Exam 2 genetics Flashcards
linked genes
Genes that are close together on a chromosome and likely to be inherited together
Recombinant class
the gametes that result when chromosomes experience crossing over and exchange material
also the lowest number classes when looking at observed ratio
recombinant class is lower than expected ratio
expect linkage of genes
Recombination Frequency formula
(# of recombinant/ total offspring) * 100
< 50 means linked
Double crossover class
2 lowest # of offspring
Coefficient of Interference formula
(# of obs. double crossovers/ # of exp. double crossovers)
c > 1
Negative Interference
more double crossovers than expected
c < 1
Positive interference
less double crossovers than expected
c=1
no interference
expected amount of double crossovers
Level of Interference (I) Formula
I = 1-c
Gene Conversion
One allele is changed to another as a result of DNA repair
results in a weird tetrad pattern such as 5:3
Transduction
process by which a virus transfers genetic material from one bacterium to another
Bacteriophages
Viruses that infect bacteria, use the bacteria’s resources to replicate
nucleic acid surrounded by coat material
F’ factor
F plasmid genome with some of the bacterial host cell genome inside of it
HFr
Host cell genome (chromosome) contains F plasmid integrated into it’s chromosomal DNA
Conjugation
Process by which one bacterium transfers genetic material to another through direct contact.
Lytic vs Lysogenic cycles
Lytic cycle: Bacteriophage virus infects cell, and uses the host cell material to replicate and kill the cell.
Lysogenic cycle: Bacteriophage virus infects cell and inserts itself into the host cell genome to replicate when the cell replicates.
Endonuclease
Cleaves phosphodiester bond between nucleotides in DNA
Phosphodiester bonds
Linkage between adjacent bases in a DNA strand
solenoid
nucleosomes form a helix when stacked up, making a solenoid fiber, a unit of DNA compaction.
Loops
Solenoid fiber arranged into loops of varying size that are anchored to protein scaffold
Rosettes
loops arrange into these helical shapes that include about 6 loops, which then organize into a coil
Okozaki fragments
short sequences of DNA nucleotides which are synthesized discontinuously and later linked together by the enzyme DNA ligase to create the lagging strand during DNA replication
blackburn used the ciliate protists Tetrahymena and Oxchytricha to find
telomeres. Give a brief explanation of what makes these organisms so useful for
telomere studies?
Large Telomeres, both have telomorase activity, rapid growth of these organisms
