Biology Chapter on Mutations and Lab Safety
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Questions and Answers

Which type of mutation results in a premature stop codon?

  • Silent mutation
  • Nonsense mutation (correct)
  • Synonymous mutation
  • Missense mutation

A silent mutation changes the amino acid sequence of a protein.

False (B)

A mutation that results in the loss of a portion of a chromosome is called a ______.

deletion

Match the types of mutations with their definitions:

<p>Point mutation = A change in a single nucleotide Chromosomal mutation = Involves changes in chromosome structure Loss-of-function mutation = Causes a decrease or loss of gene product Gain-of-function mutation = Increases the gene product or its activity</p> Signup and view all the answers

Which type of point mutation does not affect the amino acid sequence?

<p>Synonymous mutation (D)</p> Signup and view all the answers

What is an example of a chromosomal mutation?

<p>Duplication</p> Signup and view all the answers

What should be done with gloves worn during exercises with biohazardous materials?

<p>Place them in a biohazard bin (A)</p> Signup and view all the answers

Reusable materials that require sterilization should be washed in the sink after use.

<p>False (B)</p> Signup and view all the answers

What should you never do with a wrong or unmarked reagent?

<p>Use it</p> Signup and view all the answers

When pouring concentrated acids, always pour the acid into ___ and stir continuously.

<p>water</p> Signup and view all the answers

Match the waste type with its proper disposal method:

<p>Broken glass = Sharps container Non-contaminated waste paper = Regular trash Used scalpel blades = Sharps container Bacterial culture tubes = Autoclave</p> Signup and view all the answers

What must be done with chemical bottles during transport?

<p>Use appropriate carrying arrangements (B)</p> Signup and view all the answers

It is safe to pour any chemical into a bottle regardless of the label.

<p>False (B)</p> Signup and view all the answers

Why is good hand washing technique important during laboratory exercises?

<p>To prevent contamination and contact with hazardous materials</p> Signup and view all the answers

Items that are to be sterilized should be placed in the ___ after use.

<p>autoclave</p> Signup and view all the answers

What is meant by 'parfocal' in relation to microscopes?

<p>The object will remain in focus when switching from low to high power. (A)</p> Signup and view all the answers

The field of view is square in shape when looking through a microscope.

<p>False (B)</p> Signup and view all the answers

What should you do to find an object before viewing it under high power?

<p>Always find the object under the low power field first.</p> Signup and view all the answers

The limit of resolution for a microscope using visible light is approximately _____ nm.

<p>300</p> Signup and view all the answers

Match the following types of sections with their descriptions:

<p>Longitudinal section = A cut through the long axis of an organ Transverse section = A cut along a horizontal plane dividing an organ into superior and inferior parts</p> Signup and view all the answers

What is the purpose of using the fine adjustment knob when focusing a microscope?

<p>To precisely focus the specimen at high power. (D)</p> Signup and view all the answers

The field of view increases as you switch from low power to high power lenses.

<p>False (B)</p> Signup and view all the answers

How do you calculate the size of a single cell using the low power field diameter?

<p>Diameter of the field of view divided by number of cells that fit.</p> Signup and view all the answers

Using _____ light as a light source can improve resolution to 100 nm.

<p>ultraviolet</p> Signup and view all the answers

What is the recommended procedure for moving to a higher power objective?

<p>Check if the object is centered and adjust if necessary. (C)</p> Signup and view all the answers

What does gene amplification refer to?

<p>The number of tandem copies of a locus is increased (A)</p> Signup and view all the answers

Translocation involves the exchange of broken pieces between non-homologous chromosomes.

<p>True (A)</p> Signup and view all the answers

What are mutation hotspots characterized by?

<p>Elevated rates of recombination and higher susceptibility to mutations.</p> Signup and view all the answers

Inherited changes in ______ DNA can disrupt the mitochondria's energy generation.

<p>mitochondrial</p> Signup and view all the answers

Match the following genetic concepts with their definitions:

<p>Interchromosomal insertion = Insertion on another non-homologous chromosome Intrachromosomal insertion = Insertion in a different region of the same chromosome Expanding trinucleotide repeat = Normal number of repeated sequences is increased Copy number variation = Alteration in the number of copies of a particular gene or locus</p> Signup and view all the answers

What are the two main types of nucleic acids?

<p>DNA and RNA (A)</p> Signup and view all the answers

Adenine always binds to uracil in RNA.

<p>False (B)</p> Signup and view all the answers

What is the role of ATP in cellular processes?

<p>ATP provides energy for cellular processes.</p> Signup and view all the answers

In DNA, cytosine always binds with ______.

<p>guanine</p> Signup and view all the answers

What is the primary focus of molecular biology methods?

<p>Explore molecular activity (C)</p> Signup and view all the answers

Match the following terms with their definitions:

<p>Technique = A man-made strategy or tactic Method = An approach or pathway Nucleic acids = Molecules that store and transmit genetic information CRISPR-Cas9 = A technology for editing genes</p> Signup and view all the answers

DNA synthesis involves the creation of RNA molecules.

