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Chapter 2 Flashcards

1
Q

what elements make up 96% of cells

A

C, H, N, O

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2
Q

Chemical properties of an element are determined by the number and arrangement of _____

A

electrons

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3
Q

an atom is most stable when its _____

A

outer electron shell is completely filled

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4
Q

covalent bond

A

electrons shared between two adjacent atoms

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5
Q

cells are ___% water by mass

A

70

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6
Q

most essential role of fatty acids

A

form lipids that assemble into sheetlike cell membranes

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7
Q

weak noncovalent interactions

A

hydrogen bonds
electrostatic attractions
var der Waals
hydrophobic forces

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8
Q

the atomic number of an element is determined by the number of ____

A

protons

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9
Q

ionic bond

A

electrons are donated by one atom to another

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10
Q

bond strength is measured by _____

A

the amount of energy that must be supplied to break the bond

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11
Q

positive ions are called

A

cations

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12
Q

negative ions are called

A

anions

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13
Q

hydrophilic

A

polar
“water-loving”
mix well with water

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14
Q

hydrophobic

A

nonpolar
doesn’t mix with water

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15
Q

electrostatic attraction

A

force that draws together oppositely charged atoms

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16
Q

buffers

A

mixture of weak acids and bases that maintains the pH of a solution by releasing and taking up protons

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17
Q

why can scientists substitute radioisotopes for isotopes commonly found in cells when conducting experiments?

A

radioisotopes of an element differ only in the number of neutrons, so therefore they behave the same way chemically as the isotopes that occur in cells

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18
Q

which subatomic particle is found in the nucleus of a hydrogen atom?

A

a proton only

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19
Q

the atomic weight of an atom is its mass relative to that of what?

A

hydrogen

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20
Q

four major families of small organic molecules

A

sugars
fatty acids
amino acids
nucleotide

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21
Q

isomers

A

sets of molecules with the same chemical formula but different structures

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22
Q

optical isomers

A

mirror-image pairs of molecules with different structures but the same chemical formula

23
Q

monosaccharides can be linked by ____ to form ____

A

covalent bonds
carbohydrates

24
Q

how are sugars linked together

A

a bond is formed between an -OH group on one sugar and an -OH group on another by a condensation reaction

25
Q

condensation reaction

A

chemical reaction in which a covalent bond is formed between two molecules as water is expelled

26
Q

hydrolysis

A

chemical reaction that involves cleavage of a covalent bond with the accompanying consumption of water (breaks bonds)

27
Q

the monosaccharide ____ has a central role as an energy source for cells

A

glucose

28
Q

sugars ___ function exclusively in the production and storage of energy

A

DO NOT

29
Q

sugars can be used to make ________ such as cellulose

A

mechanical supports

30
Q

smaller oligosaccharides can be covalently linked to proteins to form ____ or to lipids to form ____

A

glycoproteins
glycolipids

31
Q

fatty acid

A

molecules that consists of a carboxylic acid attached to a long hydrocarbon chain

32
Q

what are fatty acids mainly used for

A

major source of energy during metabolism as a starting point for the synthesis of phospholipids

33
Q

amphipathic

A

possess both hydrophobic and hydrophilic regions

34
Q

when is a hydrocarbon tail saturated

A

contains the maximum possible number of hydrogens and therefore has no double bonds between its carbon atoms

35
Q

when is a hydrocarbon tail unsaturated

A

contain one or more double bonds between carbon atoms

36
Q

fatty acids are stored in the ___ of many cells in the form of fat droplets composed of _____ molecules

A

cytosol
triacylglycerol

37
Q

lipids

A

organic molecule that is insoluble in water but readily dissolves in nonpolar organic solvents

38
Q

lipid bilayer

A

thin pair of closely juxtaposed sheets, composed mainly of phospholipid molecules, that forms the structural basis for all cell membranes

39
Q

amino acids

A

small organic molecules that possess a carboxylic acid group (-COOH) C-terminus and an amino group (-NH2) N-terminus, both attached to a central carbon atom

40
Q

amino acids are covalently bonded to form ____ via _____ bonds

A

proteins/polypeptides
peptide

41
Q

nucleotides

A

basic building block of the nucleic acids, DNA, and RNA (nucleoside linked to a phosphate)

42
Q

pyrimidine nucleotide bases

A

six-membered pyrimidine ring
cytosine (C)
thymine (T)
uracil (U)

43
Q

purine nucleotide bases

A

five-membered ring fused to the six-membered ring
guanine (G)
adenine (A)

44
Q

nucleic acids are formed by covalent _____

A

phosphodiester bonds

45
Q

on the basis of mass, which is most abundant in a living bacterial cell?

A

water

46
Q

covalent bonds are formed by the sharing of electrons. In the cell, how are covalent bonds broken?

A

by enzyme catalysis that is specific for a protein and its substrate

47
Q

macromolecule

A

polymer built from covalently linked subunits (monomers)

48
Q

Many proteins act as highly specific ____

A

enzymes

49
Q

why would polymer chains have great flexibility

A

covalent bonds

50
Q

what are macromolecules constrained by?

A

noncovalent bonds

51
Q

enzymes recognize their substrates via ____

A

noncovalent bonds

52
Q

which of the following would most likely interact by forming an ionic bond?
-the enzyme hexokinase and its substrate glucose
-two strands of DNA
-fatty acid chain and inorganic phosphate
-ATP and magnesium cations

A

ATP and magnesium cations

53
Q

How do protein, nucleic acid, and polysaccharide molecules polymerize?

A

by condensation reactions

bio (15 decks)

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