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Biology 2581B Lecture Notes - Lecture 3: Centromere, Mendelian Inheritance, Meiosis

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School
Western University
Department
Biology
Course
Biology 2581B
Professor
Susanne Kohalmi

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Document Summary

The flow of information in biological systems is illustrative of the central dogma of molecular biology, which states that dna is transcribed into mrna that is subsequently translated into protein. Dna acts as double-stranded storage molecule that is based on complementarity of 5"-3" and 3"-5" strands. During transcription, a single-stranded mrna (complementary to a dna template) is later translated into protein (chain of amino acids) where the n-terminus and c-terminus correspond to the 5" end and 3" end of mrna respectively. A gene is the basic unit of biological information and represents a specific segment of dna at a specific location in the genome (on a region of a chromosome) that serves as a unit of function in organisms. During translation, ribosomes commence at the 5" end with the start codon (aug) and complete the process at the 3" end (from n to c-terminus).

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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

Which of the following did Erwin Chargaff observe?

A)

Base composition changes as the organism ages.

B)

Base composition of DNA does not vary from one species toanother.

C)

In all species the number of adenines equals the number ofguanines.

D)

In all species A + T = G + C.

E)

DNAs isolated from different tissues of the same species havethe same base composition.

The melting temperature (Tm) of a DNA duplex is:

A)

the temperature at which double-stranded nucleic acids degradeinto free nucleotides.

B)

the temperature at which double-stranded DNA is toosingle-stranded to ever renature back to double strands.

C)

the temperature at which double-stranded DNA is completelymelted.

D)

the temperature at which double-stranded DNA has become 50%single-stranded.

E)

the temperature at which double-stranded DNA begins to melt.

Given your knowledge and the descriptions of each of thesemethods, which of the following does NOT rely on the ability ofnucleic acids to hybridize with each other?

A)

Southern blotting for the detection of specific DNA fragmentsthat have been separated by gel electrophoresis.

B)

Colony blot hybridization to identify a specific sequence from acollection of sequences that have been inserted into bacteria.

C)

Northern blotting for the detection of specific RNA fragmentsthat have been separated by gel electrophoresis.

D)

A DNA oligonucleotide microarray incubated with probes made fromcDNA.

E)

Western blotting for the detection of specific proteins thathave been separated by gel electrophoresis.

Which of the following is a possible reason why DNA uses thymineinstead of uracil?

A)

Cytidine is deaminated to uracil so it would be difficult forany repair mechanism to differentiate between uracil that belongsin the sequence and uracil that resulted from deamination.

B)

Adenine is deaminated to uracil so it would be difficult for anyrepair mechanism to differentiate between uracil that belongs inthe sequence and uracil that resulted from deamination.

C)

When uracil is bound to a deoxyribose it will become morereactive, forming covalent bonds with other bases.

D)

None of the above.

Which of the following is an enzyme used in cloning to breakcovalent bonds?

A)

DNA ligase

B)

Restriction endonuclease

C)

Reverse transcriptase

D)

DNA polymerase I

E)

Alkaline phosphatase

Which of the following could you use to remove the 5' phosphatesafter cleavage of a plasmid with a single type of restrictionenzyme to ensure that the plasmid would not simply fuse backtogether upon addition of ligase?

A)

Reverse transcriptase

B)

Alkaline phosphatase

C)

DNA ligase

D)

DNA polymerase I

E)

Restriction endonuclease

Which of the following would you use to create a cDNA librarythat you would not use for a genomic library?

A)

Alkaline phosphatase

B)

Reverse transcriptase

C)

Restriction endonuclease

D)

DNA ligase

E)

DNA polymerase I

A plasmid vector typically has which of the followingfeatures?

A)

An origin of replication

B)

A selectable marker to ensure that the only bacteria growingcontain the intact or recombinant vector.

C)

Unique restriction sites for insertion of DNA.

D)

Small size to facilitate entry into the cell and biochemicalmanipulation of the DNA.

E)

All of the above are features of plasmid vectors.

Which of the following is FALSE of genomic or cDNAlibraries?

A)

Genes represented in cDNA libraries include control sequencesthat direct transcription.

B)

cDNA libraries contain cDNAs made from mRNA.

C)

Genomic libraries contain fragments of genomic DNA that aregenerated by partial digests with restriction enzymes.

D)

Genomic libraries usually contain large fragments and are likelyto be constructed in YAC or BAC vectors.

E)

cDNA libraries contain sequences from expressed genes only.

Which of the following is NOT a typical component of apolymerase chain reaction (PCR)?

A)

dNTPs

B)

DNA containing the sequences to be amplified

C)

DNA ligase to connect the fragments together

D)

Primers complementary to each end of the sequence to beamplified

E)

Heat stable Taq polymerase

How can a fusion protein be formed?

A)

Site-directed mutagenesis where a fragment is replaced with asynthetic sequence containing the altered DNA sequence.

B)

Two proteins can recombine in the bacterial cell to form a newhybrid protein.

