Protein Synthesis

Question 1

give 4 structure features of prokaryotic DNA

Answer 1

• circular
• not associaed with histones
• does not contain introns
• short

Question 2

give 4 structure features of eukaryotic DNA

Answer 2

• linear
• associated with histones
• contains introns
• very long

Question 3

what is a gene

Answer 3

sequence of DNA bases that codes for a polypeptide

Question 4

what is the position of a gene called

Answer 4

locus

Question 5

what are exons

Answer 5

code for a specific sequence of amino acids in the primary structure

Question 6

what are introns

Answer 6

do not code for a specific sequence of amino acids in the primary structure

Question 7

true or false

prokaryotic DNA contains introns

Answer 7

false

Question 8

where is non coding DNA found

Answer 8

between genes

Question 9

what is genome

Answer 9

all the DNA in a cell

Question 10

what is proteome

Answer 10

the full range of proteins produced by cells

Question 11

in DNA what is a sequence of three bases called

Answer 11

triplet

Question 12

how much bases code for an amino acid

Answer 12

3

Question 13

during protein synthesis, the DNA triplets are transcribed into ….

Answer 13

mRNA codons

Question 14

give 3 features of the genetic code and explain them

Answer 14

• universal = the same 3 bases code for the same amino acids in all organisms
• non overlapping = each base is read only once in the triplet
• degenerate = more than one triplet that codes for a single amino acid

Question 15

what is the structure of mRNA

Answer 15

• single stranded
• linear
• short

Question 16

what is the structure of tRNA

Answer 16

• single stranded
• folded into cloverleaf shape by hydrogen bonds beween complementary base pairs
• smaller than mRNA

Question 17

give 2 structure differences between mRNA and tRNA

Answer 17

• mRNA is linear whereas tRNA is in a cloverleaf shape
• tRNA is smaller
• tRNA has anticodons whereas mRNA has codons

Question 18

describe the process of transciption

Answer 18

• DNA helicase breaks hydrogen bonds between base pairs
• one DNA strand acts as a template
• free RNA nucleotides align by complemntary base pairing
• uracil is used instead of thymine
• RNA plymerase joins adjacent RNA nucleotides together by phosphodiester bonds

eukaryotes only:

• pre mRNA is spliced and introns are removed

Question 19

describe the process of translation

Answer 19

• mRNA attaches to the ribosome
• tRNA brings a specific amino acid to the ribosome
• tRNA anticodons bind to complementary mRNA codons
• amino acids are joined by peptide bonds which is catalysed by the ribosome
• the joining of these peptide bonds requires energy releases from ATP hyrolysis
• tRNA is released after amino acids are joined to the polypeptide
• the ribosome moves along the mRNA to form the polypeptide

Question 20

suggest advanatges of using mRNA rather than DNA for translation

Answer 20

• shorter - breaks down quickly
• single stranded and linear - ribosome moves along strand
• contains no introns

Question 21

where does transcription take place

Answer 21

nucleus

Question 22

where does translation take place

Answer 22

cytoplasm