chapter 3- nucleic acids

Question 1

what are 2 examples of nucleic acids

Answer 1

DNA and RNA

Question 2

what are nucleic acids composed of

Answer 2

monomers called nucleotides

Question 3

what are the subunits of a nucleotide molecule and how are they joined

Answer 3

a pentose sugar attached to a phosphate and a nitrogenous base. they are joined by covalent bonds but the phosphate one is an ester

Question 4

what is different about the nitrogenous bases on DNA and RNA

Answer 4

DNA nitrogenous bases are A, T, C, G and RNA bases are A, U, C, G. thymine is replaced with uracil

Question 5

what are the essential ideas for translation

Answer 5

mRNA is translated into an amino acid sequence

it depends on the complementary base pairs between codons and anticodons

Question 6

what are the purines

Answer 6

guanine and adenine

Question 7

what are the pyrimidines

Answer 7

cytosine
thymine
uracil

Question 8

how do purines differ from pyrimidines (structurally)

Answer 8

purines have 2 rings comtaining nitrogen whereas pyrimidines only have 1

Question 9

how many hydrogen bonds join A to T

Answer 9

2 hydrogen bonds

Question 10

how many hydrogen bonds join G to C

Answer 10

3 hydrogen bonds

Question 11

a purine will always pair with a pyrimidine what does this accommodate

Answer 11

as purine has 2 nitrogen containing rings and pyrimidines only have 1, when the bases pair they will always be 3 across

Question 12

where is rna found

Answer 12

in the cytoplasm

Question 13

why cant dna pass through the dna envelope

Answer 13

because it is too large (long and double stranded)

Question 14

where do nucleotides that make up dna and rna exist

Answer 14

freely in the nucleus

Question 15

how do polynucleotides form

Answer 15

via a condensation reaction between the 5 carbon phosphate group of one nucleotide and the 3 carbon hydroxyl group on the sugar of another join the two together.

A phosphodiester linkage is formed between two pentose sugars (2 covalent bonds)

Question 16

what is the importance of complementary base pairings

Answer 16

always the same distance between each pair of bases.

ensures faithful dna replication and high fidelity of replication =accurate copy

Question 17

what does bi-directional mean

Answer 17

a mechanism that allows dna replication to proceed in opposite directions on the two strands due to the antiparallel nature of the strands

Question 18

in translation the ribosomes binds to

Answer 18

the mRNA and moves along the molecule in a 5’-3’ direction until it reaches the codon

Question 19

the mRNA is read how many codons at a time

Answer 19

1 codon at a time

Question 20

tRNA anticodons are what so they can what

Answer 20

are complementary to the codons on mRNA so they align.

Question 21

each tRNA molecule carries

Answer 21

a specific amino acid

Question 22

what is the end steps of translation

Answer 22

ribosomes catalyse the formation of peptide bonds between the adjacent amino acids via condensation reactions, the ribosomes moves along the mRNA strand synthesising a polypeptide chain until i reaches the stop codon, the polypeptide is then released

Question 23

what are the 5 chemical elements that make up nucleic acids

Answer 23

carbon, hydrogen , nitrogen, oxygen and phosphorus

Question 24

what is the function of nucleic acids

Answer 24

the storage and transfer of genetic information and the synthesis of proteins

Question 25

what is a phosphodiester bond

Answer 25

a covalent bond between two nucleotides in the sugar phosphate backbone resulting from a condensation reaction

Question 26

what is the function of DNA

Answer 26

to store genetic information and code for the production of polypeptides

Question 27

what is the structure of DNA

Answer 27

DNA has a double helix structure with two antiparallel polynucleotide chains twisted around each other and held together by h bonds between complementary base pairs

Question 28

what is the structure of ATP

Answer 28

the pentose sugar ribose, the nitrogenous base adenine, and three inorganic phosphate groups

Question 29

what is the function of ATP

Answer 29

an immediate source of energy for biochemical processes and synthesis of biological molecules

Question 30

how does the structure of ATP make it a good source of immediate energy

Answer 30

the bonds between the phosphate groups have a low activation energy, this means they can be easily broken, this releases energy

Question 31

which is correct about the structure of ATP
a) a pyrimidine is part of its structure
b) it is a nucleotide

Answer 31

b

Question 32

how is rRNA involved in catalysing translation

Answer 32

peptidyl transferase is an rRNA component that transfers one amino acid to another.

Question 33

how do purines and pyrimidines differ structurally (visually)

Answer 33

Purines have two carbon-nitrogen ring bases whereas pyrimidines have one carbon-nitrogen ring base.

2 or 1 rings

Question 34

difference between rna and dna structure on nucleotide pentose sugar

Answer 34

rna has an OH group on the bottom right and dna has just an H on the bottom right

Question 35

What are the five chemical elements that make up nucleic acids?

Answer 35

carbon, hydrogen, nitrogen, phosphorus, oxygen