Biomolecules, Cell Biology, Genetics, and Metabolism

Vocabulary flashcards covering core topics in biochemistry, cytology, metabolic pathways, cell division, molecular genetics, and Mendelian principles.

Hydrophilic Substance

A polar substance ($\Delta > 1.9$) that is attracted to water and dissolves or mixes easily in it.

Hydrophobic Substance

A nonpolar substance ($\Delta < 0.4$) that is repelled by water and does not dissolve easily in it.

Isomers

Molecules that share the same chemical formula but have a different arrangement of atoms, which modifies their chemical properties.

Monosaccharide

The monomer of carbohydrates; a simple sugar that cannot be hydrolyzed into smaller carbohydrate molecules.

Aldoses

Monosaccharides in which the carbonyl group ($\text{C}=\text{O}$) is positioned at the beginning of the saccharide chain.

Ketoses

Monosaccharides in which the carbonyl group ($\text{C}=\text{O}$) is located in between carbon atoms along the saccharide chain.

Glycosidic Bond

A covalent bond joining monosaccharides together formed through a condensation reaction that eliminates a water molecule.

Triglycerides

Lipids composed of one glycerol molecule attached to three fatty acid chains, functioning primarily in long-term energy storage.

Phospholipids

Structural lipids composed of glycerol, two fatty acid chains, and a phosphate group, resulting in a hydrophilic head and hydrophobic tails.

Steroids

Lipid molecules characterized by a structure made of three six-carbon rings and one five-carbon ring fused together.

Peptide Bond

A covalent bond formed between amino acids through a condensation reaction to build a polypeptide chain.

Chargaff's Rule

A principle of DNA composition stating that the amount of Adenine is always equal to Thymine ($\text{A}=\text{T}$) and Guanine is always equal to Cytosine ($\text{G}=\text{C}$).

Nucleoid

The region within a prokaryotic cell's cytoplasm where its genetic material (DNA) is located freely without a nuclear membrane.

Chromatin

The uncoiled structure formed when negatively charged DNA wraps around positively charged histone proteins ($\text{DNA} + \text{histones}$).

Rough Endoplasmic Reticulum (RER)

A cellular membrane network studded with ribosomes that synthesizes proteins and packages them into transport vesicles.

Smooth Endoplasmic Reticulum (SER)

A ribosome-free cellular membrane network that synthesizes lipids and detoxifies harmful substances like drugs and toxins.

Glycolysis

An anaerobic metabolic process in the cytoplasm where a 6-carbon glucose molecule is broken down into two 3-carbon pyruvate molecules, producing a net yield of $2\,\text{ATP}$ and $2\,\text{NADH}$.

Fermentation

An anaerobic pathway that regenerates $\text{NAD}^+$ from $\text{NADH}$ so that glycolysis can continue producing ATP when oxygen is absent.

Passive Transport

The movement of substances across a cellular membrane following their concentration gradient without requiring energy ($\text{ATP}$).

Active Transport

The movement of substances across a cellular membrane against their concentration gradient using energy ($\text{ATP}$).

Osmosis

A form of passive transport defined as the movement of water from an area of lower solute concentration to an area of higher solute concentration across a membrane.

Helicase

An enzyme involved in DNA replication that breaks the hydrogen bonds between nitrogenous bases to separate the DNA strands.

RNA Polymerase

An enzyme that binds to a promoter sequence on DNA, separates the strands, and synthesizes a complementary mRNA strand during transcription.

Codon

A sequence of three consecutive mRNA nucleotides that specifies a particular amino acid during protein synthesis.

Operon

A cluster of genes in prokaryotes controlled by a single promoter and operator.

Lytic Cycle

A viral replication cycle in which a virus infects a host cell, replicates its genome, produces new viral particles, and bursts open the host cell.

Lysogenic Cycle

A viral replication cycle in which viral DNA integrates into the host genome as a prophage and replicates alongside the cell without immediate host lysis.

Chromatid

One of two identical copies of a duplicated chromosome connected at the centromere.

Synapsis

The process during zygotene of prophase I in meiosis where maternal and paternal homologous chromosomes pair up to form a tetrad.

Nondisjunction

The mechanical failure of homologous chromosomes or sister chromatids to separate properly during meiosis, producing gametes with abnormal chromosome numbers.