BIO extra credit 2

membrane proteins and lipids are able to move relative to one another within the plasma membrane according to the ___ ___

fluid-mosaic

One layer, or half of a phospholipid bilayer, is termed a ___

leaflet

The model used to explain the structure, organization and dynamics of biological membranes is the ___ ___ model

fluid mosaic

Within the plasma membrane, where are glycolipids normally found?

extracellular leaflet

What are the three main molecular components of cellular membranes?

proteins, carbs, lipids

a lipid bilayer is composed of ____ leaflets

2

The two leaflets of the plasma membrane have the same lipid composition. True or false

false

The cytosolic leaflet of the plasma membrane faces ___

the inside of the cell

Most transmembrane segments of integral membrane proteins are folded into what type of secondary structure?

alpha-helix

Transport of ions and large molecules into and out of the cell is mediated by membrane ___

proteins

Proteins that are non-covaently bound to the hydrophilic regions of integram proteins or to the polar head groups of lipids are called ___ membrane proteins

peripheral 

Some proteins are found on the surface of the lipid bilayer of the membrane, and they are attached to it by hydrogen and/or ionic bonds. These are called ____ membrane proteins

peripheral

What types of interactions are typically involved in peripheral proteins binding to biological membranes?

ionic and hydrogen bonds

Movements that keep the phospholipid fatty acid tail within the ___ region of the bilayer are energetically favorable

hydrophobic

The transfer of phospholipids between leaflets requires the input of ___

ATP

What structural feature of a protein would suggest to a scientist that it is likely to be a transmembrane protein?

The presence of α helices

The movement of lipids between leaflets is catalyzed by the enzyme ___, which requires energy input in the form of ___

flipase, ATP

The transfer of phospholipids between leaflets requires the input of ___

ATP

Lipids with shorter tails ___ the fluidity of the plasma membrane

increase

Which of the following movements of a phospholipid are energetically favorable within the bilayer?

rotational and lateral movements

An unsaturated lipid contains ___ bonds

double

Phospholipids that have shorter tails are less likely to interact with each other, thus rendering the membranes more ___

fluid

The short, rigid molecule produced by animal cells that is involved in membrane fluidity is called ___

cholesterol

____ at low temperatures, makes the membrane more fluid and prevents freezing

cholesterol 

The presence of a ___ ___ in a phospholipid tail makes the membrane more fluid because it prevents phospholipids from packing tightly 

double bond

The Frye and Edidin experiment demonstrated that lateral protein movement within the membrane is affected by ___

temperature

Most membrane components of a eukaryotic cell are synthesized at the ___

ER

Some transmembrane proteins are restricted in their movement because they contain regions that projects into the cytosol and are anchored to components of the ____

cytoskelton

Because transmembrane proteins are much ___, than lipids, they diffuse within the membrane at a(n) ___ rate

bigger, slower

Transmembrane protein flip-flop does not occur spontaneously because it would be energetically ___

inefficient

A phospholipid consists of two ___ acids, one ___ molecule, and one phosphate attached to a polar head group

fatty, glycerol

In the process of phospholipid synthesis, the two ___ ___ molecules are activated by attachment to coenzymes A

fatty acid

In eukaryotic cells, lipids are produced by the ___ and ___ system working together

cytosol, endomembrane

Newly synthesized lipids are inserted into the cytosolic leaflet of the ___

ER membrane

The function of the enzyme called signal ___ is to remove the ER signal sequence from transmembrane proteins

peptidase

During phospholipid synthesis, fatty acids are activated by attachment to ___

coenzyme A

Most transmembrane proteins contain an ER ___ sequence that directs them to the ER membrane

signal

Some transmembrane proteins are restricted in their movement because they contain regions that project into the cytosol and are anchored to components of the ___

cytoskeleton

How are membrane proteins transferred from the ER to other regions of the cell?

vesicular transport

Which enzyme removes the ER signal sequence from transmembrane proteins?

signal peptidase

In the embryonic development of animals, the proper migration of cells relies on the recognition of cell types via the ___ on each cell’s surface

carbs

After being synthesized by ribosomes associated with the rough ER, membrane proteins are packaged into ___ which transport them to other regions of the cell

vesicles

Most transmembrane proteins contain an ER ___ sequence that directs them to the ER membrane

signal

Highly glycosylated proteins involved in the organization of the extracellular matrix are produced via what process?

o-linked glycosylation

Highly (O-linked) glycosylated proteins that are secreted from cells are called ___ One of their main biological functions is to organize the extracellular matrix surrounding cells. 

proteoglycans

What types of protein glycosylation occur in eukaryotes?

