Biol 3130 Lecture 2: DNA as Genetic Material (Ch 8.1–8.3)

Vocabulary flashcards covering key terms and concepts from the notes on DNA as the genetic material (Ch. 8.1–8.3).

Heredity

The inheritance of genetic traits from one generation to the next.

Genetic material

The substance that carries heritable information; in most organisms, DNA.

DNA

Deoxyribonucleic acid; the molecule that contains genetic information and replicates faithfully.

Nucleotides

Building blocks of DNA and RNA, consisting of a sugar, a phosphate, and a nitrogenous base.

Replication

The process by which DNA is copied, with high fidelity and low error rates.

Genotype

The genetic makeup of an organism (the DNA sequence that encodes traits).

Phenotype

The observable traits of an organism resulting from genotype and environment.

Alleles

Different versions of a gene that can vary among individuals.

Transforming principle

The substance from dead virulent bacteria that can convert non-virulent bacteria to virulent.

Griffith

Frederick Griffith's 1928 experiment showing transformation in S. pneumoniae.

R strain

Non-virulent Streptococcus pneumoniae strain lacking a polysaccharide coat.

S strain

Virulent Streptococcus pneumoniae strain with a smooth polysaccharide coat.

Polysaccharide coat

Capsule surrounding some bacteria; affects virulence and immune evasion.

Virulent

Capable of causing disease.

Non-virulent

Not capable of causing disease.

Phagocytosis

Engulfment and destruction of pathogens by white blood cells.

Heat-killed bacteria

Bacteria killed by heat used in Griffith’s experiments to test transformation.

Transformation

Uptake and incorporation of foreign DNA by a cell, leading to a phenotypic change.

Recombinant DNA

Host DNA with foreign DNA inserted.

Avery, MacLeod, McCarty

1944 experiments showing DNA is the transforming principle.

DNA is the transforming principle

Conclusion that DNA carries the genetic information responsible for transformation.

Nucleases

Enzymes that degrade nucleic acids; include RNase, DNase, and proteases in context.

Hershey & Chase

1952 experiments using bacteriophage T2 showing DNA is the genetic material.

Phage

A virus that infects bacteria.

Lytic cycle

Phage life cycle that lyses the host cell to release new phage particles.

Lysogenic cycle

Phage genome integrates into the host and can later enter the lytic cycle.

T2 phage

A well-studied bacteriophage used by Hershey-Chase to study genetic material.

32P labeling

Radioactive phosphorus used to label DNA in genetic material experiments.

35S labeling

Radioactive sulfur used to label proteins in Hershey-Chase experiments.

Double helix

Two long strands of nucleotides wound around each other in a right-handed spiral.

Base pairing

Specific pairing: A with T (or U in RNA) and C with G via hydrogen bonds.

A-T base pair

Adenine pairs with Thymine (2 hydrogen bonds) in DNA.

G-C base pair

Guanine pairs with Cytosine (3 hydrogen bonds) in DNA.

Chargaff's Rule

In DNA, amounts of A ≈ T and C ≈ G; base pairs are complementary.

Purines

Two-ring bases: Adenine (A) and Guanine (G).

Pyrimidines

One-ring bases: Cytosine (C) and Thymine (T); Uracil (U) in RNA.

Deoxyribose

Five-carbon sugar in DNA ribose lacking an extra OH group at C2'.

Ribose

Five-carbon sugar in RNA with an OH group at C2'.

Phosphate group

Phosphate moiety linking sugars to form the DNA backbone.

Polynucleotide strand

A chain of nucleotides connected by phosphodiester bonds.

Phosphodiester bond

Covalent bond linking a sugar’s 3'-OH to the next phosphate, forming the backbone.

5' end

End of a DNA strand with a free phosphate group at the 5' carbon.

3' end

End of a DNA strand with a free hydroxyl group at the 3' carbon.

B-DNA

Right-handed DNA form common under physiological conditions; ~10 bp per turn.

Major groove

Open, wide groove in the DNA double helix where proteins often bind.

Minor groove

Narrow groove in the DNA double helix; also important for protein interactions.

Primary structure

Linear sequence of nucleotides in DNA or RNA.

Secondary structure

The double-helix arrangement formed by base pairing between strands.

Tertiary structure

Higher-order folding and packing of DNA with proteins.

Denaturation

Separation of DNA strands due to breakage of base pairing; influenced by GC content.

Net charge of DNA

Overall negative charge, due to the negatively charged phosphate backbone.