Bio-181 biological molecules
Structure of phospholipids
(a) Chemical structure and space-filling model of phosphatidylcholine, a common phospholipid found in living organisms. Phospholipids contain both polar and nonpolar regions, making them amphipathic. The fatty acid tails are nonpolar. The rest of the molecule is polar.
formation and breakdown of polymers
(a) Monomers combine to form polymers in living organisms by dehydration reactions, in which a molecule of H2O is removed each time a new monomer is added to the growing polymer (b) Polymers can be broken down into their constituent monomers by hydrolysis reactions, in which a molecule of H2O is added each time a monomer is released.
Hydrolysis of a triglyceride yields
1 glycerol and 3 fatty acids.
waxes
create a barrier to water loss
The four major classes of organic molecules are
carbohydrates lipids proteins nucleic acids
starch
found in plant cells
Which of the following classes of organic molecules are important for storing energy?
carbohydrates and lipids
purine
The bases adenine (A) and guanine (G), with double rings of carbon and nitrogen atoms.
peptide bond
The covalent bond formed between a carboxyl group and an amino group
C-terminus
The other end of the polypeptide, called the carboxyl end has a free carboxyl group
base
1. A molecule that when dissolved in water lowers the H+ concentration. 2. A component of nucleotides that is a single or double ring of carbon and nitrogen atoms.
domains
1. defined region of a protein with a distinct structure and function 2. one of the three major categories of life; bacteria, archaea, and eukarya
ribose
A five-carbon sugar present in RNA
Deoxyribose
A five-carbon sugar that is a component of DNA nucleotides
thymine
A pyrimidine base found in DNA.
cytosine
A pyrimidine base found in dna and rna that pairs with guanine.
cellulose
A substance (made of sugars) that is common in the cell walls of many organisms
α helix
A type of protein secondary structure in which a polypeptide forms a repeating helical structure stabilized by hydrogen bonds
β pleated sheet
A type of protein secondary structure in which regions of a polypeptide lie parallel to each other and are held together by hydrogen bonds to form a repeating zigzag shape.
The hydrolysis of triglycerides releases their fatty acids, which can be metabolized to provide energy to make ?
ATP
Triglycerides contain long fatty acid chains that can be metabolized to make
ATP
Four bases of DNA
Adenine, Thymine, Guanine, Cytosine
nucleotide
An organic molecule having three components: one or more phosphate groups, a five-carbon sugar (either deoxyribose or ribose), and a single or double ring of carbon and nitrogen atoms known as a base.
Structure of phospholipid bilayer
Arrangement of phospholipids in a biological membrane, such as the plasma membrane that encloses cells. The hydrophilic region of the phospholipid faces the watery environment, whereas the hydrophobic regions associate with each other in the interior of the membrane, forming a bilayer.
Disacharides
Carbohydrates that are made up of two monosaccharides
what type of molecule is shown in the diagram?
DNA
? is used by the cell to store genetic info while ? is involved in decoding the genetic info
DNA and RNA
two major classes of nucleic acids
DNA and RNA
The double-stranded structure of DNA.
DNA consists of two strands coiled together into a double helix. The bases form hydrogen bonds (dashed lines) in which A pairs with T, and G pairs with C.
store genetic information coded in the sequence of their building blocks.
DNA molecules
ribonucleic acid (RNA)
One of two classes of nucleic acids; the other is deoxyribonucleic acid (DNA). RNA consists of a single strand of nucleotides.
deoxyribonucleic acid (DNA)
One of two classes of nucleic acids; the other is ribonucleic acid (RNA). A DNA molecule consists of two strands of nucleotides coiled around each other to form a double helix, held together by hydrogen bonds according to the AT/GC rule.
The mechanism of polypeptide formation.