<p>False (B)</p> Signup and view all the answers

Name one common method used in molecular biology.

<p>Nucleic acid methods</p> Signup and view all the answers

The process of ______ involves the extraction of DNA from cells.

<p>DNA extraction</p> Signup and view all the answers

Which of the following is NOT a type of DNA mutation?

<p>Protein mutation (B)</p> Signup and view all the answers

What is the total magnification when using a 10X ocular lens with a 40X objective lens?

<p>400 (A)</p> Signup and view all the answers

Immersion oil is required when using lower magnification lenses.

<p>False (B)</p> Signup and view all the answers

What is the main purpose of a stereomicroscope?

<p>To observe the surfaces of large specimens and provide 3D information.</p> Signup and view all the answers

The field of view is the area of the slide that you see when looking through the microscope's ______.

<p>eyepiece</p> Signup and view all the answers

Match the following objective lenses with their respective magnifications:

<p>Scanning Power = 4X Low Power = 10X High Power = 40X Oil Immersion = 100X</p> Signup and view all the answers

Which statement correctly describes the use of immersion oil in microscopy?

<p>Only necessary for high power objectives (A)</p> Signup and view all the answers

The eyepiece lens is responsible for projecting the image onto the detector.

<p>True (A)</p> Signup and view all the answers

What is the primary purpose of a phase contrast microscope?

<p>To enhance contrast in transparent specimens (B)</p> Signup and view all the answers

Fluorescent microscopy uses light from below the sample to excite fluorescent molecules.

<p>False (B)</p> Signup and view all the answers

What type of light source is commonly used in fluorescence microscopy?

<p>UV light, high-pressure mercury or xenon vapor lamps, lasers, or LED sources</p> Signup and view all the answers

In a phase contrast microscope, light that passes through thicker parts of the cell is held up relative to the light that passes through thinner parts of the __________.

<p>cytoplasm</p> Signup and view all the answers

Match the microscopy method with its main characteristic:

<p>Phase Contrast Microscopy = Enhances contrast in transparent specimens Fluorescent Microscopy = Uses specific wavelengths to excite fluorophores Epifluorescence Microscopy = Light source from above the sample Light Microscopy = Basic visualization of stained specimens</p> Signup and view all the answers

What is the benefit of using fluorescent microscopy over traditional light microscopy?

<p>It has a superior signal to noise ratio (D)</p> Signup and view all the answers

Phase contrast microscopy requires standard light objective lenses without any special modifications.

<p>False (B)</p> Signup and view all the answers

What allows a fluorescent molecule to emit light after absorbing it?

<p>The ability to absorb light at a specific wavelength and then emit it at a higher wavelength</p> Signup and view all the answers

Fluorescent microscopes often use __________ of filters to separate excitation and emission wavelengths.

<p>combinations</p> Signup and view all the answers

What bond occurs between a slightly positive hydrogen and a slightly negative oxygen or nitrogen?

<p>Hydrogen bond (B)</p> Signup and view all the answers

Nonpolar molecules attract water, making them hydrophilic.

<p>False (B)</p> Signup and view all the answers

What is the pH value of a neutral solution?

<p>7</p> Signup and view all the answers

Acids release ______ ions when dissolved in water.

<p>hydrogen</p> Signup and view all the answers

Match the following types of biomolecules with their main components:

<p>Carbohydrates = Monosaccharides Proteins = Amino acids Lipids = Fatty acids Nucleic acids = Nucleotides</p> Signup and view all the answers

Which of the following describes a buffer?

<p>A solution that resists changes in pH (D)</p> Signup and view all the answers

The pH scale ranges from 1 to 10.

<p>False (B)</p> Signup and view all the answers

What ion is a characteristic of strong bases when dissolved in water?

<p>hydroxide ion (OH−)</p> Signup and view all the answers

Water is often referred to as a universal ______ because of its ability to dissolve many substances.

<p>solvent</p> Signup and view all the answers

What is the main purpose of a DNA microarray?

<p>To detect the expression of thousands of genes simultaneously (C)</p> Signup and view all the answers

Somatic mutations cannot be inherited by offspring.

<p>True (A)</p> Signup and view all the answers

What type of mutation occurs due to environmental factors and increases mutation frequency?

<p>Induced mutations</p> Signup and view all the answers

The cost of gene synthesis is approximately $_____ per base pair.

<p>0.09</p> Signup and view all the answers

Match the following types of mutations with their characteristics:

<p>Germline mutations = Occur in gametes and can be inherited Somatic mutations = Occur in body cells and are not inherited Spontaneous mutations = Arise naturally during DNA replication Induced mutations = Result from environmental factors</p> Signup and view all the answers

What type of reaction links subunits together into macromolecules?

<p>Dehydration reaction (D)</p> Signup and view all the answers

Lactose is a polysaccharide.

<p>False (B)</p> Signup and view all the answers

What are the three components of an amino acid?

<p>Amino group, carboxyl group, R group</p> Signup and view all the answers

Triglycerides are composed of one glycerol and ______ fatty acids.

