Biological Macromolecules, Molecular Biology, and Genetics Vocabulary

Vocabulary flashcards covering biological macromolecules, carbohydrates, lipids, proteins, nucleic acids, DNA replication, gene expression, genetics, mutations, chromosomal aberrations, and recombinant DNA technology.

Biological macromolecules

Large molecules found in living organisms that are necessary for survival by providing energy, forming cell structures, controlling body processes, and carrying genetic information.

Monomers

Smaller units that join together through covalent bonds to form larger biological polymers.

Polymers

Larger molecules formed when smaller monomer units join together through covalent bonds.

Dehydration synthesis

A chemical reaction in which monomers combine and form covalent bonds to produce larger polymers, forming new bonds and requiring energy.

Hydrolysis

A chemical reaction in which polymers are broken down into monomers by adding water, which splits chemical bonds and releases energy.

Carbohydrates

Organic macromolecules made of carbon, hydrogen, and oxygen with the general formula $(CH_2O)_n$ that serve as a primary energy source and structural support.

Triose

A three-carbon monosaccharide with the molecular formula $C_3H_6O_3$.

Pentose

A five-carbon monosaccharide with the molecular formula $C_5H_{10}O_5$, such as ribose.

Hexose

A six-carbon monosaccharide with the molecular formula $C_6H_{12}O_6$, such as glucose, fructose, and galactose.

Monosaccharides

Simple sugars usually containing $3\text{--}7$ carbons whose names commonly end in -ose.

Aldose

A monosaccharide sugar containing an aldehyde functional group ($-CHO$).

Ketose

A monosaccharide sugar containing a ketone functional group.

Isomers

Molecules that share the same molecular formula but have different structural arrangements of atoms.

Structural isomers

Molecules that have the same molecular formula but possess different bonding arrangements.

Stereoisomers

Molecules with the same molecular formula and bonding pattern that differ in the three-dimensional arrangement of their atoms.

Enantiomers

Stereoisomers that are non-superimposable mirror images of one another.

Epimers

Stereoisomers that differ in configuration at only one chiral carbon atom.

Anomers

A special type of epimer that differs in configuration specifically at the anomeric carbon after a sugar forms a ring.

Glycosidic bond

A covalent linkage formed between a carbohydrate molecule and another molecule through a dehydration reaction.

Disaccharides

Carbohydrate molecules formed when two monosaccharides join through a dehydration reaction and a glycosidic bond.

Oligosaccharides

Short carbohydrate chains consisting of about $3\text{--}10$ monosaccharides joined by glycosidic bonds.

Polysaccharides

Long chains of monosaccharides linked together by glycosidic bonds.

Starch

An energy storage polysaccharide in plants composed of a mixture of amylose and amylopectin.

Glycogen

The storage form of glucose in humans and other vertebrates, serving as the animal equivalent of starch.

Cellulose

A highly insoluble structural polysaccharide that forms plant cell walls.

Chitin

A structural polysaccharide found in fungal cell walls and arthropod exoskeletons.

Iodine indicator

A chemical indicator used to detect starch, yielding a blue-black, dark purple, or nearly black color upon interacting with the helical structure of amylose.

Lipids

A chemically diverse group of mostly hydrophobic or amphipathic biomolecules functioning in long-term energy storage, membrane structure, signaling, insulation, protection, and metabolic regulation.

Phospholipids

Major constituents of the plasma membrane composed of one glycerol molecule, two fatty acids, and a phosphate-containing head group.

Saturated fatty acids

Fatty acids containing no carbon-carbon double bonds, possessing straight chains that pack tightly and are usually solid at room temperature.

Unsaturated fatty acids

Fatty acids containing one or more carbon-carbon double bonds, which cause liquid fluidity at room temperature.

Cis double bond

A carbon-carbon double bond configuration in fatty acids that creates a kink in the carbon chain, preventing tight packing.

Trans double bond

A carbon-carbon double bond configuration in fatty acids that keeps the hydrocarbon chain straight, causing it to behave like a saturated fat.

Triglyceride

A lipid formed from one glycerol molecule bonded to three fatty acids that functions primarily in energy storage.

Steroids

Lipids characterized by a basic structure of four fused carbon rings.

Proteins

Abundant biological polymers constructed from $20$ different amino-acid monomers.

Amino acid

A monomer of proteins consisting of a central alpha carbon bonded to an amino group ($-NH_2$), a carboxyl group ($-COOH$), a hydrogen atom, and a variable R-group.

R-group

The unique side chain attached to the central carbon of an amino acid that determines its distinct chemical properties.

Peptide bond

A covalent linkage formed by joining the carboxyl group of one amino acid to the amino group of another.

Polypeptide

A polymer chain consisting of more than $20$ amino acids linked by peptide bonds.

Primary structure

The unique sequence of amino acids in a polypeptide chain linked together by peptide bonds.

Secondary structure

Local folding patterns within a polypeptide chain, such as alpha helices and beta-pleated sheets, maintained by hydrogen bonds.

Tertiary structure

The overall three-dimensional folding of a single polypeptide chain driven by hydrophobic, ionic, and disulfide interactions among R-groups.

Quaternary structure

The protein structure formed when two or more distinct polypeptide subunits assemble together.

Nucleic acids

Biological macromolecules that carry the genetic blueprint of a cell, direct cell functions, and provide instructions for protein synthesis.

