Cell Structure/Cytoskeleton
What are the three cytoskeleton structures and what are they made of?
microfilaments (actin) , microtubules (tubulin polymers), and intermediate filaments (keratin protein).
Define diffusion
Diffusion is the tendency for molecules to spread out evenly into an available space. Although each molecule moves randomly, a population of molecules may diffuse directionally (e.g. from high concentration to low concentration)
What is the difference between a catabolic and anabolic pathway? Which would describe protein synthesis? What about cellular respiration?
Catabolic pathways release energy by breaking down complex molecules into simpler compounds
Anabolic pathways consume energy to build complex molecules from simpler ones
What is the difference between aerobic respiration and anaerobic respiration? Which does cellular respiration use?
Aerobic respiration: consumes organic molecules and O2, yielding ATP through a multistep process that involves electron transfer
Anaerobic respiration: similar to aerobic respiration, but consumes compounds other than O2.
Cellular respiration includes both aerobic and anaerobic respiration, but most often refers to aerobic respiration
Chloroplasts are found mainly in the cells of the ___.
mesophyll
True or False: Vesicles that are headed to the plasma membrane typically depart from the trans Golgi network.
True
What is active transport and why is it important for our cells?
Active transport moves substances against their concentration gradients and requires energy(usually in the form of ATP)
Active transport allows cells to maintain concentration gradients that differ from their surroundings.
A reaction with a DG<0 ______ energy, whereas a reaction with DG>0 ________ energy.
Releases; requires
Which species is reduced and which is oxidized?
Xe- is oxidized
Y is reduced
___ enters and ___exits the leaf through microscopic pores called stomata.
CO2
O2
If you treated a cell with a solution that inhibited the construction of microtubules, what are some cell functions that wouldn't occur?
1. The shape of the cell would be compromised.
2. Organelles would no longer be able to be transported across the cell
3. Movement of cells would be compromised. (flagella and cilia).
4. Chromosomes wouldn't separate during cell division.
Transport proteins that are involved in facilitated diffusion are ___ and _____.
channel and carrier proteins
What is the difference between an endergonic and exergonic reaction?
Exergonic reaction: proceeds with a net release of free energy and is spontaneous (DG is negative)
Endergonic reaction: absorbs free energy from its surroundings and is nonspontaneous (DG is positive)
During cellular respiration_____ is oxidized and ___ is reduced
O2
Where do the 'light reactions' occur?
Occurs in the thylakoids, resulting in splitting of H20, release of 0 2, reduction of NADP+ to NADPH, generates ATP from ADP by photophosphorylation.
List from smallest to largest: histones, groups of nucleotides on DNA strands, chromosomes, chromatin
Groups of nucleotides on DNA strands
histones
chromatin
chromsomes
Which will diffuse fastest through the plasma membrane?
Cl- , H2O, glucose, NH3, CO2, nucleotides, or HCO3-
CO2
Small nonpolar/hydrophobic molecules
What is the difference between a competitive inhibitor and a noncompetitive inhibitor?
Competitive inhibitor:something that binds to the active site of an enzyme, preventing the substrate from binding
Noncompetitive inhibitors: bind to a part of the enzyme that is NOT the active site, causing the enzyme to change shape (folding) and make the active site less effective/accessible (these are also referred to as allosteric inhibitors)
What two molecules serve as the electron carriers in cellular respiration?
NADH & FADH2
The calvin cycle occurs in the ___, results in formation of ___ from C02, using ATP and NADPH
stroma, sugar
Motor proteins that walk along microtubules are ___ and___.
dyneins and kinesins
The Na+/K+ ATPase pumps _______ ions out of the cell in exchange for pumping ________ ions into the cell.
3 Na+; 2 K+
What is allosteric regulation and how do you describe their inhibitors and activator functions?
Allosteric regulation occurs when a regulatory molecule binds to a protein at one site and affects the protein’s function at another site (e.g. at the active site of an enzyme)
Allosteric activators bind to the enzyme and stabilize the active form
Allosteric inhibitors bind to the enzyme and stabilize the inactive form of the enzyme
When does fermentation occur? What are the two types and what is generated?
In the absence of O2, the electron transport chain will not operate so gycolysis will couple with fermentation to produce ATP.
Alcohol fermentation: pyruvate is converted to ethanol in two steps
1.Release of CO2
2.Production of ethanol
Lactic acid fermentation: pyruvate is reduced to NADH, forming lactic acid (lactate), with no release of CO2
What is the main photosynthetic pigment? What about the accessory pigments?
Chlorophyll a
Accessory pigments: chlorophyll b(broaden the spectrum used for photosynthesis) and carotenoids(absorb excessive light that would damage chlorophyll)