DNA structure and chromosomes Flashcards
what are the three parts of nucleic acids?
pentose sugar
nitrogenous base
phosphate
what are the two types of pentose sugars?
DNA
RNA
what are the two types of nitrogenous base?
purine
pyrimidine
what are the bases considered purines?
guanine
adenine
what are the bases considered pyrimidine?
cytosine
thymine
uracil
what is the difference between RNA and DNA?
the type of chemical group bound to the 2’ carbon
RNA= OH
DNA= H
what is a nucleoside?
molecules of a sugar and a base
what do Deoxyribonucleosides consist of?
2 deoxyribose sugar and a nitrogenous base
where does a base bind on a deoxyribonucleoside?
carbon 1 of a deoxyribose/ribose
what are nucleotides?
a nucleoside molecule and phosphate
where does the phosphate group attach on a nucleotide?
carbon 5 of the deoxyribose/ribose
what is DNA?
a polymer of deoxyribonucleotides
how do nucleotide monomers polymerize?
by phosphodiester bonds
where do covalent bonds form in the pentose phosphate backbone?
between phosphate and the c-3 and c-5 of two pentose sugars
why is DNA polar?
because the 3’ end has an OH which differs from the 5’ end
what did chargaff study?
overall quantities of the four nitrogenous bases in various organisms
what is Chargaffs rule?
%A=%T; %C=%G
what are 3 conclusions of Chargaffs rule?
%purines= %pyrimidines
C+G does not equal A+T
C, G, A, T aren’t present in equal amounts
what evidence suggested
what is DNA associated with?
proteins and organized into structures called chromosomes
what is chromatin?
a given region of DNA with its proteins on a chromosome
what are 2 shapes of chromosomes?
linear
circular
what is a plasmid?
small circular independent DNA
where are plasmids in the cell?
the cytoplasm
