what is the difference between an organelle and a membrane-bound organelle
an organelle can be a ribozyme. and a membrane bound organelle is attached to membrane such as the ER or the mitochondria
telomerase shortening due to childhood diversity
studies have shown that an abused/neglected child who has had a tough life has a shorter line of telomers
what do telomers affect
the longevity of life, how many times a cell divides
how does cancer use telomers
cancers have over-active telomerase meaning cancer cells can divide uncontrollably and more than other normal cells can
how many divisions of telomer occur before you grow up and the telomerase activity is stopped
60 divisions
if you were to cut open your skin and muscle which cells would re-generate
the skin cells like gut cells replicated constantly, but muscle cells will never re-grow because after you stop growing those cells never turn back on. Once you reach a certain age re-growth isn't often. Body builders make their muscles bigger but then do
super coiling
when DNA rounds around itself
types of super coiling
positive, negative,
topoisomerase
type 1 and type 2
type 1 topoisomerase
cuts one strand of DNA to enable twisting
type 2 topoisomerase
cut two strands of DNA
what does topoisomerase do
the enzyme responsible for adding and removing turns in the coil
how does DNA supercoil around itself
it normally wouldn't seem like this was possible due to the negative charges on phosphates but the proteins allow this to be possible
over-wound DNA can't be
transcribed
positive DNA
is usually over-wound
negative DNA
is looser, or under-wound which is more likely for the DNA to be transcribed because hydrogen bonds break easily
how is bacteria DNA
highly folded in E.coli
heterochromatin
highly condensed such as mitotic chromatin, "non-moveable" histones
euchromatin
less condensed "moveable" histones
histone proteins
form nucleosomes
constitutive heterochromatin
constant
facultative heterochromatin
in interphase it is transcripable
eukaryotic chromatin
has a highly complex structure with several levels of organisms
in the most condensed form of DNA
no transcription occurs. transcriptional proteins need to be able to get to the DNA nucleotides to transcribe another strand
HAT proteins
acetylate the tails and activate transcription
Histone D acetylates
chromatin becomes fixed or stuck heterochromatin
salamanders have more complex DNA than corn
corn has more complex DNA than humans
why does corn have such complex DNA
because if doubles it's chromosome
generally besides mammals
organisms become more complex with the more DNA they have
A lot of experimental data come from which organism
the fruit fly
what does C equal
the number of nucleotides in a genome
What are chromosome puffs
they are sensitive to DNAase that are transcriptionally active
endonuclease is able to cut DNA from the form of a
circle
exonuclease is able to cut DNA from the form of a
line
why is euchromatin more likely to be cut
because it is less condensed, and the looseness leads to easier cutting
chromosome puffs
are regions of relaxed chromatin where active transcription is taking place
variation in DNA methylation
an epigenetic change at the agouti locus produces different coat colors in mice
What is a DNA if it had two turns added
Over turned super coiled
What's DNA when it has two turns removed
Under rotate, negative supercoil
each loop of DNA is a domain and each DNA Can have
A different amount of supercooling
Histone proteins
Form nucleosomes in eukaryotes. A chromatid one equals nucleosomes plus histone. Linker DNA. High order chromatin structure for example packaging DNA
Eu chromatin general overview
Less condensed, on chromosome arms, unique sequences, many genes present, transcription occurs often and cross over is coming
Hetero chromatin
Highly condensed, transcription is infrequent, few genes are present, repeated sequences and they are located at centromers, telomeres, and other specific places
How would neutralizing the positive charges effect histone proteins
it would make them bind less tightly to the negatively charged DNA
Eukaryotic chromatin
Has a highly complex structure with several levels of organization
Genome sizes in order of smallest to largest
Bacteriophage, ecoli bacterium, yeast, plant, insect, human, corn, and salamander
Changes in chromatin structure
Polytene: chromosome puffs, DNA I sensitivity, epigenetic changes.
Chromosomal puffs
Region of relaxed chromatin where active transcription takes place
DNAase 1 sensitivity
Correlates gene activity
Epigenetic changes
Methylation, capable of being reversed and often due to environmental factors
An epigenetic change example
Variation in DNA methylation at the agouti locus produces different colors in mice fur
all E.Coli DNA is
unique
mitochondrial and chloroplast DNA differs in certain life why
possibly from aerobic respiration
Do humans have mitochondrial DNA
humans have mitochondrial DNA. this DNA is commonly received from the mother but may be from the father
heteroplasmic cells
can produce homoplasmic cells through the process of appreciative segregation