Chapter 16 Flashcards
Who showed that genes exist as parts of chromosomes?
T.H. Morgan’s group
DNA replication
The process by which a DNA molecule is copied; also called DNA synthesis
Pathogenic is _____, while nonpathogenic is ____
disease-causing, harmless
Transformation
A change in genotype and phenotype due to the assimilation of external DNA by a cell
When Fredrick Griffith killed pathogenic bacteria with heat and then mixed the cell remains with living bacteria of the nonpathogenic strain what happened to the cells?
some of the living cells became pathogenic
showing transforming principle
Phages
A virus that infects bacteria; also called a bacteriophage.
How do viruses produce more viruses
a virus must infect a cell and take over the cell’s metabolic machinery
Virus
An infectious particle incapable of repli- cating outside of a cell, consisting of an RNA or DNA genome surrounded by a protein coat (capsid) and, for some viruses, a membranous envelope.
What did Alfred Hershey and Martha Chase’s experiment show?
That DNA is the genetic material of a phage known as T2. (one of many phages that infect E. coli)
Base composition varies from species to species T or F?
T
Adenine bonds with…
Thymine
Guanine bonds with…
Cytosine
What are Chargaff’s rule?
(1) DNA-base composition varies between species
(2) For each species, the %s of A and T bases are roughly equal, as are G and C bases
Who discovered the structure of DNA?
James Watson and Francis Crick
What is the structure of DNA?
Double Helix
What did Rosalind Franklin do?
(1) Took an X-ray diffraction image of DNA- helped Watson and crick confirm DNA structure
(2) Concluded that the Sugar-Phospahte back- bones were on the outside of the DNA molecule (phosphates have a negative charge)
DNA strands runs parallel to each other T or F?
F. They run Antiparallel- run in opposite directions
How long (length) does it take for the DNA double helix to make one full turn
3.4nm (10 layers of base pairs)
How far are bases stacked apart from each other
.34nm
How many bonds are between A and T?
2 hydrogen bonds
How many bonds are between G and C?
3 hydrogen bonds
Semiconservative model
Two stands of the parental molecule separate
each functions as a template for synthesis of a new complementary strand
Where does the replication of chromosomal DNA begin?
particular sites called origins of replication
A eukaryotic chromosome may have hundreds or even thousands replication origins T or F?
True. Multiple replication bubbles form and eventually fuse, thus speeding up the copying of the very long DNA