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Cheatography

AP Biology Unit 6 - Inheritance Cheat Sheet (DRAFT) by

i dont wanna write this

This is a draft cheat sheet. It is a work in progress and is not finished yet.

experi­ments

Griffith - transf­orm­ation experiment
experi­ments w several deff strains of bacteria diploc­occus pneumonia
some virulent
some harmless
discovered bacterial transf­orm­ation
bacteria can transform harmless cells into virulent ones by transf­erring some genetic factor from one bacteria to another
Avery, MacLeod, McCarty
found out that transf­orm­ation factor was DNA
DNA not protein was the genetic material
DNA was the agent that carried genetic charac­ter­istics from virulent dead bacteria to living nonvir­ulent bacteria
Hershey & Chase
supported that DNA was genetic material
tagged bacter­iop­hages w radioa­ctive isotopes 32P which labeled DNA bc has phosphorus this leveled DNA f phage viruses
35S for protein bc had sulfur and leveled protein coat of phage viruses
radioa­ctive phosphorus in the phage always entered the bacterium while sulfur remained outside the cells
proved DNA from viral nucleus not protein from viral coat was infecting bacteria and producing thousands of progeny
rosalind franklin
DNA is helix (photo 51)
X ray crysta­llo­graphy analysis of DNA that showed DNA to be a helix
her work was critical to Watson and crick
watson and crick
but first model of DNA
popsed double helix structure of DNA and used to build model
used bioche­mical analysis of dna from Erwin chargaff
a nd x ray diffra­ction analysis of Rosalind Franklin
led to how we replicate dna
meselson and stahl
proved dna replicates in a semico­nse­rvative fashion
cultured bacteria in medium containing heavy nitrogen allowing bacteria to incorp­orate heavy nitrogen into dna as they replicate
bacteria then transfered to medium containing light nitrogen and allowed to replicate and dive only once
resulting bacteria were spun in centrifuge
found to be midway density bet bacteria grown in heavy nitrogen and light nitrogen
new bacteria contained one heavy and one light
 

structure of dna

double helix shaped like twisted ladder w two strands running in opp directions (antip­ara­llel)
one strand runs 5' to 3' right side up
other runs 3' to 5' upside down
has repeating units of nucleo­tides
nucleo­tide: 5 carbon sugar, phosphate, nitrog­enous base
carbon atoms in deoxyr­ibose are labelled 1 to 5
adenine and guanine purines
A G pure
cytosine and thymine pyrimidine
C T pyr
bases of opp chains are paired. by hydrogen bonds
C G covergirl // more makeup­//t­riple hydro bond
AT double bc less makeup
DNA gets packed and unpacked as needed in nucleus
eukaryotic dna combines w proteins called histones
only separates from these BRIEFLY during replic­ation
DNA + histon­es=­chr­omatin
double helix wraps twice around a core of histones
forms nucleo­somes
look like beads on a string
purines have double ring structure
pyrimi­dines have single ring structure

rna

single stranded helix
uracil replaces thymine
5 carbon sugar is ribose

central dogma

from dna to protein
transc­rip­tion, rna proces­sing, transl­ation
 

DNA replic­ation in eukaryotes

making an exact replica of the dna molecule by semi conser­vative replic­ation
predicted by watson and crick, proven by meselson
dna double helix unzips
each strand serves as a template fro the formation of a new strand composed of comple­mentary nucleo­tides
two new molecules each consists of one old strand and one new
replic­ation begins at origins of replic­ation
where 2 dna strands separate to form replic­ation bubbles
speed up process of replic­ation along the giant dna molecule
bubble expands as replic­ation proceeds in both directions at once
each end of replic­ation bubble is replic­ation fork
Y shaped region where new strands of dna are elongating
eventually all bubbles fuse
DNA polymerase catalyzes antipa­rallel elongation of new DNA strands
DNA pol builds new strand from eh 5' to 3' direction by moving along the template strand and pushing replic­ation fork ahead of it
DNA pol canNOT initiate synthesis
can only add nucleo­tides to the 3' end of a preexi­sting chain
preexi­sting chain consists of RNA and is called RNA primer
primate makes primer by joining rna nucleo­tides
DNA pol replicates two strands differ­ently
builds both in 5' to 3' direction
one is formed TOWARD replic­ation fork in unbroken linear fashion
(leading strand)
others formed AWAY from the replic­ation fork in a series of segments called Okazaki fragments
(lagging strand)
joined into one continuous strand by enzyme DNA ligase
helicase
unzips double helix at replic­ation fork
separate two parental strands, making them available as templates
single stranded binding protein
act as scaffo­lding holding dna strands apart
topois­omerase lessens the tension on tightly wound helix by breaking, swiveling, and rejoining DNA strands
DNA pol carries out mismatch repair
proofr­eading that corrects errors
damaged regions of dna are excised by dna nuclease
each time dna replicates some nucleo­tides from ends of chromo­somes are lost
to protect against this possible loss of genes, eukaryotes have special nonsense nucleotide sequences (TTAGGG) at ends of chromo­somes that repeat thousands of times
called telomeres
protective ends
created and maintained by enzyme telomerase
normal body cells have little telomerase so every time the DNA replic­ates, telomeres get shorter, this serves as clock that counts cell divisions and causes the cell to stop dividing as cell ages

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