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Bio 243 Midterm > Theme 2c > Flashcards

Theme 2c Flashcards

1
Q

What is the structure of an amino acid

A

Contain an amino and carbonyl bonded to a central carbon with a hydrogen and a R group
Joined together by a peptide bond

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2
Q

What are peptides

A

Linear chains of amino acids linked by peptide bomds

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3
Q

Draw the structure of an amino acid

A
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4
Q

How can non polar amino acids be identified

A

R groups contain -CH2 or -CH3

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5
Q

How can an uncharged amino acid be identified

A

R groups contain oxygen or -OH

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6
Q

How can charged amino acids be identified

A

R groups contain acids or bases that can ionize

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7
Q

How can aromatic amino acids be identified

A

R groups contain a carbon ring with alternating single and double bonds

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8
Q

What are the 3 special functional amino acids

A

1) methionine: first amino acid in polypeptide
2) proline: causes kink in polypeptide chains
3) cysteine: disulfide bridge contributes to structure of polypeptides

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9
Q

What is the general function of tRNAs

A

Adaptors between codons (mRNA) and amino acids

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10
Q

What type of RNA are codons and anticodons and how to they base pair (parallel or antiparallel)

A

Codon = mRNA
Anticodon = tRNA
Antiparallel base pairing

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11
Q

What is aminoacyl-tRNA

A

Adding the amino acid to the acceptor stem tRNA

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12
Q

What is the charging reaction

A

amino acid + tRNA + ATP —> aminoacyl-tRNA + AMP + PPi

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13
Q

What is the “wobble” in the tRNA anticodon

A

The base at the 5’ end of the anticodon can form H-bonds more then the base located at the 3’ end of a codon
Pairing of the other two nucleotides in the anticodon with the codon is precise (no wobble)

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14
Q

What are the two subunits that make up ribosomes

A

Large (50s): contains enzymes activity called peptidyltransferase
Small (30s): reads codons of mRNA
*exist separately in the cytoplasm but join together on the mRNA molecule

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15
Q

What are the 3 tRNA binding sites

A

1) aminoacyl (A): binds to the tRNA carrying the next amino acid to be added
2) peptidyl (P): binds to the tRNA attached to the growing peptide chain
3) exit (E): binds the tRNA that carried the previous amino acid added

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16
Q

In eukaryotes what does the translation initiation complex contain

A

The ribosome, mRNA and the initiator tRNA

17
Q

Where is the initiatior tRNA^met brought on the small ribosome subunit

A

The p-site (reaction requires GTP)
Then goes to the capped 5’ end of mRNA and scans until it reached the start codon

18
Q

How does the initiator tRNA^met help to initiate translation

A

Complementary base pairing between it and start codon on mRNA
Large ribosomal subunit bind small subunit to form initiation complex which can now accept the first tRNA in the A site
GTP is hydrolyzed to GDP and translation begins

19
Q

What are the 4 steps of translation elongation

A

1) aminoacytl tRNA is loaded to the A-site and complementary to the tRNA anticodon
2) peptidyl transferase (large subunit) forms a peptide bond between carboxyl group and amino group in the A site
3) tRNA with the polypeptide shifts from A to P site and uncharged tRNA shifts from P to E site (ejected)
4) next codon is now in the A site and steps repeat

20
Q

What proteins recognize the stop codons

A

Release factors

21
Q

Do ribosome subunits, mRNA and tRNA get recycled

A

Yes

22
Q

What is phosphoraylation

A

Addition of phosphate to proteins by kinase

23
Q

What is ubiquitination

A

Addition of ubiquities molecules to proteins for their destruction by proteasomes
Controls protein expression

24
Q

What is proteolysis

A

Specific cleavage at the protein

25
Q

What is epigenetics

A

Posttranslational modification of histones that affect transcription
No change in DNA sequence

26
Q

What does histone acetyltransferase add to histone tails and why

A

Add acetyl groups (CH3CO-) by loosening DNA binding
Because if histone become more negative then DNA will pull away

27
Q

What does the methylation of histone tails do

A

Can activate and repress transcription of genes

28
Q

What does chromatin remodelling complex do

A

Displeases nucleosides from promoter regions and activates transcription

29
Q

What is translational regulation

A

Control of protein synthesis

30
Q

What is Posttranslational regulation

A

Control of protein abundance and activity

Bio 243 Midterm (7 decks)

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