Polypeptides are polymers of amino acids. They are formed by linking amino acids via dehydration reactions to make peptide bonds. Every polypeptide has an amino end, or N-terminus, and a carboxyl end, or C-terminus.
involved in decoding this information into instructions for linking a specific sequence of amino acids to form a polypeptide.
RNA molecules
what 3 things are composed of thousands of glucose molecules linked together in long chains, differing in the extent of branching and the orientation of monomers along the chain ?
Starch, glycogen, and cellulose
Four different nucleotides are present in DNA, corresponding to the four different bases that can be linked to deoxyribose
The purine bases, adenine (A) and guanine (G), have fused double rings of carbon and nitrogen atoms, and the pyrimidine bases, cytosine (C) and thymine (T), have a single-ring structure
acts as an acid; it loses a hydrogen ion and is negatively charged at neutral pH
The —COOH group
double helix
Two strands of DNA hydrogen-bonded with each other. In a DNA double helix, two DNA strands are twisted together to form a structure that resembles a spiral staircase.
becomes positively charged
When an amino acid is dissolved in water at neutral pH, the —NH2 group acts as a base and accepts a hydrogen ion
Polypeptide
When multiple amino acids are joined by peptide bonds, the resulting molecule
N-terminus
When two or more amino acids are linked together, one end of the resulting molecule has a free amino group
Phospholipids
a class of lipids that are similar in structure to a triglycerides, but the third hydroxyl group of glycerol is linked to a phosphate group instead of a fatty acid; a key component of biological membranes
polymer
a large molecule formed by linking many smaller molecules called monomers
steroids
a lipid containing four interconnected rings of carbon atoms; functions as a hormone in animals and plants
Guanine
a purine base found in DNA and RNA
adenine
a purine base found in DNA and RNA
Examples of hydrolysis reactions
a sugar is broken down into fructose and glucose molecules a strand of DNA is broken down into individual nucleorides
dehydration reaction
a type of condensation reaction in which a molecule of water is lost
Found in both DNA and RNA
adenine, guanine, cytosine
what type of molecule is shown in this diagram?
amino acid
What are the monomers of proteins?
amino acids
When a peptide bond is formed, two amino acids are linked together between the ? group of one amino acid and the ? group of the other
amino and carboxyl
what functional groups are found at the N-terminus and the C-terminus of a polypeptide?
an amino group is the N-terminus a carboxyl group is at the C-terminus
protein subunits
an individual polypeptide within a functional protein; most functional proteins are composed of two or more polypeptides
monomers
an organic molecule that can be used to form larger molecules (polymers) consisting of many repeating units of the monomer
proteins
are macromolecules composed of carbon, hydrogen, oxygen, nitrogen, and small amounts of other elements, such as sulfur.
three basic components of a nucleotide?
base sugar phosphate group
In water, phospholipids become organized into a double layer of molecules called a ?, with their polar heads interacting with the H2O molecules and their nonpolar tails facing the interior, where they avoid contact with water.
bilayer
amino acids
building blocks of proteins, contain a carbon atom, called the α-carbon, that is linked to an amino group (—NH2) and a carboxyl group
3 atoms found in all carbohydrates
carbon oxygen hydrogen
lipids are molecules that are composed of primarily what two elements?
carbon and hydrogen
three major structural components of an amino acids?
carboxyl group amino group side chain (R)
what elements play a structural rather than energy-storing role?
cellulose, peptidoglycans, chitin, and gylcosaminoglycans
____________ is ____________ and most organisms lack the necessary enzyme to hydrolyze the beta-D-glucose monomers. It is used primarily for ____________ in plants.
