Oral Revalida Flashcards
Biological agent
- any organism, virus, or toxin
- has the potential to cause
harm, disease, or some form of biologically mediated damage. - infectious pathogens like bacteria, viruses, fungi, or toxins produced by living organisms.
Biological material
- any substance derived from living organisms
- cells, tissues, proteins, enzymes, DNA, RNA, or any other biological component.
Standard Precautions
“Treat ALL human blood samples and other body fluids as infectious”
- Healthcare professionals and laboratory workers are trained to
handle these samples with utmost care, using appropriate personal protective equipment (PPE) .
- Proper handling, labeling,
transportation, and disposal procedures are followed strictly to minimize accidental
exposure or contamination.
- fundamental part of infection control practices
Biosecurity
Deals with preventing intentional harm or misuse of biological agents
Biosafety
Preventing accidental exposure or harm to
individuals and the environment when handling biological agents
Similarities of Biosecurity and Biosafety
Crucial in managing biological materials responsibly and safely in various settings.
Serves as the storage of genetic information
DNA
intermediary role in
translating that information into proteins.
RNA
What are the differences between DNA and RNA?
- Both DNA and RNA are crucial in the central dogma of molecular biology, where DNA
serves as the storage of genetic information, and RNA plays an intermediary role in
translating that information into proteins. - DNA consists of a double-stranded helical structure. While RNA is usually single-stranded.
Two types of nitrogenous bases that are essential
components of nucleotides, the building blocks of DNA and RNA.
Pyrimidines and purines
Pyrimidines
- smaller, single-ring nitrogenous bases
- cytosine (C), thymine (T, found in DNA), and uracil (U, found in RNA)
- consist of a six-membered ring made up of four carbon atoms and two nitrogen atoms.
Purines
- larger, double-ring nitrogenous bases
- They consist of a six-membered ring fused (attached) to a five-membered ring.
- two purine bases: adenine
(A) and guanine (G).
DNA replication
- Process by which a cell makes an exact copy of its DNA before
cell division. - It occurs during the S (synthesis) phase of the cell cycle
Steps of DNA replication process
- Unwinding
- Initiation
- Primer Binding
- Elongation
- Proofreading and Correction
- Ligase Activity
- Termination
Unwinding (DNA Replication process)
- DNA double helix is unwound by enzymes called helicases.
- These enzymes break the hydrogen bonds between the complementary base pairs, separating the two DNA strands and creating a replication fork.
Initiation (DNA Replication process)
- Enzymes known as DNA polymerases recognize specific sequences called origins of replication along the DNA strands.
- These polymerases initiate
the replication process by binding to the DNA at these sites.
Primer Binding (DNA Replication process)
- RNA primers are synthesized by another enzyme called primase.
- it provides a starting point for DNA polymerases to begin adding new nucleotides.
Elongation (DNA Replication process)
- DNA polymerases start adding complementary nucleotides to the
exposed DNA strands. They can only add nucleotides in the 5’ to 3’ direction, so one strand (the leading strand) is synthesized continuously in the direction of the replication fork. - The other strand (the lagging strand) is synthesized discontinuously in short segments called Okazaki fragments, as it must be synthesized in the opposite direction of the replication fork.
Proofreading and Correction (DNA Replication process)
- DNA polymerase is utilized
- It adds nucleotides, they can recognize and correct mistakes in base pairing,
ensuring accuracy in the newly synthesized DNA.
Ligase Activity (DNA Replication process)
Once the new nucleotides are added, DNA ligase seals the nicks
or gaps between the Okazaki fragments, joining them together into a continuous
strand.
Termination (DNA Replication process)
- The replication continues bidirectionally along the DNA until the
entire DNA molecule is replicated. - The process ends when the replication forks
meet, and the entire DNA molecule has been duplicated.
After DNA replication, what will happen?
- Two identical DNA molecules are formed, each containing one original
strand and one newly synthesized strand. - This semiconservative replication ensures
genetic continuity and fidelity in daughter cells during cell division.
Protein synthesis
Process by which cells generate new proteins based on the
genetic information encoded in DNA.
Main stages of Protein Synthesis
- Transcription
- Translation
Stages of Transcription
- Initiation
- Elongation
- Termination
Initiation (Transcription)
- The process begins in the nucleus of eukaryotic cells or the
cytoplasm of prokaryotic cells. - RNA polymerase, along with various
transcription factors, binds to a specific region of DNA called the
promoter. - Promoter marks the start of transcription.
Elongation (Transcription)
- RNA polymerase moves along the DNA strand, unwinding the double helix and synthesizing a complementary RNA strand.
- The enzyme
adds complementary RNA nucleotides (adenine, cytosine, guanine, and
uracil) based on the DNA template. - RNA nucleotides pair with their
complementary bases on the DNA template
What will happen after the Transcription process?
