module 2 - 3.8 nucleic acids Flashcards
what type of reaction is the synthesis of DNA?
anabolic
how many chromosomes does almost every human cell contain?
46
how many nucleotides does almost every human cell contain?
3 billion
what is the length DNA in almost every human cell?
2 metres
what is DNA?
the genetic material within organisms
why is base pairing important?
allows the molecule to replicate
what are nucleotides a type of?
monomers
what happens to nucleic acids under neutral conditions?
- the remaining OH group of the phosphate is deprotonated
- the oxygen atom has a negative charge
how to base pairs form? (which bond)
they hydrogen bond with each other
what are nucleic acids?
polymers of nucleotides
how are nucleotides joined together?
by condensation reactions that make PHOSPHODIESTER BONDS
how are nucleic acids broken down?
by hydrolysis reactions that break the phosphodiester bonds
what are the 3 subunits in a single nucleotide?
- an organic pentose monosaccharide (sugar)
- an inorganic phosphate group PO4^2-
- an inorganic nitrogenous base
what does organic mean?
carbon based
what does inorganic mean?
not carbon based
where are nucleotides from?
food
what happens once nucleotides have been broken down in food?
rebuilt for chromosomes in the body and rebuild into nucleic acids
which position is the phosphate at?
5 prime carbon
what is the difference in number of strands between DNA and RNA?
DNA - double stranded
RNA - single stranded
what is the different pentose sugars in DNA and RNA?
DNA - deoxyribose sugar
RNA - ribose sugar
what is the difference in nitrogenous bases between DNA and RNA?
DNA - adenine, thymine, guanine, cytosine
RNA - adenine, uracil, guanine, cytosine
where is DNA found?
in the nucleus
where is RNA found?
inside and outside nucleus
what are the base pairs for DNA?
adenine - thymine
guanine - cytosine
what are the base pairs for RNA?
adenine - uracil
guanine - cytosine
what is the difference between ribose (RNA) and deoxyribose (DNA)?
RNA contains one more oxygen atom than DNA
why is it important that RNA contains one more oxygen atom than DNA?
allows the enzymes to distinguish between the 2 types of nucleotides
what are pyramidines?
SMALLER bases: cytosine and thymine
what are purines?
LARGER bases: adenine and guanine
what type of molecules are the bases?
planar molecules (flat molecules)
what do we encode DNA in the form of?
genes
what is a base pair?
double-stranded unit of DNA made of 2 bases bound by hydrogen bonds
what do base pairs form and contribute to?
- form building blocks of DNA double helix
- contribute to the folded structure of DNA and RNA
what does the complimentary nature of the base pairs provide?
provides redundant copy of genetic information encoded in each strand of DNA
what is the regular structure and data redundancy make DNA well suited for?
makes DNA well suited to store genetic information
what is the regular structure and data redundancy provided by for DNA?
provided by DNA double helix
what do incoming nucleotides provide for DNA and RNA polymerase?
provides the DNA polymerase to replicate and RNA polymerase to transcribe DNA into RNA
how is a new DNA strand formed?
- hydrogen bonds between nitrogenous base pairs are broken
- forming 2 separate strands
- a new complimentary strand is formed with the old strand (semi-conservative)
when do nucleotides form strong covalent bonds with each other?
when the sugar group of one nucleotide bonds to the phosphate group of another nucleotide
which type of bonds hold the polynucleotide together?
strong, covalent sugar-phosphate bonds
what does DNA consist of? (strands)
2 polynucleotide strands
what is the backbone and how are the bases arranged?
sugar-phosphate backbone
the base arrangement - project toward the inside of the double helix
what is antiparallel?
the first and second polynucleotide chains run parallel to each other but in opposite directions (left - 3 prime to 5 prime (upwards), right - 5 prime to 3 prime (downwards))
how many hydrogen bonds are between adenine and thymine?
2 (pyrimidines)
how many hydrogen bonds are between guanine and cytosine?
3 (purines)
what is uracil?
demethylated form of thymine (in RNA not DNA)
is uracil a purine or pyrimidine?
pyrimidine
what does uracil base pair with?
adenine
what does it mean if a base pair is ‘planar’?
the base pair is flat
rather than a double stranded paired molecule, what is RNA’s structure?
single stranded molecule that is folded onto itself
what is the size difference between RNA and DNA?
RNA molecules are much shorter than DNA molecules
what does the hydroxyl group in the ribose backbone do?
makes RNA more unstable than DNA by lowering the activation energy of hydrolysis
what does the functional form of single-stranded RNA frequently require and what does this lead to?
- requires a specific tertiary structure
- this leads to several recognisable secondary structures
what do cellular organisms use messenger RNA (mRNA) for?
to convey genetic information using nitrogenous bases that direct the synthesis of specific proteins
how do many viruses encode their genetic information?
using an RNA genome
how many strands does a tRNA molecule?
1
why does a tRNA molecule appear to be double stranded?
it base pairs with itself, forming hydrogen bonds with itself