<p>three</p> Signup and view all the answers

Match the following types of carbohydrates with their descriptions:

<p>Monosaccharides = Single sugar molecules like glucose Disaccharides = Two sugar molecules joined together Polysaccharides = Long chains of glucose units Oligosaccharides = Short chains of monosaccharides</p> Signup and view all the answers

Which structure is primarily found in plasma membranes?

<p>Phospholipids (A)</p> Signup and view all the answers

Denaturation of a protein can occur at normal physiological temperatures.

<p>False (B)</p> Signup and view all the answers

What is the primary function of carbohydrates?

<p>Energy source</p> Signup and view all the answers

Lipids are generally soluble in ______ solvents.

<p>nonpolar</p> Signup and view all the answers

What bonds amino acids together in a protein?

<p>Peptide bonds (C)</p> Signup and view all the answers

Which type of muscle is involuntarily controlled and found in the walls of hollow organs?

<p>Smooth Muscle (B)</p> Signup and view all the answers

What feature of cardiac muscle fibers helps prevent fatigue during contractions?

<p>Complete relaxation between contractions (D)</p> Signup and view all the answers

Skeletal muscles are primarily responsible for which of the following functions?

<p>Supporting the body against gravity (C)</p> Signup and view all the answers

Which type of muscle tissue is characterized by tubular and striated fibers that are voluntarily controlled?

<p>Skeletal Muscle (D)</p> Signup and view all the answers

What is the role of calcium ions (Ca2+) in muscle contraction?

<p>They activate troponin, causing tropomyosin to uncover myosin-binding sites. (B)</p> Signup and view all the answers

What is the shape of smooth muscle fibers?

<p>Cylindrical with pointed ends (D)</p> Signup and view all the answers

What is the first step in the sliding filament theory of muscle contraction?

<p>The myosin heads attach to actin, forming cross-bridges. (C)</p> Signup and view all the answers

What structural feature distinguishes skeletal muscle fibers from other types?

<p>Cross-striations (D)</p> Signup and view all the answers

What happens to acetylcholine (ACh) after it is released into the synaptic cleft?

<p>It diffuses across the cleft and binds to receptors on the sarcolemma. (A)</p> Signup and view all the answers

Which statement best explains a general feature of muscle tissue?

<p>Muscle tissue is essential for movement of the organism and internal materials. (A)</p> Signup and view all the answers

What is the consequence of ATP binding to myosin heads during muscle contraction?

<p>It causes myosin to release from actin. (A)</p> Signup and view all the answers

What is the primary function of the neuromuscular junction?

<p>To transmit nerve signals from motor neurons to muscle fibers. (D)</p> Signup and view all the answers

What is the term for the muscle that is relaxing during a contraction?

<p>Antagonist (B)</p> Signup and view all the answers

Which of the following is NOT a cellular component of a muscle fiber?

<p>Cardiomyocytes (A)</p> Signup and view all the answers

What provides energy for muscle contraction within muscle fibers?

<p>Glycogen (B)</p> Signup and view all the answers

Which component of a muscle fiber serves as the plasma membrane?

<p>Sarcolemma (C)</p> Signup and view all the answers

Thick myofilaments within muscle fibers are primarily composed of which protein?

<p>Myosin (D)</p> Signup and view all the answers

What is the role of myoglobin in muscle fibers?

<p>To bind oxygen (D)</p> Signup and view all the answers

Which muscle type is responsible for voluntary movements in the body?

<p>Skeletal muscle (C)</p> Signup and view all the answers

What would happen if both the agonist and antagonist muscles contracted simultaneously?

<p>No movement (D)</p> Signup and view all the answers

What is the main function of the sarcoplasmic reticulum in muscle fibers?

<p>Calcium storage (A)</p> Signup and view all the answers

In a skeletal muscle fiber, myofibrils are made up of smaller units called what?

<p>Myofilaments (B)</p> Signup and view all the answers

What is the primary role of fascia in the muscular system?

<p>To cover muscles and extend to become tendons (A)</p> Signup and view all the answers

What describes the relationship between agonist and antagonist muscles?

<p>Agonists are responsible for the primary movement while antagonists perform the opposite action. (A)</p> Signup and view all the answers

Which structure serves to protect internal organs from physical damage?

<p>Muscles (A)</p> Signup and view all the answers

What happens to ATP during muscle contraction?

<p>It breaks down, releasing heat. (C)</p> Signup and view all the answers

Where is the origin of a muscle typically located?

<p>On the stationary bone (B)</p> Signup and view all the answers

Which structure often acts as a cushion between tendons and bones?

<p>Bursae (A)</p> Signup and view all the answers

In the context of muscle pairs, what does the term 'insertion' refer to?

<p>The attachment on the moving bone (D)</p> Signup and view all the answers

What is the function of small, fluid-filled sacs known as bursae?

<p>To provide lubrication and reduce friction (B)</p> Signup and view all the answers

Which of the following best describes a fascicle?

<p>A bundle of muscle fibers surrounded by connective tissue (C)</p> Signup and view all the answers

What is the primary function of myoglobin in muscle fibers?

