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Ministry of Higher Education & Scientific ‫وزارة اﻟﺘﻌﻠﯿﻢ اﻟﻌﺎﻟﻲ واﻟﺒﺤﺚ اﻟﻌﻠﻤﻲ‬ Research ‫ ﻛﻠﯿﺔ طﺐ اﻷﺳﻨﺎن‬-‫ﺟﺎﻣﻌﺔ اﺷﻮر‬ Ashur University- Colle...

Ministry of Higher Education & Scientific ‫وزارة اﻟﺘﻌﻠﯿﻢ اﻟﻌﺎﻟﻲ واﻟﺒﺤﺚ اﻟﻌﻠﻤﻲ‬ Research ‫ ﻛﻠﯿﺔ طﺐ اﻷﺳﻨﺎن‬-‫ﺟﺎﻣﻌﺔ اﺷﻮر‬ Ashur University- College of Dentistry Subject: Medical Biology Allowed Time:1 Hr Class: 1st Examiner: Dr. Khadija Date: Abbas First Semester/ First Examination Signature: (2023 – 2024) Note: Answer All. Lec.1 Q1: Cell Biology: Is a special branch of biology which deals with the study of structure and function of cell organelles. Q2: Prokaryotes and Eukaryotes are different in their Nucleus and ribosome structure. Q3: Prokaryotes and Eukaryotes are similar in their DNA and Cytoplasm structure Q4: The plasma membrane is the cell’s flexible outer surface, separating the cell’s internal environment (inside the cell) from the external environment (outside the cell). Q5: Plasma membrane is a selective barrier that regulates the flow of materials into and out of a cell. Q6: The selectivity of Plasma membrane helps establish and maintain the appropriate environment for normal cellular activities. Q7: The plasma membrane plays a key role in communication among cells and between cells and their external environment. Q8: The membrane lipids allow passage of several types of lipid-soluble molecules but act as a barrier to the entry or exit of charged or polar substances. Q9: Nucleus is a large organelle that contains most of a cell’s DNA. Q10: Within the nucleus, each chromosome, is associated with several proteins, contains thousands of hereditary units called genes that control most aspects of cellular structure and function. Q11: Cytoplasm has two components: cytosol and organelles. Q12: Cytosol, the fluid portion of cytoplasm contains water, dissolved solutes, and suspended particles. Q13: several different types of organelles found in the cell. Each type of organelle has a characteristic shape and specific functions. Examples include Mitochondria and Ribosome. Q14: Some integral membrane proteins form ion channels, pores or holes through which specific ions, such as potassium ions (K), can flow to get into or out of the cell. Q15: Some integral proteins act as carriers or transporters, selectively moving a polar substance or ion from one side of the membrane to the other. Q16: Some Integral proteins called receptors serve as cellular recognition sites. Q17: Some integral proteins are enzymes that catalyze specific chemical reactions at the inside or outside surface of the cell. Q18: Some Integral proteins may serve as linkers; who anchor proteins in the plasma membranes of neighboring cells to one another or to protein filaments inside and outside the cell. Q19: Membrane glycoproteins and glycolipids often serve as cell identity markers. They may enable a cell to recognize other cells of the same kind during tissue formation or to recognize and respond to potentially dangerous foreign cells. The ABO blood type markers are one example of cell identity markers. Q20: Peripheral proteins help support the plasma membrane, anchor integral proteins, and participate in mechanical activities such as moving materials and organelles within cells, changing cell shape in dividing and muscle cells, and attaching cells to one another. Lec.2 Q1: Functions of Plasma Membrane: Protective barrier Regulate transport in & out of cell (selectively permeable) Allow cell recognition Provide anchoring sites for filaments of cytoskeleton Provide a binding site for enzymes Contains the cytoplasm Q2: Permeable means that a structure permits the passage of substances through it. Q3: Impermeable means that a structure does not permit the passage of substances through it. Q4: Plasma membranes permit some substances to pass more readily than others. This property of membranes is termed selective permeability. Q5: Membrane fluidity depends both on: The number of double bonds in the fatty acid tails of the lipids that make up the bilayer. The amount of cholesterol present. Q6: Membrane fluidity allows interactions to occur within the plasma membrane, such as the assembly of membrane proteins. Q7: Membrane fluidity enables the movement of the membrane components responsible for cellular processes such as cell movement, growth, division, and secretion, and the formation of cellular junctions. Q8: Fluidity allows the