2.3 Nucleic Acids

Question 1

monomer of nucleic acid

Answer 1

pentose sugar
phosphate group
nitrogenous base

Question 2

monomer

Answer 2

unit made form polymer

Question 3

nucleiotide

Answer 3

molecule consisting of
a five-carbon sugar
a phosphate group
a nitrogenous base

Question 4

nucleoside

Answer 4

pentose sugar
nitrogenous base
e.g adenosine

Question 5

ladder shape why(1)

Answer 5

sugar-phosphate backbone

Question 6

DNA strand:

“ antiparallel”

Answer 6

two stands run in opposite direction

Question 7

4 nitrogenous base

Answer 7

Adenine
Guanine
Thymine 
Cytosine
A G T C

Question 8

ladder shape why (2)

Answer 8

sugar-phosphate backbone of antiparallel polynucleotide stand

Question 9

DNA strands:

“opposite direction”

Answer 9

direction of 3rd & 5th carbon molecules of pentose sugar deoxyribose face

Question 10

DNA stands
5’ end
3’ end

Answer 10

5’ end of molecule:
phosphate group attached to 5th carbon atom of deoxyribose

3’ end
phosphate group attached to 3rd carbon atom of deoxyribose sugar

Question 11

semi-conservative replication

Answer 11

how DNA replicates
–> 2 new molecule ( 1 new, 1 old)
1 old is conserved in each new molecule

Question 12

DNA replication:

requirements EZ

Answer 12

1 DNA template
2 free DNA nucleotides 
3 DNA polymerase
4 Primers
5 ATP

Question 13

DNA replication:

requirements not EZ

Answer 13

1. Original DNA template
2. Free DNA nucleotides –
3. DNA polymerase – an enzyme that adds new nucleotides to a growing strand of DNA.
4. Primers – needed to start the process because DNA polymerase can only add nucleotides to an existing strand of DNA.

Question 14

DNA replication:

Answer 14

1 DNA unwinds, unzips
H-bonds breaks

2 enzyme polymerase adds DNA nucleotides in a 5’ to 3’ direction
DNA nucleotides are added to exposed bases on both stands
A primer is needed to start replication

3 2 new stand twist to form double helix

Question 15

transcription

Answer 15

formation of mRNA from DNA template

Question 16

translation

Answer 16

• formation of a protein
• at ribosome
• by assembling amino acid into
  a particular sequence according to coded instructions carried from DNA to ribosome by mRNA

Question 17

describe transcription

Answer 17

• a gene unwinds and unzips
  H-bond break–> expose nucleotide bases
• one stand acts as template
• RNA polymerase catalysts formation of H-bond between free, activated RNA nucleotides & unpaired DNA bases
• a length of DNA, complimentary to template strand of gene is produced
  –> copy of coding strand
• mRNA leaves nucleus

Question 18

describe translation

Answer 18

• tRNA transports amino acid to ribosome
• as each mRNA codon codes for specific amino acid
  anticodon forms H bonds with their complimentory on mRNA strand
• tRNA brings 2 amino acid together and forms a peptide bonds
  -ATP
• stop codon is reached on mRNA strand
  → signals end of polypeptide
  → polypeptide released
• polypeptide folded into 3D shape with help of chaperone cell

Question 19

what type of nucleotide acid is RNA?

Answer 19

ribonucleic acid

Question 20

difference between

RNA x DNA

Answer 20

RNA x DNA
strand : single x double
sugar : ribose x deoxyribose
base : U x T

Question 21

mRNA

Answer 21

• formed in nucleus
• rewrites sequence of bases of section of DNA in transcription
• carries code for building specific protein

Question 22

tRNA

Answer 22

• in cytoplasm
• picks up specific amino acid from cytoplasm to SA ribosome
  for translation

Question 23

why DNA is described as 1.macromolecule and 2.polynucleotide

Answer 23

1. a molecule of DNA is very large( thousands of base pairs)

2. molecule is a polymer, made of many nucleotides

Question 24

explain why nucleotides are important to cell metabolism, other than being a part of nucleic acid

Answer 24

ATP is a phosphorylated nucleotide, and it is involved in all energy-requiring metabolic reactions; and many coenzymes contain nucleotides

Question 25

how purines and pyrimidines differs

Answer 25

purines: 2 rings
pyrimidines: 1 ring

Question 26

complementary base pairing

Answer 26

In DNA, adenine always pairs with thymine and cytosine always pairs with guanine.

Question 27

DNA molecule: “ antiparallel”

Answer 27

• run in the 5’ to 3’ direction, in opposite directions to each other
• determined by the orientation of the sugar molecules.
• the 3’ refers to carbon 3, and the 5’ refers to carbon 5.

Question 28

chromosome to DNA

Answer 28

chromosome is a molecule of DNA

Question 29

structure of DNA enables its frunctions

Answer 29

• 2 strand → stable
• bases inside sugar-phosphate backbone → protected, integrity of code is maintained
• long molecules → store alot of genetic info
• H-bond can break → molecules to unzip for translation, transcription

Question 30

cytokinesis: difference between animal and plant cells

Answer 30

animal cell: a cleavage furrow separates the daughter cells

plant cell: a cell plate separates the daughter cells

Question 31

tumors

Answer 31

uncontrolled cell division

Question 32

mRNA

Answer 32

• made in nucleus
• 2 adj bases ‘codon’
• carries genetic code from DNA in nucleus to cytoplasm ( for translation)

Question 33

tRNA

Answer 33

• in cytoplasm
• has an amino acid binding site at one end and a sequence of 3 bases at one end ‘anticodon’
• carries amino acid to ribosome during translation

Question 34

rRNA

Answer 34

• forms the 2 subunits in a ribosome

- ribosome moves along mRNA strand. rRNA in ribosome helps to catalyze formation of peptide bonds between amino acids