protein synthesis Flashcards

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1
Q

what is a gene

A

the base sequene of DNA that codes for the amino acid sequence of a polyppetide, a functional RNA.

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2
Q

how does RNA differ from DNA

A

RNA has a U base instead of T base

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3
Q

what are the 3 types of RNA

A

-messenger RNA. transfer RNA. ribosomal RNA.

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4
Q

what is a codon

A

3 adjacent bases on the MRNA

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5
Q

what is mRNA

A

a single polynucleotide strand. mRNA carries the genetic code from the DNA in the nucleus to the cytoplasm/ribosomes, where its used to make a protein during translation.

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6
Q

what is tRNA structure

A

a single polynucleotide strand thats folded into a clover shape. has an anticodon at one end, and amino acid binding site at the other end

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7
Q

how is tRNA held in a clover shape

A

hydrogen bonds between specific base pairs hold the molecule in this shape

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8
Q

where do u find codons

A

in mRNA

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9
Q

where do u find anti codon

A

in tRNA

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10
Q

where is mRNA made

A

the nucleus, during transcription

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11
Q

where is tRNA found

A

the cytoplasm

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12
Q

what is tRNA for

A

carries the amino acids that are used to make proteins to the ribosomes

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13
Q

what is special between anticodons on tRNA and codons on mRNA

A

they are complimentary to one another

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14
Q

what is rRNA

A

it forms the 2 subunits in a ribosome, along w proteins

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15
Q

what does rRNA do

A

the ribosome moves along the rRNA strand during protein synthesis. the rRNA in the ribosomes helps to catalyse the formation of peptide bonds between the amino acids

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16
Q

what is the genetic code

A

the triplet code - ecah amino acid is coded for by a sequence of 3 bases

17
Q

where are proteins made

A

ribosomes

18
Q

what are the 2 stages of protein synthesis

A

transcription + translation

19
Q

what does DNA code for

A

proteins

20
Q

Why does DNA convert to MRNA

A

DNA (codes for proteins) is too big to leave the nucleus so cannot travel to ribosomes

21
Q

What is the process of DNA turning to MRNA called

A

Transcription

22
Q

Where does transcription occur

A

Nucleus

23
Q

What are the 5 steps of transcription

A

1 - DNA helicase attaches to DNA at the beginning of a gene
2 - This causes unwinding of DNA helix and breaking of H bonds between the two DNA strands
3 - The template strand is used to make an MRNA copy of the DNA. U REPLACES T
4 - Free MRNA nucleotides line up by complementary base pairing next to exposed DNA bases on the template strand
5 - RNA polymerase joins the sugar phosphate backbone of the new MRNA molecule being made.
(after becoming functional the functional mrna leaves the nucleus + travels to a ribosome)

24
Q

What are the two separated strands called

A

coding strand and template strand

25
Q

What are introns

A

Non coding DNA

26
Q

What is pre MRNA and why is is not functional huh

A

introns are located in the MRNA duh isis. introns make it unfuctional

26
Q

Whar are exons penchodah

A

Coding DNA

27
Q

HOW do u make functional MRNA

A

INTRONS ARE CUT OUT OF THE MRNA BEFORE IT LEAVES THE NUCLEUS. THE MRNA IS ALSO CAPPED BEFORE IT LEAVES TO PREVENT IT FROM BEING DAMAGED IN THE CYTOPLASM

28
Q

when does translation happen

A

once the mrna leaves the nucleus and attaches to a ribosome (or on the RER)

29
Q

what are the 9 steps for translation

A

1 - the genetic code on the MRNA will be used to assemble a corresponding chain of amino acids
2 - the MRNA attaches to a ribosome (free or on RER), every group of 3 bases on the mrna is called a codon
3 - trna molecule contain triplets of bases at one end called anticodons. these line up next to the codons on the MRNA by complementary base pairing
4 - the other end of the TRNA molecule has a specific amino acid attached
5 - the ribosome can hold 2 TRNA molecules in position at the same tie allowing their amino acids to join by a peptide bond
6 - the first TRNA molecule now leaves the ribosome, leaving its amino acid behind, and another TRNA arrives with its amino acid
7 - the ribosome moves along so that the next 2 TRNA molecules are in position allowing their amino acids to join then the 2nd TRNA molecule moves away and so the process continues
8 - this happens untila stop codon on the MRNA is reached, signaling the polypeptide is now complete
9 - the polypeptide is then released into the cytoplasm, this is the primary protein structure, and is then built up further into a complete functioning protein.

30
Q

how can lots of the same polypeptide be made

A

if several ribosomes move along the same piece of MRNA at once

31
Q

what does a degenerate code mean

A
32
Q

code is non overlapping what does this mean

A

it means base triplets do not share their bases, each triplet is different from the next (GUC/UCA).

33
Q

with the bases G U C, what orders would make them overlappin

A

GUC/UCU/CUC

34
Q

code is universal, what does that mean

A
35
Q

what are the 3 natures of the genetic code

A

degenerate, non overlapping, universal

36
Q

what is splicing

A

removing introns

37
Q

spliced pre MRNA =?

A

mrna