Biochemistry Study Guide: DNA, Techniques, Repair & CRISPR

A collection of vocabulary flashcards covering key terminology and concepts related to DNA structure, techniques, repair mechanisms, and CRISPR technology.

Nucleotide

A building block of DNA, consisting of a ribose sugar, a phosphate group, and a nitrogenous base.

5' end

The end of a DNA strand where a phosphate group is attached to the 5th carbon of the sugar.

3' end

The end of a DNA strand where a hydroxyl group is attached to the 3rd carbon of the sugar.

Purines

Nitrogenous bases with a two-ring structure; includes adenine and guanine.

Pyrimidines

Nitrogenous bases with a single-ring structure; includes cytosine and thymine.

A=T

A base pair in DNA where adenine bonds with thymine through 2 hydrogen bonds.

G≡C

A base pair in DNA where guanine bonds with cytosine through 3 hydrogen bonds.

Eukaryotic DNA

DNA that is linear and chromatin-packed, found in organisms with complex cells.

Prokaryotic DNA

DNA that is circular, found in organisms with simpler cell structures.

Chromatin

A complex of DNA and histone proteins; its packing level affects gene expression.

Methylation

A chemical modification that silences gene expression.

Acetylation

A chemical modification that activates gene expression.

Heterologous Expression

The process of expressing a gene in a foreign host.

PCR

A technique for amplifying DNA, involving denaturation, annealing, and elongation.

Restriction Enzymes

Enzymes that cut DNA at specific sequences.

Selectable Marker

A gene used to identify if a cell has taken up a plasmid, often conferring antibiotic resistance.

MMR

Mismatch Repair, a system that fixes replication errors.

BER

Base Excision Repair, which fixes small base lesions.

NER

Nucleotide Excision Repair, which removes bulky DNA lesions.

NHEJ

Non-homologous End Joining, an error-prone DNA repair process.

HDR

Homologous Directed Repair, a high-fidelity repair process that uses a template.

CRISPR

A bacterial adaptive immune system that provides resistance to phages.

Cas9

An endonuclease enzyme that cuts DNA, used in CRISPR technology.

sgRNA

Synthetic guide RNA that directs Cas9 to specific DNA sequences.

PAM

A sequence necessary for Cas9 to recognize and bind to target DNA.

dCas9

A dead Cas9 variant that regulates gene expression without cutting DNA.