BIOC 3021 Lecture Notes - Lecture 24: X-Ray Crystallography, Transfer Rna, Ribosomal Rna

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27 Apr 2018

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- Translation = protein synthesis:

- mRNA is NOT chemically converted into protein, instead it carries nucleotide

sequence that can be translated into sequence of amino acids

- Properties:

- Sequences of three bases is code for one amino acid

- Codons

- Code is non-overlapping and “comma-less” (continuous)

- Code is universal

- Basically the same code for everyone

- Code is degenerate

- Several codons = one amino acid

- 64 ways to code 20 amino acids

mRNA is read in the 5’ → 3’ direction, DNA/RNA is

synthesized

in 5’ → 3’ direction

- RNA:

- mRNA: template for protein synthesis

- Distinct mRNA per gene in eukaryotes

- tRNA: carries amino acids in activated form to the ribosome for peptide-bond

formation

- Anticodon of tRNA is complementary to codons on mRNA

- rRNA: constitutes the major component of ribosomes

- Catalytic and structural role in protein synthesis

- Protein Synthesis

- Nucleic acid to sequence of amino acid

- Mediated by interplay of more than 100 macromolecules

- tRNA, mRNA, rRNA< aminoacyl-tRNA synthetases and protein factors

- Accurate process in which the incorporation of an incorrect amino acid occurs

less than 10-4% of the time

- tRNA’s are adaptors that forge link between nucleic acid (mRNA codons) and an

amino acid

- L-shaped structure

- Occurs on ribosomes

- transcription/translation closely coupled in prokaryotes

- Ribosomes:

- 65% rRNA, 35% proteins

- Prokaryotes: 70S → 50S and 30S subunits

- Eukaryotes: 80S

- Structure seen with X-ray crystallography

- tRNA:

- 30-50 types of tRNA

- Minimum of 1 per each amino acid

- 70-80 nucleotides in length

- Contains distinctive rare bases

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Document Summary

Mrna is not chemically converted into protein, instead it carries nucleotide sequence that can be translated into sequence of amino acids. Sequences of three bases is code for one amino acid. 64 ways to code 20 amino acids. Mrna is read in the 5" 3" direction, dna/rna is synthesized in 5" 3" direction. Distinct mrna per gene in eukaryotes trna: carries amino acids in activated form to the ribosome for peptide-bond formation. Anticodon of trna is complementary to codons on mrna rrna: constitutes the major component of ribosomes. Catalytic and structural role in protein synthesis. Nucleic acid to sequence of amino acid. Mediated by interplay of more than 100 macromolecules trna, mrna, rrna< aminoacyl-trna synthetases and protein factors. Accurate process in which the incorporation of an incorrect amino acid occurs less than 10-4% of the time trna"s are adaptors that forge link between nucleic acid (mrna codons) and an amino acid. Prokaryotes: 70s 50s and 30s subunits.

Related Questions

thank you

1. _________________________ is the name of the process that produces proteins using RNA molecules.

a.Transcription

b Translation

c. Replication

d. Mutagenesis

2. The peptide bonding site on the ribosome:

a. A site

b. P site

c. E site

d. D site

3. The name given to the bond formed between two amino acids.

a. Hydrogen bond

b. Double bond

c. Peptide bond

d. Negative bond

4. __________________________ is the movement of the mRNA molecule on the ribosome to open up the A-site for the new incoming amino acid.

a. Transformation

b. Mutation

c. Translocation

d. Initiation

5. What does the term semi-conservative mean.

a. Replication of RNA is semi-conservative, each new strand consists of one old strand of RNA and one new strand of RNA.

b. Replication of DNA is semi-conservative, each new strand consists of one old strand of DNA and one new strand of DNA.

c. Replication of DNA is semi-conservative, each new strand consists of new strands of nucleotides.

d. Transcription of RNA is semi conservative.

6. This molecule functions during protein synthesis to recognize the codon and bring the proper amino acid back to the ribosome for translation.

a. mRNA

b. tRNA

c. rRNA

d. DNA polymerase

7. What is meant by the base-pairing rule.

a. Bases on a single strand of DNA are always found as pairs

b. Adenine always base pairs with guanine; cytosine with thymine

c. Adenine always base pairs with thymine; cytosine with guanine

d. Bases on a single strand of RNA are found in pair.

8. In this step of protein synthesis, amino acids are added to a growing polypeptide chain.

a. Initiation.

b. Elongation.

c. Termination.

d. Transpiration.

9. Three complementary bases found in a mRNA are called ____________________.

a. Anti-codon.

b. Triplet.

c. Doublet.

d. Codons.

10. Which statement best describes the job or function of the messenger RNA.

a. Carries the map of the gene sequence in the form of codons to the cytoplasm

for translation of the protein.

b. It transfers amino acids to the ribosome for protein synthesis.

c. It forms the ribosomes.

d. It helps replicate DNA.

ceruleangnat663

Fill in the blank. Elongation during translation does NOT involve ____________.

Question 16 options:

	the translation of codons according to the genetic code
	the formation of bonds catalyzed by the ribosome
	complementary base pairing between RNA molecules
	amino acids being linked together in a polypeptide
	reading the DNA template 3' to 5'

For a given gene, what establishes the reading frame for translation?

Question 17 options:

	the location of the enhancer relative to the gene
	the first three nucleotides at the 5' end of the mRNA
	the first three nucleotides at the 3' end of the mRNA
	the start codon in the mRNA
	the location of the promoter relative to the gene

Which of the following is the LEAST likely direct consequence of a substitution mutation?

Question 18 options:

	changing the length of a protein coded for by a gene
	changing one amino acid in a protein
	creating a stop codon
	eliminating a start codon
	changing the length of the DNA molecule containing a gene

Suppose that the pre-mRNA transcript from a eukaryotic gene is 30,000 nucleotides long, and the gene codes for a sequence of 300 amino acids. What is the best explanation for the relationship between these numbers?

Question 19 options:

	only the first 900 nucleotides of the pre-mRNA transcript are translated
	it takes 100 nucleotides to specify a single amino acid
	300 of the nucleotides in the transcript are important, and the rest are "junk"
	only the last 900 nucleotides of the pre-mRNA transcript are translated
	large portions of pre-mRNA transcripts are cut out during RNA processing

Suppose an individual is born into a population with a novel mutation. Is the new mutation an evolutionary change, and why?

Question 20 options:

	no, because it is not a big enough change to count
	yes, because new mutations are always adaptive
	yes, because the appearance of a new genetic variant is a genetic change in a population
	no, because not enough individuals have the mutation for it to matter
	no, because most mutations are not adaptive

BIOC 3021 Lecture Notes - Lecture 24: X-Ray Crystallography, Transfer Rna, Ribosomal Rna

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