cellulose, unbranched, structural support
secondary structure
certain sequence of amino acids form hydrogen bonds that cause the region to fold into a spiral or sheet
all the parts that make up the polar hydrophilic region of a phospholipid molecule
charged nitrogen-containing region phosphate group glycerol backbone
triglycerides
consist of a glycerol molecule linked to three fatty acids
disulfide bridges
covalent chemical bond formed between two cysteine residues in a protein; important in the tertiary structure of proteins
monomers, such as amino acids combine to polymers in a process known as ? reaction
dehydration
proteins are made by ? reactions, in which water is removed as amino acids are linked together to form polypeptides
dehydration
the process by which monomers combine to form polymers is called a ? reaction, whereas the reversible process by which a polymer is broken down into monomers is called a ? reaction
dehydration and hydrolysis
how are fats synthesized
dehydration synthesis links three fatty acids to glycerol
the nucleotides of DNA molecules contain the sugar ? as part of the backbone of the molecule
deoxyribose
Monosaccharides can join together by a dehydration reaction to form?
disaccharides
The structure of DNA consists of two strands coiled around each other to form a structure called
double helix
fats
energy storage
chitin
exoskeleton of insects and crustaceans and the cell wall of fungi
Glycosaminoglycans
extracellular matrix and cartilage of animals
Chain of carbon and hydrogen atoms with a carboxyl group at one end
fatty acid
sterols
found in fungi, plant, and animals and contain an -OH group at a particular carbon (cholesterol)
starch, glycogen, and cellulose are all polymers of the monosaccharide
glucose
what sugar monomer forms the polysaccharides starch, cellulose, and glycogen?
glucose
? is a storage polysaccharide commonly found in the cells of animals.
glycogen
Glycogen is a polysaccharide that is stored in muscle tissue. It is ____________ allowing hydroxyl side groups to be readily exposed to water in the surrounding tissue, for easy hydrolysis.
glycogen and highly branched
what type of bond forms between two sugar molecules?
glycosidic bond
a phospholipid consists of a
gylcerol attached to two fatty acids and a phosphate group
Fats, or triglycerides, are composed of
gylcerol covalently bound to three fatty acids
Glucose, galactose, and fructose are examples of
hexoses and isomers
what type of bond is responsible for the base pairing between two strands of DNA in the double helix
hydrogen
the two strands are held together by ? between a ? in one strand and a pyrimidine base in the opposite strand.
hydrogen bonds purine base
what type of chemical reaction can break down a polysaccharide into monosaccharides?
hydrolysis
water is a reactant when a macromolecule is broken down in a ? reaction, and water is a product when a macromolecule is formed in a ? reaction
hydrolysis and dehydration
lipids
hydrophobic molecules composed mainly of hydrogen and carbon atoms, and some oxygen
phospholipid tail
hydrophobic, non-polar, made of fatty acids, and inside of the membrane
The glycerol backbone, phosphate group, and charged molecule constitute a polar (hydrophilic) head at one end of the phospholipid, whereas the two fatty acids are nonpolar (hydrophobic) tails at the opposite end
important
nuclear receptors
involved in animal development, reproduction, metabolism, and homeostasis
the α-carbon
is linked to a hydrogen atom and a side chain, which is given a general designation R.
Which of the following is the primary structure of a protein?
its amino acid sequence
amino acids
joined together by a dehydration reaction that links the carboxyl group of one amino acid to the amino group of another
primary structure
linear sequence of amino acids
hexoses may exist where?
linear structure, or more typically in a ring
Include triglycerides, phospholipids, steroids, and waxes
lipids
nonpolar and are poorly soluble in water
lipids
Olive oil and butter both contain fats; however, one is liquid at room temperature and the other is solid. Why?
low melting point of unsaturated fats is due to double bounds forming structures that stop tightly bound formations
? are small molecules that are linked together to form polymers, such as proteins, polysaccharides, and nucleic acids
monomers
what type of organic molecule can assume both a linear or ring form?
monosaccharide
list the carbohydrates in order of increasing size, smallest to largest
monosaccharide disaccharide polysaccharide
carbohydrate monomers are known as
monosaccharides
what type of monomers are combined to form carbohydrates
monosaccharides
carboxyl group
negatively charged at neutral pH
what feature of lipid molecules makes them insoluble or poorly soluble in water?
