Cell Bio Chapter 16 - Exam 4

Genes

Distinct units that transmit hereditary information.

Nucleus

The organelle that houses the chromosomes of eukaryotic cells.

Johann Miescher

Swiss physician that discovered DNA.

Nuclein

The old name for DNA.

Eduard Zacharias

Botanist that inferred that DNA is genetic material.

Frederick Griffith

Studied pneumonia-causing bacteria; discovered the “transforming principle”.

Oswald Avery

Furthered Griffith’s research, confirming DNA makes up genes.

Bacteriophages

Viruses that infect bacteria.

Virulent phage

Bacteriophage that always produces lytic growth.

Temperate phage

Bacteriophage that may produce lytic growth or directly integrate its DNA into bacteria without causing immediate harm.

Prophage

DNA of a temperate phage.

Hershey and Chase

Two scientists that discovered DNA in viruses.

Retrovirus

Viruses that contain RNA, useful in treating conditions such as HIV.

Chargaff’s Rule

Rule that states that bases are paired A-T and C-G.

Watson and Crick

Two scientists that discovered DNA’s double helix structure.

3.4 nm

The length each turn of the helix adds to a DNA molecule, in nm.

2 nm

The diameter of a DNA helix, in nm.

B DNA

Right-handed DNA.

Z DNA

Left-handed DNA.

A DNA

Short, thick, right-handed.

Supercoiled DNA

Super compacted DNA, first identified in small viruses.

Positive supercoil

Coiled in the same direction as the DNA.

Negative supercoil

Coiled in the opposite direction of the DNA. Favored in cells.

Topoisomerases

Enzyme that relaxes supercoiled DNA.

Type I topoisomerase

Relaxes supercoiled DNA using transient single-strand breaks.

Type II topoisomerase

Relaxes supercoiled DNA using transient double-strand breaks.

DNA gyrase

A type II topoisomerase present in bacteria that can induce or relax supercoiling.

DNA denaturation

The separation of DNA strands experimentally.

DNA renaturation

The reformation of DNA strands into a double helix.

30 degrees

What is the most energetically favorable angle for the DNA backbone?

Nucleic acid hybridation

A family of procedures for identifying nucleic acids based on the ability of base sequences to bind.

Nucleoid

A special region of a bacterial cell where DNA is localized

Ribonuclease

Enzyme that degrades RNA

Plasmids

Small, circular molecules of DNA that carry genes for bacterial replication and cell function.

Fertility factors

Plasmids involved in the process of conjugation.

Resistance factors

Plasmids involved in drug resistance.

Colicinogenic factors

Plasmids that allow bacterium to secrete colicins.

Colicins

Compounds that kill other bacteria lacking the col factor.

Virulence factors

Plasmids that enhance a bacteria’s ability to cause disease.

Metabolic plasmids

Plasmids that produce enzymes required for certain metabolic reactions.

Cryptic plasmids

Plasmids with no known function, found in some strains of E. Coli.

Chromotin

DNA-protein fibers that make up chromosomes.

Lysine and arginine

What two amino acids do histones have large concentrations of?

Positive

What charge do histones have?

Nucleosome

The “bead” found in the bead-and-string chromatin structure, along with its associated strand of DNA.

H1

Which histone is not part of a histone octamer?

Cohesin

Protein that stabilizes DNA loops and keeps chromosomes attached to each other prior to anaphase.

DNA packaging ratio

The total length of DNA divided by the length of the chromatin fiber or chromosome it has been packaged into.

Histone methyltransferase

Enzyme that catalyzes the addition of methyl groups to histones.

Histone acetyltransferase

Enzyme that catalyzes the addition of acetyl groups to histones.

Histone deacetylase

Enzyme that removes acetyl groups from histones.

Chromodomains

Proteins with these domains associate with methylated histones characteristic of compact chromatin.

Bromodains

Proteins with these domains bind to acetylated DNA associated with open chromatin.

Epigenetic change

Alteration in the expression of a gene rather than a change in the structure of the gene itself.

Heterochromatin

Chromatin compacted so tightly it shows up as dark spots on micrographs.

Euchromatin

A loosely packed, diffuse form of chromatin. Associated with active DNA transcription.

Constitutive heterochromatin

Permanently compacted chromatin, found in centromeres and telomeres.

Centromeres

Maintains sister chromatid cohesion and acts as sites of assembly for kinetochores.

CEN sequences

Highly repetitive DNA sequences that characterize centromeres.

Telomeres

Found at the tips of chromosomes, contains highly repetitive DNA sequences.

Karyotype

An individuals complete set of chromosomes.