nucleic acids

Question 1

where are nucleic acids contains

Answer 1

in the nucleus of the cell

Question 2

what are the two types of nucleic acid

Answer 2

DNA- deoxyribonucleic acid
and
RNA- ribonucleic acid

Question 3

what do nucleic acids contain

Answer 3

Carbon
Hydrogen
Oxygen
Nitrogen
Phosphorus

Question 4

what are nucleotides

Answer 4

nitrogen-containing organic substances forming the basis of nucleic acids

Question 5

describe the structure of each nucleotide

Answer 5

a phosphate group is attached to either C5 or C3 by a covalent bond in a condensation reaction. a pentose sugar where a nitrogenous base is attached to C1.

Question 6

functions of a nucleotide

Answer 6

form monomers of nucleic acids such as DNA and RNA. can regulated many metabolic pathways e.g. ADP, ATP, AMP

Question 7

what does it mean if a nucleotide is phosphorylated

Answer 7

it contains more than one phosphate group e.g ATP, ADP

Question 8

what is the covalent bond between phosphate group and sugar called in a nucleotide

Answer 8

phosphodiester bond

Question 9

what is the covalent bond between nitrogenous base and sugar called in a nucleotide

Answer 9

glycosidic bond

Question 10

what are the four possibilities of a nitrogenous base

Answer 10

Adenine, thymine, guanine and cytosine

Question 11

what is a polynucleotide strand

Answer 11

a strand made up of many nucleotides

Question 12

why is DNA an anti-parallel structure

Answer 12

its two polynucleotide strands run in opposite directions

Question 13

what is the double helix

Answer 13

shape of DNA due to the coiling of the two sugar-phosphate backbone strands

Question 14

what are the two examples of pyrimidine bases

Answer 14

thymine and cytosine (T&S)

Question 15

what are the two examples of purine bases

Answer 15

adenine and guanine (A&G)

Question 16

what is the difference between pyrimidine and purine bases

Answer 16

purine bases are 2 ring structures whereas pyrimidines are 1 ring structures

Question 17

how many hydrogen bonds do adenine and thymine pair with

Answer 17

2

Question 18

how many hydrogen bonds do cytosine and guanine pair with

Answer 18

3

Question 19

the polynucleotide strand is held together by what bonds

Answer 19

phosphodiester bonds

Question 20

the two polynucleotide strands are held together by what bonds

Answer 20

hydrogen bonds

Question 21

what is the 3’ end vs 5’ end

Answer 21

3’ end is where the phosphate group is bonded to the carbon 3 of pentose sugar whereas 5’ end is where the phosphate group is bonded to carbon 5 of the pentose sugar

Question 22

what is the difference in nitrogenous bases between DNA and RNA

Answer 22

DNA has thymine whereas RNA has uracil

Question 23

what are the three main biological processes that require energy

Answer 23

-synthesis (energy is needed to create large molecules out of small molecules),
-transport (energy is needed to move substances via active transport),
-movement (muscle fibres require energy to contract)

Question 24

what is the structure of ATP

Answer 24

adenine, ribose, three phosphate groups

Question 25

why does DNA need to replicate

Answer 25

cell division- for growth and repair reproduction- gametes require DNA to pass on genetic information

Question 26

what is the process of semi-conservative replication

Answer 26

1. DNA will unwind. The double helix will untwist a bit at a time. 2. The DNA will unzip. This means hydrogen bonds between nitrogenous groups are broken. 3. free nucleotides in the nucleoplasm bond to the exposed single strands. 4. once in place DNA polymerase joins the new nucleotides together by strong covalent bonds forming the sugar-phosphate backbone.

Question 27

what enzyme catalyses the unwinding of DNA

Answer 27

gyrase

Question 28

what enzyme catalyses the unzipping of DNA

Answer 28

helicase

Question 29

what enzyme catalyses the joining of the new nucleotides

Answer 29

DNA polymerase

Question 30

what direction does DNA polymerase join the new nucleotides to the free strands

Answer 30

5' to 3' direction

Question 31

how is the lagging strand of DNA formed

Answer 31

dna polymerase fills in the complimentary base pairs in fragments called the okazaki fragments going in the 3' to 5' direction. each fragment is started off by a rna primer. once the dna strand is complete all primers are removed by the enzyme exonuclease. dna polymerase then fills in the gaps. once both strands are replicated dna lipase seals the fragments of DNA.

Question 32

why does each gene need to be transcribed (copied)

Answer 32

as the instructions for each gene cant pass out of the nucleus

Question 33

what is each gene copied into in order to pass out of the nucleus

Answer 33

mRNA

Question 34

what is the sequence of base triplets called in the form of mRNA

Answer 34

codon

Question 35

what are the steps of transcription

Answer 35

1. DNA helix unwinds to expose the bases to act as a template. only one chain of the DNA acts as a template. like in dna replication the helix unwinds by the enzyme helicase and hydrogen bonds are broken between nitrogenous bases. 2. free RNA nucleotides in the nucleoplasm align opposite their complimentary DNA base pairs. 3. RNA polymerase joins the RNA nucleotides by phosphodiester bonds to create a new RNA polymer chain

Question 36

what are the steps of translation

Answer 36

1. once the modified mRNA has left the nucleus it attaches to a ribosome in the cytoplasm. 2. the ribosomes are attached to the start codon (the first three mRNA bases at the start of the sequence) 3. the tRNA molecule, which has an amino acid attachment site determined by the complimentary anti-codon, aligns opposite the mRNA molecule and they are held in place by a ribosome. 4. the ribosome will then move along the mRNA molecule to allow a different tRNA to attach to the complimentary mRNA codon. 5. while the ribosome holds the mRNA and tRNA together the amino acids of the tRNA form peptide bonds with eachother. 6. once the ribosome has moved along, the tRNA molecule of the previous codon detaches and is reused. 7. this continues until ribosome reaches the stop codon and it does not code for an amino acid so translation ends. 8. polypeptide chain is now created and enters golgi fpr packaging and modifying

Question 37

what is the role of the ribosome in translation

Answer 37

holds the mRNA and tRNA in place