<p>To store oxygen for muscle contraction (B)</p> Signup and view all the answers

What structure releases Ca2+ in response to impulses conveyed by T tubules?

<p>Sarcoplasmic reticulum (B)</p> Signup and view all the answers

Which statement describes the role of the sliding filament model in muscle contraction?

<p>Thin filaments slide past thick filaments, causing sarcomeres to shorten. (D)</p> Signup and view all the answers

What is the composition of thick myofilaments in skeletal muscle?

<p>Myosin with a head structure (C)</p> Signup and view all the answers

Which statement correctly defines the Z lines in a sarcomere?

<p>They represent the end of the myofibril segments. (A)</p> Signup and view all the answers

What happens to the I band during muscle contraction according to the sliding filament model?

<p>It shortens as the sarcomere contracts. (C)</p> Signup and view all the answers

How are sarcomeres organized within myofibrils?

<p>Linearly, extending between Z lines (C)</p> Signup and view all the answers

What is the main energy source that supports muscle contraction?

<p>ATP that is regenerated during contraction (C)</p> Signup and view all the answers

What is the primary role of thin myofilaments in muscle contraction?

<p>To enable cross-bridge formation with myosin (B)</p> Signup and view all the answers

What is the H band within the A band of a sarcomere composed of?

<p>Only thick myofilaments (B)</p> Signup and view all the answers

Flashcards

Point Mutation

A mutation affecting only one or a few nucleotides in a DNA sequence.

Substitution Mutation

A point mutation where one nucleotide base is replaced by another.

Insertion Mutation

A point mutation where one or more nucleotides are added to the DNA sequence.

Deletion Mutation

A point mutation where one or more nucleotides are removed from the DNA sequence.

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Loss-of-Function Mutation

A mutation that decreases or eliminates the activity of a gene product.

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Chromosomal Deletion

A chromosomal mutation where a segment of a chromosome is lost.

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Chromosomal Duplication

A chromosomal mutation where a segment of a chromosome is repeated.

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Biohazard Disposal

Gloves and items exposed to biohazardous materials are placed in a biohazard bag for potential sterilization.

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Sharps Container

Used for disposing of broken glass, needles, blades, and other sharp items.

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Regular Trash

Non-contaminated waste (paper, trash) is placed here.

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Autoclave

A device for sterilizing items placed in a biohazard bag to eliminate potential contamination.

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Reusable Materials

Items like culture tubes, glass rods, and certain instruments that are sterilized or washed after use.

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Chemical Container Safety

Always keep chemical containers closed to prevent spills and maintain their integrity.

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Unmarked Reagents

Do not use reagents that are unmarked or of unknown composition.

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Proper Chemical Handling

Carry chemicals in appropriate containers, label should always face upward, and avoid putting the wrong chemicals in a container.

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Acid Dilution

Always dilute acids by pouring the acid slowly into the water, stirring continuously, never the reverse.

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Interchromosomal insertion

A gene insertion into a non-homologous chromosome.

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Intrachromosomal insertion

A gene insertion within the same chromosome, in a different location.

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Genome Structural Variation

Mutations (like inversions and translocations) that change the genome's structure.

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Gene amplification

Increased number of copies of a gene.

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Mitochondrial DNA mutation

Inherited changes in mtDNA affecting growth, development, and function.

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Nitrogenous base

A molecule with nitrogen atoms that form part of a nucleic acid.

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Nucleic acid

Large biological molecules, either DNA or RNA, containing genetic instructions.

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DNA

Deoxyribonucleic acid, a crucial part of the genetic material.

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RNA

Ribonucleic acid, involved in gene expression and protein synthesis.

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Complementary base pairing

Adenine with Thymine, and Cytosine with Guanine, fundamental to DNA structure.

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Molecular biology methods

Techniques used to study the molecular basis of biological activity.

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DNA cloning

Making multiple copies of a specific segment of DNA.

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DNA extraction

The process of isolating DNA from a sample.

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CRISPR-Cas9 system

A powerful gene editing tool.

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DNA synthesis

The process of creating DNA molecules.

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Parfocal microscope

A microscope where an object in focus under low power is almost in focus under high power.

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Focusing Procedure

Steps to use a microscope correctly, emphasizing low power view first then high power.

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Field of View (FOV)

The circular area visible through microscope eyepiece.

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Low Power Field Diameter (LPD)

Diameter of the field of view when using the lowest power objective lens, measured in micrometers.

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Micrometer

Unit of measurement used for microscopic objects, equal to one-millionth of a meter.

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Longitudinal Section

A cut through the long axis of an organ.

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Cross Section

Cut through the horizontal plane of an organ, creating a superior-inferior division.

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Resolution

A lens' ability to distinguish between closely located objects, improving with shorter wavelengths of light.

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Oil Immersion Lens

A lens used to enhance resolving power. Placing oil on top of the specimen.

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High Power Objective

The highest magnification objective lens on a compound light microscope, improving detail.

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Microscope Objective Lens

A glass lens used to magnify the image of a specimen viewed under a microscope.

