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bio : mod 2 : chap 2 > nucleic acids > Flashcards

nucleic acids Flashcards

1
Q

where were nucleic acids discovered in ?

A

cell nuclei

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2
Q

what are the 2 types of nucleic acid ?

A

DNA and RNA

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3
Q

what do they both have roles in ?

A

the storage and transfer of genetic information and the synthesis of polypeptides (proteins)

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4
Q

what elements does nucleic acids contain ?

A

carbon, hydrogen , oxygen , nitrogen and phosphorous

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5
Q

what is the structure of nucleic acids ?

A

large polymers formed from many nucleotides (the monomers) linked together in a chain.

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6
Q

what is are the 3 components an individual nucleotide made up of?

A
  • a pentose monosaccharide (sugar) , containing 5 carbon atoms
  • a phosphate group, -PO42-, an inorganic molecule that is acidic and negatively charged
  • a nitrogenous base- a complex organic molecule containing 1 or 2 carbon rings in its structure as well as nitrogen.
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7
Q

draw the structure of nucleotide

A

find a picture of ;)

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8
Q

how are nucleotides linked together and what do they form ?

A

linked together by condensation reactions to form a polymer called polynucleotide

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9
Q

what are phosphodiester bonds ?

A

covalent bonds that consists of a phosphate group and 2 ester bonds

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10
Q

what do phosphodiester bonds form ?

A

a long , strong sugar phosphate’backbone’ with a base attached to each sugar.

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10
Q

how does a phosphodiester bond form ?

A

it forms by a condensation reaction between 2 nucleotides

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11
Q

how are phosphodiester bonds broken?

A

through hydrolysis , the reverse condensation , releasing the individual nucleotides.

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12
Q

what does DNA stand for?

A

deoxyribonucleic acid

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13
Q

what is DNA ?

A

a sugar with one fewer oxygen atoms than ribose

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14
Q

how many bases does each of the nucleotides in DNA have ?

A

4 different bases

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15
Q

what 2 groups can the 4 bases be divided into ?

A

pyrimidines & purines

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16
Q

what 2/3 bases are pyrimidines ?

A

thymine , cytosine and uracil

17
Q

what 2 bases are purines ?

A

adenine & guanine

18
Q

what is the structure of pyrimidines ?

A
  • the smaller bases
  • contains single carbon ring structures
19
Q

what is the structure of purine ?

A
  • the larger bases
  • contains double carbon ring structures
20
Q

which 2 bases are the complementary pair ? (A & T )

A

adenine & thymine

21
Q

which 2 bases are the complementary pair ? (C & G )

A

cytosine & guanine

22
Q

how many hydrogen bonds does the complementary pair ( A & T ) form ?

23
Q

how many hydrogen bonds does the complementary pair ( C & G ) form ?

24
describe the structure of DNA
- molecule twists to form double helix of 2 deoxyribose polynucleotide strands ( so there are 2 sugar-phosphate backbones ) - hydrogen bonds form between complementary base pairs ( AT & CG ) on strands that run antiparallel
25
what does the pairing between the bases allow ?
DNA to be copied and transcribed
26
what does the rule mean ? (CBP)
a small pyrimidine base always binds to a larger purine base
27
what does this arrangement maintain ?
a constant distance between the DNA 'backbones' which results in parallel polynucleotide chains
28
what does complementary base pairing mean ?
DNA always has equal amount of adenine and thymine and equal amounts of cytosine and guanine
29
who determined the detailed structure of DNA and when ?
Watson and Crick in 1953
30
what carries genetic information of an organism ?
the sequence of bases along a DNA strand .
31
what essential role does RNA take part in ?
transfer of genetic information from DNA to the proteins that make up the enzymes and tissues for the body .
32
what does the fact that DNA in the eukaryotic chromosome is a very long molecules affect ?
it is unable to leave the nucleus in order to supply the information directly to the sites of protein synthesis.
33
how do they get around this problem ?
relatively short section of the long DNA molecule corresponding to a single gene is transcribed into similarly short messenger RNA molecule
34
where is DNA found ?
nuclei of eukaryotes & cytoplasam of prokaryotes
35
what are the difference between DNA and RNA nucleotides ?
- DNA - Stands for deoxyribonucleic acid. Pentose sugar is deoxyribose (Has a H group attached to Carbon-2), Has four nitrogenous bases - A (Adenine), T (Thymine), C (Cytosine) & G (Guanine). 1 molecule of DNA is made of 2 polynucleotide chains. - RNA - Stands for ribonucleic acid. Pentose sugar is ribose (Has an OH group attached to Carbon-2), Has four nitrogenous bases - A (Adenine), U (Uracil), C (Cytosine) & G (Guanine). 1 molecule of RNA is made of a single polynucleotide chain.
36
explain how the structure of DNA is ideally suited to its role ?
enables DNA to coil so that the long molecule is compact and lots of information can be stored in a small space
37
a sample of DNA was tested and 17 % of the total bases present were found to be adenine. calculate the percentages of each of the other 3 bases present in this sample
thymine - 17% guanine - 33% cytosine - 33%
38
how do the RNA nucleotides from polymers ?
the same way as DNA nucleotides - by the formation of phosphodiester bonds in condensation reactions.
39
the way RNA polymers are formed allows ?
as they are small enough to leave the nucleus and travel to ribosomes which is where the central in process of protein synthesis
40
what happens after protein synthesis to the RNA molecules ?
they are degraded in the cytoplasm. the phosphodiester bonds are hydrolysed and the RNA nucelotides are released and reused.
41
how can DNA be extracted ?
- grind sample in a mortar and pestle --> this breaks down the cell walls -mix sample with detergent --> this breaks down the cell membrane,releasing cell contents into the solution -add salt - this breaks the hydrogen bonds between the DNA and water molecules -add protease enzyme --> this will break down the proteins associated with the DNA in the nuclei - add a layer of alcohol (ethanol) on top of the sample --> alcohol causes the DNA o precipitate out of the solution - the DNA will be seen as white strands forming between the layer of sample and layer of alcohol. the DNA can be picked up by 'spooling' it onto a glass rod

bio : mod 2 : chap 2 (8 decks)

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