C)

Portions of two different genes are ligated together to create anew hybrid gene. When expressed the gene product is a fusion of thetwo gene products.

D)

Using oligonucleotide-directed mutagenesis to introduce specificmutations that cause the expressed protein to fuse to otherproteins.

E)

A portion of the gene can be removed to form a shorter gene andtherefore a shorter protein.

Why is green fluorescent protein (GFP) so useful in visualizingfusion proteins in eukaryotes?

A)

The GFP protein recognizes and binds to fusion proteins allowingthe location of the fusion protein to be determined.

B)

The reaction is only dependent on the presence of GFP and oneother cofactor.

C)

It is easily cloned and expressed in bacterial cells.

D)

The presence of just a few molecules of GFP fusion proteins canbe sufficient for observing the proteins microscopically allowingthe study of its location and movements in the cell.

E)

It is derived from fire flies, which are easy to cultivate inthe lab.

You wish to determine the cellular location of a protein butunfortunately it is not particularly antigenic (can t develop astrong antibody response). How could you solve this problem?

A)

Create a fusion protein with an epitope tag that can bevisualized by incubation with fluorescently tagged antibody to theepitope.

B)

Create a fusion with green fluorescent protein (GFP).

C)

Express the protein as a fusion with biotin. The addition of GFPwill cause fluorescence.

D)

A and B might work.

E)

A, B, and C might work.

F)

None of the above will work.

A positive result for the yeast two-hybrid analysis means thefollowing:

A)

The proteins that you are studying can be made into fusionproteins, but do NOT interact with each other within the nucleus ofyeast.

B)

A fusion protein containing the Gal4p activation domain, hasbound to RNA polymerase resulting increase transcription ofnumerous genes, including the reporter gene, and formation ofcolonies.

C)

Two fusion proteins, one containing the Gal4p binding sitedomain and one containing the Gal4p activation domain, haveinteracted through their Gal4p domains resulting in transcriptionof the reporter gene.

D)

Two fusion proteins interact with each other and because of theGal4p binding site domain and the Gal4p activation domain containedin each fusion protein, the reporter genes are activated and thecells die resulting in no colonies.

E)

The colonies growing are expressing the two fusion proteins, butthe two proteins have not interacted with each other.

Which of the following is the approximate size of the humangenome?

A)

3 Gm

B)

300 Kb

C)

3 Mb

D)

3 Gb

E)

3 Mm

Which of the following is correct about the structure orlocation of genes?

Question 22 options:

A)

Prokaryotic genes typically possess their own regulatorysequences that only control expression of a single gene.

B)

Eukaryotic genes often encode introns that are spliced outbefore translation.

C)

Eukaryotic genes are mostly located at the telomeres and thecentromeres of chromosomes.

D)

Eukaryotic genes are typically arranged in operons.

E)

Prokaryotic genes often encode exons that are spliced out beforetranslation

DNA Structure and Function LabReport

  1. DNA Structure
  2. Which two scientists are credited with discovering DNA?
  1. Name the nitrogen bases that are purines.
  1. Which nitrogen base pairs with thymine?
  1. List the three components of a nucleotide.
  1. DNA Replication
  2. What is the purpose of DNA replication?
  1. How many times does replication occur in the life of acell?
  1. In the Lab, Exercise 2, the original strand on the left had thebases shown below. Input the new bases that correctly pair with theoriginal strand.

Original

New

C

A

G

T
  1. RNA Structure
  1. Describe the structure and function of RNA.
  1. Refer to Exercise 3 and record the bases of the RNA strandproduced from the replicated DNA strand.

DNA

RNA

C

A

G

T

  1. Record the differences between DNA and RNA in the tablebelow.

DNA

RNA

Sugars

Bases

Strands

  1. RNA Synthesis

  1. The process of assembling RNA is called _________.
  1. How is replication different from transcription?
  1. Refer to Exercise 4. Write the letters for the base sequence ofmRNA in the spaces below DNA. Note that the order is reversed;start with the 3’ end of the DNA strand and the 5’ end of the mRNAstrand. Transcription is DNA to mRNA. Note RNA contains Uracilinstead of Thymine; There is no thymine in RNA.

DNA

3’

C

G

T

C

G

T

C

C

A

A

T

T

5’

mRNA

5’

3’

  1. Protein Synthesis

  1. What type of RNA provides amino acids to build polypeptidechains?

  1. If a mRNA strand has the bases 5’ CUC 3’, what amino acid willbe translated? Refer to the printable chart in Exercise 5.

  1. Where in the cell does translation occur?
  1. Genes

  1. What could be the problem if there is a change in the basesequence of a gene as it is passed down to the offspring?
  1. Give an example of a disorder that results from changes in theamino acid sequence.
  1. What causes sickle cell anemia?
  1. Gene Cloning
  1. What is the function of a plasmid?
  1. Print the document from Lab, Exercise 6. Complete the activityalong with the video demonstration. Sign, date, and take an imageof your final product and include with this lab report.