bio 2200 Flashcards
hereditary molecule
molecular substance that carries and conveys the genetic information of a species
what are the 5 major characteristics of hereditary material
- localized in the nucleus and component of chromosomes
- present in stable form in cells
- sufficiently complex to contain information for structure, function, development, and reproduction of an organism
- able to accurately replicate itself so offspring can contain same information as parent cells
- mutable, low rate of mutation that introduces genetic variation and serves as a foundation for evolutionary change
what is the shape of bacterial and archaeal chromosomes
most cases, a single circular chromosome or less likely several chromosomes, or linear chromosomes
how is the chromosomes of bacteria and archaea organized
they are bound by small amounts of protein that localize bacterial chromosomes to a region of the cell known as the nucleoid.
how many copies of the genome do bacterial and archaea have
one set/ haploid
who identified the transforming principle
fred griffith
who identified that transforming principle is likely DNA
avery, mcarthy, and macleod
who definitively showed that DNA is the transforming principle
hershey and chase
what was the conclusion that frederick griffith came to with S and R bacteria and the rat experiment
hereditary molecule from the S3 bacteria transformed the R2 bacteria into S3 bacteria
what process did griffith discover that we now know to be true of bacteria to transfer DNA between cells
transformation
why is it unlikely that R2 bacteria mutated into the S3 bacteria (which were killed)?
because they are two different antigen strains (out of the four possible ones) and that means that a type 2 bacteria cannot be changed into a type 3 bacteria by a single mutation and it is unlikely for how often it was observed.
what year was DNA localized to chromosomes making it a candidate for hereditary material
1923`
what year was it discovered that nucleic acid is the genetic material
1944
what live bacteria were recovered from the dead mice
SIII
what were the options for the transformation factor?
DNA, RNA, protein, lipid, polysacharide
what was avery, macleod, and mccartys experiment
they used head killed SIII bacteria, live RII bacteria and mice with alliquots, each with either DNA, RNA, protein, lipid or polysaccharide
what was the result of avery, mcleod and mccartys experiement. why was this not conclusive
all the alliquots killed the mice except for the one which all the DNA was destroyed. this wasnt conclusive because what if there were still trace amounts of protiens, lipids, polysaccharides left in the alliquots
what did hershey and martha chase use to show that dna and not protein was responsible
bacteriophage infection of bacterial cells
what is the protein shell of bacteriophages called
capsid
where is the DNA of a bacteriophage
the head
what is the singular of bacteria
bacterium
what is the plural of bacteria
bacteria
do proteins have a lot of sulfur or phosphorus
large amounts of sulfur and almost no phosphorus
does DNA have lot of sulfur or phosphorus
large amounts of phosphorus and no sulfur
what were the phage proteins labelled with
S35
what were the phage DNA labelled with
P32
what was the process of hershey and chases experiment
they let the bacteriophages grow in the labelled chemicals, let the infection of the bacteria to begin, and they agitated the cell structures using a blender to seperate the empty phage particles from the infected bacteria
what were the results of hershey and chases experiment
the protein labelling (s35), the radioactivity was detected in empty phage particles
in the DNA lablelling (p32), the radioactivity was detected inside the infected bacteria
when was DNA identified to be the principle component of nuclein
in 1920
what are the four bases of DNA
cytosine, guanine, adenine, thymine
what is DNA
it is a polynucleotide consisting of non-identical repeating nucleotide units
how did watson and crick contribute to the structure of DNA
they figured out how the units that make up DNA are arranged in the bigger molecule
who was the forgotten scientist who paved the way for discovery of DNA’s structure
J. Michael Creeth
what did creeth show
that DNA had hydrogen bonds. he found that the viscosity in extreme temperatures and pH was lost and this was due to the loss of hydrogen bonds. he knew there was two chains in DNA and each had a sugar backbone on the outside and hydrogen bonded bases on the inside
who determined the percentages of the four nucleotide bases and found that adenine and thymine were close and cytosine and guanine were close?
erwin chargaff
what did watson and crick use to find the structure of DNA
fibre diffraction patterns
what are the two forms of the 4 bases
the enol and the keto form. they are in equilibrium and the normal form is the keto form
what happens when the alternate tautomeric forms happen
they cause mispairing and mutation
who obtained the x-ray diffraction patterns of DNA fibres that suggested a helical structure
maurice wilkins and rosalind franklin
which from of the DNA pattern A or B was the one that wilkins showed to watson which is of “wetter” DNA fibres
the B pattern
what are the characteristics of the DNA strands
they are complimentary and antiparallel.
what are the bonds holding the nucleotides together in DNA
covalent phosphodiester bonds
what comprises the backbone of DNA
sugar-phosphate in alternating sugar and phosphate groups
what makes up a nucleotide
a base, a sugar, and a phosphate group
what are the two purines
adenine and guanine
what are the two pyrimidines
cytosine and thymine
what differentiates RNA from DNA
it has a ribose (2’OH) in place of deoxyribose