bio 212 unit 2: nucleic acids (DNA, RNA, synthesis)

nucleic acids (specifically DNA)

contain hereditary information to make proteins

what is a nucleic acid?

structure of nucleotide

5 carbon sugar (labeled clockwise), nitrogenous base, phosphate group

ribonucleotides (2 hydroxyl groups)(CUGA) makes

RNA

deoxyribonucleotides (one hydroxyl group)(CTGA) make

DNA

nucleotides (monomers) form

nucleic acids (polymer) (endergonic reaction)

nucleotides → nucleic acids is a _______ reaction

condensation

primary structure of nucleic acid

string of bases hanging off sugar-phosphate backbone (5’ → 3’ ends to reflect direction of growth) (5’-UAGC-3’)

secondary structure of DNA

helical structure (# of purines = # of pyrimidines)/(A+G=T+C)

Watson and Crick determine DNA strands run

antiparallel (strands form complementary base pairs A-T and C-G)

A-T base pair has _____ hydrogen bonds

2

C-G base pair has _____ hydrogen bonds

3

when RNA folds over it forms a ______ structure (secondary structure)

hairpin

both DNA and protein primary structure have a _____ backbone and side groups sticking out

carbon

both DNA and protein secondary structure is held together by _____ bonds

hydrogen

DNA is important because it

holds genetic information

hereditary information is in chromosomes, these contain both

proteins and DNA

genes are responsible for

physical characteristics

proteins have _____ functional groups that vary in size, shape and polarity/non-polarity

20

DNA has _____ functional groups that are similar shape, size, and are all polar (chemically stable)

4

___________ experiment helped understand that DNA stores hereditary information

Hershey Chase

Hershey Chase experiment

viruses grown in presence of radioactive isotopes to determine if DNA or proteins are being used

in the Hershey Chase experiment, DNA was labeled with ________ because DNA contains a lot of it, but it wouldn’t show in proteins

Phosphorus

in the Hershey Chase experiment, proteins were labeled with _______ because proteins contains a lot of it, but it wouldn’t show in DNA

Sulfur

DNA is synthesized by ____________ enzymes

DNA polymerase

DNA polymerase BUILDS the ________ direction

5’ to 3’

DNA polymerase READS in _______ direction

3’ to 5’

the enzyme ________ synthesizes RNA primer so DNA polymerase can build from a 3’ end (forms the 5’ end)

primase

leading strand is synthesize in a _______ manner

continuous

lagging strand is synthesize in a _______ manner

discontinuous, synthesized in fragments

synthesis of leading strand

primase creates an RNA primer for DNA polymerase 3, this synthesizes DNA in 5’ to 3’ direction towards the replication fork, then DNA polymerase 1 replaces the RNA primer with DNA.

synthesis of lagging strand

primase creates a primer for DNA polymerase 3, which synthesizes lagging strand in short Okazaki fragments, DNA polymerase 1 REPLACES the RNA primers with DNA, DNA ligase joins Okazaki fragments into a continuous strand.

replisome

DNA synthesis proteins grouped together in one large complex

helicase

breaks hydrogen bonds between DNA strands so replication can begin

primase

matches ribonecleotides to exposed DNA and bonds the strand and bonds them together

DNA polymerase

matches deoxyribonucleotides to exposed DNA strand and bonds them together

topoisomerase

unwinds double helix downstream as replication fork grows

ligase

bonds DNA fragments together by forming phosphodiester bonds between them

T/F: lagging stands cannot fully synthesize telomere

true

telomerase regulation

telomerase IS active primarily in cells that produce gametes, NOT active in most somatic cells though

length of telomeres is limited by

age, as you get older the telomeres get shorter

addig toelomerase to cultures allows them to

continue dividing longer

during synthesis, DNA polymerase is highly selective and can ______ its work

proofread

through DNA polymerase proofreading, it can

fix mistakes

AFTER synthesis, mismatch repair can fix it by

removing a whole fragment and redoing it

if DNA is damaged, _________ enzymes can fix it

nucleotide excision repair