BIOL 201 Lecture Notes - Lecture 15: Signal Recognition Particle, Small Nuclear Rna, Transcription Bubble

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24 Feb 2018

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Messenger rna is a molecule that carries codes from the dna in the nucleus to the sites of protein synthesis in the cytoplasm (ribosomes). It is found in both the units of ribosomes and it has multiple forms. Transfer rna is an intermediary adapter molecule between mrna and amino acids. Transfer rna molecules have amino acids covalently bonded on one end and an anti-codon that can base pair with an mrna codon at the other end. Small nuclear rna (snrna) (involved in nuclear splicing) Srp rna is mediated by srp (signal recognition particle), it contains both rna and proteins. Involved in the docking of ribosomes to er. Small rna contains micro rna (mirna) and small interfering rna (sirna). These are involved in the control of gene expression. Accurate initiation of transcription requires two sites in the dna. The promoter which acts as a recognition signal and a binding site for the rna polymerase.

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Gene ExpressionQuestions

Question 1

#1) Match the following reactions to the correct step of proteinsynthesis by ribosomes.

___ Hydrolysis of GTP and disassembly of the translationcomplex.

___ binding of initiator aminoacyl-tRNA

___ formation of the peptide bond

___ translocation of ribosome

___ Use of 2 mole-equivalents of ATP and attachment of an aminoacid to a transfer RNA molecule

Answer Choices for Number #1
A. initiation step
B. elongation step
C. termination step
D. aminoacyl-tRNA synthetase reaction

Question 2

#2) Mark which of the following are needed for the synthesis ofRNA by RNA polymerase:

___ primer

___ ATP, CTP, GTP, UTP

___ dATP, dCTP, dGTP, dTTP

___ template

Question 3

#3) Mark which of the following are properties of a bacteria(prokaryotic) messenger RNA:

___		It has a cap at the 5'-end.
___		It has a poly-A tail at the 3'-end.
___		It has a 5'-untranslated region (UTR).
___		It has a 3'-untranslated (UTR) region.

Question 4

#4) Match the following RNA molecules to their respectivefunctions in the cell.

___ transfer RNA

___ ribosomal RNA

___ messenger RNA

___ small nuclear RNA (snRNA)

Answer Choices for Number #4

A. This RNA serves as the template for protein synthesis.
B. This molecule is a molecular component of ribosomes.
C. This molecule is a component of spliceosomes and serves torecognize the exon-intron junctions
D. This RNA molecule is delivers the amino acid to the ribosome andit recognizes the appropriate codons with its anticodon loop.

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13. The arms of a human and the wing of a bat are _________________ structures, composed of the same bones that have been modified for different functions.

analogous

vestigial

c.	homologous

d.	convergent

14. Xeroderma pigmentosum is an autosomal recessive genetic disorder. People who are homozygous for the disease-causing allele have skin that is damaged by exposure to ultraviolet radiation; this can lead to skin cancer at an early age. The mutation that causes this disorder is in a gene that functions:

a.	to repair DNA by excising (removing) nucleotides damaged by UV light.

b.	in lysosomes, to break down lipids that otherwise accumulate in the nervous system.

c.	to produce the UV blocking pigment melanin in the skin cells

d.	in red blood cells to carry oxygen to the skin.

15. The Amish are a religious sect descended from a small group of colonists who came to the United States over 200 years ago. Their religious beliefs have kept them isolated from society. The Amish have a much higher than average incidence of both polydactyly (extra fingers and toes) and dwarfism in their communities. This is most likely explained by:

a.	inheritance of acquired characters.

b.	the founder effect.

c.	disruptive selection.

d.	natural selection.

16. In the structure of DNA that Watson and Crick proposed, the sides of the "ladder" of the DNA molecule are always the same distance apart, making the molecule a constant width. This occurs because when the bases hydrogen bond to form the rungs of the "ladder", a:

a.	purine always pairs with a pyrimidine.

b.	purine always pairs with a purine.

c.	pyrimidine always pairs with a pyrmidine.

d.	The structure of the double helix is not determined by how the bases pair.

17. The RNA transcript of DNA that travels to the cytoplasm, carrying the instructions to make a protein, is called:

rRNA.

tRNA.

mRNA.

d.	RNA polymerase.

18. When DNA is replicated, the error rate is approximately one error for every 10,000 nucleotides copied. However, that error rate is reduced to only 1 error for every 1 billion nucleotides. The DNA sequence is "corrected" by:

a.	repeating S phase to see if the error rate is lower the second time around.

b.	enzymes that proofread the DNA and repair errors.

c.	messenger RNA during the process of transcription.

d.	Any errors made during DNA replication cannot be corrected. If errors are detected after S phase, the cell is destroyed.

19. Mendel's principle of segregation says that:

a.	when gametes are formed, each gamete receives only one allele for a particular gene.

b.	some genes are dominant to others.

c.	a testcross must be used to determine the genotype of an organism with a dominant phenotype.

d.	all of the above

20. Tay-Sachs disease is lethal before reproductive age, but the allele persists in Louisiana French Canadians because:

a.	it is a dominant allele.

b.	new mutations causing this disease are common in that population.

c.	it is not expressed in the phenotype of heterozygous individuals.

d.	the disease is contagious and can be transmitted by nonheritable means.

21. Physical features that are similar in organisms which are not closely related to each other are most likely a result of ____________. A good example of this is the similarities seen between some marsupial and placental mammals.

a.	natural selection.

b.	adaptation to similar environments

c.	convergent evolution

d.	All of the above phrases can be used to correctly fill this blank.

22. In humans, which of the following sex chromosome compliments could be found in males?

23. The proteins that are associated with eukaryotic chromosomes:

a.	help to package the DNA within the nucleus.

b.	are involved in gene expression, through binding with the DNA.

c.	may be replicating or transcribing the DNA.

d.	All of these are true of proteins that are associated with eukaryotic chromosomes.

24. A sequence of DNA nucleotides that contains the information to produce a single protein is a(n):

codon.

gene.

c.	polypeptide.

d.	anticodon.

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BIOL 201 Lecture Notes - Lecture 15: Signal Recognition Particle, Small Nuclear Rna, Transcription Bubble

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