Biology Test 2 Flashcards
What is the function of the skeleton?
support and provide structure
What is the definition of the cytoskeleton?
A network of protein filaments that extends throughout the cytoplasm
Functions of the cytoplasm
1) Maintain shape
2) Organize Cellular components
3) Interact with the environment ECM
4) Aid in movement
How does ECm and cytoskeleton interact?
Cytoskeleton interacts by being bound through adaptor protein, attached though integrin, to fibronectin, to collagen fiber
What are 3 types of protein filaments?
Intermediate Filaments
Microtubules
Microfilaments
True or False. All protein filaments are made with the same proteins.
False. They all have slightly different function so made with different proteins.
Which filament has the largest diameter?
Microtubules
Which filaments are polar (for direction)
Microtubules and microfilaments
Which filament is the most durable of the 3?
Intermediate Filaments
What is the main function of intermediate filaments?
withstand the mechanical stress that occurs when cells are stretched
Where are intermediate filaments found?
Surrounding the nucleus, anchored to the plasma membrane at desmosomes, found with the nucleus
What is the structure of Intermediate filaments?
Rope-like:long strand twisted together to provide tensile strength
N and C-terminal Head with an alpha helical rod
Two intermediate filament proteins wrap around each other to form what?
coiled-coil dimer
2 dimers interact to form what?
tetramer
How are filaments formed from tetramers?
Tetramers bind end to end and side by side to form the filament (through non-covalent bonding)
Where are Intermediate filaments generally found?
cells that are subject to mechanical stress such as Neurons, Muscle cells, Epithelial cells
What are the four main classes of Intermediate Filaments?
Keratin
Vimentin
Neurofilaments
Nuclear Lamins
Where are keratin filaments found?
Epithelial-gut and skin
Where are Vimentin Filaments found?
connective tissue, muscle, and glial cells
Where are Neurofilaments found?
neurons
Where are Nuclear Lamins found?
nucleus of ALL animal cells
What class of Intermediate Filaments is the only class to have a 2-D structure?
Nuclear Lamins
What is the structure of microtubules?
Long, relatively rigid, hollow tubes of protein
Where do microtubules grow/ anchored at
centrosome
What do microtubules create as they extend out from centrosome?
system of “tracks” that provide mechanism of transport for all things
What is the function of microtubules?
Anchors membrane bound organelles (mitochondria-video)
Guides TRANSPORT withing the cell, not random diffusion
How does a cell squeeze through an epithelial cell?
First breaks down and then reforms on other side
What are example of microtubules?
Mitotic spindle
Core of eukaryotic cilia and flagella
What protein is microtubule made of?
Tubulin
- functions as heterodimers
- alpha
- beta
How many tubulin dimers does it take to go around 1 microtubule?
13
Each microtubule has what?
Polarity (directionality)
Which end of the microtubule is minus and which is positive?
Beta-minus
Alpha-plus
Which end, alpha or beta, of microtubule is imbedded in centrosome?
Minus
Which end of the microtubule grows?
plus
What is it called when microtubules grow, shrink, grow, etc?
Dynamic instability
Dynamic instability is what?
When microtubules grow, shrink, grow, etc
Movement along the microtubules is dependent upon what?
motor proteins
How do microtubules get its ATP?
Through hydrolyze of ATP
What are the two motor protein families?
Kinesins
Dyneins
Kinesins move cargo on the microtubules which direction?
Toward plus end
Dyneins move cargo on the microtubules which direction?
Minus end (think down)
What filament is found in all eukaryotic cell?
Microfilaments
Why are microfilaments essential?
For movement of cell surface and cell division
Microfilaments comprise what four main structures?
Contractile units:muscle cells
Microvilli: small projections from intestinal cells
Finger like protrusions found in immune cells
Contractile ring: aids in cell division
Unlike microtubules, microfilaments are what three things?
thinner, flexible, and shorter
T/F There are more microfilaments in the cell than microtubules
True
What is the structure of microfilaments?
Twisted chain of identical actin proteins, have directionality, found in bundles and networks (not as single filaments)
Microfilament growth is…
similar to microtubules
faster at plus end
dynamic assembly/dissassembly
What is a cell cortex?
when cross-linking proteins keep actin filaments in a meshwork just below the membrane
How do cells function as the building blocks of multicellular organisms?
Extracellular matrix
Cells are organized into what?
tissues
What are the four main types of tissue?
Muscle
Connective
Epithelial
Nervous
Tissues are composed of two things…
cells and extracellular matrix
T/F There is a lot of ECM in bone and tendons?
True
T/F There is a lot of ECM in muscle and skin?
False
Connective tissue is mostly occupied by what?
ECM
What carries the mechanical load of the tissue?
ECM
What makes up the ECM and provides this “strength”
collagen
In what types of cells is collagen found?
In all multicellular animals
How many varieties of collagen are there in humans?
20 different
Collagen makes up what percent of total protein in the body?