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Total Magnification

The overall magnification of a microscope, calculated by multiplying the magnification of the ocular lens and objective lens.

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Field of View

The circular area of the specimen that is visible through the microscope eyepiece.

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Oil Immersion Lens

A high magnifying objective lens needing immersion oil to improve resolution, especially for high magnifications.

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Compound Light Microscope

A microscope that uses multiple lenses for high magnification and visual observation of specimens.

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Stereomicroscope

A type of microscope used to observe specimens at low magnification which requires 3 dimensional information.

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Microscope Immersion Oil

A transparent liquid used to increase light transmission and resolution with high-power objective lens.

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Phase Contrast Microscope

A microscope type to enhance contrast in transparent specimens, like unstained cells.

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Fluorescent Microscope

A microscope using UV, visible, or near-infrared light to excite fluorescent molecules and image the emitted light.

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Light Source (Fluorescence)

High-intensity sources like mercury or xenon lamps, or lasers, used to excite fluorophores.

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Fluorophore

A molecule absorbing and emitting light at specific wavelengths, creating contrast.

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Side-illumination

Light source's position next to the specimen, producing shadows.

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Objective Lens

Lens close to the specimen, magnifying and focusing light.

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Phase Condenser

Specialized component of a phase contrast microscope, controls light.

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Epifluorescence

Microscopy technique where the objective lens both condenses & projects light.

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Filters (Fluorescence)

Components that isolate excitation and emission light.

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DNA synthesis

Process of creating DNA molecules, often used to make artificial genes.

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DNA array

A tool used to simultaneously detect the expression of many genes in a sample.

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Mutations

Changes in DNA sequences, affecting gene structure.

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Spontaneous mutations

Mutations that happen naturally, at a low frequency, due to DNA instability or errors during replication.

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Induced mutations

Mutations caused by external factors, like chemicals or radiation, increasing mutation frequency.

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Water as a Solvent

Water dissolves many substances, creating solutions where solutes are mixed within it.

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Hydrophilic Molecules

Polar molecules that are attracted to water.

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Hydrophobic Molecules

Nonpolar molecules that are NOT attracted to water.

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Acid

A substance that releases hydrogen ions (H+) when dissolved in water.

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Base

A substance that takes up hydrogen ions (H+) or releases hydroxide ions (OH−).

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pH Scale

A scale measuring acidity or basicity (alkalinity) of a solution.

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Buffer

A solution that resists changes in pH when acids or bases are added.

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Biomolecules

The four major types of organic molecules in the body: carbohydrates, lipids, proteins, and nucleic acids.

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Hydrogen Bond

Attraction between a slightly positive hydrogen atom and a slightly negative atom (oxygen or nitrogen).

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Buffer Capacity

Ability of a solution to resist significant pH changes.

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Dehydration Reaction

A chemical reaction that removes water from molecules, linking subunits to form larger molecules.

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Hydrolysis Reaction

A chemical reaction that adds water to break down macromolecules into smaller subunits.

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Monosaccharide

A single sugar molecule, serving as a basic unit for carbohydrates.

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Disaccharide

Two monosaccharides joined together by a dehydration reaction.

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Polysaccharide

Long chains of glucose monomers joining together to form a complex carbohydrate.

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Amino Acid

The building block of proteins, differing by their unique side chains.

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Triglyceride

A type of lipid made of one glycerol molecule and three fatty acids.

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Phospholipid

A type of lipid with a hydrophilic head and hydrophobic tails, crucial for cell membranes.

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Protein Denaturation

The disruption of a protein's 3D shape due to extreme conditions (heat or pH).

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Lipid

A biomolecule insoluble in water, including fats, oils, and steroids.

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Types of Muscle Tissue

There are three types of muscle tissue: smooth, cardiac, and skeletal.

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Smooth Muscle Function

Smooth muscle controls involuntary movements in internal organs and blood vessels.

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Cardiac Muscle Function

Cardiac muscle is responsible for the rhythmic contractions of the heart.

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Skeletal Muscle Function

Skeletal muscle moves bones and supports the body.

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Skeletal Muscle Structure

Skeletal muscles are made up of long, tubular, multinucleated fibers that are striated.

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Muscle Fiber Structure

Muscle fibers contain structures such as myofibrils, which are responsible for contracting.

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Neuromuscular Junction

The neuromuscular junction is where nerve signals trigger muscle contractions.

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Muscle Contraction

The activation of tension-generating structures within a muscle fiber which causes movement.

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ATP Breakdown in Muscles

ATP (adenosine triphosphate) is chemically broken down, releasing energy that is converted into heat and used for muscle contraction.

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Muscle Protection of Organs

Muscles form a protective layer around internal organs, cushioning them from injury, especially the abdominal wall.

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Skeletal Muscle Fascicle

A bundle of muscle fibers, surrounded by connective tissue.

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Muscle Fiber

Individual muscle cell that is part of a fascicle.

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Fascia

Connective tissue layer that surrounds and separates muscles, and extends to form tendons.

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Tendons

Connective tissue that connects muscle to bone.

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Origin (Muscle)

The stationary attachment point of a muscle to a bone, while the muscle is contracting.

