Bios 110: DNA Structure and Replication

what is the hereditary molecule?

DNA (nucleotides)

what does Chargaff's rule state?

DNA is different between organisms and species, A complements T, C complements G, and nucleotide ratios differ from organism to organism

Who are the 3 people who founded the model of the double helix?

James Wattson, Francis Crick, and Rosalind Franklin

Is RNA single stranded, double stranded, or both?

it can be both single stranded or double stranded

What terms describe DNA's structure?

antiparallel double helix

what forms the backbone of DNA?

sugar and phosphate

what are the purines? pyrimidines?

Purines: Adenine and Guanine

Pyrimidines: Thymine, Uracil, and Cytosine

DNA replication is not ____ or _______-

passive or spontaneous

what term describes a Y-shaped region on a replicating DNA molecule where new strands are growing?

Replication fork

What unwinds double helixes and synthesizes new strands?

enzymes

which protein is needed to start DNA replication? What does this place on an Okazaki fragment?

primase; primer

are primers composed of DNA or RNA?

RNA

why do primers need to be removed?

they're composed of RNA that is unstable

which protein is responsible for a majority of DNA replication

DNA polymerase III

which protein randomly pairs up nucleotide until they fit?

DNA polymerase III

which protein removes the primer? what does it replace it with?

DNA polymerase I; DNA

which protein is responsible for "sealing" the DNA strands in place after replication is complete?

Ligase

Which protein is responsible for unzipping the DNA?

Helices

Which protein is responsible for removing supercoils?

topoisomerase

What does the unwinding of DNA create?

supercoils

How does DNA replication differ between bacteria and eukaryotes?

there is only one point of origin of replication in bacteria, and multiple points of origin in eukaryotes

what type of replication does DNA follow? What does this mean?

semiconservative replication; the old DNA becomes the template for new DNA

where can telomeres be found?

on the ends of linear chromosomes

What do telomeres contain?

repeating units of one short nucleotide sequence

what protects genes from erosion during DNA replication?

telomeric DNA

What does telomeric DNA aid in?

preventing separate chromosomes from fusing

what prevents chromosome ends from activation cell systems for monitoring DNA damage?

telomeric DNA and associated proteins

what is described as a polymerase with a built in primer?

telomerase

what term describes the enzyme that catalyzes the lengthening of a telomere?

telomerase

What is a flaw of DNA replication?

the replicated DNA is always short

what increases the length of DNA? Does this lengthening occur to the new or old strand? Which end?

telomerase; old strand; 3' end

telomerase is much more active in what cell type? What other cells possess active telomerase activity?

gamete cells; cancerous cells

what is considered a major factor in determining life span?

telomerase

Does telomerase make the new and old DNA equal in length?

no

what is a common damaged base? what can cause this?

T-T dimer; exposure to UV light (1/16)

what is the base rate error of DNA polymerase III? what is the actual rate of error? why?

1 in 1 million; 1 in 100 million; NDA polymerase III can proofread itself

how many errors occur every time DNA replicates?

30

how many base pairs are in a human genome?

3 billion