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Molecular Biology Basics

Topic updated on 02/29/16 10:45pm
Nuclear structures
  • Chromosomes
    • 46 in humans (23 pairs)
      • 22 pairs of autosomes, 1 pair of sex chromosomes
    • contains DNA and RNA
  • Deoxyribonucleic acid (DNA)
    • Thymine, adenine, guanine, and cytosine
      • adenine linked to thymine (A-T)
      • guanine linked to cytosine (G-C)
    • double stranded
    • strands linked together by phosphate groups
    • 2' hydrogen group
    • regulates cell division
    • mRNA is produced from DNA
      • an exon is portion of gene that codes for mRNA
      • exon is expressed
  • Gene
    • segment of DNA that contains the information needed to synthesize a protein
    • determines the unique biologic qualities of a cell
    • exon
      • coding information 
    • intron
      • does not code for mRNA
  • Ribonucleic acid (RNA)   
    • usually single stranded but can be double stranded
      • double stranded RNA found in some viruses
      • certain interactions between single stranded RNA in human cells can form double stranded RNA
    • has ribose sugar
    • Uracil, adenine, guanine, and cytosine (no thymine)
    • less stable than DNA
    • 2' hydroxyl group
    • can be located in either the nucleus or cytoplasm
    • messenger RNA (mRNA)
      • translates DNA information into protein
    • ribosomal RNA (rRNA)
      • major part of ribosome, which helps synthesize a protein
    • transfer RNA (tRNA)
      • transfers amino acids to mRNA
Genetic Terms
  • Nucleotides
    • thymine, adenine, guanine, and cytosine
  • Codon
    • sequence of three nucleotides
    • each codon correlates to one of the 20 amino acids
    • linking of the amino acids create a protein
  • Gene promotor
    • regulatory portion of DNA that controls initiation of transcription
  • Gene enhancers
    • site on DNA that transcription factors bind to
    • regulate transcription
  • Transcription 
    • DNA => mRNA
  • Translation 
    • mRNA => protein
  • Haploid
    • Haploid is the amount of DNA in a human egg or sperm cell (half the amount of DNA in a normal cell)
Cell Cycle
  • Phases 
    • G0
      • represents a "stable" phase
      • cells are diploid (2N) in the G0 and G1 phases
    • G1
      • initial growth phase
      • cells are diploid (2N) in the G0 and G1 phases
    • S
      • DNA replication/synthesis phase 
      • cells become tetraploid (4N) at the end of S and for the entire G2 phases
    • G2
      • gap phasse
      • cells become tetraploid (4N) at the end of S and for the entire G2 phases
    • M
      • mitosis phase
Apoptosis
  • Defined as programmed cell death
  • Requires a series of intracellular signaling events
  • Different from cell lysis - where a cell releases its contents into the surrounding area
  • One hallmark of cancer is the cell's loss of apoptosis 
Research techniques
  • Agarose gel electrophoresis
    • separates DNA based on size
    • DNA is negatively charged
    • gel exposed to electric field
    • smaller pieces moves through gel faster
  • Southern blotting
    • restriction enzymes cut up DNA
    • separate on agarose gel
    • identifies DNA sequence
  • Northern blotting
    • restriction enzymes cut up RNA
    • separate on agarose gel
    • identifies RNA sequence
  • Western blotting
    • SDS-PAGE gel
    • identifies protein
  • DNA ligation
    • combining different DNA fragments not found together naturally to create recombinant DNA
  • Plasmid vector
    • an extrachromosomal element, often circular, that can replicate and be transferred independently of the host chromosome 
    • one example of the function of a plasmid is antibiotic resistance
    • can be introduced into bacteria in the process of transformation
  • Polymerase chain reaction (PCR)
    • DNA => DNA
    • a molecular biology tool used to generate many copies of a DNA sequence 
    • uses "primers" specific to a segment of DNA
    • requires temperature-mediated enzyme DNA polymerase
  • Reverse transcription polymerase chain reaction (RT-PCR) 
    • RNA => DNA
    • variant of polymerase chain reaction (PCR) used in molecular biology to generate many copies of a DNA sequence from fragments of RNA
    • RNA strand is first reverse transcribed into its DNA complement
    • amplification of the resulting DNA proceeds using polymerase chain reaction

 

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Qbank (6 Questions)

TAG
(OBQ07.157) What is the post-amplification product of reverse transcription polymerase chain reaction (RT-PCR)? Topic Review Topic

1. RNA
2. DNA
3. Protein
4. Mitochondria
5. Immunoglobulins

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TAG
(OBQ07.178) DNA replication occurs during which phase of the cell cycle? Topic Review Topic

1. M
2. S
3. R
4. G1
5. G2

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TAG
(OBQ05.122) All of the following statements regarding RNA are true EXCEPT? Topic Review Topic

1. RNA uses thymine while DNA uses uracil
2. RNA may be either single or double-stranded
3. RNA has a hydroxyl group at the 2' position in the ribose
4. DNA has a hydrogen group at the 2' position in the deoxyribose
5. RNA helix is of A-Form

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TAG
(OBQ04.195) Tumor necrosis factor receptor 1 is involved in which of the following cellular events? Topic Review Topic

1. Replication
2. Agenesis
3. Apoptosis
4. Senescence
5. Ectopy

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TAG
(OBQ04.199) Which of the following statements best describes a plasmid? Topic Review Topic

1. An extrachromosomal, circular piece of DNA that replicates independently of host DNA
2. An extrachromosomal, linear piece of RNA which replicates independently of host DNA
3. A protein which promotes transcription of DNA to RNA
4. A gene which leads to cancerous cell transformation
5. A gene which suppresses cancerous cell transformation

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