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Insertion (Muscle)

The movable attachment point of a muscle to a bone, where the muscle pulls when it contracts.

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Agonist Muscle

The muscle that is contracting during a movement.

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Antagonist Muscle

The muscle that is relaxing or lengthening during a movement.

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Muscle Types

The three types of muscles in the human body are smooth, cardiac, and skeletal.

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Skeletal Muscle Location

Skeletal muscles are attached to bones and other structures throughout the body.

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Skeletal Muscle Function

Skeletal muscles cause movement of bones and support body posture.

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Sarcolemma

The plasma membrane of a muscle fiber.

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Sarcoplasm

The cytoplasm of a muscle fiber.

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Sarcoplasmic Reticulum

Endoplasmic reticulum in a muscle cell, stores calcium.

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Myofibrils

Contractile units within muscle fibers.

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Myofilaments

The smaller cylinders that compose myofibrils.

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Motor Neuron

A nerve cell that stimulates muscle fibers to contract.

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Neuromuscular Junction

Where an axon terminal (end of a nerve) nears a muscle fiber's membrane (sarcolemma).

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Synaptic Cleft

The small gap between the axon terminal and the sarcolemma.

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Acetylcholine (ACh)

Neurotransmitter released at the neuromuscular junction causing muscle contraction.

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Sliding Filament Theory

Mechanism where actin and myosin filaments slide past each other during muscle contraction.

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Sarcoplasm

The cytoplasm of a muscle fiber, containing organelles like myofibrils.

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Myoglobin

A red pigment that stores oxygen crucial for muscle contraction.

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T tubule

An extension of the muscle cell membrane, conveying impulses for calcium release.

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Sarcoplasmic reticulum

The smooth ER of a muscle fiber, storing calcium ions for muscle contraction.

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Myofibril

A bundle of myofilaments contracting during muscle contraction.

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Myofilament

An actin or myosin filament, causing muscle striations and contraction.

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Sarcomere

The segment between Z-lines in a myofibril, the basic unit of muscle contraction.

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Sliding Filament Model

The mechanism of muscle contraction where filaments slide past each other.

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I band

Light band in a sarcomere, containing only thin filaments.

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A band

Dark band in a sarcomere, containing overlapping thick and thin filaments.

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Study Notes

Biotechniques (BMS 34010A)

  • Course offered Fall semester 2023-2024
  • Instructor: Dr. Tania Tahtouh
  • Email: [email protected]

Basic Principles: Biosafety in the Laboratory

  • The lab setting presents hazards that need consideration during any exercise.
  • Laboratory safety ensures protection of all personnel and safe equipment use.
  • The disposal of contaminated materials and chemicals follows strict protocols.

Potential Laboratory Hazards

  • Science labs present hazards like corrosive chemicals, sharp tools/glass, and open flames.
  • Extreme caution is needed when handling open flames (e.g., Bunsen burners).
  • Attention should be paid to materials near the flame.
  • Infectious organisms also pose a threat; microorganisms are classified into biosafety levels (BSL).
  • BSL levels (1, 2, 3, 4) are based on transmission ease and pathogenicity.
  • Most undergraduate labs use BSL 1 organisms (cause no disease).
  • Working with BSL 4 organisms demands extensive safety measures (e.g., specialized labs).

Standard Practices in the Laboratory

  • Lab coats are crucial for contamination protection (microorganisms or corrosive substances).
  • Coats should be appropriately sized for coverage without restricting movement.
  • Lab coats are not chemical suits; remove immediately if on fire.
  • Gloves should not touch surfaces outside the lab (door handles, etc.).
  • Do not consume food, drink, or chew gum in the lab.
  • Eating and drinking in a lab is prohibited to avoid hazardous substances.
  • Do not apply makeup or adjust contacts while in a lab.
  • The lab bench must remain clean.
  • Cell phones, purses, bags, and other personal items must be stowed away from the benchtop.
  • Never leave active experiments unattended, especially if they involve heating or visible reactions.
  • Disinfect the lab bench before and after each experiment to prevent contamination.
  • Correct hand washing techniques are essential; review module techniques.
  • Follow correct hygiene procedures. Do not run or sit on benches.
  • Tie back long hair and secure loose clothing when working with open flames.
  • Goggles, safety glasses, or face shields are compulsory during UV light or chemical procedures.
  • Safety glasses should be worn over glasses.
  • Always wear closed-toed shoes to prevent chemical spills or dropped sharp objects from injuring feet.
  • Know the location of lab safety equipment (eyewash, chemical shower, first aid kit, fire extinguisher).
  • Adhere to chemical hygiene plans and policies.

Laboratory Safety Equipment

  • Chemical hygiene plans protect personnel from potential health hazards of using chemicals.
  • Fume hoods or biosafety cabinets must be used according to instructions or lab procedures.

Lab Emergencies

  • In the event of a lab emergency (spill, injury, accidents), immediately notify the instructor.
  • Report any spills, injuries, broken equipment, or other emergencies.

