Biology: DNA structure and replication Flashcards
what are DNA and RNA are made up of _____________. What components does ____________ have?
nucleotide monomers.
5 carbon sugar, phosphate, and a nitrogenous base
what did gregor mendel do?
father of genetics, discovered that heritable factors were passed down from parent to offspring
what did thomas hunt morgan do?
proved genes are carried on chromosomes and are the mechanism of inheritance
what is the identity of genetic material
protein and DNA
Describe Frederick Griffith’s experiment
He had experimented with bacterium that causes pneumonia. He used a pathogenic and a nonpathogenic strain. He killed the pathogenic strain through heat and mixed the dead one with the nonpathogenic strain. He found out that the living cells and the future offsprings of the living ones became pathogenic. He called this transformation. He didn’t know what the transforming principle was tho
What is transformation?
change in genotype and phenotype due to the assimilation of foreign DNA by a cell
Avery McCarty Macloid experiment
they said the transforming principle from Griffith’s experiment was DNA. they isolated different solutions containing the heat killed S bacteria cells and examined which solutions transformation still occurred with the R bacteria strain. Solution of S strain DNA led to transformation of R strain. Many scientists didn’t believe this tho
Hershey and Chase experiment
showed DNA was the genetic material of bacteriophage (T2). They used radioisotopes of sulfur and phosphorus. Results showed that viruses transferred DNA, not proteins, into bacteria cells.
what is a bacteriophage?
a virus that infects bacteria
T2 viruses are composed of what
DNA and protein
what is the pentose (5 carbon) sugar found in DNA nucleotides
deoxyribose
what are the carbon atoms in the pentose sugar numbered?
1’ to 5’ (‘ = prime)
what is nitrogenous base bound to?
What is phosphate group bound to?
1’
5’
what are the two families of nitrogenous bases
pyrimidines and purines
pyramidines include what
cytosine, thymine, uracil
purines include what
adenine, and guanine
Thymine is found where?
Uracil is found where?
where are the others found?
DNA
RNA
Both
nucleotides are joined together by a series of ________ to form a strand called _______________
dehydration reactions, polynucleotide
covalent bonds are formed between the ____________ of one nucleotide and the phosphate group of the next nucleotide
3’ carbon
phosphodiester linkage
link between 3’ carbon of one nucleotide and the 5’ carbon of the next nucleotide
polynucleotides have two ends:
3’ end (hydroxyl) and 5’ end (phosphate)
where are nucleotides added during DNA and RNA synthesis
3’ end of the growing strand
Franklin and Wilkin’s contribution
used crystallography to study 3D structure of DNA. concluded that two outer sugar phosphate backbones, with the nitrogenous bases paired in the molecule’s interior, formed helical structure
Watson and Crick’s contribution
developed final model of DNA, added onto franklin and wilkin’s contribution, .
chargaff’s rules
adenine pairs with thymine,
guanine pairs with cytosine
erwin chargaff
discovered organism’s DNA base composition of adenine always equals thymine, and cytosine equals guanine
DNA’s double helix are held together by what
hydrogen bonds between the nitrogenous bases
cytosine (pyrimidine) makes
3 hydrogen bonds with guanine (purine)
adenine (purine) makes
2 hydrogen bonds with thymine (pyrimidine), in DNA or uracil in RNA
DNA strand has two ends: ____________.
What are the double helix?
5’ and 3’ end
anti parallel - oriented in opposite directions
- one runs in 5’ –> 3’ and the other runs in 3’ —> 5’
DNA in prokaryotes is organized into a
DNA in eukaryotes is organized into
single circular chromosome
Linear chromosomes
Bacteria cells, viruses, and some eukaryotes contain what?
plasmids
what are plasmids?
small circular double stranded DNA molecules that are different from cell’s chromosomal DNA
two strands of DNA are _________ so each strand acts as a ________________ for building a new strand in replication
complementary, template
in DNA replication, parent molecule _____ and the two new daughter strands are build based on ___________
unwind, base pairing rules
semiconservative model
when double helix replicates, each daugter molecule will have one old strand and one newly made strand. proven in an experiment done by meselson and stahl
Meselson-Stahl experiment
DNA was with a heavy isotope of nitrogen and placed in a medium containing lighter isotope of nitrogen and allowed to replicate. after one replication, all DNA contained half the heavy isotope and half the light isotope. After two replication cycles, half the DNA molecules contained only light and the other half contained a 50/50 mixture of light and heavy isotopes
replication begins at
origin of replication, where two DNA strands are separated
eukaryotic chromosome has a lot of origins of replication
at the end of each replication bubble is a replication for,k, y shaped region
replication of DNA involves
many proteins: DNA polymerases, primase, DNA ligase, Helicase, and Topoisomerase
Helicase
enzyme that unwinds double helix at replication forks
topoisomerase
relieves strain after helicase unwinds it
dna polymerase
catalyzes the elongation of new DNA at a replication fork by adding nucleotides complementary to template strands
what direction does DNA polymerase synthesize the new DNA strand
5’–>3’
template strand: 3’–>5’
complementary strand: 5’–>3’
DNA polymerase works in the direction ________ from the replication fork
away
mRNA
messanger RNA, copies genetic code from DNA and brings info to ribosomes
rRNA
ribosomal RNA, binds with proteins to make ribosomes
tRNA
transfer RNA, bring amino acids to the ribosomes so that a polypeptide chain can be built from mRNA
miRNA
microRNA, involved in regulating gene expression
ymes
enzymes make of RNA molecules that catalyze specific chemical reactions
RNA is ____________ __________ of many types of _________ and is responsible for _________ and __________ heritable info
genetic material, viruses, storing, transmitting
