DNA Structure & Replication Lesson3

A set of vocabulary flashcards covering key terms and concepts from DNA structure and replication.

Nucleic acids

Polymers made of nucleotides; include DNA and RNA and carry genetic information.

Nucleotide

Building block of nucleic acids consisting of a phosphate group, a sugar, and a nitrogenous base.

Phosphate group

Chemical group linked to the sugar in nucleotides; part of the DNA/RNA backbone.

Sugar (in nucleotides)

Pentose sugar; DNA contains deoxyribose, RNA contains ribose.

Nitrogenous base

Purines and pyrimidines that pair to form DNA/RNA; A, T (or U in RNA), G, C.

Adenine (A)

Purine base that pairs with Thymine in DNA and with Uracil in RNA.

Thymine (T)

Pyrimidine base that pairs with Adenine in DNA.

Guanine (G)

Purine base that pairs with Cytosine in DNA and RNA.

Cytosine (C)

Pyrimidine base that pairs with Guanine.

Uracil (U)

Pyrimidine base in RNA that replaces Thymine and pairs with Adenine.

DNA (Deoxyribonucleic acid)

Genetic material that is typically double-stranded, uses deoxyribose, and bases A–T and G–C.

RNA (Ribonucleic acid)

Nucleic acid usually single-stranded, uses ribose, and base Uracil instead of Thymine.

Deoxyribose-phosphate backbone

The sugar-phosphate chain that forms the structural framework of DNA.

Anti-parallel

Opposite orientation of the two DNA strands in a double helix.

5' and 3' ends

Ends of a DNA/RNA strand indicating the direction of nucleotide linkage (5' phosphate to 3' hydroxyl).

Hydrogen bonds

Non-covalent bonds that stabilize base pairs (A–T with 2 bonds; G–C with 3 bonds in DNA).

Base pairing

Specific pairing: A pairs with T (DNA) or with U (RNA); G pairs with C.

Double helix

Two antiparallel DNA strands wound around each other to form the classic DNA shape.

Complementary base-pairing

Rule that ensures accurate DNA/RNA pairing: A–T (or A–U in RNA) and G–C.

DNA replication

Process of copying the genome so genetic information is preserved in daughter cells.

Leading strand

The DNA strand synthesized continuously toward the replication fork.

Lagging strand

The DNA strand synthesized discontinuously away from the replication fork, forming Okazaki fragments.

Okazaki fragments

Short DNA fragments synthesized on the lagging strand during replication.

Ligase

Enzyme that joins Okazaki fragments to form a continuous strand.

RNA primer

Short RNA sequence that starts DNA synthesis by providing a starting 3'OH.

Origin of replication

Specific sequence where DNA replication begins; prokaryotes have one, eukaryotes have multiple.

Replication fork

Y-shaped region where the DNA double helix is unwound for replication.

Prokaryotic DNA vs. Eukaryotic DNA (shape and packaging)

Prokaryotes: circular DNA, one origin, single bubble, located in cytoplasm; Eukaryotes: linear DNA, multiple origins, multiple bubbles, located in nucleus.

Chromosome

DNA packaged with proteins; varies in number and shape; location differs by organism type.

Histone

Protein around which DNA wraps to form nucleosomes in chromatin.

Nucleosome

Basic unit of chromatin: DNA wrapped around a histone core.

Chromatin

DNA-protein complex that organizes DNA; can be loosely packed or tightly packed.

Genome

Complete set of genetic material in an organism; metaphor: cookbook collection.

Chromosome

Individual DNA molecule with its associated proteins; carries genes.

Gene

Basic unit of heredity; a specific sequence that encodes a functional product.

Protein

A biological molecule produced from gene expression; determines traits and functions.

Central dogma

Concept: DNA is transcribed into RNA, which is translated into protein (with replication as DNA to DNA).