Biohazard Bin

  • Biohazardous waste (non-reusable items, infectious organisms, body fluids) must be placed in appropriately-labelled bins or bags.
  • Gloves worn while handling the biohazardous waste must also be disposed of in the bin.
  • Sterilization using an autoclave is an option before final disposal.

Sharps Containers & Trash Cans

  • Sharps containers are for disposing of broken glass, needles, used scalpel blades, or other sharp objects.
  • Non-contaminated waste (paper, etc.) should be put in regular trash cans.

Reusable Materials

  • Reusable materials requiring sterilization should be placed into the autoclave after use.
  • These include tubes, glass rods or instruments requiring sterility for use.
  • Materials not requiring sterilization can be washed in the sink (dissection tools, glassware, staining trays, etc).

General Guidelines for Handling Chemicals

  • Keep chemical containers closed (dust, vapor escape).
  • Never use wrong or unmarked reagents. If unsure, dispose of properly.
  • Do not carry chemicals by their neck, instead use appropriate containers (e.g., buckets, trolleys).
  • Always ensure labels face upward to prevent spills damaging the label.
  • Never put a chemical into a container unless it is the correct chemical type.
  • Handle concentrated acids with specialized precautions; add acid to water, gently stir.

The Importance of Hand Washing

  • Good hand washing practices are essential in lab settings, especially in microbiology.
  • Hands can be contaminated by infectious organisms, chemicals, stains, and potentially dangerous materials.
  • Wash hands before, after, and whenever there's possible contamination.

Steps for Correct Hand Washing

  • Remove all jewelry (rings, bracelets, etc.).
  • Wet hands with clean running water and apply soap.
  • Rub hands together to generate a lather.
  • Scrub hands thoroughly, including fingers, backs of hands, and under nails (20 seconds).
  • Rinse hands.
  • Dry hands using a clean towel or air drying.

Metric Systems

  • The SI (International System of Units) system is the preferred measurement system used by scientists.
  • The English system is still used in the US and uses different units of measurement.
  • The SI system is based on the number 10.
  • SI system prefixes (e.g., kilo, hecto, deca, deci, centi, milli, micro) indicate multiples or fractions of 10.
  • Units are essential in specifying measurements.

Microscopy: Types and Principles

  • Biological objects, viewed with microscopes, vary in scale.
  • Microscopes allow observation of small biological objects.
  • Microscopy comes in various types, including:
  • Light microscopy (compound, binocular dissecting/stereomicroscope, phase contrast, fluorescent, confocal)
  • Electron microscopy (transmission electron, scanning electron).

Learning Outcomes: Microscopy

  • Students should identify and understand the function of compound light microscope parts.
  • Calculate total magnification using objective and ocular lenses.
  • Follow microscope use procedures.
  • Recognize the difference between low power and high power microscopy.
  • Define field of view (at low and high power), longitudinal & cross sections, and resolution.

Light Microscope

  • The simplest light microscope is a single magnifying glass.
  • The specimen requires minimal preparation.
  • Focusing is done via moving the lens/specimen relative to each other.
  • Light source can typically be the sun, ambient indoor light.
  • Detection mechanism is the human eye.
  • Recording involves hand-drawing.

Compound Light Microscope

  • Modern light microscopes have multiple combined lenses (condenser, objective, and eyepiece).
  • Light source is often a lamp, focused onto the specimen.
  • The image is magnified through the objective lens, and then projected onto an eye or digital camera.

The Parts of the Microscope and Their Function

  • Functions of various microscope components (body tube, arm, stage, stage clips, coarse adjustment knob, fine adjustment knob, base, etc.).

Lenses and Their Magnifications

  • Scanning (4x), low (10x), high (40x), oil immersion (100x).
  • Total magnification is calculated by multiplying the ocular and objective lens magnifications.

Field of View

  • The field of view is the observable area when looking through the microscope.
  • The FOV is circular and its size varies based on the objective lens magnification.

Microscope Immersion Oil

  • Immersion oil is typically needed with high magnification objective lenses.

Stereomicroscope, Phase Contrast, Fluorescent Microscope

  • Stereomicroscope: used for observing large specimens, suitable for micromanipulation and dissection.
  • Phase contrast microscope: enhances contrast for transparent/colorless samples (e.g., viewing unstained cells).
  • Fluorescent microscope: widely used for highly specific labelling of cellular components. Microscopy method with typically white (fluorescent) on a black (non-fluorescent) background.

Fluorescent Proteins & Stains

  • Fluorescent proteins and stains are used to specifically label and visualize components of the cells.

Immunofluorescence

  • Technique involving specific antibodies conjugated with fluorescent dyes.

Confocal Microscopes

  • Laser scanning confocal microscopes create optical sections of the specimen by scanning point by point.

Electron Microscopes

  • Electron microscopes use electron beams for magnifying and focusing on the sample.

Rules for Microscope Use

  • Keep both eyes open when viewing.
  • Avoid touching the eyepiece with eyelashes.
  • The lowest power objective should be positioned at the start and end of the observation.
  • Use regular paper tissue/wipes for cleaning lenses.
  • The microscope should not be tilted while viewing.
  • Parts of the microscope should not be removed.
  • Always find the object under low power before viewing using high power.

