Genetics exam 1 study

Biosphere

The global ecosystem encompassing all living organisms (plants, animals, bacteria) and ALL the regions of Earth they inhabit.

Artificial selection

A term coined by Charles Darwin to describe the intentional breeding of plants and animals for certain traits or combinations of traits.

Johan Friedrich Miescher

A biochemistry researcher who, in $1869$, isolated a weakly acidic, phosphorous-rich material from the nuclei of leukocytes (found in pus) and named it nuclein.

Nuclein

The name originally given to DNA by Johan Friedrich Miescher when it was first isolated from the nuclei of white blood cells.

Ernst Haeckel

A researcher best known for the phrase "ontogeny recapitulates phylogeny" who speculated in $1866$ that the nucleus contains hereditary factors.

Albrecht Kossel

A student of Hoppe-Seyler who modified nuclein to nucleic acid (NA), identified purine ($A$, $G$) and pyrimidine ($C$, $T$) bases, and identified histones.

Oscar Hertwig

A researcher who studied sea urchin embryos and in $1875$ noted the fusion of two nuclei in fertilized eggs, one from the sperm and one from the egg.

Theodor Boveri

A scientist who discovered that each chromosome has a unique genetic makeup and correlated chromosomes with Mendel’s laws of inheritance.

Tetranucleotide hypothesis

A hypothesis by Phoebus Levene which suggested DNA was a simple, repeating sequence of four nucleotides in equal proportions, leading many to believe proteins were the hereditary molecule.

Frederick Griffith

A scientist who in $1928$ studied Streptococcus pneumoniae and discovered transformation through experiments with virulent ($S$) and nonvirulent ($R$) strains.

Transformation

The transfer of genetic information, such as virulence, from dead cells into live cells, a process first identified by Frederick Griffith.

Chargaff’s rules

The observation that in DNA, approximately $50\%$ of bases are purines and the other half are pyrimidines, specifically where $A = T$ and $C = G$.

Avery, MacLeod, & McCarthy Experiments

$1944$ experiments that used specific enzymes to demonstrate that DNA, rather than protein or RNA, is the transforming material.

Bacteriophages

Viruses that infect bacteria, composed only of DNA and protein, used by Hershey and Chase to confirm DNA as the genetic material.

Hershey-Chase Experiments

$1952$ experiments using radioactive phosphorus ($^{32}P$) for DNA and radioactive sulfur ($^{35}S$$) for protein to prove only DNA enters a host bacteria to produce more viruses.

Nucleotide

The monomer of DNA and RNA consisting of a pentose ($5$ carbon sugar), a phosphate group, and a nitrogenous base.

Phosphodiester bond

The bond formed between the phosphate group of one nucleotide and the $3'$ $-OH$ of the next nucleotide, creating a chain with a $5'$ to $3'$ orientation.

Rosalind Franklin and Maurice Wilkins

Researchers who used X-ray diffraction to identify that DNA is helical, with a diameter of $2$ nm and a complete turn every $3.4$ nm.

Watson and Crick

Scientists who in $1953$ deduced the double helix structure of DNA using evidence from Chargaff and Franklin.

Antiparallel

The orientation of the two sugar-phosphate backbones in a DNA double helix, which run in opposite directions.

B form

The "normal" DNA conformational isomer surrounded by water; it is a right-handed spiral with $10$ base pairs per turn.

Z form

A left-handed (counterclockwise) DNA spiral with $12$ base pairs per turn, featuring $C-G$ base pairs and a characteristic zigzag structure.

Chromatin

The material in Eukaryotes that makes up chromosomes, consisting of a $2:1$ ratio of protein to DNA by weight.

Nucleoid

The region in prokaryotic cells where double-stranded, supercoiled DNA is located, as they lack a membrane-bound nucleus.