25%
Where is collagen chiefly found?
proteins in bone, tendon, and skin
What is collagen’s structure?
Three collagen chains wind together to form a triple-helical structure
The triple helices of collagen for polymers called
collagen fibrils
Many collagen fibrils pack together to form
collagen fiber
What are collagen producing cells?
Fibroblasts
Osteoblasts
Where are fibroblasts found?
in skin, tendon, etc
where are osteoblasts found?
Bone
Do cells produce collagen intracellularly or externally?
intracellularly then secrete it outside the cell
What drives the formation of collagen?
Intermolecular forces, happens spontaneously
What is collagen produced by?
Ribosomes
How does the cell keep the collagen from forming fibers INSIDE the cell?
secretes collagen as “procollagen” and then once outside cuts off the end by collagen proteinases that allows them to assemble
Defects in production or assembly of collagen can lead to what diseases
Ehlers-Danlos and Osteogenesis Imperfecti
What is responsible for organizing the collagen fibers found in ECM
The cell is responsible for its own area
Cells are connected to collagen through what?
fibronectin
What is fibronectin?
a protein specifically that connects collagen to integrin
Fibronectin is connected to the cell through an integral membrane called…
integrin
What interacts with the cytoskeleton (actin filament)
intracellular domain of integrin
What provides hydrated substance around joints, fills spaces and creates a gel-like substance in connective tissues?
Proteoglycans
Are proteoglycans hydrophillic or hydrophobic?
hydrophillic
How are cells usually connected to each other?
With cell junctions
What are the three types of cell junctions?
Tight, Gap, and Adhesive
What are tight junctions?
Create a seal between neighboring cells, cells are packed and water tight
What are Gap Junctions?
Allow passage of small water-soluble ions and molecules in the cytosol
What are Adhesive Junctions?
Connect filaments of one cell to those in an adjacent cell
What are the 4 stages of Aerobic Respiration?
1) Glycolysis
2) TCA cycle
3) Electron Transport
4) ATP synthesis
After glycolysis, where is the free energy found?
3 Coenzymes generated
What is the largest organelle other than the nucleus?
Mitochondria
TCA cycle is also called…
Krebs Cycle or Citric Acid Cycle
What does the TCA cycle do?
metabolizes Acetyl-CoA
- carbon ecetyl group attached to carrier molecule
Where does acetyl CoA come from (2 things)
Pyruvate
Breakdown of fatty acids
The TCA cycle steps…
1) entry of 2-Cs
2) release of 2 Cs (CO2)
3) Regeneration of oxaloacetate
The TCA cycle involves how many oxidation steps?
4 that involve reduction of Coenzymes
The Oxidation of Coenzymes will later generate what?
ATP
Where does energy come from in anaerobic respiration?
oxidation steps
What is Oxidative decarboxylation?
PDH catalyzes an oxidation and a decarboxylation
How many molecules of ATP are made during 1 cycle?
1
How many molecules of ATP are made during TCA cycle with 1 molecule of glucose?
2 molecules
How many times does TCA cycle proceed for each molecule of glucose?
twice
How many ATPs have been made from glycolysis and TCA cycle?
4
Where do the 10NADHs come from?
6 from TCA cycle
2 from glycolysis
2 before TCA cycle
T/F Amino acids (catabolized proteins) can enter the TCA cycle
True
What is the process called to reoxidize the coenzymes and transfer the electrons to OXYGEN?
electron transport
Re-oxidation of NADH and FADH2 are highly what?
exergonic
What is the free energy value of reoxidation of NADH?
-52.4 kcal/mol
What is the free energy value of re-oxidation of FADH2
-45.9 kcal/mol
What are the byproducts of aerobic metabolism?
Water and CO2
Where is the byproduct of Water produced in aerobic metabolism?
Electron Transport System
Where is the byproduct of CO2 produced in aerobic metabolism?
TCA cycle
In aerobic respiration, where are respiratory complexes located?
inner mitochondrial membrane
As electrons are passed through the transport chain, what occurs.
Protons are pumped into the inner membrane space creating a huge gradient
What proteins are mostly involved in the steps of electron transport?
cytochromes
What complex does FADH skip
complex 1
Electrons are transferred from complexes of what to what
lower E0 to complexes with a Greater E0
What has the highest E0 and is the final electron acceptor?
Oxygen
What is E0
the reduction potential:the affinity a compound has for electrons
How many protons pumped does 1 NADH make?
10 H+
How many protons does FADH2 make?
6H+
How many protons does it need to make an ATP molecule?
3
How many ATPs can a NADH molecule give?
3
How many ATPs can a FADH2 molecule give?
2
Before crossing through the membrane, what does the NADH molecule go through?
ATP synthase
How many ATPs are made in total from Aerobic Oxidation of Glucose?
38 ATPs
Glycolysis yields how much CO2?
0
How much CO2 is made in Pyruvate Oxidation
2
How much CO2 is made in TCA cycle?
4
What is regulated in aerobic metabolism and why?