Focusing the Microscope

  • Always begin focusing with the scanning power objective (4x).
  • Use the coarse adjustment knob to lower the stage and slowly raise the stage while looking through the eye piece until the object comes into view.
  • Use the fine adjustment knob to sharpen focus if needed.

Low Power Field Diameter (LPD)

  • Measure the diameter of the field of view using the 10x (low power) objective and a ruler.
  • Convert the measurement to micrometers (mm to µm).
  • Calculate the size of a single cell by dividing the LPD by the number of cells.

Longitudinal Section vs Cross Section

  • Longitudinal sections: cut through the long axis of an organ/structure.
  • Transverse (cross) sections: cut through a horizontal plane.

Resolution

  • Resolution is its ability to distinguish between two close objects in the specimen.
  • Shorter wavelengths allow higher resolution.
  • Visible light has a limit of about 300 nm, oil immersion allows 200 nm.

DNA Synthesis

  • Artificial gene synthesis allows making DNA molecules without relying on natural DNA templates.
  • Exact nucleotide sequence can be designed.
  • Gene synthesis is often priced per base pair.

DNA Microarray

  • DNA microarray (microarray) is a laboratory tool for analyzing gene expression with high throughput.
  • The technique uses labeled DNA or RNA probes to detect target genes at different expression levels in the genome. Complementary sequences within a DNA molecule tend to bind one another.

Mutations and Causes

  • Mutations are alterations within DNA sequences that change the structure of a gene.
  • Mutations can be spontaneous (chemical instability or errors during replication) or induced by environmental factors, such as chemical mutagens or ionizing radiation.

Main Types of Mutations

  • By the cell type, mutations can be classified as germline (in gametes, inheritable) or somatic (in other body cells).
  • By size, mutations can be classified as point mutations (substitutions, insertions, deletions), chromosomal (deletion, duplication, inversion, translocation), and copy number variations (CNVs).

Point Mutations:

  • Substitution (incorrect base added during replication).
  • Insertion (one or more extra nucleotides).
  • Deletion (one or more nucleotides skipped during replication).
  • Types of point mutations (missense, nonsense, synonymous, and neutral).

Point Mutations: Types

  • Missense (codon codes for a different amino acid).
  • Nonsense (premature stop codon).
  • Synonymous (same amino acid).
  • Neutral (no change to function).

Point Mutations: Categorization

  • Loss-of-function mutations: reduced/absent gene product or activity.
  • Gain-of-function mutations: increased gene product or activity, causing potentially new or harmful traits.

Chromosomal Mutations:

  • Deletion: a part of the chromosome is lost.
  • Duplication: a part of the chromosome is repeated.
  • Inversion: a region of the chromosome is flipped and reinserted.
  • Insertion: the insertion of DNA sequence into a chromosome.
  • Translocation: the exchange of chromosomes' segments.

Copy Number Variation (CNV)

  • Gene amplification (increased number of tandem copies).
  • Trinucleotide repeat expansion.
  • Classification as forms of genome structural variation.

Mutation Hotspots

  • Genomic areas prone to more mutations.
  • Usually due to high accessibility to mutagens.

Mitochondrial DNA Mutations

  • Inherited changes in mitochondrial DNA can cause problems in growth, development, and functioning.
  • MtDNA mutations impact the mitochondria, affecting energy production.

PCR & Electrophoresis

  • Techniques used in molecular biology for DNA amplification and analysis.

PCR Technique

  • PCR is a technique for amplifying short DNA sequences.
  • The method uses primers that target DNA sections for amplification.
  • DNA polymerase is used to create numerous copies of the target sequence.

PCR Enzymes

  • DNA polymerases, such as Taq and Pfu, are used to synthesize new DNA strands in PCR reactions.

TA Cloning

  • TA cloning uses the non-template activity (TAq DNA polymerase) to add a single adenine nucleotide after the 3' end of a DNA fragment.
  • Cloning vector with single 5' thymine overhang at each end is used.
  • Enables cloning of amplified DNA products.

Gel Electrophoresis

  • Method to separate DNA, RNA, or proteins according to size.
  • DNA is negatively charged, so it moves towards the positive electrode.
  • Separated molecules are observable based on their distinct sizes in a gel matrix.

DNA/RNA Ladders

  • DNA/RNA ladders are reference mixtures.
  • Commonly include standard sized DNA molecules of varying lengths.
  • Used in gel electrophoresis to estimate the sizes of unknown samples.

Loading Buffer

  • Used in gel electrophoresis to load DNA samples into wells.
  • Usually contains a colored dye and a reagent to increase sample density.

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Related Documents

Muscular System - Part 1 PDF
Biotechniques (BMS 34010A) Fall 2023-2024 PDF

Description

This quiz covers various types of mutations, their effects, and essential laboratory safety practices related to handling chemicals and biohazardous materials. It includes multiple-choice questions and matching exercises to reinforce understanding of genetic mutations and safe lab procedures.

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