Nucleotide

The monomer unit of nucleic acids, composed of a nitrogenous base, a pentose sugar, and a phosphate group.

Purines

Double-ring nitrogenous bases found in nucleic acids, specifically adenine (A) and guanine (G).

Pyrimidines

Single-ring nitrogenous bases found in nucleic acids, specifically cytosine (C), thymine (T), and uracil (U).

Nucleoside

A molecule consisting of a nitrogenous base covalently bonded to a pentose sugar, lacking a phosphate group.

DNA (deoxyribonucleic acid)

A double-stranded antiparallel nucleic acid containing deoxyribose sugar that stores hereditary genetic instructions.

RNA (ribonucleic acid)

A generally single-stranded nucleic acid containing ribose sugar and uracil that converts genetic instructions from DNA into functional proteins.

Antiparallel strands

The structural arrangement of the double helix where the two complementary strands run in opposite directions ($5' \rightarrow 3'$ and $3' \rightarrow 5'$).

Chargaff's Rule

The rule establishing that in double-stranded DNA, the percentage of adenine equals thymine ($\%A \approx \%T$) and guanine equals cytosine ($\%G \approx \%C$), adding up to $100\%$.

Central Dogma

The principle describing the directional flow of genetic information through DNA replication, RNA transcription, and protein translation.

Semiconservative replication

The mechanism of DNA duplication where each resulting daughter DNA molecule contains one original template strand and one newly synthesized strand.

Topoisomerase

An enzyme that relaxes supercoiling and twisting in the DNA double helix to assist in unwinding during replication.

Helicase

An enzyme that unzips parental DNA strands by breaking the hydrogen bonds holding complementary nitrogenous base pairs together.

Primase

An enzyme that synthesizes a short RNA primer to supply a starting $3'$ end for DNA polymerase.

DNA polymerase III

The primary enzyme that adds complementary DNA nucleotides in the $5' \rightarrow 3'$ direction during DNA replication.

DNA polymerase I

An enzyme that removes RNA primers and replaces them with corresponding DNA nucleotides during DNA replication.

Ligase

An enzyme that covalent links DNA fragments together by forming phosphodiester bonds, particularly on the lagging strand.

Leading strand

The DNA strand synthesized continuously toward the advancing replication fork in the $5' \rightarrow 3'$ direction.

Lagging strand

The DNA strand synthesized discontinuously away from the replication fork as a series of short Okazaki fragments.

Promoter

A specific sequence region on DNA where RNA polymerase binds and initiates transcription.

Codon

A triplet sequence of mRNA nucleotides that specifies a single amino acid or serves as a translation start or stop signal.

Anticodon

A sequence of three nucleotides on a tRNA molecule that is complementary and antiparallel to a corresponding codon in mRNA.

Alleles

Alternative forms or variants of a specific gene located at the same locus on homologous chromosomes.

Genotype

The specific combination of alleles an organism inherits at fertilization.

Phenotype

The observable physical or functional traits displayed by an organism.

Law of Segregation

Mendel's law stating that allele pairs separate during gamete formation so that each gamete carries only one allele for each gene.

Law of Independent Assortment

Mendel's law stating that alleles of unlinked genes segregate independently into gametes during meiosis.

Test cross

A genetic cross between an individual showing a dominant phenotype and a homozygous recessive individual to determine the dominant parent's genotype.

Incomplete dominance

An inheritance pattern in which a heterozygous genotype expresses a phenotype intermediate between those of the two homozygous parents.

Codominance

An inheritance pattern in which both alleles in a heterozygous individual are fully and simultaneously expressed without blending.

Somatic variant

A DNA mutation occurring in non-germline body cells that is not transmitted to offspring.

Germ-cell variant

A DNA mutation occurring in reproductive cells (eggs or sperm) that can be passed from parent to child.

Missense variant

A single-base substitution mutation that alters a codon to code for a different amino acid.

Nonsense variant

A base substitution mutation that converts an amino-acid codon into a premature stop codon, leading to truncated proteins.

Silent variant

A base substitution mutation that does not alter the amino acid sequence due to the redundancy of the genetic code.

Frameshift variant

An insertion or deletion of nucleotides not in multiples of three that shifts the genetic reading frame of mRNA.

Transition

A nucleotide substitution where a purine is replaced by another purine ($A \leftrightarrow G$) or a pyrimidine is replaced by another pyrimidine ($T \leftrightarrow C$).

Transversion

A nucleotide substitution where a purine is replaced by a pyrimidine or vice versa.

Aneuploidy

A chromosomal condition involving the gain or loss of individual chromosomes from a normal set.

Polyploidy

A condition in which an organism possesses more than two complete sets of chromosomes.

Nondisjunction

The failure of homologous chromosomes or sister chromatids to separate properly during meiotic or mitotic cell division.

Transformation

A bacterial gene transfer process in which a cell directly takes up foreign naked DNA from its surrounding environment.

Transduction

The transfer of bacterial DNA from one cell to another mediated by a bacteriophage virus vector.

Conjugation

Direct transfer of genetic material between two bacterial cells connected via a pilus.

Restriction enzyme

An endonuclease enzyme that recognizes specific DNA sequences and cleaves the DNA backbone at or near those sites.

Vector

A DNA molecule, such as a bacterial plasmid, used as a vehicle to artificially carry foreign genetic material into another cell.