Prokaryotes and Eukaryotes Flashcards

Vocabulary flashcards based on lecture notes about Prokaryotes and Eukaryotes.

Prokaryotes

Cells with a circular chromosome and no nucleus; Bacteria.

Eukaryotes

Cells with multiple linear chromosomes contained within a nucleus.

Chromosome

A thread-like structure of nucleic acids and protein that carries genetic information in the form of genes.

Chromatid

One of two identical halves of a replicated chromosome.

Nucleus

A membrane-bound organelle in eukaryotic cells containing the chromosomes.

Telomere

A region of repetitive nucleotide sequences at each end of a chromosome, protecting the chromosome from deterioration or fusion with neighboring chromosomes.

Centromere

The region of a chromosome to which the microtubules of the spindle attach, via the kinetochore, during cell division.

Plasmid

Extra DNA in bacteria, much smaller than bacterial chromosomes.

Operon

A cluster of genes in prokaryotes transcribed together under a single promoter, resulting in a polycistronic transcript.

Polycistronic transcript

A single mRNA molecule that codes for multiple proteins, common in prokaryotes.

Ploidy

The number of complete sets of chromosomes in a cell.

Chromatin

The material of which chromosomes are made; DNA packaged with proteins (histones).

Nucleosome

The basic unit of chromatin, composed of DNA wrapped around histone proteins.

Histone

Proteins around which DNA is wrapped to form nucleosomes.

Euchromatin

Transcriptionally active chromatin.

Heterochromatin

Transcriptionally silent chromatin.

Nucleotide

The repeating units that make up each chain of the DNA double helix, composed of a sugar, a triphosphate, and a nitrogenous base.

Promoter

DNA sequences that define where transcription of a gene by RNA polymerase begins, typically located upstream or at the 5' end of the transcription initiation site.

RNA Polymerase (RNAP)

The enzyme responsible for transcription.

Transcription factors

Proteins required by RNA polymerase to bind to the promoter sequence and initiate transcription.

Template Strand (Antisense Strand)

The DNA strand that mRNA is built from.

Coding Strand (Sense Strand)

Corresponds to the mRNA sequence with uracil instead of thymine.

Cis-acting elements

DNA sequences that regulate the expression of genes located on the same DNA molecule; promoter.

Trans-acting factors

Proteins that bind to cis-acting elements to regulate gene expression; RNA polymerase and other transcription factors.

Core promoter

DNA elements found at the 5’ of a gene close to the transcription start site.

Upstream Regulatory elements

Proximal and Distal regulatory elements located upstream of the core promoter.