01:447:380 Lecture Notes - Lecture 4: Spliceosome, Consensus Sequence, Polyadenylation

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purpleant173

3 Aug 2018

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Special sequences tell the spliceosome where to cut. There are consensus sequences around the intron/exon borders that orient the spliceosom so it cuts at the right places. Alternative splicing allows one gene to make different proteins in different tissues. Guide rnas bind to the mrna and cause it to be cleaved and edited. Nucleotides can be added or deleted, and one nucleotide can be substituted for by anoth. The resultant mrna base sequence and protein"s amino acid sequence will not match th that are predicted from the gene"s coding sequence. The ribosome reads the mrna three bases at a time. Each codon instructs the ribosome to add one amino acid to the growing polypepti. A stop codon terminates translation and releases the polypeptide. The polypeptide is folded, adorned with chemical side groups and sent to where it needs. Some polypeptides join with others to form multimers.

Related Questions

Which of the following statements is true?

A.) Molecules of mRNA are translated from 3' to 5'

B.) For each amino acid found naturally in proteins, there is only one codon in the genetic code.

C.)The Shine-Dalgarno sequence is found in the promoters of genes in both prokaryotic and eukaryotic organisms.

D.) During translation, both strands of DNA are used as templates for the construction of two new strands of protein.

E.) When considering the initiation of transcription one often finds consensus sequences, such as the TATA box, located in the region of the DNA where RNA polymerase(s) bind.

If one is testing a goodness of fit to a 9:3:3:1 ratio, how many degrees of freedom would be associated with the Chi-square?

not enough information to determine

Which of the following choices does not describe a type of posttranslational modification of proteins?

The amino terminal methionine may be removed.

Glycoproteins are produced by the attachment of phosphates to newly synthesized proteins.

Precursor proteins are cleaved and trimmed by protease enzymes to produce a functional protein.

Molecular chaperones help proteins fold correctly.

Amino acids in the amino terminal of the protein can be acetylated.

A eukaryotic DNA sequence that affects transcription at distant promoters is called a(n)

long distance promotor

regulator

operon

enhancer

DNA methylation may be a significant mode of genetic regulation in eukaryotes. Meythylation refers to

altering RNA polymerase activity by adding methyl-groups

changes in DNA-DNA hydrogen bonding

altering translation activity via methylated tRNAs

adding methyl groups to certain cytosines in DNA

If a nucleotide lacks a 3â-OH group, what will happen?

itâs transformed into RNA

another nucleotide can bond at the 3â site during replication

replication will halt

no effect

Which of the following describe posttranscriptional modifications commonly seen in mRNA of eukaryotes?

5â capping, 3â-poly-A tail addition, splicing

3â capping, 5â poly-A tail addition, splicing

heteroduplex formation

5â capping, 3âpolyA tail addition, removal of exons

In birds, females are the heterogametic sex. This means that

females have chromosomes in pairs.

emales produce eggs.

females determine the gender of their offspring.

males have two identical sex chromosomes (ZZ)

An anticodon on a tRNA has the sequence 5'âGCAâ3'. What would be the effect on translation if the G in the anticodon were mutated to a U?

The anticodon could pair to the serine codon 5'âUCAâ3', and a cysteine would be incorporated at all points where a serine should have been incorporated.

The anticodon could pair to the threonine codon 5'âACUâ3', and a threonine would be incorporated at all points where a cysteine should have been incorporated.

The anticodon could pair to the serine codon 5'âAGUâ3', and a serine would be incorporated at all points where a cysteine should have been incorporated.

The anticodon could pair to the stop codon 5'âUGAâ3', and instead of stopping translation, a cysteine would be incorporated and translation could continue.

Cell Biology (#1-5)

1) What does a non-synonymous DNA mutation cause?

a) No amino acid change

b) A change in the reading frame of the mRNA

c) The substitution of an amino acid

d) Creates a premature termination codon

e) All of the above

2) What does a non-sense DNA mutation cause?

a) No amino acid change b) Alters the normal reading frame of the mRNA

c) The substitution of an amino acid

d) Creates a premature termination codon

e) All of the above

3) If you sequence the genome of 100 cells from different tissues of the same multicellular organism. How do you expect the sequences to be?

a) 10% identical c)100% identical

b) 50% identical d) 100% different e) will depend on the tissue selected

4) Multicellular organisms are comprised of a variety of cells with different morphologies and different functions. Which is the underlying mechanism that leads to the generation of diverse cell in one organism?

a) The expression of all genes in all cell types

b) The duplication of the genome in certain cell types

c) The elimination of specific group of genes from different cell types

d) The differential expression of particular sets of genes requires for a particular cellular phenotype

e) All of the above

5)You are growing bacteria which can use lactose and glucose. The culture medium has lactose, which induces transcription of the enzymes required to use lactose. If you add glucose to the medium. What do you expect to happen?

a) The bacteria will keep using lactose

b) The bacteria will shut down the Lac operon and use glucose

c) The bacteria will stop growing

d) The bacteria will die

e) The bacteria will use both lactose and glucose

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01:447:380 Lecture Notes - Lecture 4: Spliceosome, Consensus Sequence, Polyadenylation

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