O-linked, N-linked

The cell maintains a favorable internal environment due to the selective ___ of the plasma membrane

permeability

What is the target for N-linked glycosylation?

membrane proteins

Which of the following processes require a transport protein?

active transport and facilitated diffusion

Which type of transport requires a source of energy and a transport protein?

active

To move a substance through a membrane against a concentration gradient, which of the following are necessary?

a source of energy and a transport protein

Small, uncharged molecules pass through the membrane via ___ ___

passive diffusion

In a solution, the ions that are dissolved are called the ___ molecules, and the liquid in which they are dissolved is called the ___

solute, solvent

When the concentration of a solute is higher on one side of membrane than the other, a transmembrane ___ is  established

gradient

A term that describes a situation in which the concentration of a solute is higher on one side of a membrane than the other is ___

transmembrane gradient

A cell contains less sodium than the surrounding environment. What type of transport is required to import sodium ions into the cell?

facilitated 

When the concentration of solutes on both sides of the plasma membrane are equal, the two solutions are said to be ___

isotonic

A cell contains a higher concentration of glucose than the surrounding environment. What type of transport is required to import glucose into the cell?

active

A solution whose solute concentration is higher than the concentration of solutes inside a cell is ___

hypertonic

A solution with a concentration of solutes lower than that in a cell is said to be ___ relative to the cell

hypotonic

Osmosis is the flow of ___ across a membrane

water

Osmosis describes the movement of water from areas where the solute concentration is ___ to areas in which the solute concentration is ___

lower, higher

Animal cells will take up water if present in
 ___ solutions. In extreme cases, the cells can rupture in a process called osmotic lysis.

hypotonic

A sample of cells is placed in a salt solution. The cells subsequently shrink, and the membrane deforms. Relative to the cells, the salt solution is ___

hypertonic

What is the result of placing a plant cell into a hypertonic solution?

plasmolysis

If the medium surrounding a plant cell is ___ water exits the cell membrane pulls away from the cell wall in a process known as plasmolysis

hypertonic

What component of plant cells prevents changes in cell volume that result in osmotic lysis?

the cell wall

What is one way that solutes that cannot diffuse across the membrane can still gain access to the interior of the cell?

transport proteins

What is the function of channel proteins?

facilitated diffusion

A contractile vacuole is an important feature of microorganisms living in a(n) ___ environment

hypotonic

If the medium surrounding a plant cell is ___ , water exits the cell and the cell membrane pulls away from the cell wall in a process known as plasmolysis.

hypertonic

Ions and hydrophilic molecules are able to cross the phospholipid bilayer via transmembrane proteins called ___ proteins

channel

When channel proteins are ___ , it means they can open and close to regulate the movement of ions and molecules across the cell membrane.

gated

What are the categories of proteins that assist in the movement of molecules and ions across membranes?

channels, transporters

What type of proteins forms an open passageway for facilitated diffusion of ions or molecules across the membrane?

channels

Some freshwater microorganisms that live in hypotonic environments use a contractile vacuole to help prevent ___ ___

osmotic lysis

What is the function of channel proteins?

facilitated diffusion

Unlike channel proteins which provide an open passageway all the way across the plasma membrane, proteins known as ___ bind solutes and then undergo a conformational change

transporters

Which type of protein is the principal pathway for the uptake of sugars, amino acids, and nucleotides?

transporter proteins

Some proteins act as channels to allow the facilitated diffusion of water across a membrane. These proteins are called ___

aquaporins

This figure depicts a transporter known as a…

symporter

An integral membrane protein that transports two different molecules across the plasma membrane in the same direction is called a(n) ___

symporter

Which type of protein is the principal pathway for the uptake of sugars, amino acids, and nucleotides?

transporter proteins

an ___ is a channel for water

aquaporin

Which of the following move solutes in only one direction?

uniporter and symporter

Active transport is the movement of a solute across the membrane ___ its concentration gradient

against

In order to move a solute from areas of low concentration to areas of high concentration ___ is required

an input of energy 

Moving a solute against its chemical or electrochemical gradient requires a source of ___

energy

what form of membrane transport is this?

primary active transport

Which of the following types of transport involves pumping ions against a gradient using ATP as a source of energy?

primary active transport

What type of transport uses a pre-existing gradient to drive the transport of another molecule?

secondary active transport

The use of a pre-existing gradient to drive the active transport of another solute is termed ___ active transport

secondary

The Na⁺/K⁺-ATPase actively transports Na⁺ and K⁺ ions ___ their gradients by using the energy from ATP hydrolysis

against

Due to the Na⁺/K⁺-ATPase, cells are able to maintain concentration gradients so that the concentration of ___ ions is greater outside the cell than inside, and the concentration of ___ ions is greater inside the cell than outside

Na, K

The Na⁺/K⁺-ATPase pump is considered a(n) ______ because it binds both Na⁺ and K⁺ and transports them in opposite directions.

antiporter

A pump that creates an electrical gradient is called a(n) ___

electrogenic pump

Eukaryotic cells can transport large molecules such as proteins and polysaccharides via ___ and ___. Both of these mechanisms involve membrane vesicles or vauoles

endocytosis, exocytosis

Bacterial swimming, nerve signaling, and osmotic regulation depend on the maintenance of ___ gradients

ionic/electrochemical

What processes are used by eukaryotic cells to transport large molecules such as proteins and polysaccharides?

exycytosis, endocytosis