Ch 6 Quiz Review Flashcards
diploid
the presence of two complete sets of chromosomes in an organism’s cells, with each parent contributing a chromosome to each pair
histone
a special protein molecule that is the core around which the DNA strand wraps
nucleosome
a unit of DNA storage, consisting of 8 histones with DNA strands wrapped around them
gene
a unit of heredity which is transferred from a parent to offspring and is held to determine some characteristic of the offspring
plasmid
a small circular section of DNA found in the cytosol of bacteria; replicates independently of the chromosomal DNA
nucleotide base pair
Two nitrogen-containing bases (or nucleotides) that pair together to form the structure of DNA.
The four bases in DNA are adenine (A), cytosine (C), guanine (G), and thymine (T).
These bases form specific pairs (A with T, and G with C)
semiconservative replication
a mechanism of DNA replication in which each of the two strands of parent DNA is incorporated into a new double-stranded DNA molecule
DNA helicase
a replication enzyme that separates and unwinds the DNA strands
topoisomerase
a class of enzymes that relieve tensions caused by the unwinding of parent DNA; they cleave one or two of the DNA strand(s), allow the strands to untwist, and then rejoin the strand(s)
single-strand binding protein (SSBP)
a replication enzyme that prevents parent DNA strands from annealing to each other once they have been separated by helicase
replication bubble
the separating of DNA in both directions during replication
DNA polymerase l
a prokaryotic replication enzyme that fills in gaps in the lagging strand between Okazaki fragments; also proofreads the final strands
DNA polymerase ll
a prokaryotic replication enzyme that repairs damage to DNA, including damage that occurs between replication events
DNA polymerase lll
a prokaryotic replication enzyme that builds new DNA strands from nucleotides
okazaki fragment
the piece of new DNA on the lagging strand
leading strand
the DNA strand that is copied in the direction toward the replication fork
lagging strand
the DNA strand that is copied in the direction away from the replication fork
RNA primase
a replication enzyme that produces RNA primers
RNA primer
a replication molecule that acts as a starting point for replication
DNA ligase
an enzyme that catalyzes the formation of a phosphodiester bond between 2 DNA strands, as well as between okazaki fragments
telomere
a repeating sequence of DNA at the end of a chromosome that protects coding regions from being lost during replication
telomerase
an enzyme that adds new telomere sequences to the ends of chromosomes
Hayflick limit
the total number of times that a normal cell can divide
Gregor Mendel
hypothesized the existence of a hereditary molecule that passes genetic info through generations
Frederick Meischer
Studied the composition of the nucleus
-collected pus from bandages and extracted an unknown substance that was acidic and contained phosphorus
-named it “nuclein”
Frederick Griffith
studied pneumonia bacteria
-used 2 diff strains of the pneumonia bacterium
-showed some sort of hereditary transmission
–> transformation
Avery, McLeod and McCarty
based on Griffith’s findings, they carried out similar studies in 1944 using streptococcus
-results showed that DNA was the hereditary substance
Hershey and Chase
In 1952, they attempted to verify if DNA or protein was the genetic material
-found radioactivity only inside cell’s DNA
Edward Chargaff
disagreed with thinking that there was an equal concentration of A,T,C and G
-discovered that the bases occur in definite ratios (A=T and C=G)
Rosalind Franklin and Wilkins
Used x-ray crystallography to study shape of DNA molecule
-x-ray suggested double helix rotating clockwise, with sugar-phosphate backbone on the outside
Watson and Crick
in 1952, they were building a variety of models of DNA to determine structure
-discovered it has a double helix shape
