ap bio cpt 6

nucleotide

The basic building block of nucleic acids, consisting of a sugar, a phosphate group, and a nitrogenous base.

five-carbon sugar

found in nucleotides, such as ribose or deoxyribose.

phosphate

a chemical group consisting of a phosphorus atom bonded to four oxygen atoms, critical for forming the backbone of nucleic acids.

nitrogenous base

a component of nucleotides that contains nitrogen and acts as a site for hydrogen bonding in nucleic acids, including adenine, thymine, cytosine, and guanine.

deoxyribose

A five-carbon sugar that is a component of DNA nucleotides, differing from ribose by lacking one oxygen atom.

adenine

a nitrogenous base found in DNA and RNA, pairing with thymine in DNA and uracil in RNA.

guanine

A nitrogenous base found in DNA and RNA, pairing with cytosine in DNA and with uracil in RNA.

cytosine

A nitrogenous base found in DNA and RNA, pairing with guanine in both DNA and RNA.

thymine

A nitrogenous base found in DNA, pairing with adenine. Thymine is not present in RNA.

plasmids

Small, circular DNA molecules found in bacteria that replicate independently of chromosomal DNA.

phosphodiester bonds

Covalent bonds that link nucleotides together in DNA and RNA, forming the backbone of the nucleic acid structure.

double helix

The structure of DNA, consisting of two intertwined strands that are complementary and anti-parallel, held together by base pairs.

Watson, Crick, and Franklin

Key scientists who contributed to the discovery of the DNA double helix structure through X-ray diffraction and model building.

base pairing

The specific hydrogen bonding between complementary nitrogenous bases in DNA and RNA, where adenine pairs with thymine (or uracil in RNA) and cytosine pairs with guanine.

complementary

nucleotide sequences that pair with each other in DNA, ensuring accurate replication and transcription.

antiparallel

Refers to the opposite orientation of the two strands of DNA, where one strand runs in the 5' to 3' direction and the other runs 3' to 5'.

gene

A segment of DNA that contains the instructions for building a specific protein or functional RNA molecule, ultimately influencing traits in an organism.

genome

The complete set of genetic material present in an organism, including all of its genes and non-coding sequences.

chromosome

A long, thread-like structure made of DNA and proteins that contains many genes, found in the nucleus of eukaryotic cells.

histone

A type of protein that helps package and organize DNA into structural units called nucleosomes, playing a crucial role in gene regulation and chromatin structure.

nucleosome

The basic unit of DNA packaging in eukaryotic cells, consisting of a segment of DNA wound around a core of histone proteins.

euchromatin

A less condensed form of chromatin that is transcriptionally active, allowing for gene expression and DNA replication.

heterochromatin

A tightly packed form of chromatin that is generally transcriptionally inactive, serving to maintain structural integrity and regulate gene expression.

DNA replication

The process by which a cell duplicates its DNA before cell division, ensuring that each daughter cell receives an exact copy of the genetic material.

helicase

An enzyme that unwinds the DNA double helix during DNA replication, allowing the strands to separate for copying.

replication fork

The Y-shaped region where the DNA double helix is separated into two single strands during DNA replication, allowing for the synthesis of new DNA strands.

origins of replication

Specific sites on the DNA where replication begins, allowing the DNA strands to separate and initiate the copying process.

topoisomerase

These enzymes are capable of relaxing supercoiled DNA and of decatenating interlocked DNA

DNA polymerase

An enzyme that synthesizes new DNA strands by adding nucleotides complementary to the template strand during DNA replication.

RNA primase

An enzyme that synthesizes short RNA primers needed for DNA polymerase to initiate DNA synthesis during replication.