protein synthesis - transcription and translation

Question 1

what is transcription

Answer 1

the process of making messenger RNA from a DNA template

Question 2

what is translation

Answer 2

formation of a protein, at ribosomes, by assembling amino acids into a particular sequence according to the coded instructions carried from DNA to the ribosome by mRNA

Question 3

what is the sugar molecule in RNA

Answer 3

ribose

Question 4

what is the nitrogenous base in RNA

Answer 4

uracil

Question 5

which base does uracil replace

Answer 5

thymine

Question 6

is uracil purine or pyrimidine

Answer 6

pyrimidine

Question 7

which is shorter - RNA and DNA

Answer 7

RNA

Question 8

what are the three forms of RNA

Answer 8

mRNA, tRNA or rRNA

Question 9

what does mRNA stand for

Answer 9

messenger RNA

Question 10

what does tRNA stand for

Answer 10

transfer RNA

Question 11

what does rRNA stand for

Answer 11

ribosomal RNA

Question 12

what is the nuclear envelope

Answer 12

a double membrane that encloses the nucleus, DNA is contained within inside

Question 13

what does the nuclear envelope do

Answer 13

protects DNA from being damaged inside the nucleus.

Question 14

where do protein synthesis occur

Answer 14

in the cytoplasm at ribosomes

Question 15

what does DNA contain

Answer 15

the coded information needed to determine the amino acid sequence

Question 16

what is the problem with DNA

Answer 16

one DNA molecule is too large to leave the nucleus

Question 17

what does transcription do

Answer 17

produces shorter molecules of DNA called RNA

Question 18

what has to happen during transcription

Answer 18

base sequences of genes have to be copied and transported to the site of protein synthesis

Question 18

what is transcription similar to

Answer 18

DNA replication

Question 19

what happens first in transcription

Answer 19

a section of DNA containing the gene unwinds and unzips under the control of DNA helicase (starts with the START codon). the DNA helicase breaks the hydrogen bonds between complementary bases

Question 20

do both the strands of DNA contain the code for the protein to be synthesised

Answer 20

only one of them do

Question 21

what is the sense strand

Answer 21

the strand running from 5’ to 3’ - contains the code for the protein to be synthesised

Question 22

what is the antisense strand

Answer 22

acts as the template strand during transcription. runs from 3’ to 5’. complementary to the sense strand

Question 23

what is different about the antisense strand

Answer 23

doesnt code for a protein

Question 24

what carries the same base sequence as the sense strand

Answer 24

the complementary RNA strand that is formed

Question 25

what happens after the DNA unzips

Answer 25

free RNA nucleotides will base pair with complementary bases exposed on the antisense strand when the DNA unzips

Question 26

what does uracil pair with

Answer 26

adenine

Question 27

what does RNA polymerase do

Answer 27

forms phosphodiester bonds between RNA nucleotides

Question 28

when does transcription stop

Answer 28

at the end of the gene

Question 29

what is the completed short strand of RNA called

Answer 29

messenger RNA (mRNA)

Question 30

what is similar about mRNA and DNA

Answer 30

it has the same base sequence as the sequence of bases making up the gene on the DNA except RNA has uracil instead of thymine

Question 31

what does the mRNA after it has been transcripted

Answer 31

it detaches from the DNA template and leaves the nucleus through a nuclear pore. The DNA double helix reforms.

Question 32

where does the mRNA molecule go to

Answer 32

travels to a ribosome in the cytoplasm

Question 33

how does RNA polymerase read the strand compared to how it works with the strand

Answer 33

reads strand 3' to 5' and works on it 5' to 3'

Question 34

what is another word for the sense strand

Answer 34

coding strand

Question 35

what is another word for the antisense strand

Answer 35

the template strand

Question 36

show the two different strands at transcription

Answer 36

coding strand/ sense strand 5' A T G A T C T C G T A 3' RNA 5' A U G A U C 3' template strand/antisense strand 5' T A C T A G G A G C A T 3'

Question 37

what are ribosomes made up of in eukaryotic cells

Answer 37

two subunits - one large one small

Question 38

what are the subunits in ribosomes composed of

Answer 38

equal amounts of protein and a form of RNA called ribosomal RNA

Question 39

what is ribosomal RNA

Answer 39

important in maintaining the structural stability of the protein synthesis sequence and plays a biochemical role in catalysing the reaction

Question 40

what happens after the mRNA leaves the nucleus

Answer 40

it binds to a specific site on the small subunit of a ribosome. the ribosome holds mRNA in position while it is decoded or translated into a sequence of amino acids

Question 41

what is process of decoding the mRNA into a sequence of amino acids

Answer 41

translation

Question 42

what is necessary for translation

Answer 42

transfer RNA

Question 43

what is tRNA composed of

Answer 43

of an RNA strand folded so that 3 bases are at one end of the molecule

Question 44

what is an anticodon

Answer 44

its complementary to a codon on mRNA following the normal base pairing rules

Question 45

what do tRNA molecules do

Answer 45

they carry an amino acid corresponding to that codon

Question 46

does the tRNA add all the amino acids at the same time

Answer 46

no they are added once at a time and the polypeptide chain grows as this happens

Question 47

what do the ribosomes do

Answer 47

act as the binding site for mRNA and tRNA and catalyse the assembly of the protein

Question 48

what is the process of translation

Answer 48

1) the mRNA binds to the small subunit of the ribosome at its START codon (AUG) 2) a tRNA with the complementary anticodon (UAC) binds to the mRNA START codon. this tRNA carries the amino acid methionine 3) another tRNA with the anticodon UGC and carrying the corresponding amino acid, threonine, then binds to the next codon on the mRNA (ACG) - a maximum of two tRNAs can be bound at the same time 4) the first amino acid, methionine is transferred to the amino acid (threonine) on the 2nd tRNA by the formation of a peptide bond 5) the ribosome moves along the mRNA releasing the first tRNA. the 2nd tRNA becomes the first. these steps are repeated

Question 49

what does each amino acid do each time

Answer 49

adds to the chain each time

Question 50

when does the process of translation stop

Answer 50

until the ribosome reaches the end of the mRNA at a stop codon and the polypeptide is released

Question 51

what do amino acids join to become

Answer 51

the primary structure of the protein

Question 52

what does the primary structure do

Answer 52

folds into secondary and tertiary structures

Question 53

what does the primary structure determine

Answer 53

the folds and bonds formed

Question 54

what may also happen to the protein

Answer 54

may undergo further modifications at the Golgi Apparatus before it is fully functional and ready to carry out the specific role for which it has been synthesised

Question 55

how can multiple identical polypeptides be synthesised simultaneoulsy

Answer 55

many ribosomes can follow mRNA behind the first one