Chapter 5 Flashcards
Macromolecules
Carbohydrates
Lipids
Proteins
Nucleus acids
Polymer
Is a long molecule consisting of many similar or identical building blocks linked by covalent bonds.
Monomers
Are the repeating units that serve as the building blocks of a polymer. (Are smaller molecules)
Chain-like macromolecules
Carbohydrates
Proteins
Nucleic Acid
Enzymes
Specialized macromolecules that speed up chemical reactions.
Dehydration reaction
A reaction in which two molecules are covalently bonded to each other, with the loss of a water molecule. This is how monomers are connected to each other.
Hydrolysis
The bond between monomers is broken by the addition of a water molecule, with a hydrogen from water attaching to one monomer and the hydroxyl group attaching to the other.
Carbohydrates
Include sugars and polymers of sugars.
Monosaccharides, disaccharides, and polysaccharides.
Monosaccharides’ general molecular formula
CH2O
Glucose structure
C6H12O6. Has a carbonyl group and multiple hydroxyl groups. Is an aldose (aldehyde sugar). Forms rings.
Most common monosaccharide
Glucose
Carbohydrate carbon skeleton size
Three to seven carbons long
Trioses
Three-carbon sugars.
Pentoses
Five-carbon sugars. Form rings.
Asymmetric carbon
A carbon attached to four different atoms or groups of atoms.
Glycosidic linkage
A covalent bond formed between two monosaccharides by a dehydration reaction.
Maltose
Disaccharide formed by two molecules of glucose. Present in beer.
Sucrose
Disaccharide made of glucose and fructose. Known as table sugar.
Lactose
Disaccharide made of glucose and galactose. Present in milk.
Polysaccharides
Are macromolecules, polymers with a few hundred to a few thousand monosaccharides joined by glycosidic linkages.
Architecture and function of a polysaccharide is determined by…
It’s sugar monomers and the position of its glycosidic linkages.
Starch
Plants use starch to store excess glucose. Starch represents stored energy.
Glycogen
A polymer of glucose that is like amylopectin (complex starch) but more extensively branched. Animals use glycogen to store sugar mainly in muscle and liver cells.
Cellulose
Polysaccharide present in cell walls. The most abundant organic compound on Earth.
Two rings that form glucose
Alpha and beta
Chitin
Carbohydrate used by arthropods to build their exoskeletons.
Lipids
They mix poorly, if at all, with water. Generally not big enough to be considered macromolecules.
Lipids consist of mostly…
Hydrocarbon regions.
Lipids most biologically important molecules
Fats, phospholipids, and steroids
Fats
A fat is constructed from glycerol and fatty acids.
Glycerol
Is an alcohol. (Each of its 3 carbons carries a hydroxyl group)
Fatty acid
A fatty acid has a long carbon skeleton, usually 16 or 18 carbon atoms in length. The carbon at one end is part of a Carboxyl group (acid). The rest of the skeleton is a hydrocarbon chain (hydrophobic).
Triacylglycerol
Three fatty acid molecules are each joined to glycerol by an ester linkage, a bond formed via dehydration reaction between a hydroxyl group and a carboxyl group.
Saturated fatty acid
Has a carbon skeleton without double bonds, only single bonds.
Unsaturated fatty acid
Has one or more double bonds. Nearly all of these double bonds are cis double bonds.
Saturated fats are solid at room temperature
True
Unsaturated fats are liquid at room temperature
True
Trans fats
Have trans double bonds resulting from hydrogenating unsaturated fats.
Major Function of fats
Energy Storage
A gram of fat stores more than twice as much energy as a gram of polysaccharide
True
Phospholipid
Has only two fatty acids attached to glycerol. The third hydroxyl group of glycerol is joined to a phosphate group, which has a negative charge.
A phospholipid’s phosphate group and its attachments form a…
Hydrophilic head
When phospholipids are added to water
They for a bilayer, shielding their hydrophobic tail from water.
Steroids
Are lipids characterized by a carbon skeleton consisting of four fused rings.
Cholesterol
A type of steroid. It is a common component in animal cell membranes and is the precursor form from which other steroids are synthesized.
Proteins account for more than 50% of the dry mass of most cells, and they are instrumental in almost everything organisms do.
True
Different protein functions
Speed up chemical reactions
Defense
Storage
Transport
Cellular communication
Movement
Structural support
Catalysts
Chemical agents that selectively speed up chemical reactions without being consumed by the reaction.
Proteins are the most structurally sophisticated molecules known
True
Proteins are constructed from a set of…
20 amino acids
Peptide bond
The bond between amino acids
Polypeptide
Polymer of amino acids linked by peptide bonds.
Protein
Is a biologically functional molecule made up of one or more polypeptides, each folded and coiled into a specific three-dimensional structure.
Amino acid
Is an organic molecule with both an amino group and a carboxyl group.
The R group (the side chain)
A variable group that differs with each amino acid. Determines the unique characteristics of a particular amino acid.
How do the amino groups and carboxyl groups usually exist at the pH found in a cell?
In ionized form.
Groups of amino acids acids according to the properties of their side chains (R groups)
Nonpolar side chains; hydrophobic
Polar side chains; hydrophilic
Electrically charged side chains; hydrophilic
How does a Peptide bond occur?
Results from two adjacent amino acids; where the carboxyl group of one amino acid is next to the amino group of the other, here they can become joined via dehydration reaction resulting in a peptide bond.
Polypeptide backbone
The amino acids in a polypeptide with the exception of the R groups.
Single amino end in a polypeptide
N-terminus
Single carboxyl end in a polypeptide
C-terminus
The chemical nature of a polypeptide is determined by…
The kind and sequence of the side chains.
