BIOL1003 Lecture Notes - Lecture 14: Open Reading Frame, Covalent Bond, Catalytic Cycle

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Translation

The genetic code

The rules used to convert RNA information into protein information

oCombinations of 4 bases must specify 20 amino acids

o3 bases per word (codon) is the minimum number that will give 20

possibilities

Crick and Brenner demonstrates that the code was a triplet code

o3 bases= 1 codon= 1 amino acid

Amino acids have multiple codons to code for it, which is a protective mechanism

Breaking the genetic code

Marshall Nirenberg and JH Matthaei

Got a cell-free protein mixture which has all the enzymes and chemicals needed for

life except for nucleic acids

Then made synthetic RNA- polyuracil

Features of the genetic code

Degenerate and redundant, but unambiguous

Start and stop codons

Non-overlapping (only reading one frame at a time)

Universal (almost)

Three possible reading frames

Reading the genetic code

Conversion of a base sequence to an amino acid sequence requires an

adaptor molecule- bases and amino acids are not complementary

The adaptor molecule is a small RNA molecule called a transfer RNA

(tRNA)

Hydrogen bonding between complementary base pairs makes the

interaction between a codon and tRNA anticodon specific

Structure of a tRNA molecule

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Protein synthesis is catalysed by the ribosome

The ribosome has two subunits

Each subunit consists of proteins and RNA molecules

(called ribosomal RNA, or rRNA)

Three types of RNA participate in protein synthesis

mRNA- encodes a protein

tRNA- adaptor molecule that converts a sequence of

codons to a sequence of amino acids

rRNA- a component of the ribosome

Product molecule of transcription can be mRNA, tRNA

or rRNA but only mRNA codes for proteins

Formation of a peptide bond

Joining amino acids by covalent bonds

Things only add to the C end

Protein synthesis on the ribosome

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Document Summary

The rules used to convert rna information into protein information: combinations of 4 bases must specify 20 amino acids, 3 bases per word (codon) is the minimum number that will give 20 possibilities. Crick and brenner demonstrates that the code was a triplet code: 3 bases= 1 codon= 1 amino acid. Amino acids have multiple codons to code for it, which is a protective mechanism. Got a cell-free protein mixture which has all the enzymes and chemicals needed for life except for nucleic acids. Non-overlapping (only reading one frame at a time) Conversion of a base sequence to an amino acid sequence requires an adaptor molecule- bases and amino acids are not complementary. The adaptor molecule is a small rna molecule called a transfer rna (trna) Hydrogen bonding between complementary base pairs makes the interaction between a codon and trna anticodon specific. Each subunit consists of proteins and rna molecules (called ribosomal rna, or rrna)

Related Questions

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

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

The TATA-binding protein (TBP) binds to the TATA box sequence in eukaryotic promoters. What is its function in transcriptional initiation?

It blocks access of RNA polymerase to the promoter, until removed by general transcription factors.

It is the subunit of prokaryotic RNA polymerase that is required to recognize promoters.

It modifies histones so nucleosomes can be removed from DNA for transcription.

It bends and partly unwinds DNA at a promoter.

The genetic code is said to be âdegenerateâ because

there are more codons than amino acids.

there are more amino acids than codons.

different organisms use different codons to encode the same amino acid.

some codons specify more than one amino acid.

Three general mechanisms appear to be responsible for the conversion of proto-oncogenes to oncogenes

overexpression, point mutations, deletions

inversions, translocations, methylation

familial, sporatic, phosphorylation

None of the above account for the conversion of proto-oncogenes into oncogenes

Transcriptional control of genes that acts by regulating the continuation of transcription is called

induction

attenuation

antitermination

negative inducible control

The genetic code is fairly consistent among all organisms. The term used to describe this consistency is

The F, G, and H loci are linked in the order written. There are 30 cM between F and G and 30 cM between G and H. If a plant Ff Gg Hh is testcrossed, what proportion of the progeny will be ff gg hh, assuming no interference?

DNA synthesis is always from 5â to 3â because

replication must be continuous

the strands are antiparallel

primers lack 3â to 5â exonuclease activity

In the ZZ-ZW sex-determination system, if an AaBb female was crossed to an individual of genotype Aa Bb, what is the probability of a female offspring with the two dominant traits given by alleles A and B? Assume A and B are dominant alleles.

BIOL1003 Lecture Notes - Lecture 14: Open Reading Frame, Covalent Bond, Catalytic Cycle

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