Water and Biological Molecules

if a DNA sample were composed of 15% adenine, what would be the percentage of cytosine

35%

A carbon atom is considered versatile because it can bond with up to ____ other atoms

4

upon chemical analysis, a particular polypeptide was found to contain 100 amino acids. how many peptide bonds are present in this protein

99

the primary energy transferring molecule in the cell is known as __________

ATP

(picture page 10) which bond is a peptide bond

C-N

the molecular formula for glucose is C6H12O6. What would be the molecular formula for amolecule made by linking three glucose molecules together by dehydration reactions

C16H32O16

Which of the following hydrocarbons has a double bond in its carbon skeleton

C2H4

Approximately 32 different monmeric carbohydrate subunits are found in various natural polysaccarides. Proteins are composed of 20 different amino acids.DNA and RNA are each synthesized from four nucleotides. amoung these biological polymers, which has the least structural variety

DNA

T or F Denaturation of a protein affects the primary structure of the protein

F

T or F Ice cools a beverage because kinetic energy is transferred from the colder substance to the warmer substance

F

T or F Salt (NaCl) is an example of an organic molecule

F

T or F an enzyme protein assists in the proper folding of other proteins

F

(picture page 6) which molecule shown above can form a cross-linkage

H I H---C---SH I H

Which molecule shown above contains an amino functional group but is not an amino acid

H I H H------C-----N< I H H

The slight negative charge at one end of one water molecule is attracted to the slight positive charge of another water molecule. what is this attraction called?

Hydrogen bonds

You have two beakers. One contains pure water, the other contains pure methanol (wood alcohol) The covalent bonds of methanol molecules are nonpolar, so there are no hydrogen bonds amoung methanol molecules. You poor crystals of table salt (NaCl) into each beaker. Predict what will happen

NaCl crystals will dissolve readily in water but will not dissolve in methanol

essay: explain how waters high specific heat and high heat of vaporization help moderate climate

Specific heat is how much heat a material can take in before the temperature changes. Large bodes of water resist temperature change. Heat of vaporization is when the molecules greatest amount of heat would vaporize.

T or F unlike most substances, water is less dense as a solid than as a liquid

T

one of the buffers that contribute to pH stability in human blood is carbonic acid (H2CO3) Carbonic acid is a weak acid that, when placed in an aqueous solution, dissociates into a bicarbonate ion (HCO3- and a hydrogen ion (H+) Thus, H2CO3<--> HCO3+ H+ if the pH of the blood increases, one would expect

a decrease in the concentration of H2CO3 and an increase in the concentration of HCO3-

Essay: explain the basic structure of a fat. Ho does a saturated fat differ from an unsaturated fat

a fat is made up of two smaller molecule. Which are glycerol and 3 fatty acids. Saturated fat has no carbon-carbon double bonds, and is solid at room temperature Unsaturated fat has one or more carbon-carbon double bonds, and is liquid at room temperature

thalidomide and L-dopa, shown below, are examples of pharmaceutical drugs that occur as enantiomers, or molecules that

are mirror images of another

Lactose, a sugar in milk, is composed of one glucose molecule joined by a glycosidic linkage to one galactose molecule. How i lactose classified?

as a disaccharide

Compared to a hydrocarbon chain where all the carbon atoms are linked by single bonds, a hydrocarbon chain with the same number of carbon atoms, but with one or more double bonds will

be more likely to form a planar structure

essay: explain why structure and function are inseparable

because depending on how the structure looks it will determine the function. so without either structure of function you wouldn't have the other one

buffers are substances that help resist shifts in pH by

both donating H+ to a solution when bases are added, and accepting H+ when acids are needed

if cells are grown in a medium containing radioactive 32P-labeled phosphate, which of these molecule will be labeled

both phospholipids and nucleuic acids

which two functional groups are always found in amino acids

carboxyl and amino

the four major types of biological molecules are: _______, ____________, ______________, _______________

carbs proteins lipids nucleic acid

(picture page 5) thw two molecules shown in the figure above are best described as

cis-trans isomers

waters ability to stick together is referred to as __________whereas waters ability to stick to another substance is referred to as ___________

cohesion and adhesion

Water molecules are able to form hydrogen bonds with

compounds that have polar covalent bonds

A carbon atom is most likely to form what kind of bond(s) with other atoms

covalent

Which of the following best summarizes the relationship between dehydration reactions and hydrolysis

dehydration reactions assemble polymers by removing water and hydrolysis reactions break down polymers by adding water

Which of the following is not a polymer

glucose

humans can digest starch but not cellulose because

humans have enzymes that can hydrolyze a alpha glycosidic linkages of starch but not the beta glycosidic linkages of cellulose

what maintains the secondary structure of a protein

hydrogen bonds between the amino groups of one peptide bond and the carboxyl group of another peptide bond

Why does ice float in liquid water

hydrogen bonds stabilize and keep the molecules of ice farther apart than he water molecules of liquid water

in a normal cellular protein, where would you expect to find a hydrophobic amino acid like valine

in the interior of the folded protein, away from the water or in a trans membrane portion interacting with lipid fatty acid chains

(picture page 3) based on you knowledge of the polarity of water molecule, the solute molecule depicted here is most likely

positively charged

Approximately 32 different monmeric carbohydrate subunits are found in various natural polysaccarides. Proteins are composed of 20 different amino acids.DNA and RNA are each synthesized from four nucleotides. which class of biological polymer had the greatest functional variety

proteins

(picture page 9) what is the structure shown in figure 5.4

steroid molecule

Many mammals control their body temperature by sweating. Which property of water is most directly responsible for the ability of sweat to lower body temperature

the absorption of heat by breaking of hydrogen bonds

which of the following statements best describes the carbon atoms present in a seed- eating bird

the carbon atoms ultimately came from carbon dioxide incorporated into sugars through photosynthesis

If the cytoplasm of a cell is at pH 7, and the mitochondrial matrix is at pH 8, this means that

the concentration of H+ ions is tenfold higher in the cytoplasm than in the mitochondrial matrix

the partial negative charge in a molecule of water occurs because

the electrons shared between the oxygen and hydrogen atoms spend more time around the oxygen atom nucleus than around the hydrogen atom nucleus

which of the following is not a monomer/ polyer pairing

triglyceride/ phospholipid bilayer

the tertiary structure of a protein is the

unique 3 dimensional shape of the fully folded polypeptide