The newly formed RNA molecule, known as messenger RNA (mRNA), carries the genetic information from the DNA in the nucleus to the cytoplasm, where protein synthesis continues.
initiation (Translation)
- mRNA binds to a ribosome, and the process of
translation begins. - Ribosomes serve as the site for protein synthesis.
- Initiation factors and the start codon (AUG) on the mRNA signal the
recruitment of the first transfer RNA (tRNA) molecule carrying the amino
Elongation (Translation)
- Ribosome moves along the mRNA
strand in a 5’ to 3’ direction, reading the genetic code in sets of three
nucleotides called codons. - Each codon corresponds to a specific amino acid carried by a tRNA molecule. - The ribosome facilitates the binding of
the appropriate tRNA carrying the correct amino acid to the mRNA codon
via complementary base pairing.
Peptide Bond Formation (Translation)
- As each tRNA brings its amino acid in sequence, a peptide bond forms between adjacent amino acids, catalyzed by the ribosome.
- Forms a growing polypeptide chain.
Termination (Translation)
- Translation continues until a stop codon (UAA, UAG, or UGA)
is encountered on the mRNA which signal the end of protein synthesis. - Release factors bind to the
ribosome, causing the completed polypeptide chain to be released
DNA extraction
- Process of isolating DNA from cells or tissues in a biological
sample. - Allows scientists to study and analyze the genetic material.
Sample Collection
Biological samples, such as blood, saliva, tissues, plants, bacteria, or cells,
are collected and stored properly to preserve the DNA.
Cell lysis
- The first step involves breaking open the cells to release the DNA.
- This is achieved through a process called lysis, where cells are disrupted using various methods.
Methods for Cell Lysis
Mechanical methods like grinding, crushing, or homogenization, and
chemical methods using detergents or enzymes can be employed to break
down cell membranes and release the DNA.
Removal of Proteins and RNA:
Enzymes like proteases are used to degrade proteins, and RNases break down RNA, leaving only DNA in the solution.
DNA precipitation
- To separate the DNA from other cellular components, a precipitation step
is performed. - This involves adding a salt solution (such as sodium chloride) and alcohol (like ethanol or isopropanol) to the DNA-containing solution. This causes the DNA to clump together and precipitate out of the solution.
DNA Purification
- The precipitated DNA is then collected by centrifugation, forming a pellet
at the bottom of the tube. - The supernatant (liquid above the pellet) is discarded,
- The DNA pellet is washed with alcohol to remove any
remaining impurities or salts.
Resuspension
The purified DNA pellet is then resuspended or dissolved in a suitable
buffer or solvent, such as Tris-EDTA (TE) buffer or distilled water, to obtain
a concentrated DNA solution
DNA EXTRACTION
- Sample Collection
- Cell Lysis
- Removal of Proteins and RNA
- DNA Precipitation
- DNA Purification
- Resuspension
RNA isolation
- Process of extracting and purifying RNA molecules from cells, tissues, or biological samples.
- Allowing scientists to study gene expression, RNA structure, and function.
RNA ISOLATION STEPS
- Sample Collection and Preservation
- Cell Lysis and RNA Stabilization
- Separation of RNA from DNA and Proteins
- RNA Extraction and Purification
- RNA Precipitation and Washing
- RNA Resuspension
Sample Collection and Preservation (RNA isolation)
- Collect the biological sample (cells, tissues, blood, etc.) and preserve it
immediately to prevent RNA degradation. - RNA is highly susceptible to
degradation by RNases (ribonucleases) present in the environment.
Cell Lysis and RNA Stabilization (RNA Isolation)
- Break open the cells to release the RNA through mechanical disruption (homogenization, grinding), chemical lysis (detergents), or enzymatic lysis.
- To prevent RNA degradation, RNA stabilizing agents like RNase inhibitors
or chaotropic salts are often added to the lysis buffer.
Separation of RNA from DNA and Proteins (RNA Isolation)
- RNA needs to be separated from other cellular components like proteins and DNA.
- Enzymes like DNase (to degrade DNA) and proteases (to degrade
proteins) are used to remove DNA and proteins from the RNA solution.
RNA Extraction and Purification (RNA isolation)
- RNA extraction typically involves the addition of an organic solvent (e.g.,
phenol-chloroform) and subsequent centrifugation to separate the RNA
from other components. - After extraction, the RNA-containing aqueous phase is carefully collected
and transferred to a new tube.
RNA Precipitation and Washing (RNA isolation)
The RNA is precipitated by adding alcohol (such as isopropanol or
ethanol) which RNA molecules forms visible pellet, as it remove residual salts and contaminants.
RNA Resuspension (RNA isolation)
Purified RNA pellet is then dissolved or resuspended in a suitable
buffer or solvent, such as RNase-free water or RNase-free buffers, to
obtain a concentrated RNA solution.