FOUNDATIONS EXAM 1

The amino acid_____ can from disulfide bonds with another _____ either in the same protein or between two proteins.

cysteine, cysteine

Antibodies, peptide hormones or other export proteins have to be secreted from the cells in the tissues or glands that produce them. In what compartment are these molecules synthesized?

cytoplasm

Escherichia coli, the best known bacterial model organism, is a bacillus (rod-shaped) with a diameter of about 1 um. What is the appropriate volume of an E-coli cell. Hint: V= nr^(2)h for a cylinder.

1.57 um^(3)

A protocol to prepare 250 mL of a 7m CaCl solution to be used in a density-gradient ultracentrifugation experiment requires 294.63 g of the salt. What is the f.w. of the cesium chloride?

168.36 g/mols

The following is correct regarding Svedburg units (S)

All of the above .

One of the following precursors is mismatched with its macromolecule:

fatty acids -- ribosomes

The pH of an aqueous solution is an indication of the concentration of available protons. However, you should not expect to find protons in solution; rather, the proton is added to a water molecule to form a _______ ion.

hydronium

Proteins bind selectively to small-molecule targets called ligands. The selection of one ligand out of a mixture of possible ligands depends on the number of weak, noncovalent interactions in the protein's ligand-binding site. Where is the binding site typically located in the protein structure?

inside a cavity on the protein surface

One of these organic groups is not properly identified. Which one is it?

ketone

Which of the following is not a feature commonly observed in a helices?

left-handedness

One of these organelles is mismatched with the type of organism indicated, which one is it?

lysosome -- bacteria

Cell length is usually measure in ______, abbreviated _______ and equivalent to ___________.

micrometers, um, 10^(-6) m

The blond between two amino acids that occurs through the a-carboxyl group of one with the a-amino group of the other is a special type of amide called __________ bond.

peptide

Which one of these molecules contains polar covalent bonds?

water (H2O)

Aspartic Acid, which has three pKa values (2.1, 9.82, 3.86)

C

The cell membrane can be describes most accurately as

permeable to some molecules and impermeable to others.

pH= ________ and is an indicator of ________: the ________- the pH, the higher the concentration of protons in a solution.

-log [H+], acidity; lower

Refer to the diagram below (Central Dogma of Molecular Biology). What processor structure is incorrect?

4- Long non-coding RNA (in RNA)

The dalton (1Da) is a commonly used unit in biological sciences. Which value is incorrect?

6.02 x 10 ^(23)

Lysine, which has three pKa values (2.18,8.95,10.53)

A

Protein structures have several different levels of organization. The primary structure of a protein is its amino acid sequence. The second and tertiary structures are more complicated. Consider the definitions below select the one that best fits the term "protein domain".

A protein segment that folds independently and has a specific function.

Which statement is incorrect regarding prokaryotic cells and eukaryotic cells?

All eukaryotic cells have cell walls.

Biomolecules display several types of chemical bonds. The strength of a bond is measured by the amount of energy required to break it. What is the conversion factor between kJ and kcal?

All of the above

Which statement is correct regarding stereoisomers of biological molecules?

All of the above

A cell exchanges matter and energy with the environment, which is one of the characteristics of living organisms.

All of the above.

The mimivirus, illustrated on the figure on the right, infests the amoeba Acanthomoeba polyphaga. The following is correct regarding the mimivirus.

All of the above.

What characteristic distinguish Megavirus from other viral groups ?

All of the above.

Which of the following is true of fluorescence microscopy?

All of the above.

Prolin, an amino acid

D

Indicate which of the following statements is false.

Lysosomes are small organelles where fatty acid synthesis occur.s

Find the incorrect statement.

Microscopic algae and fungi are prokaryotes

The eukaryotic organelles originated by endosymbiosis

Mitochondria (rickettsias) and chloroplasts (cyanobacteria)

Find the incorrect statement regarding the plasma membrane and the membrane and the internal membrane systems in eukaryotes.

None of the above.

The drawing on the right represents a water molecule as a permanent dipole. Find the incorrect statement.

None of the above.

Protein folding can be studied using a solution of purifies protein and a denaturant such as a urea, a molecule that interferes with non covalent interactions. Which of the following is observed after the denaturant is removed from the protein solution?

The polypeptide returns to its original conformation

Why do polar substances such as NaCl dissolve so readily in water?

The sodium ions repel the negative end of the water molecule. Spheres of hydration form between the water and the ions.

Which of the following is incorrect regarding prions.

They are nucleic-acid-- containing virus-related structures.

The synthesis of a protein by condensation of a-L-amino acids occurs by ______ reaction in which a molecule of water is eliminated; in contrast, the _______ of a polypeptide requires a molecule of water and produces free amino acids

a dehydration, hydrolysis

These amino acids would contribute to forming bridge salts in protein secondary and tertiary structures:

arginine, lysine, glutamic acid and aspartic acid

Which of the following buffering systems keep blood and other bodily fluids at pH near neutral (e.g 7.4)?

carbonate-bicarbonate

The nucleus, an organelle found in eukaryotic cells, confines the _______, keeping them separated from other components of the cell.

chromosomes

The a helices and B sheets are examples of protein

secondary structure

Tryptophan, an aromatic amino acid

B

Glutamic acid, which has three pKa values (2.19,9.57,4.25)

E

Globular proteins fold up into compact, spherical structures that have uneven surfaces. They tend to form multi-subunit complexes, which also have a rounded shape. Fibrous proteins, in contrast, span relatively large distances within the cell and in the extracellular space. Which of the proteins below are not fibrous or filamentous?

Elastase

The diet of a human adult must include the amino acids leucine, isoleucine, valine, lysine, threonine, methionine, tryptophan, phenylalanine, and histidine. Infants must consume arginine. What are these 10 amino acids called?

Essential

Which type of ribosomes would you expect to find in a bacterial cell?

Only 70S

Which a-amino--acid- related molecules are abundantly present in the animal protein collagen?

Proline and hydroxyproline

The human immune system produces __________ of different immunoglobulins, also called ________ which enable the immune system to recognize and fight germs by specifically binding one or a few related ______.

billions, antibodies, antigens

A protein, the order (sequence) of its component amino acids is called ________. The directionality of a protein is _________, which corresponds to the ________ nuceloride sequence in DNA.

primary structure, N-terminal to C-terminal, 5' to 3'

Which of the following choices best describes the role of the mitochondrion?

production of ATP

The catalytic activity of certain enzymes actually depends on RNA and not on protein. RNA-dependent enzymes are called __________.

ribozymes

A covalent bond between two atoms is formed as a result of the

sharing of electrons