nonpolar molecules
An amino acid is to a protein as a ________ is to a nucleic acid.
nucleotide
What are the monomers of nucleic acids?
nucleotides
Carbohydrates
organic molecule composed of carbon, hydrogen, and oxygen atoms. a carbon-containing compound that includes starches, sugars, and cellulose`
the main elements that make up proteins are carbon, hydrogen, ? and ?, in addition to small amounts of other elements like sulfur
oxygen and nitrogen
what type of bond forms between amino acids during dehydration synthesis
peptide bond
Which of the following are highly amphipathic?
phospholipids
Have a single ring structure
phyrimidine
phospholipids
plasma membrane structure
Phospholipid head
polar, hydrophilic, out of the membrane, and contain phosphate and charged nitrogen
How are monomers and polymers related?
polymers are large macromolecules composed of many monomers linked together
refers to a structural unit composed of a linear sequence of amino acids.
polypeptide
what type of molecule is shown in this diagram?
polypeptide
carbohydrate polymers are called
polysaccharides
amino group
positively charged at neutral pH
glycogen
present in certain types of animal cells
Scientists view protein structure at four progressive levels
primary, secondary, tertiary, and quaternary
a functional unit composed of one or more polypeptides that have folded and twisted into a precise three-dimensional shape.
protein
? of all living organisms are composed of the same set of 20 amino acids, corresponding to 20 different side chains
proteins
which of the following are categories of macromolecules
proteins, nucleic acids, and carbohydrates
have fused double rings of carbon and nitrogen atoms
purine
uracil(U)
pyrimidine base, RNA ONLY
Formation of polymers from monomers typically involves
removal of a molecule of water and and a dehydration reaction.
nucleic acids
responsible for the storage, expression, and transmission of genetic information
tertiary structure
secondary structures and random coiled regions into 3 dimensional shape
Monosaccharides
simplest carbohydrates or sugar common ones contain 5 carbons called pentoses
energy storage in plants
starch
what are an efficient means of storing energy for those times when a plant or an animal cannot obtain sufficient energy from its environment or diet for its metabolic requirement?
starch and glycogen
living organisms, polysaccharides include
starch and gylcogen
____________ is a polysaccharide that is found primarily in plant cells as a form of energy storage. It is ____________ and as a result, it is not very soluble in water.
starch and moderately branched
in what organism are starch and glycogen found?
starch is found in plants and glycogen is found in animals
what type of lipid contains ring structures?
steroid
form hormones important in reproduction
steroids
A peptide bond is formed between
the amino group of one amino acid and carboxyl group of another amino acid
In a peptide bond, which parts of the two amino acids are joined together?
the amino group of one amino acid and the carboxyl group of the other
Pyrimidine
the bases thymine and cytosine and uracil with a single ring of carbon and nitrogen atoms present in DNA
why do phospholipids arrange into bilayers?
the bilayer is the most energetically favorable arrangement in aqueous solution the hydrophilic ends attract water while the hydrophobic ends exclude water
glycosidic bond
the bond formed between two sugar molecules by such a dehydration reaction
phosophate group pentose sugar (deoxyribose or ribose) a single or double ring of carbon and nitrogen atoms known as a base
three components of a nucleotide
glycerol
three-carbon molecule with one -OH group bonded to each carbon
Certain organisms, most notably mammals, have the ability to store large amounts of energy by accumulating ?
triglycerides
which of the following correct names for fat molecules, one of the major classes of lipids?
triglycerides
the major classes of lipids
triglycerides, phospholipids, steroids, and waxes
a protein may be composed of more than one polypeptide
true
quarternary structure
two or more polypeptides may bind to each other to form a functional protein
are nonpolar and exclude water, and they often are found as protective coatings on leaves and the surfaces of some animals' bodies.
waxes
Polysaccharides
when many monosaccharides are linked together to form long polymers