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DNA History/Structur
Human Genetics Exam 1
Term | Definition |
---|---|
4 criteria to be considered genetic material: | storage of info, expression of info, transmission of info, and variation |
bacteriophage | a virus that infects bacteria |
steps in bacteriophage infection: | physically attach to bacterial cell, inject DNA inside of bacterial cell, protein coat left externally, viral replication (bacterial cell bursts) |
proteins contain: | sulfur, nucleic acids, and phosphorus |
nucleic acids consists of: | a sugar, nitrogen base, and phosphorus |
nucleic acid sugars are either: | ribose or deoxyribose |
the most basic building block of DNA is a nucleotide consisting of: | pentose sugar, phosphate group, and a nitrogenous base |
purines | 2 fused rings, adenine and guanine |
pyridimines | 1 ring, thymine and cytosine |
A pairs with T via: | 2 hydrogen bonds |
C pairs with G via: | 3 hydrogen bonds |
nuceloside | sugar + base |
nucleotide | nucleoside + phosphate groups |
forms of DNA: | A-form (right handed), B-form (right handed), Z-form (left handed) |
scaffold proteins | frame that guides DNA |
histones | proteins that DNA coils around |
nucleosome | set of 8 histones |
chromatin | 30% histone proteins, 30% scaffolding proteins, 30% DNA, 10% RNA |
3 main steps of DNA replication: | initiation, elongation, and finalization (all occur in the S phase of cell cycle) |
origin of replication | particular sequence where replication will begin, replication bubbles form here with their associated replication forks |
DNA helicase | binds to the replication fork area, unwinds and separates strands |
topoisomerase | enzyme that binds ahead of replication fork |
single strand binding proteins | keep strands separated |
RNA primers | act as a starting site for new synthesis |
primase | enzyme that binds RNA primers to strand |
RNA primers attract DNA polymerase which: | adds nucleotides and proofreads for errors |
alpha (type of polymerase) | inititiates DNA replication with primase, makes the primer, then alpha and epsilon take over |
epsilon (type of polymerase) | replication of the leading strand |
delta (type of polymerase) | replication of the lagging strand |
gamma (type of polymerase) | replication of mitochondrial DNA |
kappa (type of polymerase) | replication of benzopyrene damaged DNA |
eta (type of polymerase) | replication of thymine dimer damaged DNA |
leading strand | continuous replication in same direction of the unwinding |
lagging strand | replicated discontinuously |
Okazaki fragments | fragments of replication on the lagging strand |
DNA ligase | connects Okazaki fragments |
flap endonucleases | remove original RNA primers, replaces with DNA |
telomere sequence: | TTAGGG |
DNA polymerase can only synthesize DNA in: | a 5' to 3' direction |
DNA polymerase can't link together: | the first two nucleotides |
telomerase | enzyme that recognizes sequence and synthesizes additional repeats, binds the 3' strand |
critical point | can't divide anymore=aging |
cancer cells | increase telomerase activity |
Bloom syndrome | mutated helicase, dilated blood vessels, reddening of skin, increased risk of cancer |
Xeroderma pigmentosum | mutated DNA damage repair, severe sunburn after a few minutes in sun, cancer by age 10 |
Werner syndrome | mutated Werner protein, develop normally until puberty, then advanced aging |