DAT Biology 2.8

Refer to both DNA & RNA, which are both polymers composed of nucleotides

nucleic acids

nucleic acids Function

store, transmit, and express genetic information

nucleic acids are made of this monomer and bonds via?

nucleotides, phosphodiester bonds

what additional bond other than the phosphodiester bonds connecting the adjacent nucleotides exist in DNA?

base pairing through hydrogen bonds on nucleotides of opposite strands

nucleotide structure in RNA vs DNA?

in general, phosphate group, nitrogenous base, 5-carbon sugar

RNA: single stranded, nitrogenous bases= A,C,G,U and 5-carbon sugar is ribose

DNA: double stranded, nitrogenous bases= A,C,G,T and 5-carbon sugar is deoxyribose

why is DNA deoxyribose?

on Carbon 2 of the 5 carbon ring, it lacks a oxygen.

what are the purines?

adenine, guanine (think PURe as silver Ag)

2 rings

what are the pyrimidines?

cytosine, uracil, thymine (CUT the PYe)

single ring

what is the orientation in which two nucleotides connect via phosphodiester bond?

between the phosphate group of one nucleotide at the 5’ carbon and the hydroxyl group on 3’ carbon of the 5-carbon sugar of an adjacent nucleotide

how many hydrogen bonds between different base pairs?

2 H bonds between A + T

3 H bonds between G + C

why use higher temperature to break DNA with more G-C bonds?

DNA with more G-C bonds have a higher melting temperature since they have more bonds that need to be broken to separate the two strands (3 H bonds per base pair instead of 2 H bonds)

Both strands runs 5’ → 3’ but in _____ directions

opposite (its antiparallel)

If the left strand runs 5’ to 3’ bottom to top, then the strand it is base paired with runs 5’ to 3’ from ____.

top to bottom

The two strands in DNA being A to T and G to C is called them being ____to each other

complementary

What does 5’ to 3’ mean?

They are the terminal ends of the DNA strands

5th C has the phosphate group attached to it while 3rd C have the OH group attached to it.

5’ end begins the strand with a phosphate group attached to the 5th carbon on the first nucleotide and 3’ end terminates the strand with OH group attached to the 3rd carbon of the last nucleotide

what is the chargaff’s rule?

The total number of purines is always equal to the number of pyrimidines in a double stranded nucleic acid

A + G = T + C

meaning, adenine and thymine should always be in equal amounts in DNA. same with guanine and cytosine

If a sample of DNA has 15% Adenine, then what percentage of cytosine does it have?

35%

Thymine =15%

so A+T would be 30% of sample DNA

we have remaining 70% for guanine and cytosine, divide by 2 = 35%

what is the difference between a nucleoside and nucleotide? how does a nitrogenous base connect to it?

a molecule with a nitrogen atom that acts as a base is a nitrogenous base.

A nucleotide consists of a nitrogenous base, phosphate group and 5-carbon sugar while nucleoside is same it is missing the phosphate group.

difference between a ribonucleoside and deoxyribonucleoside. give examples too

ribonucleoside- no phosphate group, just 5-carbon sugar (ribose) and nitrogenous base

ex: adenosine

deoxyribonucleoside- no phosphate group, just 5 -carbon sugar (deoxyribose), nitrogenous base and lack an OH group

ex: deoxyadenosine

how can a nucleoside become a nucleotide?

add a phosphate group to the nucleoside.

ATP= adenosine triphosphate is a nucleotide

adenosine is a nucleoside + 3 phosphate groups attached = ATP is a nucleotide

what type of bond is a phosphodiester bond?

covalent bond , it forms through a dehydration synthesis, releasing water