Globular proteins
Roughly spherical proteins
Fibrous proteins
Proteins that are shaped like long fibers.
The function of a protein depends on…
It’s ability to recognize and bind to some other molecule.
All proteins share ___ levels of superimposed structure.
Three; primary, secondary, and tertiary structure.
Primary structure
The primary structure of a protein is its sequence of amino acids, which is determined by inherited genetic information.
Secondary structure
The coils and folds in a polypeptide.
How is the secondary structure of a protein (the coils and folds) sustained?
The coils and folds are the result of hydrogen bonds between the repeating constituents of the polypeptide backbone. Within the backbone, the oxygen atoms have a partial negative charge, and the hydrogen atoms attached to the nitrogens have a partial positive charge; therefore, hydrogen bonds can form between these atoms.
α (Alpha) helix
A delicate coil held together by hydrogen bonding between every fourth amino acid.
β pleated sheet
Two or more segments of β strands that are connected by hydrogen bonds.
β strand
The polypeptide chain lying side by side.
Tertiary structure
Is the overall shape of a polypeptide resulting from interactions between the side chains (R groups) of the various amino acids.
Hydrophobic interaction
A type of weak chemical interaction caused when molecules that do not mix with water coalesce to exclude water. This contributes to tertiary structure.
What holds close non polar amino acid side chains together?
van der Waals interactions
Disulfide bridges
Covalent bonds where two cysteine monomers, which have Sulfhydryl groups (—SH) on their side chains, are brought close together by the folding of the protein. The sulfers bond and form the disulfide bridge (—S—S—). This bridge rivets parts of the protein together.
Quaternary structure
Is the overall protein structure that results from the aggregation of it’s polypeptide subunits. These proteins must consist of two or more polypeptide chains.
Collagen account for __% of the protein in a human body.
40%
Examples of proteins with quaternary structure
Fibrous protein : Collagen
Globular protein : Hemoglobin
Sickle-cell disease
An inherited blood disorder that is caused by the substitution of valine (amino acid) for glutamic acid (amino acid) at a particular position in the primary structure of hemoglobin.
Denaturation
A change caused by the wrong pH, salt concentration, temperature, or other aspects of the environment that destroys the weak bonds and interaction within a protein, which causes the protein to unravel and lose its native shape.
A denatured protein is…
Biologically inactive
Denaturing agents include:
Chemicals that disrupt the hydrogen bonds, ionic bonds, and disulfide bridges of a protein.
The information for building specific shape is intrinsic to the protein’s ____________
Primary structure
Chaperonins (chaperone proteins)
Protein molecules that assist in the proper folding of other proteins.
Diseases caused by misfolding of polypeptides:
Cystic fibrosis, Alzheimer’s, Parkinson’s, and mad cow disease.
X-ray Cristallography
Technique used to determine the 3D structure of proteins.
Nuclear Magnetic Resonance Spectroscopy (NMR)
Another method for analyzing protein structure which does not require protein crystallization.
Bioinformatics
Can be used to predict protein structure and function.
Nucleic acids
Are polymers made of monomers called nucleotides.
Two types of Nucleic acid
Deoxyribonucleic acid (DNA)
Ribonucleic acid (RNA)
Process of gene expression
- DNA provides information for its own replication
- DNA directs RNA synthesis and controls protein synthesis
Each chromosome contains _____________ which carries several hundred or more _____
One long DNA molecule
Genes
Proteins are required to _________
Implement genetic programs
messenger RNA (mRNA)
mRNA interacts with ribosomes to direct production of a polypeptide.
Polynucleotide
Polymer of Nucleic acid
Nucleotide
Three parts:
Five-carbon sugar (pentose)
Nitrogen-containing (nitrogenous) base
One or more phosphate groups
In a polynucleotide, each monomer has only ________________
One phosphate group
Nucleoside
The portion of a nucleotide without any phosphate groups.
Each nitrogen base has…
One or two rings that include nitrogen atoms.
Why are they called nitrogen ‘bases’?
Because the nitrogen atoms tend to take up H+ from solution, thus acting as bases.
Two families of nitrogenous bases
Pyrimidines
Purines
Pyrimidine
Has one six-membered ring of carbon and nitrogen atoms.
Members of the pyrimidine family
Cytosine (C)
Thymine (T)
Uracil (U)
Purines
Are larger, with a six-membered ring fused to a five-membered ring.
Members of the purine family
Adenine (A)
Guanine (G)
Thymine is found only in ____
DNA
Uracil is only found in ____
RNA
Deoxyribose
DNA sugar
Ribose
RNA sugar
Difference between deoxyribose and ribose
Deoxyribose lacks an oxygen atom on the second carbon in the ring.
Nucleoside monophosphate
Nucleotide
Phosphodiester linkage
Bond which joins adjacent nucleotides.
Sugar-phosphate backbone
Sugar, phosphate group, and phosphodiester linkages.
Two free ends of polynucleotide
One end has a phosphate attached to a 5’ carbon
And the other end has a hydroxyl group on a 3’ carbon.
Genes are ______ of nucleotides long
Hundreds to thousands
Double helix of DNA is formed by…
Two polynucleotides that wind around an imaginary axis; they are antiparallel and are held together by hydrogen bonds between the bases.
Adenine pairs with…
Thymine
Guanine pairs with…
Cytosine
Thymine pairs with…
Adenine
Cytosine pairs with…
Guanine
RNA molecules exist as single strands.
True
The functional shape of RNA results from
Base pairing.
In RNA, adenine pairs with…
Uracil
