8a Flashcards
what are the characteristics of the genetic material?
replication
storage of info
expression of that info
variation by mutation
what was the experiment performed by Frederick Griffith about?
to confirm DNA as the genetic material rather than proteins(1927-1928)
what was used by Griffith to inject in mice for his experiment
BACTERIUM-Streptococcus penumoniae- causing lung disease pneumonia
WHAT TWO DIFF STRAINS OF THE BACTERIUM WERE USED?
SMOOTH STRAIN
ROUGH STRAIN
differentiate the strains used by Griffith as virulent and non virulent
Smooth(S) stain- virulent-mice died
Rough(R) stain-non virulent- mice survived
what present in S strain protect bacteria
they have a protective layer, polysaccharide coat, capsule- protects the cell from immune system or host’s defence system
why can R stain be destroyed easily
it lacks capsule, hence it can be easily killed by immune system(host defense)
what happened when heat killed s bacteria was injected
mice lived
thus heath killed S cells are benign
heat-killed S bacteria+R Bacteria
mice died
living type R cells have transferred into virulent type S cells
what was the end hypothesis of Griffith’s experiment
a macromolecule from type S bacteria which functions as the genetic material will be able to convert the type R bacteria into type S
fredericks experiment was about ____ transformation
prokaryotic bacterium
who identified the unknown macromolecule in Griffith experiment?
1944-Oswald Avery et al.
identified it as DNA
what did Griffiths and further Oswalds experiments established?
DNA is the genetic material in cells.
what was the Hershey-chase experiment about?
BACTERIOPHAGE infection
what virus was used by Hershey-chase?
T2 that affect bacteria
what is the structure of a virus
outer protein coat with DNA inside
what radioactive compounds were in use to infect radioactive compounds
p32 (phosphorous), S35 (sulphur)
what was the conclusion form the Hershey chase experiment
1.virus DNA enters the host bacterial cell rather than proteins
2.DNA is the hereditary material
3.Dna contains the info not only for forming th new DNA but also the new protein coat in new viruses.
what happens when virus attacks the host bacteria
inserts its DNA into host
where it replicates, takes over cell machinery
produce Many more T2 viruses
define nucleic acids
polymers consisting of many nucleotide monomers, including DNA and RNA.
define nucleotides?
Building blocks of DNA
what are the 3 essential components of nucleotides?
1.A nitrogenous base(thymine, adenine, cytosine, guanine)
2.a pentose(ribose, five carbon sugar)
3.phosphate group
what is the front and back end of nucleotide?
5’ prime back end
3’ prime front end
two strands in a double stranded DNA molecule are arranges in ___________ direction.
opposite
what are the 2 kinds of nitrogenous bases?
Purines(adenine, guanine)
Pyrimidines(cytosine, thymine, uracil)
what is a nuclease composed of?
nitrogenous base and a ribose/deoxyribose sugar
how are nucleoside and nucleotides named?
according to the specific nitrogen base(A,C,T,G and U)
example of a nucleoside and nucleotide
nucleoside-(deoxy)adenosine
nucleotide-(deoxy)adenylic acid
what replaces thymine in RNA?
Uracil
nucleotides can also be described as?
nucleoside monophosphate
nucleoside diphosphate
nucleoside triphosphate
differentiate diff types of nitrogenous bases as double ring or single ring
?
purine-double ring
pyrimidine single ring
what forms nucleic acids?
polymerization of mononucleotides
define phosphodiester bonds
linkage between two mono nucleotides consists of a phosphate group linked to 2 sugars forming a phosphodiester bon
how is DNA sequence read
from 5’-end(five prime end) to the 3’-end(three prime end)
how and who demonstrated that the dna molecule is a helix?
X-ray crystallography
Franklin and Wilkins
what revealed Chargaff’s rule
biochemical analysis of hydrolyzed samples of DNA revealed
what is char-gaff’s rule?
- the amount of adenine equals the amount of thymine:(A=T)
2.the amount of guanine equals the amount of cytosine :(G=T)
name the key player in dna story
Rosalind Franklin
Maurice wilkins
Francis crick
James Watson
DNA is in the form of ______
Double-stranded Helix
who proposes that structure of dna is in a double stranded helix?
James Watson, Francis Crick
DNA molecule consists of 2 strands what are __________ to each other
antiparallel
nitrogenous bases concepts the strands in the middle through_________
H bonds
the bases in 2 strands are complementary to each other via ________.
base pairing
why are they referred to as double helix?
2 strands are twisted(coiled) to the right
RNA structure
single strand polynucleotide(sometimes folded upon itself to form base pairing)
what sugar molecule is present in RNA
ribose instead of deoxyribose
what are the 3 major types of RNA
MESSENGER RNA(mRNA)
TRANSFER RNA(tRNA)
RIBOSOME RNA(rRNA)
Define mRNA
transcript of the gene carries info for the synthesis of proteins
define transfer RNA
transports amino acids from the cytoplasm of a cell to ribosome
_________ functions as an interpreter between nucleic acid and protein language.
Transfer RNA(tRNA)
________- is the most abundant type of RNA
Ribosome RNA
define ribosome rna
together with proteins forms the most structure of ribosomes.
how Is the genetic material coded in the DNA molecule
the info must lie on the linear sequences of the nitrogenous bases i.e., the arrangement of bases
how is info passes on from 1 cell to another during mitosis
it must be because of the complementary base pairing of nitrogenous bases, that one strand serves as a template to form a new strand(DNA replication)
how does the genetic material function
DNA passes on its info (transcription) where is this used in cell function.
