PREPARATION FOR FINAL EXAM for molec cell Flashcards
describe secondary structure of amino acids
It is composed of alpha helics and a spiral conformation in which every backbone N-h group donates a hydrogen bond to the backbone C=O group
Why do nonpolar amino acid chains tend to be on the interior
Nonpolar amino acids are typically found on the interior because they have hydrophobic properties and tend to repel water
Describe detergents
They are ampiathetic and disruptive agents
, the hydrophobic ends of detergent molecules interact with the membrane-spanning hydro-
phobic regions of the transmembrane proteins, as well as with the hydrophobic tails of the phospholipid molecules, thereby disrupting
the lipid bilayer and separating the proteins from most of the phospho
lipids
THEY DO NOT ASSOCIATE THE HEAD FROM THE TAIL AND DO NOT SEPERATE THE LIPS
do proteins bind to their ligand as tight as possible
nope this is because a tight configuration will not provide strong enough binding if it is not acessible
When are GTP binding proteins in their active conformation
They are active when it is bound to GTP and inactive or off when bound to GDP
Why are alpha helics more common than beta barrels
Alpha helices are good to anchor proteins into the membrane, or forming small holes that is suitable for compounds like ions, while with beta barrels larger compounds such as sugars, or various drugs can be transported
Which of these do we know that flipase opccurs
Flippases are responsible for transporting phosolipids from the extracelluar sideor noncytosolic to the cytosolic side of the membrane
Describe the cell cortex and it functions
The cell cortex can restrict movement, maintain shape, orgsnizing the cell’s internal components
describe a protein domain
any segment of a polypeptide chain that folds independantly into a compact and stable structure
explain Disulfide bonds
the covalent bond formed between the sulfur atoms of twp cysteines in a protein
covalent cross linkages
reinforce structure of a protein
DO NOT CHANGE THE STRUCTURE
describe hydrolase
breaks down bonds using water in a reaction called hydrolysis
what is a nuclease
A nuclease is an enzyme thatr cuts DNA or RNA by breaking phospphodiester bonds between nucleotides
what is a protease
A protease is an enzyme that breaks down proteins by breaking peptide bonds between amino acids
what does a ligase do
A ligase is an emzyme that connects two frag,emts of DNA to make a single fragment
what does synthase do
Synthase is an enzyme that combines two molecules to create a new molecule without ATP hydrolsis
what does an isomerase do
An isomerase is an enzyme that rearranges bonds within a molecule
what do polymerases do
An enzyme that catalyzes polymerization reactions such as the synthesis of DNA and RNA
what does phosphatase do
Is an enzyme that removes a phosphate group from a molecule
what does oxidoreductase do
An enzyme that catalyzes redox reaction when one molecule is oxidized while the other one is reduced
what does ATPase do
An atpase is an enzyme that hydrolyzes ATP to ADP
What is an alloesteric enzyme
An enzyme that both an active site for substrate binding site and alloesteric site for binding of regulatory molecules
what are the functions of the cell membrane
Cell growth and Motility
Cell communication
Import and export of molecules
What are the properties of a lipid
The properties of a lipid is a hydrophillic head and a hydrophobic tail
What is the most common phospholipid in the cell membrane
The most common phospholipid in cell membrane is phosphatidylcholine
What is the difference between an unsaturated and saturated fatty acid
An unsaturated fatty acid has one or more double bonds and saturated fatty acid are connected by a single bond and allows less fluid
Which side of the lipid bilayer is hydrophobic and hydrophillic
The interior of the bilayer is very hydrophobic with is tails and the exterior of the hydrophilic with the heads and interacts with water
What impacts the fluid of the bilayer
The temperature
The saturation of the hydrocarbon tails
The composition and the length
Explain the effects of temperature on fluidity
The higher the temp the more fluid in the bilayer
The less the fluid means the temperature has lowered
Describe the relationship between cholesterol and fluidity
The more cholesterol in a lipid bilayer the less fluid and it will be stiffened
The less cholesterol and the more fluid
Where does the production of lipid synthesis takes place
The production of lipid shyntheis takes place in the smooth ER
What does scramblases do
Scramblases is an enzyme that randomly move lipids from one monolayer to the other
What is the function of flippases do
Flippases remove specific phosolipids from the side of the non cytosolic bilayer facing the exterior space and flipping them into the monolayer that faces the cytosol
Explain the process of membrane synthesis
The membrane is made in the smooth ER and phospholipids are added to the cytosolic side of the ER membrane. Scrambalases function in making sure lipids are evenly distributed between both membranes. Then mebranes goes into the Golgi and the flippases in the Golgi flips specific phospholipids from the noncytosolic monolayer to the cytosolic monolayer
What is the difference between a integral protein versus peripheral protein
Integral proteins is a membrane protein that spans across the entire lipid bilayer and is permeanetly embeded and peripheral mebrane protein is a membrane protein that is only temporarily attached to the mebrane surface
what is a spectrin
Spectrin it forms a lattice that provides support for thered blood cell biconcave shape
what is the portion of the transmembrane protein that spans the bilayer is
hydrophobic
What is one way to change fluidity ?
Increasing proportion of unsaturated hydrocarbon tails
how do new membrane synthesis occurs by
Incorporation into one monolayer and specific redistribution by flipases
How is it possible for many proteins to have these common elements like alpha helix and beta pleated sheets
Due to hydrogen bonds that bond along to the protein backbone
What does polymerase do
The enzyme that joins nucleotides together
The genetic code
They all codons do not specify more than one and purines pair with pyrimidines
New membrane synthesis occurs
Random redistribution by scrambalases and redistribution by flippases
Looking at two sequences for an enzyme and coding region is similar
a mutation occured in a coding region it would be selected against
What does DNA polymerase need
It needs a 3 prime hydroxyl group to add the next nucleotide
how are DNA replication and synthesis similar
They are similar in that they both occur in the 5 to 3 direction
What determines the function of that are contained in the cell membrane
Proteins because they can help transport substance across the cell membrane
Receptors proteins on the cell membrane recieves signals
serve as cell to cell recogniton like glycoproteins that serve as identification of other tags that are recognized by other cells
Intracellular joining
The mebrane lipids are composed of
Composed of a hydrophilic portion and hydrophobic which is ampiathetic
All membranes have what
A lipid bilayer structure and tails on the inside and head groups on the outside
what is a head group of a lipid
The head group of a lipid is sugar which is known as a glycolipid
