Macromolecules: Nucleic Acids, Polysaccharides, and Lipids

Comprehensive vocabulary flashcards covering the structure and function of nucleic acids, polysaccharides, and lipids as discussed in the lecture.

Nucleic Acids

Linear polymers of nucleotides that store, transmit, and express genetic information, appearing in two forms: DNA (deoxyribonucleic acid) and RNA (ribonucleic acid).

Phosphate Group

The component of DNA and RNA responsible for the "acidic" property of nucleic acids.

Purines

A class of nitrogenous bases used in nucleic acids that includes Adenine (A) and Guanine (G).

Pyrimidines

A class of nitrogenous bases used in nucleic acids that includes Cytosine (C), Thymine (T) in DNA, and Uracil (U) in RNA.

Nucleoside

A molecule consisting of a nitrogenous base and a five-carbon sugar, without a phosphate group.

Adenosine Triphosphate (ATP)

A nucleoside with three phosphate groups; its structure includes adenine, ribose, and three phosphate groups linked by phosphoanhydride and phosphoester bonds.

$3',5'$ phosphodiester bridge

The link between linear polymers of nucleotides, consisting of a phosphate group joined to two adjacent nucleotides via two phosphodiester bonds.

5' and 3' ends

The directionality markers of a polynucleotide representing the $5'$ phosphate group at one end and the $3'$ hydroxyl group at the other.

Template

A preexisting molecule used during nucleic acid synthesis to ensure that new nucleotides ($NTPs$ for RNA or $dNTPs$ for DNA) are added in the correct order.

Anti-parallel

The arrangement of the two strands in a DNA double helix where they run in opposite directions ($5'$ to $3'$ versus $3'$ to $5'$).

Polysaccharides

Long chain polymers of sugars and sugar derivatives that serve primarily in structure and storage.

Aldosugars

Sugars characterized by a terminal carbonyl group (aldehydes).

Ketosugars

Sugars characterized by an internal carbonyl group (ketones).

Glycosidic bond

The linkage formed between two monosaccharides by the elimination of water; can be categorized as $\alpha$ or $\beta$ depending on the form of glucose involved.

Starch

A storage polysaccharide in plant cells consisting of $\alpha$-D-glucose units, appearing as unbranched amylose or branched amylopectin.

Glycogen

A highly branched storage polysaccharide in animal cells and bacteria composed of $\alpha$-D-glucose units linked by $\alpha(1 ightarrow 4)$ and $\alpha(1 ightarrow 6)$ bonds.

Cellulose

A structural polysaccharide found in plant cell walls composed of repeating monomers of $\beta$-D-glucose that form rigid linear rods called microfibrils.

Chitin

A structural polysaccharide found in insect exoskeletons and crustacean shells, composed of N-acetylglucosamine ($GlcNAc$) units.

Lipids

Amphipathic or hydrophobic macromolecules that are not formed by linear polymerization; they function in energy storage, membrane structure, and signal transmission.

Fatty Acid

A long, unbranched hydrocarbon chain with a carboxyl group at one end, serving as a building block for several classes of lipids.

Saturated Fatty Acid

A fatty acid with no double bonds between carbon atoms, such as Palmitate or Stearate.

Unsaturated Fatty Acid

A fatty acid containing one or more double bonds (cis or trans) which cause structural kinks, such as Oleate or Linoleate.

Triacylglycerols

Storage lipids (fats in animals, oils in plants) consisting of a glycerol molecule linked to three fatty acids.

Phospholipids

Amphipathic lipids essential to membrane structure, including phosphoglycerides and sphingolipids.

Glycolipids

Specialized membrane components containing a carbohydrate group instead of a phosphate, occurring largely on the outer monolayer of the plasma membrane.

Steroids

Lipids derived from a four-ringed hydrocarbon skeleton; examples include cholesterol and hormones like estradiol and testosterone.