Pyruvate Dehydrogenase. It’s at the beginning so it stops right away if not needed and you don’t waste energy
In muscle contraction, what is needed?
Prior: Nerve Triggers
During: Actin, Myacin, sliding of the filament
What does the body need during muscle contraction?
ATP energy
What cells require energy?
ALL
What is energy? (definition)
The ability to cause change or do work
What is energy not?
A feeling
Why is energy needed?
1) Synthetic work: Biosynthesis
2) Mechanical work: changes in location within a cell or movement of an entire cell
3) Concentration work: movement of molecules against a concentration gradient
4) Electrical work: movement of molecules against an electrochemical gradient
5) Heat: energy is needed to maintain body temp
6) Light: energy is needed to produce light
In concentration work, what does not require energy?
When flowing from high to low gradient
What term do we measure energy changes?
calories (cal)
1 calorie is equal to the amount of what?
the amount of energy needed to raise 1 gram of water by 1°C
What is thermodynamics?
Study of energy flow that accompanies chemical and physical processes.
How does the body get energy?
Metabolizing in which the end product is ATP
What is the most useful concept in thermodynamics that applies to biology?
Free energy (G)
What was free energy named after?
Gibbs
What is delta G?
Change in free energy
What measure is free energy given in?
spontaneity of a reaction
What does delta H mean?
enthalpy
What is delta S mean?
entropy
What is enthalpy?
the specific energy from a reaction
What is entropy?
the overall order of a system itself
What is a reaction with a negative delta G called?
exergonic (energy yielding/ gives)
Can exergonic reactions proceed on its own?
Yes
exergonic reactions are what?
Spontaneous (proceed on its own)
What is a reaction with a positive delta G
endergonic
Can endergonic reactions proceed on its own?
No
How many kcal of energy is stored in one molecule of ATP
7.3 kcal
What is the stored form of energy in the body?
ATP
T/F Delta G only indicates whether a reaction CAN proceed, nothing to whether it will proceed.
T
What is the magnitude (number) of delta G indicate?
How much energy will be released as the reaction proceeds
All cellular reactions are mediated by a category of proteins called
enzymes
Even if the free energy change is negative, most biological reactions do NOT occur in the absence of
an enzyme
What is the activation of energy?
The energy required to get the reactants to the higher energy transition state
In order for reaction to proceed, reactants must reach what?
higher energy transition state
How do enzymes affect the activation energy barrier?
They lower it
What do enzymes do in a reaction?
bring the reactants close together and in a conformation that is favorable for the reaction to proceed
What are enzymes also known as?
Catalysts
Do enzymes change the property?
No they just push for the reaction to proceed
Do reactions occur slower or faster with enzymes as catalysts?
faster
What are the 3 properties of catalysts?
1) increases reaction rate by lowering activation energy requirement
2) Forms transient complexes with reactants by binding them in a manner that facilitates their interaction
3) Catalysts only change the RATE at which a reaction proceeds, does not change the reaction properties
What is the active site:
specific location on an enzyme where a few amino acids interact with substrate
What is the perfect temperature for human enzymes to peak efficiency?
37C
what is the physiological pH level of our bodies?
7.4
Binding of substrate to enzyme is dependent on what?
Random collision
Once the substrate collides with active site, it is bound usually through what?
ionic or hydrogen bonds
Once binding occurs what changes?
conformation (shape)
What does the change in shape do?
distorts the substrate to get it to the transition state
Enzyme inhibitors can be what?
reversible or irreversible
How does irreversible enzymes bind?
covalently
What is irreversible inhibitors usually to the cell?
toxic
How do reversible inhibitors bind?
non-covalently so inhibitor can dissociate from the enzyme
the level of inhibition depends on what?
concentration of inhibitor
Reversible inhibitors can be what? (2 kinds)
competitive or non-competitive
What is reversible competitive inhibitors?
binds to the active site and competes with substrate
What is reversible non-competitive inhibitors?
Binds to the enzyme surface at a location other than the active site and cause a conformation change
What is feedback inhibition?
where products of a reaction or maybe at the end will feed back and inhibit one of the enzymes in the pathway
Cells don’t function efficiently if what
enzymes are all ON at the same time
Enzymes are regulated in the cell by what
non-competitive mechanisms
what are the two non-competitive mechanisms that enzymes are regulated by?
Allosteric regulation “another shape”
Covalent modification
What is allosteric regulation?
where something binds and the enzyme changes shape
What is covalent modification?
cell has mechanisms to break covalent bonds as well as enzymes to take the off
The cell will usually regulate what enzyme and why?
Th First enzyme so it saves energy and materials
Allosteric Regulation works by binding what
allosteric effectors
Where does allosteric regulation bind?
allosteric site
The effector may be what?
allosteric inhibitor or allosteric activator
T/F Covalent modification is not very common mechanism of enzyme regulation in the cell
False
Enzyme is affected by addition or removal of chemical groups such as…
phosphate
methyl
acetyl
Covalent modification is often times what
reversible
