ch 3 the macromolecules of the cell Flashcards
(79 cards)
1
Q
macromolecules
A
large molecules composed of thousands of covalently connected atoms
2
Q
4 families of macromolecules
A
proteins (amino acids)
nucleic acids (nucleotides)
polysaccharides (sugars)
lipids (fatty acids)
3
Q
polymers are synthesized by
A
condensation reactions in which activated monomers are linked together by the removal of water
4
Q
9 major classes of proteins
A
- enzymes
- structural proteins
- motility proteins
- regulatory proteins
- transport proteins
- signaling proteins
- receptor proteins
- defensive proteins
- storage proteins
5
Q
enzymes
A
serve as catalysts, increase the rates of chemical reactions
6
Q
structural proteins
A
physical support and shape
ex. keratin and collagen
7
Q
motility proteins
A
contraction and movement of cells and intracellular materials
8
Q
regulatory proteins
A
control and coordinate cell function
ex. transcription factors such as activators and repressors - ensure that cellular activities are regulated to meet cellular needs
9
Q
transport proteins
A
move substances into and out of cells
10
Q
signaling proteins
A
communication btw cells
11
Q
receptor proteins
A
enable cells to respond to chemical stimuli from the environment
12
Q
defensive proteins
A
protect against disease
13
Q
storage proteins
A
reservoirs of amino acids and metal ions to be used in later stages of organism development
14
Q
amino acid components
A
carboxyl group
amino group
hydrogen atom
r group
alpha carbon
15
Q
4 broad categories of amino acids
A
non polar
polar
acidic (- charge)
basic (+ charge)
16
Q
peptide bond
A
a covalent bond btw the amino group of one amino acid and the carboxyl group of a second amino acid
- dehydration reaction
17
Q
N-terminus
A
the end with the amino group
18
Q
C-terminus
A
the end with the carboxyl group
19
Q
a polypeptide does not become a protein until it has assumed
A
a unique, stable, three-dimensional shape (conformation), and is biologically active
20
Q
4 representations of protiens
A
ribbon model
space-filling model
wire
backbone
21
Q
monomeric protein
A
protein that consists of a single polypeptide chain
22
Q
multimeric protein
A
protein that consists of two or more polypeptide chains
23
Q
bonds and interactions important for protein folding and stability
A
- disulfide bonds (covalent)
- hydrogen bonds
- ionic bonds
- van der waals forces
- hydrophobic interactions
24
Q
disulfide bonds
A
covalent bond formed btw two sulfur atoms by oxidation (removal of two hydrogen ions) of sulfhydryl groups
- important in stabilizing the tertiary structure
25
intramolecular disulfide bonds
form between cysteines in the same polypeptide
26
intermolecular disulfide bonds
form between cysteines in two different polypeptides
27
noncovalent bonds and interactions
binding forces that do not involve the sharing of electrons
- hydrogen bonds
- ionic bonds
- van der waals interactions
- hydrophobic interactions
28
hydrogen bonds
weak attractive interaction btw an electronegative atom and a hydrogen atom that is covalently linked to a second electronegative atom
29
ionic bonds
attractive forces btw a positively charged chemical group and a negatively charged chemical group
- pH can disrupt
30
van der waals interactions
weak attractive interaction btw two atoms caused by transient asymmetries in the distribution of charge in each atom
31
hydrophobic interaction
tendency of hydrophobic groups to be excluded from interactions with water molecules
32
molecular chaperone
protein that facilitates the folding of other proteins but is not a component of the final folded structure
33
4 levels of organization of protein structure
primary
secondary
tertiary
quaternary
34
primary structure
sequence of amino acids linked together by peptide bonds, forming a polypeptide
- interactions: covalent peptide bonds
- importance: genetically - sequence is specified by the order of nucleotides in the corresponding messenger RNA
structurally - order and identity of amino acids directs the formation of higher-order structures
35
secondary structures
level of protein structure involving hydrogen bonding btw atoms in the peptide bonds along the polypeptide backbone creating two main patterns - alpha helix and beta sheets
- interactions: hydrogen bonds btw NH and CO groups of the peptide bonds in the backbone
- motifs - region of secondary structure consisting of small segments of a helices and b sheets
- important for finding patterns
36
tertiary structure
level of protein structure involving interactions btw amino acid side chains of a polypeptide, regardless of where along the primary sequence they happen to be located; results in 3D folding of a polypeptide chain
- interactions: disulfide bonds, hydrogen bonds, ionic bonds, van der waals interactions, hydrophobic interactions
- native conformation - the most stable 3D structure for that particular sequence of amino acids
37
fibrous proteins
have extensive regions of secondary structure, giving them a highly ordered, repetitive structure
ex. fibroin, keratin, collagen, elastin
38
globular proteins
protein whose polypeptide chains are folded into compact structures rather than extended filaments
- most proteins and enzymes
most consist of domains
39
domain
a discrete, locally folded unit of tertiary structure, usually with a specific function
- typically 50-350 amino acids long
- proteins with similar functions often share a common domain
- a protein may have multiple domains
40
quaternary structure
level of protein structure involving interactions btw two or more polypeptide chains to form a single multimeric protein
