individuals, and even cell types within individuals
which molecules pass/do not pass through plasma membrane?
- hydrophobic (nonpolar) molecules dissolve in lipid bilayer and pass through membrane
- hydrophilic and polar molecules (sugars) must be transported by proteins
mechanisms and benefits of facilitated diffusion
*speeds up passive movement of molecules and allows for the transport of polar molecules!
- channel proteins: hydrophilic channels that allow specific molecules to cross (i.e. ion channels)
- aquaporins: facilitate the passage of water
- carrier proteins: bind to molecules, change the molecule’s shape to shuttle them across the membrane