BIO 1113 exam 1 pearson questions

Which of the following occurs when a covalent bond forms?

shared electrons

Which of these functional groups is known to be used for storing large amounts of chemical energy?

phosphate

What factors determine whether a chemical reaction is spontaneous or not?

energy change, temperature

What two functional groups are bound to the central carbon of every free amino acid monomer?

an amino and carboxyl

What type of bond is directly involved in the formation of an α-helix?

Peptide bonds between amino acid residues

What type of information is used to direct different polypeptides to fold into different shapes?

amino acid sequence

Is the active sight where enzyme substrates bind?

true

is the enzyme sight where catalysis occurs?

true

Why are proteins not considered to be a good candidate for the first living molecule?

they cant store info or self replicate

What determines the primary structure of a DNA molecule?

deoxyribonucleotide sequence

What is responsible for the increased stability of DNA compared to RNA?

it has deoxyribose instead of ribose, i

What are three ways monosaccharides differ from one another?

carbon number, carbonyl position, and 3D arrangement of atoms.

What type of bond is formed between two sugars in a disaccharide?

glysocolic linkage

What holds cellulose molecules together in bundles large enough to form fibers?

hydrogen bonds

Although cellulose and starch are identical in terms of stored chemical energy, our ability to harvest the energy from these two polysaccharides differs considerably. What is responsible for this difference?

our enzymes can break α-glycosidic bonds, but not β-1,4 bonds.

How do the phospholipids in archaea differ from those in other cells?

They have isoprenoid tails instead of fatty acid tails.

What two conditions are commonly present when observing the effects of osmosis in a cell?

osmosis happens when there’s a selectively permeable membrane and a difference in solute concentration across that membrane.

Integral membrane proteins are anchored in lipid bilayers. Which of the following groups of amino acid residues would likely be found in the portion that crosses the lipid bilayer?

non polar

Cooking oil lipids consist of long, unsaturated hydrocarbon chains. Would you expect these molecules to form membranes spontaneously? Why or why not? Describe, on a molecular level, how you would expect these lipids to behave in water.

Cooking oil lipids do not form membranes. In water, they clump into droplets (like oil and vinegar salad dressing) instead of bilayers, because they are fully hydrophobic and lack the amphipathic nature of phospholipids.

n terms of structure and function, how do channel proteins differ from carrier proteins?

channel proteins act like open doors (fast, passive flow), while carrier proteins act like turnstiles (bind → change shape → release).

What are three attributes of mitochondria and chloroplasts that suggest they were once free-living bacteria?

own DNA, own ribosomes, reproduce independently

Which of the following results provided evidence of a discrete nuclear localization signal somewhere on the nucleoplasmin protein?

After cleavage of the nucleoplasmin protein, only the tail segments appeared in the nucleus.

Molecular “zip codes” direct molecules to particular destinations in the cell. How are these signals read?

They bind to receptor proteins.

How does the hydrolysis of ATP result in the movement of a motor protein along a cytoskeletal filament?

Each ATP hydrolysis cycle powers a step of the motor protein along the filament, turning chemical energy into mechanical work.

Which of the following cell structures would you expect to be most important in the growth of bacteria on the surface of your teeth?

fimbriae

Cells that line your intestines are known to possess a large number of membrane proteins that transport small molecules and ions across the plasma membrane. Which of the following cell structures would you expect to be required for this characteristic of the cells?

the endoplasmic reticulum

Why do phospholipids form bilayers spontaneously in water?

Amphipathic structure (hydrophilic head + hydrophobic tails)

What makes a membrane selectively permeable?

ipid bilayer + embedded proteins control what passes in/out.

Microtubules:

shape, transport, cell division.

Actin filaments:

shape, movement.

Intermediate filaments:

structural support.

Channel protein

pore, fast diffusion, no shape change.

Carrier protein

binds molecule, changes shape, slower.

how do nucleotides polymerize?

phosphodiester bonds via dehydration

Protein targeting to cellular locations

Signals like NLS or ER signal peptide are recognized by receptor proteins, directing proteins to nucleus, ER, mitochondria, etc.