cell physiology UTA test 1

In most proteins, α helices and β sheets fold into globular domains with _______ on the inside.

hydrophobic amino acids

The α (alpha) helix is an example of which level of protein structure?

secondary

The most common molecules in cellular membranes are the

phospholipids

In the primary structure of a protein, amino acids are joined together by _______ bonds.

peptide

Phospholipids in a membrane commonly

move laterally and rotate within the bilayer

Water is an ideal solvent in cells because it

is a polar molecule that can form hydrogen bonds with itself and with other polar molecules.

A disulfide bond is formed between _______ residues.

cysteine

Proteins must have more than one _______ to have a quaternary structure.

A. polypeptide chain

Cholesterol is an amphipathic molecule.

true

Which part of amino acid makes it unique from all others?

side chain

Lipids play a major role in cells as

a form of energy storage, components of cell membranes, and part of the cell signaling function.

Which of the following are involved in forming the tertiary structure of proteins?

H Bonds, Hydrophobic interactions, Ionic bonds

Each membrane phospholipid contains 3 fatty acid chains.

False

In the primary structure of a protein, amino acids are joined together by _____ bonds.

peptide

In the fluid mosaic model of biological membrane structure, transmembrane proteins are

Embedded nearly randomly in the lipid bilayer

Cell membranes are composed principally of

lipids

America ya!

Hallo! Hallo! Hallo! Hallo! Hallo!

The linear order of amino acids in a protein determines its

structure

The interaction of the α and the β subunits to form the hemoglobin molecule is an example of __________ structure.

Quaternary

Proteins can be described as which of the following?

They carry out the program encoded by genes

Mutation in the DNA will ONLY affect primary structure of the protein but never tertiary

False

Introducing a double bond into a fatty acid has the effect of putting a(n) _______ into the conformation of the molecule.

KInk

Proteins can be described as which of the following?

they carry out the program encoded by genes

Lipid bilayers are permeable only to molecules that are ____ and _____

small and uncharged

The Vatican Archives maintain a vault where century's worth of old documents are stored in very high N2 levels to prevent oxidation of the papyrus. When you do research in the vault how does this affect the amount of O2 in your body?

decrease

Coupled transport of glucose and Na+ into the intestinal epithelial cell is an example of

symport

If a suspension of cells is frozen and fractured, the most likely path of the fracture plane will be

between the two leaflets of the cell membranes

Transport across biological membranes is speeded by what class of biological molecules?

proteins

About 50% of the mass of most biological membranes consists of lipids and about 50% consists of proteins. Therefore,

The membranes contain more molecules of lipid than of protein

Active transport is transport

In an energetically unfavorable direction always coupled to another reaction or source of energy.

Passive transport molecules

Carry small molecules across membranes.

The most abundant molecules in cells are

water

Facilitated diffusion is a lipid-mediated process.

false

Chemotherapy drugs that are engineered as hydrophobic molecules will

Diffuse through the membrane until equilibrium is reached

Which of the following substances does not require transport proteins to cross into the blood from the intestines?

alcohol

The sugar groups of glycolipids and glycoproteins are found on the outer surface of the plasma membrane.

true

A feature common to most transmembrane proteins is

An α-helical region of about 20-25 hydrophobic amino acids.

The plasma membrane barrier to passive diffusion is primarily a function of the membrane's

phospholipids

Passive transport across a membrane refers to

Transport in the energetically favorable direction.

All cells in the body have a gradient of Na+ and K+ established by the pumps. Bacterial toxins damage our cells by "punching" holes in the membranes. What happens?

K+ escapes from the cell

Which of the following has the fastest rate of transport?

Channel-mediated diffusion

The Na+ and K+ ion gradients across the plasma membrane are produced primarily by the

action of the Na+-K+ pump.

Molecules that traverse a membrane against their concentration gradient do so by _______ transport.

active

Active transport differs from facilitated diffusion in that

active transport involves the transport of molecules up their concentration gradient.

The unique properties of different membranes are primarily a function of their

proteins

Glut 1

glucose that enters is used for feeding not storage, provides energy for cellular respiration,

Glucose transport

uniporters (gluts) facilitated diffusion

If blood glucose levels range from 90 to 130 mg/dL before meals, and below 180 mg/dL within 1 to 2 hours after a meal, would a normal, non-diabetic person exceed 180 mg/dL after eating 6 donuts?

No (glut 4 in normal person removes excess glucose)

What happened to the molecule of glucose after it entered the brain cell?

It was broken down to pyruvate

If you were told you needed to consume a large dose of carbs quickly which of the following would you consume? OJ, Milk, chicken wings, whole grain rice

OJ

Gluts are

integral protein

Uniporters are important for what reason

They have a high affinity for a specific substrate that they transport across the membrane

A resting neuron

is more positively charged on the outside of its membrane than on the inside.

Based on your knowledge of the chemistry of the cell membrane, which of the following compounds would you couple with a new hydrophilic drug in order to achieve better uptake by cells?

a. carbohydrates

b. polar amino acids

c. lipids

d. any hydrophilic substance

c. lipids

which of the following is defined as the tertiary structure of a protein

structural domains such as a DNA binding domain. Multiple twists and bends. Governed by hydrogen and disulfide bonds.

Lipid bilayer is

asymmetric, lateral mobility, self-sealing,

Phospholipid membrane is permeable to

gases ie oxygen, carbon dioxide, hydrophobic molecules: benzene, glycerol small uncharged polar molecules: alcohol (etoh)

Energy in ATP is in the

phosphate-phosphate bond