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biology IB > D1.2 protein synthesis > Flashcards

D1.2 protein synthesis Flashcards

1
Q

what are the steps in protein synthesis

A

transcription
splicing
translation
protein modification and folding

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2
Q

explain the process of transcription general summarized

A

first step in protein synthesis
happens in nucleus
mRNA is formed from a dna strand (anti-sense) through complementary base paring
uses enzyme called RNA polymerase (catalyses phosphodiester bonds between free RNA nucleotides to form and RNA polynucleotide= the mRNA)
input= DNA
Output=mRNA
molecules used= rna polymerase and rna nucleotides

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3
Q

explain process of splicing summarized

A

second step in protein synthesis
post transcriptional modification
processes mRNA to form a mature mRNA
mRNA leaves the nucleus and enters the cytoplasm
non protein coding regions of the RNA strand are removed

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4
Q

explain process of translation summarized

A

thrid step in protein synthesis
happens in cytoplasm
polypeptide is formed from mRNA
uses ribosome to form peptide bonds between amino acids
tRNA is used to bring specific amino acids thus free amino acids are used

RNA molecules used as a code for protein assembly at the ribosome
input= mRNA
output=Protein
molecules used= ribosome, amino acid, tRNA, tRNA activating enzyme

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5
Q

explain protein modification and folding summarized

A

gives output to functional protein
post translational modification
protein folding of the 2nd to the 4th structure
addition of chemical groups (sugar, lipid, methyl, acethyl, phosphate etc.

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6
Q

what dos protein synthesis ultimately due

A

turns DNA message into proteins

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7
Q

in prokarayotic cells where is dan found

A

loosely in cytoplasm thus no slicing is necessary

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8
Q

explain differences between transcription and translation

A

transcription:
input= dna
output= mrna
location=nucleus
molecules used= rna polymerase and rna nucleotides

translation
input= mrna
output= protein
location= cytoplasm
molecules usd= ribosome, amino acids, trna activatin enzyme and trna

