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(2020-21 BY2MB1) Molecular Genetics > Intro > Flashcards

Intro Flashcards

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1
Q

What are genetic materials?

A

Materials that play fundamental roles in the composition of living organisms

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2
Q

What are the two types of genetic materials?

A

Deoxyribonucleic acid (DNA) and Ribonucleic acid (RNA)

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3
Q

Where are genetic materials located?

A

DNA:

  • Located in the nucleus of eukaryotic cells (animals and plants) and the cytoplasm of prokaryotic cells (bacteria)
  • Also located in the mitochondria

RNA:

  • Located in the Cytosol
  • Located in Ribosomes
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4
Q

How does DNA differ from RNA?

Draw the bases in each

A
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5
Q
A
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6
Q

What is the difference between a nucleoside and a nucleotide?

A

A building block of DNA or RNA, a nucleotide is made up of the sugar, nitrogenous bases, and phosphate while the nucleoside is made up of sugar and base only

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7
Q

Explain the structure of DNA

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8
Q

Draw a table of comparision of the structure, function and length between DNA and RNA

A
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9
Q

Draw a table of comparison between DNA and RNA

Consider;

  • Bases
  • Base pairs
  • Sugars
  • Location
  • Reactivity
  • Ultraviolet (UV) sensitivity
A
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10
Q

Demonstrating DNA is the Genetic Material:

Describe the methodolgy of the Pneumococcus bacterium transformation experiment by Fred Griffiths

A

Virulent Type 1:

  •  disease causing
  •  protected by slime capsule
  •  giving smooth appearance
  •  Causes pneumonia

Non-virulent Type 2:

  •  harmless
  •  lost its slime capsule
  •  rough appearance
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11
Q

Describe the outcome (findings) of the Pneumococcus bacterium transformation experiment by Fred Griffiths

A
  1. He took smooth virulent type 1 bacteria and injected into mouse→The mouse died When examined, live type 1 smooth virulent bacteria was found
  2. Injected the mouse with type II rough, avirulent bacteria→ The mouse survived Immune system took care of the bacteria
  3. Griffith took a heat killed sample of the type 1 bacteria and injected it into mouse→ The mouse survived
  4. A sample of type I heat killed bacteria was mixed with type II rough avirulent bacteria→The mouse died. Live type 1 smooth bacteria was found upon examination
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12
Q

Describe the conclusion of the Pneumococcus bacterium transformation experiment by Fred Griffiths

A
  • Concluded something from heat killed cell converted rough avirulent type II cell to type I one cell
  • We now know that something was gene for type I slim capsule
  • At the time, the gene was not known
  • Griffith just knew something was causing the conversion and he called it ‘ transforming principle’
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13
Q

How did Avery discover the bio-molecule in S (type 1, virulent bacteria) that can transform R (type 2, avirulent bacteria)?

A
  1. Remove the lipids and carbohydrates from a solution of heat-killed S cells. Only proteins, RNA and DNA remain
  2. Subject the solution to treatments of enzymes that destroy either the proteins, RNA or DNA
  3. Add a small portion of each sample to a culture containig R cells.
  4. Observe whether transformation has occured by testing the presence to virulent S cells

Conclusion: Transformation cannot occur unless DNA is present. Therfore, DNA must be the hereditary material.

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14
Q

Why do we need to obtain genetic materials?

A
  • To study the genetic causes of disease, e.g. cystic fibrosis
  • Development of diagnostics and drugs
  • Carrying out forensic science
  • Sequencing genomes
  • Detecting bacteria and viruses in the environment
  • Determining paternity
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15
Q

Why are model systems/organisms important?

A

Model Systems/organisms for Molecular/Cellular Biology are chosen because they are convenient to study or are of practical importance.

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16
Q

Give examples of model organisms

A
  • Bacteria (E. coli)
  • Yeast (Saccharomyces cerevisiae)
  • Round worms (Caenorhabditis elegans)
  • Fruit fly (Drosophila melanogaster)
  • Zebrafish (Danio rerio)
  • Animals (e.g. rodents, pigs, primates……)
  • Humans
17
Q

What makes an organism amenable to molecular biology research?

A
  • Location in the tree of life
  • Ability to obtain candidate genes via either sequencing or cloning
  • Ability to determine gene expression patterns at different stages of the organism’s development
  • Ability to grow or obtain large numbers of organisms
  • Ability to knockout or functionally inactive genes to ascertain the role of the gene plays in the organism’s growth, development, metabolism etc.
18
Q

What are some of the different methods of obtaining genetic material from model organisms?

A
  • Breaking open the cells to release DNA/RNA
  • Separate DNA/RNA from protein:

Traditional Phenol extraction

Column-based extraction: Silica and anion exchange resins

  • DNA purification:

Removal of RNA using ribonuclease

DNA purification via ethanol precipitation

19
Q

What are some other sources of genetic material (artificial DNA)?

A
  • Amplification
  • Reverse transcription of mRNA
20
Q

What is PCR?

A

Polymerase Chain Reaction (PCR):

  • A laboratory technique for DNA replication that allows a “target” DNA sequence to be selectively amplified.
  • PCR can use the smallest sample of the DNA to be cloned and amplify it to millions of copies in a short period of time
21
Q

Breifly describe how PCR works

A

First cycle:

  1. Start with a region of double stranded chromosomal DNA to be amplified
  2. Separate the DNA strands and add a DNA oligonucleotide primer
  3. DNA is synthesised in this first cycle to produce two double-stranded DNA molecule

Second cycle:

  1. Separate the DNA strands and anneal the primer
  2. DNA is synthesised in this second cycle to produce four double stranded DNA molecules

Third cycle:

  1. Separate the DNA strands and anneal the primer
  2. DNA is synthesised in this this third cycle to produc eight double-stranded DNA molecules
22
Q

What is RT-PCR?

A

Reverse transcriptase PCR (RT-PCR):

A laboratory technique combining reverse transcription of RNA into DNA (in this context called complementary DNA or cDNA) and amplification of specific DNA targets using PCR.

23
Q

Briefly describe how RT-PCR works

A
  1. From a tissue sample lyse the cells and purify the mRNA
  2. Hybridise the mRNA with a poly(T) primer
  3. Make a DNA copy with the reverse transcriptase enzyme
  4. Degrade RNA with RNase H enzyme
  5. Synthesise a complementary DNA strand using DNA polymerase; the RNA fragment acts as a primer
  6. A double stranded cDNA copy of the original mRNA is produced
24
Q

What are the advantages of using mRNA?

A
  • Represents only contiguous coding material - introns occupy 9/10ths of a eukaryote gene. Hence using mRNA can get a gene into a vector
  • mRNA free from wild type promoters
  • mRNA represents the genes most actively coding for proteins - only 2% of genomic material is involved in protein coding

(2020-21 BY2MB1) Molecular Genetics (12 decks)

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