- interactions: disulfide bonds, hydrogen bonds, ionic bonds, van der waals interactions, hydrophobic interactions
- subunit formation is usually spontaneous - may require use of molecular chaperones
41
multiprotein complex
two or more proteins (usually enzymes) bound together in a way that allows each protein to play a sequential role in the same multistep process
42
nucleic acids
a linear polymer of nucleotides joined together in a genetically determined order
- store, transmit, and express genetic info
- composed of ribose or deoxyribose, a phosphate group, and the nitrogenous base (GCATU)
43
purines
adenine and guanine
44
pyrimidines
thymine, cytosine, uracil
45
nucleoside
molecules consisting of a nitrogen-containing base linked to a five-carbon sugar
(no phosphate)
46
phosphodiester bridge
a phosphate group liked to two adjacent nucleotides via two phosphodiester bonds
47
polynucleotide
linear chain of nucleotides linked by phosphodiester bonds
48
polysaccharides
polymer consisting of sugars and sugar derivatives linked together by glycosidic bonds
- usually consist of a single kind of repeating unit or an alternating pattern of two kinds
- primarily in cellular structures and in energy storage
49
oligosaccharides
shorter polymers
when attached to protein surface, play an important role in cellular recognition of extracellular signal molecules and of other cells
50
monosaccharides
simple sugar
repeating units of polysaccharides
51
aldehyde
aldosugar
have a terminal carbonyl group
52
ketone
ketosugar
internal carbonyl group
53
carbonhydrate
hydrates of carbon
CnH2nOn
54
most stable form of glucose
D-glucose
55
fischer projection
model depicting the chemical structure of a molecule as a chain drawn vertically with the most oxidized atom on top and horizontal projections that are understood to be coming out of the plane of paper
56
haworth projection
model that depicts the chemical structure of a molecule in a way that suggests the spatial relationship of different part of the molecule
57
disaccharide
carbohydrate consisting of two covalently linked monosaccharide units
58
glycosidic bond
bond liking a sugar to another molecule
- formed btw two monosaccharides by condensation reaction
59
storage polysaccharides
highly branched sugars and sugar derivatives that are stored in the cell for future use in energy production
ex. starch and glycogen
60
glycogen
stored mainly in the liver (as a source of glucose) and muscle tissues (as a fuel source for muscle contraction)
61
starch
glucose reserve commonly found in plant tissue
unbranched amylose and branched amylopectin
62
cellulose
found in plant cell walls
composed of repeating monomers of B-D-glucose
63
chitin
structural polysaccharide found in insect exoskeletons, crustacean shells, and fungal cell walls
64
lipid
any of a large and chemically diverse class of organic compounds that are poorly soluble or insoluble in water but soluble in organic solvents
- final steps in synthesis involve condensation reactions
65
functions of lipids
energy storage
membrane structure
specific biological functions such as transmission of chemical signals into and within the cell
66
6 main classes of lipids
fatty acids
triacylglycerols
phospholipids
glycolipids
steroids
terpines
67
fatty acids
long amphipathic, unbranched hydrocarbon chain that has a carboxyl group at one end; usually contains an even number of carbon atoms and may be of varying degrees of unsaturation
- energy storage
68
saturated fatty acids
each carbon atom in the chain is bonded to the maximum number of hydrogens
69
unsaturated fatty acids
have one or more double bonds
70
trans fats
type of unsaturated fatty acid with a particular type of double bond that causes less of a bend in the chain - cis or trans
- relatively rare in nature
71
essential fatty acids
not synthesized in the human body and must be supplied through diet
ex. omega-3
required for normal growth, protection against cardiovascular disease
72
triacylglycerols
a glycerol molecule with three fatty acids linked to it
- energy storage
- insulation against low temps
solid at room temp = saturated fats
liquid at room temp = unsaturated
73
glycerol
three-carbon alcohol with a hydroxyl group on each carbon
74
phospholipids
lipid possessing a covalently attached phosphate group and therefore exhibiting both hydrophilic and hydrophobic properties
- main component of the lipid bilayer that forms the structural backbone of all cell membranes
75
phosphoglycerides
predominant phospholipid component of cell membranes, consisting of a glycerol molecules esterified to two fatty acids and a phosphate group (phosphatidic acid)
76
sphingopilids
class of lipids containing the amino alcohol sphingosine as a backbone
- predominantly found in the outer leaflet of the plasma membrane bilayer
- important in communication btw a cell and its external environment
77
glycolipids
lipid molecule with a carbohydrate attached by a glycosidic bond
- occur mostly on the outer monolayer of the plasma membrane
- sites of biological recognition on the surface of the plasma membrane
78
steroids
derivatives of a four-ringed hydrocarbon skeleton, which distinguishes them from other lipids
- relatively nonpolar and therefore hydrophobic
steroid hormone - synthesized from cholesterol
glucocorticoids - promote synthesis of glucose and suppress inflammation
mineralocorticoids - regulate ion balance by promoting reabsorption of sodium, chloride, and bicarbonate ions by the kidney
79
terpenes
lipid constructed from the five-carbon compound isoprene and its derivatives
- joined in various combos to produce substances such as vitamin A and carotenoid pigments