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9
Q

which structure cannot leave the nucleus

A

DNA

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10
Q

which structure is the smallest part of a protein

A

amino acid

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11
Q

which structure is the organelle responsible for making proteins

A

ribosome

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12
Q

which structure is responsible for translation

A

trna, mrna, ribosome

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13
Q

which structure is the smallest part of a nucleic acid

A

nucleotide

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14
Q

which structure recognizes a mrna codon

A

trna, anticodon

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15
Q

what nucleotide is present in rna and not in dna

A

uracil

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16
Q

why is uracil necessary

A

makes a more stable hydrogen bond

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17
Q

what type of bond holds together the two strands of dna

A

hydrogen bonds

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18
Q

what type of bond holds together a strand of DNA

A

phosphodiester bond

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19
Q

what type of bond holds together amino acids in a protein

A

peptide bond

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20
Q

the message of the dna code is informatio for building

A

proteins

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21
Q

can there be more tan one codon for the same amino acid

A

yes

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22
Q

can there be more than one anticodon for one codon

A

no only one

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23
Q

why is the genetic code said to be universal

A

a codon represents the same nucelotide in all organisms

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24
Q

proteins are made in

A

the cytoplasm of the cell

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25
the process of making rna from dna is called
transcription
26
mrna caries info from
the dna to the ribosomes
27
thymine, adenine, guanine, cytosine and uracil are
nucleutides, or nitrogenous bases
28
the process by which dna makes a copy of itself is called
replication
29
trna brings amino acids to the ribosomes for
assembly of proteins
30
the procss of converting rna code into an amino acid sequence is
translation
31
promoter
noncoding dna sequence located near a gene and acts as the starting point of transcription. it can be regulated by other dna sequences called silencers and enhancers
32
transcription unit
adjacent gene is transcribed but the promoter region is not
33
terminator
non coding dna sequence located near gene acts as ending point of transcription
34
what is the sense strand
non transcribed strand it has same sequence (accept for t where in mrna it is a u) as mrna 5'-3'
35
what is the antisense strand
acts as template to make mrna, it is transcribed and mrna has comlementary bases to the antisense
36
what happens during intiation (transcription)
first step of transcription RNA polymerase attaches to promoter at dna it then unwinds and unzips the dna by breaking the hydrogen bonds between complementary bases. Unzipping exposes dna bases for pairing with RNA nucleotides
37
elongation (transciprtion)
second step of transcription RNA polymerase snthesizes mrna complementary to dna strand (antisense) uses it as a template by adding complementary ribonucleotides in a 5'-3' direction rna nucleotides are matched to the complementary bases in the dna A-U C-G rna polymerase moves via a 3'-5' direction
38
terminatio (transcription)
last step of transcription rna polymerase reaches the terminator sequence on dna which dislodges the growing rna strand and releases the polymerase once the rna from a particular region has made the dna double helix quickly reforms, displacing the growing single strand of rna many rna molecules can be transcribed from same gene simutaneously simultanes to unwinding rewidning takes place
39
explain process of transcription in prokarayotes (8 marks)
dna sequence promoter signals start of transcription rna polymerase unwinds dna and using dna antisense (3'-5') strand as a template joins free rna nucleotides complementary to dna antisense U will substitue T the mrna built by the rna polymerase is an exact copy (excpet for t and u) of the dna sense strand (5'-3') once the terminator dna sequence is reached the polymerase detaches from the dna and so does the mrna there is simultaneous unwidning and rewidning of the dna the mrna formed moves in the oppoite direction to the movement of dna (mrna moves in 5'-3')
40
what happens in rna splicing
non protein coding regions of rna strands are removed, introns are "spliced" out of the rna and exons are joined together prokarayotic cells do not recquire splicing this happens after transcription, still inside nucleus and it is done by rna splciing enzymes called snRNPs
41
eukarayotic genomes contain
exons= real gene expressed coding dna introns= junk does not code for proteins, non coding dna in between sequence
42
name of enzymes which do the splicing
snRNPs
43
explain process of splicing
splicing turns premrna into mature mrna spliceosome is formed by the folding of the introns the spliceosome is a complex formed of several snRNPs that recognize introns the snRNPs whicha re small nuclear rna molecules associated with proteins are what do the actual splicing the excised intron in lariat shape, after being spliced form pre rna trascription some of the intronic rna is degraded by rna nucleases and recycled back to RNA nucleotides the mature mrna is what leaves the nucleus and is translated into proteins
44
what is alternative splicing
a process where a single gene can produce multiple different protein variants by varying the combinations of exons (coding regions) that are included in the mature mRNA
45
explain process of alternative splicing
can happen after removal of introns from pre mrna matura mrna can be formed by joining exons in a different sequence producing different proteins alternative mrna produced from same gene; different segments treated as exons
46
whats rna modification
during rna processing, rna is modified before leaving the nucleus, necessary to protect mrna from enzymes in cytoplasm that attack mrna
47
how does rna modification protect the ends of the rna molecules
they add a 5'GTP cap at the beginning of the rna and a 3'poly-A tail to end of RNA
