Chapter 2: The Molecules of Life - Vocabulary Flashcards

Flashcards covering key vocabulary terms from Chapter 2: The Molecules of Life, focusing on elements, atoms, chemical bonds, water properties, organic molecules, carbohydrates, lipids, proteins, and nucleic acids.

Rhizobia

Nitrogen-fixing microorganisms isolated by Martinus Beijerinck from the root nodules of legumes.

Atoms

Basic unit of matter composed of neutrons, protons, and electrons. Normally has equal numbers of protons and electrons, therefore overall it has no charge

Neutrons

Uncharged particles in the atom.

Protons

Positively charged particles in the atom.

Electrons

Negatively charged particles in the atom.

Atomic Number

Number of protons in the nucleus of an atom.

Mass Number

Sum of protons and neutrons in the nucleus of an atom.

Valence Electrons

Electrons in the outermost shell of an atom.

Isotopes

Atoms of an element with different numbers of neutrons.

Atomic Mass

The average of mass numbers of atoms of an element.

Ions

Atoms that have gained or lost electron(s).

Anions

Ions that gain electron(s) and are negatively charged.

Cations

Ions that lose electron(s) and are positively charged.

Ionic Bonds

Form because of attraction between negative and positive charges.

Covalent Bonds

Form when atoms share electrons.

Molecule

Two or more atoms joined together by covalent bonds.

Compound

Molecules containing atoms of different elements.

Non-polar Covalent Bond

Equal sharing of electrons between atoms.

Polar Covalent Bond

Unequal sharing of electrons between atoms.

Hydrogen Bonds

Weak bonds formed when a hydrogen atom in a polar molecule is attracted to an electronegative atom in the same or another polar molecule.

Molarity (M)

The number of moles dissolved in 1 L of the solution.

Reactants

Starting components of a reaction that are changed to products.

Oxidation-Reduction (Redox) Reactions

Reactions in which electrons are transferred from one reactant to the other.

Enzymes

Biological catalysts that speed the rate of reactions.

Substrates

Reactants in enzyme-catalyzed reactions.

Hydrophilic

Polar and charged substances that dissolve in water ('water loving').

Hydrophobic

Non-polar substances that do not dissolve in water ('water fearing').

pH

Measure of acidity based on the concentration of H+ in a solution.

Buffers

Chemicals that help maintain a relatively constant pH of a solution.

Organic Molecules

Molecules that contain carbon and hydrogen.

Macromolecules

Large organic molecules including carbohydrates, lipids, proteins, and nucleic acids.

Polymers

Macromolecules made by joining monomers (subunits).

Dehydration Synthesis

Removes water and joins monomers to build polymers.

Hydrolysis

Requires water and breaks a polymer into monomers.

Carbohydrates

Diverse group including sugars and starches that serve as an energy source, energy storage, carbon source, component of DNA & RNA and structural component of cells.

Monosaccharide

Basic unit of carbohydrates (e.g., glucose, fructose).

Disaccharides

Composed of two monosaccharides (e.g., sucrose, lactose).

Polysaccharides

Chains of monosaccharides (e.g., cellulose, starch, glycogen).

Lipids

Non-polar, hydrophobic molecules important in membrane structure.

Fatty Acids

Linear carbon skeletons with a carboxyl group (-COOH) at one end.

Saturated Fatty Acids

Fatty acids with no double bonds.

Unsaturated Fatty Acids

Fatty acids with double bonds between carbon atoms.

Triglycerides

Most common simple lipids, composed of three fatty acids linked to glycerol.

Phospholipids

Compound lipids containing fatty acids and glycerol in addition to a non-lipid component. Contain hydrophilic phosphate group and hydrophobic fatty acid tails.

Steroids

Lipids with a characteristic four-ring structure (e.g. cholesterol, hormones).

Proteins

Composed of one or more chains subunits called amino acids. Functions include enzyme catalysis, transport, signal reception, regulation, motility, and support.

Amino Acids

Subunits of proteins. Share common structure with a central carbon, carboxyl group, amino group, and a side chain (R group).

Peptide Bonds

Covalent bond formed by dehydration synthesis reaction between carboxyl group and amino group that hold amino acids together forming a peptide (short chain) or polypeptide (longer chain).

Protein Denaturation

When a protein loses its characteristic shape, can be caused by high temperature, extreme pH, certain solvents, which may cause them to become non-functional.

Nucleic Acids

Carry genetic information in sequence of nucleotides.

