Studied by 1 person
chromatin
dna and proteins (histones)
what does the nucleosome consist of
dna wound twice around a protein core of eight histones, two of each of the main histone types
when is chromatin compacted, and folded further in some areas by looping
during interphase
heterochromatin
dense areas of chromatin- during cell division
euchromatin
the more dispersed, less compacted chromatin- during the resting stage
can a condensed region be condensed, loosened, modified, and remodeled as needed for various cell processes?
yes
how can histones change chromatins
histones can undergo chemical modifications that result in changes in chromatin organization
are centromere condensed during metaphase
yes, and so are some other parts of the chromosome
how was transformation bad for mice
nformation specifying virulence passed from the dead S strain cells into the live R strain cells
bacteriophages- what they are composed of
viruses that infect bacteria- dna and protein
dna is... (conclusion of hersey and chase)
genetic material
Adenine to
Thymine
Cytosine to
Guanine
general structure of dna
sugar- phosphate backbone with nitrogenous base pairs
are backbones parallel or antiparallel
anti
purines connect to
pyrimidines- proper width
what is dna- building blocks
nucleic acid which the building blocks are nucleotides
nucleotides are connected by what
phosphodiester bonds
what do covalent sugar-phosphate bonds link
nucleotides
where are the hydrogen bonds in dna
between the bases and hold the stand together
where are van der waals interactions in dna
between stacked base pairs help hold the molecule together
which carbon is the nitrogenous base attached to
1 prime
the -OH is attached to what carbon
3 prime
DNA replicates in a
semiconservative way
semiconservative model
each strand of dna acts as a template for the synthesis of a new strand
three steps to the basic process of dna replication
initiation
elongation
termination
replication fork
a Y-shaped region where the parental strands of DNA are being unwound
helicase
untwists the double helix at the replication forks
single strand binding proteins
bind to and stabilized single-stranded dna
topoisomerase
relieves the strain caused by tight twisting ahead of the replication fork by breaking, swiveling, and rejoining dna strands
why is a primer needed
DNA polymerase can only add nucleotides to an already existing chain base-paired with the template
primase (RNA polymerase)
enzyme that starts an rna chain with a single rna nucleotide and adds rna nuleotides one at a time using the parental dna as a template
what does dna polymerase do
catalyze the elongation of new dna at a replication fork
what end does dna polymerase add to
the three prime end of a preexisting chain
what happens as each monomer nucleotide joins the dna strand
it loses two phosphate groups as a molecule of `pyrophosphate
why can't dna polymerase be added 3'-5'
If DNA polymerase added dNTPs 3′- to-5′, the growing 5′-chain end, would carry the activating triphosphate
what happens to mistakes in polymerization
simply hydrolyzed away
leading strand
dna polymerase synthesizes it moving toward the replication fork- only one primer needed
lagging strand
strand in replication that is copied 3' to 5' as Okazaki fragments and then joined up by ligase
many primer needed
okazaki fragments
sections of the lagging strand
ligase
joins okazaki stands together
errors in the completed DNA molecule amount to only...
one in ten billion
mismatch repair
other enzymes correct errors in base pairing
base excision repair
nitrogenous base replaced
nucleotide excision repair
nucleotide replaced
what do telomeres do
ends each of the chromosomes with repetitive sequences
postpone shortening
what does telomerase express and extend telomeres in
germ line cells
some stem cells
cancer cells
nucleic acid hybridization
the base pairing of one strand of nucleic acids to another, complementary sequence
form the foundation of virtually every technique used in genetic engineering
genetic engineering
the direct manipulation of genes for practical purposes
plasmids
small circular DNA molecules that replicate separately from the bacterial chromosome
where the dna that scientist want to be replicated is injected
gene cloning
production of multiple copies of a single gene
cloning vector
the plasmids that carries the cloned dna
restriction endonucleases
enzyme that cleave dna at specific sites
what are the most useful restriction enzymes
the ones that cleave the DNA in a staggered manner to produce sticky ends
sticky ends
can bond with complementary sticky ends of other fragments
EcoRI
6 base pair cutter: recognizes a 6 base pair (b.p.) specific sequence
ligation
re-joining stands
what molecules more the furthers towards the positive electrode
small negatively charged