48
what does it mean when an mrna has a longer tail
poriduces more protein, will remain inside the nucleus for longer time
49
the completed, spliced mrna strand leaves the nucleus through the
nuclear pore
50
the process of adding a protective strucutre called gtp cap to the 5'end of the mRNA molecule is important because
protets it from degredation and assits in ribosome recognition
51
the poly A tail added to teh 3'end of the mrna is importa for
mrna stability and translation efficiency
52
in eukarayotes the non coding dna regions of the rna transcript it known as
intrns and must be removed before the mature rna can be translated
53
the remaining coding region in rna transcript is known as
exons they are spliced together forming mature rna
54
the introns are removed by the
spliceosome complex which contains snRNPs
55
after being spliced out from premrna transciprt what happens to the introns
some are degraded and recycled back into RNA nucleotides
56
the genetic code is universal meaning...
all living things has same code all living things have same bases codons code for same amino acids no matter the organism
57
what doesnt it mean to say the genetic code is degenrate
there are 64 codons but only 20 amino acdis (+ stop) same amino acid may be coded for more than one codon this means there is a reduced ipact in base subtitution mutation, as amino acid produced could still be the same
58
describe the ribosome structure
large and small subunit each subunit is composed of rna molecules and proteins the small subunit binds to the mrna large subunit has binding sites for trnas and also catalyzes peptide bonds betwen amino acids binding site= E,P,A
59
E binding site
exit site, where trna's leave the ribosome
60
P binding site
where the trna currently holding the growing peptide bond is located
61
A binding site
where the trna carrying the amino acids bind firstly to enter the ribosome
62
describe the structure of a trna
single stranded chain of rna clover leaf strucutre 3'end terminal end (acceptor oop) binds to the amino acid double stranded sections are base paired (H-bonds) in the loops of the structure, the bases are not paired, there are 3 loops anticodon (3 bases) attach to mrna codon
63
whats the ultimate function fo the trna
to bring the amino acids from the cytoplasm to the growing polypeptide and to attach them in correct location
64
explain process of trna picking up/ binding to an amino acid
trna picks up a new amino acid when activated by specific trna activating enzymes, this uses atp the energy in the bond linking the trna molecule to the amino acid will be used in translation to form a peptide bond between adjacent amino acids once the trna has an amino acid= charged trna
65
describe first step of translation
initiation 1. mrna binds to the small subunit of the ribosome 2. the small subunit of the ribosome moves along the mrna molecule in a 5'-3'direction until it reaches a start codon (AUG) 3. a molecule of TRNA with its anticodon UAC complementary to the start codon (AUG), is charged with met (amino acid), 4. this first tRNA will bind to the P site of ribosome, all other following trnas will bind to the A site
66
describe second step of translation
1. second trna (with amino acid attached), with anticodon complemetnary to the second codon on the mrna, binds with A site of ribosome 2.amino acid carried by trna in the P site is transferred to amino acid in A site as a consequence of the ribosome catalyzing a new peptide bond (condensation reaction), growing polypeptide chain increases in length 3. ribosome moves one codon along the mrna (5'-3') - trna in p site moves to e site -the charged trna in a site moves into p site 4.another trna with anticodon complementary to next codon on mrna binds to the A site 5. process repeated until stop codon is reached
67
explain last step of translation
1. when a stop codon is reached translation is stopped - release factor attaches to A site -the polypeptide chain is released -the ribosome complex dissembles, ready for reuse translating another mrna molecule 2. the used mrna will be broken down by rna nucleises into free RNA nucleotides
68
what does post translation modification include
protein folding into a functional protein modification in the golgi degredation of protein after its use into amino acids
69
whats the proteome
all proteins in an organism
70
whats the genome
exons + introns
71
whats the transcriptome
just exons
72
rank fro largest to smallest (proteome, genome, transcriptome)
proteome genome transcriptome
73
explain post translation modification
1. ribosomes attached to the RER produce pre-pro insulin 2. NH3+ signal of prepro insulin is detected by transport vesicles which transfers the protein to the golgi 3. NH3+ signal removed from pro insulin 4. Once it enters secretory vesicles it loses the C terminal, fomring insulin 5. exocytosis of mature insulin
74
what is the primary function of free ribosomes
synthesizing proteins to be used within the cell
75
what is the primary function of attached ribosomes
synthesizing proteins to be secreted from the cell
76
what do DNA replication, transcription and translation have in common
complementary base pairing
77
do mutations in inrons have an effect on the primary structure of protein
no
78
which regions of dna code for the production of specific proteins
exons
79
outline how transcription depends on complementary base pairing
converts a sequence of mrna nucleotides to a sequence of amino acids triplets of bases on trna pair with compelmentary bases on mrna base pairing: A-U, G-C
80
5' capping and 3'polydenylation are two kinds of post transcriptional modification that are present in eukarayotes describe another post translational modification necessary to produce mature mRNA in eukarayotes
spliceosome binds to splice site brings about removal of introns, spliced exons joing togehter which forms the mature mRNA
81
describe how the information carried on mrna allows the synthesis of a complete polypeptide chain
mrna binds to small subunit of ribosome start codon signals the start of translation 3 bases mrna correspond to a codon each codon on mrna codes for a specific amino acid stop codon terminates translation
82
state a function of a region of dna that does not code for protein
regulator of gene expression
83
outline the role of tRNA activating enzymes in translaton
ATP produces energy for amino acid attachment, attach specific amino acid to 3'end

biology IB (24 decks)

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