Topic 4- DNA and Protein synthesis Flashcards

1
Q

What is protein synthesis?

A

The productions of proteins (polypeptides) from the information conatined within a cells DNA

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2
Q

What are the 3 main stages of protein synthesis?

A

-Transcription
-Processsing of the mRNA (splicing)
-Translation

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3
Q

What is transcription?

A

-Where the DNA code is copied into mRNA

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4
Q

What is translation?

A

-Where the mRNA joins with a ribosome and the code it carries is used to synthesise a protein

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5
Q

What is RNA, mRNA and tRNA

A

-A single polynucleotide strand

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6
Q

What base does RNA contain instead of thymine?

A

-Uracil

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7
Q

When is mRNA made?

A

-During transcription

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8
Q

What is the function of mRNA?

A

-It carries the genetic code from the DNA to the ribosomes where it is used to make a protein during translation

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9
Q

In mRNA what are the groups of 3 adjacent bases called?

A

-Codons

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10
Q

What is the function of tRNA?

A

-Involved with the process of translation
-It carries the amino acids that are used to make proteins to the ribsomes

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11
Q

What is the structure of tRNA?

A

-Single polynucleotide strand thats folded into a clover shape
-Hydrogen bonds between specific base pairs hold the molecule in this shape

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12
Q

in tRNA what are the specific sequence of 3 bases at one end called?

A

-Anticodon

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13
Q

What does tRNA have at its other end?

A

-An amino acid binding site

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14
Q

Where is mRNA found in the cell?

A

-Nucleus

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15
Q

Where is tRNA found in a cell?

A

-In the cytoplasm

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16
Q

Does mRNA have hydrogen bonds?

A

-No

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17
Q

Is mRNA or tRNA longer?

A

-mRNA

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18
Q

What is a genome?

A

-The complete set of genes in a cell,including those in the mitochondria and chlorplast

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19
Q

What is a proteome?

A

-The full range of proteins produced by a particular genome

20
Q

Step 1 transcription: When does transcription start?

A

-When RNA polymerase attaches to the DNA double helix at the begining of a gene

21
Q

Step 1 transcription: How are the DNA strands separated?

A

-DNA helicase attached to RNA polymerase which break the hydrogen bonds between the strands
-The stranbds are separted and the DNA moleccule uncoils which exposes some of the base pairings

22
Q

Step 1 transcription:How is an mRNA copy made?

A

-One of the strands is used a template strand

23
Q

Step 2 transcription:How is complementary mRNA made?

A

-The RNA polymerase lines up free RNA nucleotides alongside the exposed bases on the template strand
-The free bases are attracted ti the exposed bases
-Specific complementary base pairing means that the mRNA strand ends up being a complementary copy of the DNA template strand
-Once the rNA nucleotides have paired up with their specific bases on the DNA strand they are joined together by RNA polymerase forming an mRNA strand

24
Q

Step 3 transcription: How does the RNA polymerase move down the DNA strand?

A

-The RNA polymerase moves along the DNA assembling the mRNA strand
-The hydrogen bonds between the uncoiled strands of DNA reform once RNA polymerase has passed by and the strands coil back up into a double helix

25
Q

Step 4 transcription:What is a stop signal?

A

-When RNA Polymerase reaches a sequence of DNA called a stop signal, It stops making mRNA and detaches from the DNA.

26
Q

Step 4 transcription:Where does the mRNA move out of the nucleus from?

A

-Nuclear pores
-Attaches to a ribosome in the cytoplasm

27
Q

Explain what happens during splicing?

A

-Introns are removed and the exons are joined together forming mRNA strands
-Takes place in the nucleus
-The mRNA then leaves the nucleus for translation

28
Q

Why does splicing not take place in prokaryotic cells?

A

-mRNA is produced directly from the DNA
-No introns in prokaryotic DNA

29
Q

Where does translation take place in eukaryotic and prokaryotic cells?

A

-The ribosomes, in the cytoplasm

30
Q

What happens during translation?

A

-Amino acids are joined together to make a polypeptide chain, following the sequence of codons carried by the mRNA

31
Q

What are the differences and similarities between DNA and RNA?

A

Differences:
Sugars:
-RNA+ribose
-DNA+deoxyribose

-Same chemical structure expect that ribsoe has a hydroxyl group on its 2nd carbon

-RNA is single stranded
-Rna is much shorter
-RNA has uracil instead of thymine

Similarities:
-Both nucleic acids

32
Q

What does mRNA stand for?

A

-Messenger RNA

33
Q

What does tRNA stand for?

A

-Transfer RNA

34
Q

What are the differences between mRNA and DNA?

A

mRNA is:
-Single stranded
-Small enough to leave the nucleus via nuclear pores
-Ribose sugar
-Uracil instead of thymine
-Codons

35
Q

What are introns?

A

-Regions of DNA which do not code or proteins

36
Q

What are exons?

A

-Regions of DNA that code for proteins

37
Q

Why do the introns need to be spiced out?

A

-To produce functional proteins

38
Q

What molecule removes the introns?

A

-Spliceosome

39
Q

What is pre-mRNA?

A

RNA that contains introns and exons

40
Q

What is mature RNA?

A

RNA that only contains exons

41
Q

Which strand moves in the 5’-3’ direction?

A

-Template strand

42
Q

Which strand moves in the 3’-5’ direction?

A

-Coding strand/non template strand

43
Q

Why is there a different number of nucleotides after transcription?

A

Introns are present in the DNA

44
Q

How would copying bases more than once cause differentiation in the protein?

A

-Frameshift
-Changes in the base sequence of later triplets/ amino acid codes

45
Q

Which DNA sequence would be more slippery CCC-GGG-GGG or CCG-GGG-GGG?

A

CCG-GGG-GGG- G is present more times

46
Q

Describe translation

A

-Condensation reaction takes place and phosphodiester bonds form between the nucleotides
-mRNA strand leaves through the nuclear pores (in the nuclear envelope) and goes to the ribosome
-tRNA molecules bring specific amino acids to the ribosomes
-specific tRNA molecules for specific amino acids
-anticodon of tRNA is complementary to codon on mRNA
-peptide bonds form between the amino acids
-tRNA detaches and collects another amino acid
-ribosome moves along mRNA

47
Q

What are the 3 roles of ATP in protein synthesis

A

-Provides energy required by the ribosome to move along the mRNA strand
-tRNA molecules use it to deliver specific amino acids
-ribosome detaches from the mRNA