Nucleotides

Composed of pentose sugar, phosphate group, and nucleobase.

DNA

Deoxyribonucleic acid; the genetic information needed to build and maintain a cell. Typically double-stranded.

RNA

Ribonucleic acid; several forms of RNA involved in protein synthesis. Similar to DNA except mostly single-stranded, contains ribose instead of deoxyribose, and uracil instead of thymine.

ATP

Adenosine triphosphate; energy currency of cell with high-energy phosphate bonds that break and release energy to drive cellular processes.

Nucleotide Structure

Building blocks of nucleic acids, consisting of a pentose sugar, a phosphate group, and a nucleobase.

Pentose Sugar

A five-carbon sugar molecule found in the backbone of DNA and RNA.

Nucleobases (Nitrogenous Bases)

Nitrogen-containing compounds that form the 'rungs' of the DNA ladder. Examples include adenine, guanine, cytosine, thymine (in DNA), and uracil (in RNA).

DNA Replication

The process by which DNA is copied to produce two identical DNA molecules.

Transcription

The synthesis of RNA from a DNA template.

Translation

The process by which the information encoded in mRNA is used to assemble a protein at a ribosome.

Codon

A sequence of three nucleotides in mRNA that specifies a particular amino acid or a termination signal.

Messenger RNA (mRNA)

A type of RNA that carries genetic information from DNA to the ribosome.

Ribosomal RNA (rRNA)

A type of RNA that forms part of the structure of a ribosome and participates in protein synthesis.

Transfer RNA (tRNA)

A type of RNA that carries amino acids to the ribosome during protein synthesis.

Mutation

A change in the nucleotide sequence of DNA.

Mutagen

An agent, such as radiation or a chemical substance, that causes genetic mutation.

Genetic Code

The set of rules by which information encoded in genetic material (DNA or RNA) is translated into proteins (amino acid sequences) by living cells.

Gene

A segment of DNA that codes for a specific protein or RNA molecule.

Genome

The complete set of genetic material present in a cell or organism.

Protein Synthesis

The process of synthesizing proteins from mRNA, involving ribosomes, tRNA, and amino acids.

DNA Polymerases

Enzymes involved in proofreading and correcting errors during DNA replication.

RNA Polymerase

The enzyme that synthesizes RNA from a DNA template during transcription.

Promoter

A DNA sequence where RNA polymerase binds to initiate transcription of a gene.

Introns

Non-coding sequences interspersed within genes that are transcribed but removed during RNA processing.

Exons

Coding sequences within genes that are transcribed and translated into protein.

5' Cap

The addition of a modified guanine nucleotide to the 5' end of mRNA, protecting it from degradation and enhancing translation.

Poly-A Tail

The addition of a string of adenine nucleotides to the 3' end of mRNA, increasing stability and aiding export from the nucleus.

MicroRNA (miRNA)

Small non-coding RNA molecules that regulate gene expression by binding to mRNA and inhibiting translation or causing degradation.

Terminator

A sequence of DNA that signals the end of transcription to RNA polymerase.

Point Mutation

A type of mutation that results in the substitution of one nucleotide for another in DNA.

Frameshift Mutation

A mutation that results in the insertion or deletion of nucleotides, altering the reading frame and leading to a non-functional protein.

Silent Mutation

A mutation that has no observable effect on the phenotype of an organism.

Transduction

The transfer of genetic material from one bacterium to another by a virus (bacteriophage).

Transformation

The uptake of foreign DNA from the surrounding environment by a bacterium.

Competence

Process where cells directly absorb DNA from their surroundings. This DNA can stay separate or integrate into the host's genome.

Transformation (Artificial)

Introducing foreign DNA into host cells, often to amplify DNA, produce protein, or for genetic analysis.

Restriction Enzyme

Enzyme that cleaves DNA at specific nucleotide sequences (restriction sites), essential for creating recombinant DNA.

Plasmid

Small, circular DNA separate from chromosomal DNA, frequently carrying antibiotic resistance genes.

Gel Electrophoresis

Lab technique to separate DNA, RNA, or proteins by size and electrical charge.

Polymerase Chain Reaction (PCR)

Technique to amplify specific DNA sequences from a single copy to millions of copies.

Southern Blot

Molecular biology method to detect a specific DNA sequence in samples.

Northern Blot

Like Southern blotting, but for detecting specific RNA sequences.

Western blot

Used to identify specific proteins in a sample based on their antibodies.