Bios 3200 Exam One (proteins & membranes)

which method of studying proteins usually involves a protein called Cre?

conditional knock-out animals

in gel electrophoresis, SDS is added to the protein samples to…

coat the proteins with an abundance of negative charge.

The Sanger reaction may be problematic, but it’s still useful. How?

it adds a fluoresent label to only the N-terminal amino acid in a protein.

Why is the Sanger reation problematic in protein sequencing?

the sanger reaction breaks all the peptide bonds in the protein at once.

Enzymes which add high energy phosphates onto other proteins are known as _________.

Kinases

True or false: binding sites for additional molecules on a particular protein are usually formed directly by the primary structure of the protein itself

False

if the folding of a polypeptide chain results in the placement of two cysteine side chains near each other, a _______ may form.

disulfide bond.

Beta sheets may be constructed in 2 ways: parallel and antiparallel. The term “antiparallel’ indicates…

The polypeptide chains making up the sheet are arrageed in opposide directions.

A ____ is a protein that folds independently into a specific unit and is used to add functionality to proteins.

Domain

In proteins, alpha helices and beta sheets are examples of ________

Secondary structures

a lipid bilayer with a high percentage of phospholipids with double bond in their fatty acid tails (unsaturation) will display a high degree of_______.

fluidity

Membrane fluidity in animal cells is decreased by the presence of an increasing amount of…

Cholesterol

on the extracellular surface of the plasma membrane, you’ll find a greater amount of _______ when compared to the intracelluar surface.

Carbohydrate

Which of these protein features is/are commonly found in proteins passing through the plasma membrane?

Alpha Helices

which would be considered an ‘integral’ membrane protein?

• A protein that is anchored to the membrane by phospholipids

• a transmembrane protein that has portions both inside and outside

• a protein that has a portion buried in the cytosolic face of the membrane.

What might be present in secondary structures of a transmembrane protein that would allow for the creation of a small pore or channel?

Hydrophilic amino acids

True or false: respiratory gases, such as O2 and CO2, can pass directly through call membrane because they are non-polar.

True

what is the driving force for the movement of solutes through the plasma membrane by passive transport

the concentration gradient of the solute.

why might the passive movement of a charged substance, like potassium, through the cell membrane be limited even if the concentration gradient for the molecule is high?

The membrane electrical gradient restricts the flow of the charges.

Which is true about the action of Na+/K+ ATPase?

• The transport of odium and potassium is unequal.

• the transport protein phosphorylates itself

• its action is essential for other transport proteins.

What feature of the Na+/K+ ATPase allows it to be categorized as a primary active transporter?

it breaks down ATP directly for energy.

its very common for a transport protein to use the sodium electrochemical gradient to pump other molecules into or out of the cell.

These proteins are…

secondary active transporters

which is the most rare ion channel? (ear and bone)

Only Mechanically- gated ion channels

During Primary active transport; what is the products?

3 Na out and 2 K in

peptide form by…

the removal of water (dehydration)

proteins are made of…

individual amino acids joined by peptide bonds.

result of dehydration/peptide bond formation…

a direct linkage between the nitrogen of the amino and the carbon of the carboxyl

In prokaryotes, how many membranes are there?

One; Plasma membrane

In eukaryotes, how many membranes are there?

Two or more

What are the three roles of membranes?

1) receiving information

2) import and export of molecules

3) capacity for movement and epansion

The structure of membranes is mostly…?

lipids (phospholipids)

What is the head of phospholipids?

hydrophilic

What is the tail of phospholipids?

hydrocarbon

What do the phospholipids need in order to transport?

Proteins

__________ is the backbone that links the head and tail together.

Glycerol

what causes the bend in leg?

double bond

Electrons are _____ distributed throughout the entire hydrocarbon

evenly

still has the hydrocarbon tails, but has sugars instead of the phosphate?

glycolipid

What is the “founder” of all steroids?

cholesterol

True or False: bilayers are not linked together at all (can slip across each other

True

True or False: individual lipids can’t spin

false

More cholestral = ____ fluidity

reduced

True or False: bilayers are asymmetrical

True

the chemistry of the bilayer is ______ on the inside and the outside.

different

transporters and channels→

specialize in moving stuff into the cell or moving stuff out of the cell

anchors →

work as bolts and hold stuff (can bind to both inter and exter bilayer)

receptors →

For communication, they bind to signaling molecules that are on one side of the membrane. (communicates on the other side of the membrane)

enzymes →

very often anchored to membranes (for it keeps it in one place and for the protection of the cell)

Transmembrane→

have both intercellular and extracellular parts. → passes completely through the membrane. (*needs alpha helices) Beta sheets are less likely but still possible.

lipid linked =

anchored

to form a channel, the _____ form an aqueous pore and the _____ interacts with phopholipid tails.

Hydrophillic; hydrophobic

Integral Proteins & ß Sheets use?

on immune system to punch holes in membranes (kills the cell)

Peripheral Proteins & The Cell Cortex

peripherial make up the cell cortex

ATP Hydrolysis

a mix of both a nucleotide hydrolysis and phosphorylation