lipid bilayer to self-seal if torn or punctured. Q9: Some substances that have been produced by the cell for export as cellular waste products must move out of the cell. Q10: Substances generally move across cellular membranes via transport processes that can be classified as passive or active, depending on whether they require cellular energy. Q11: Diffusion is a passive process in which the random mixing of particles in a solution occurs because of the particles’ kinetic energy. Q12: There are three types of diffusion: Simple diffusion, Facilitated diffusion, Osmosis. Q13: Simple diffusion is a passive process in which substances move freely through the lipid bilayer of the plasma membranes of cells without the help of membrane transport proteins. Q14: Simple diffusion through the lipid bilayer is important in the movement of oxygen and carbon dioxide between blood and body cells. Q15: Facilitated diffusion characteristics: Doesn’t require energy. Uses transport proteins to move high to low concentration. Examples: amino acids moving from blood into a cell. Q16: Osmosis is the diffusion of water through a semipermeable membrane according to the concentration gradient of water across the membrane. Q17: There are three different types of solutions: Isotonic Solution, Hypertonic Solution, and Hypotonic Solution. Q18: Isotonic Solution: An isotonic solution is one that has the same concentration of solutes both inside and outside the cell. Q19: Hypertonic Solution: A hypertonic solution is one that has a higher solute concentration outside the cell than inside. Q20: Hypotonic Solution: A hypotonic solution is one that has a higher solute concentration inside the cell than outside. Q21: An animal cell survives only in isotonic solution. Q22: Active Transport characteristics: Requires energy or ATP. Moves materials from LOW to HIGH concentration. Work AGAINST concentration gradient. Q23: In primary active transport, energy derived from hydrolysis of ATP changes the shape of a carrier protein. Q24: Carrier proteins that mediate primary active transport are often called pumps. Q25: A typical body cell expends about 40% of the ATP it generates on primary active transport. Q26: Sodium- Potassium Pump is an example for PRIMARY ACTIVE TRANSPORT. Q27: Secondary active transport does NOT utilize ATP directly. Q28: Secondary active transport uses the energy stored in the gradients to move other substances against their own gradients. Lec.3 Q1: Immunity: is the body's defense against infectious organisms and other invaders, through a series of steps called the immune response. Q2: The immune system, which is made up of special cells, proteins, tissues, and organs, defends people against invaders. Q3: There are two types of Immunity: 1- Non-specific (innate) and 2- Specific (acquired). Q4: Non-specific immunity, these defense mechanisms act against each and every invader of the body. Q5: Anatomical barriers include physical, chemical and biological barriers. Q6: Skin is the first barrier and the first mechanism of non-specific defense. Q7: The epithelial surfaces form a physical barrier that is impermeable to most infectious agents, acting as the first line of defense against invading organisms. Q8: Desquamation of skin epithelium also helps remove bacteria and other infectious agents that have adhered to the epithelial surfaces. Q9: Presence of sebaceous glands in the dermis provides an environment unsuitable for the survival of microbes. Q10: Presence of sweat glands that secrete sweat which wash infections off (High salt content dries microorganisms off). Q11: The flushing action of tears and saliva helps prevent infection of the eyes and mouth. They contain anti-bacterial properties due to lysozymes. Q12: In the gastrointestinal and respiratory tract, movement due to peristalsis or cilia, respectively, helps remove infectious agents. Q13: Some epithelia produce Mucus which also acts as a barrier against infections and traps infectious agents. Q14: The gut flora can prevent the colonization of pathogenic bacteria by secreting toxic substances or by competing with pathogenic bacteria for nutrients or attachment to cell surfaces. Q15: When micro-organisms penetrate the first defense systems they meet the second line of defense including phagocytic white blood cells, antimicrobial proteins and inflammatory response. Q16: Specific immunity (Adaptive Immunity): immunity that an organism develops during lifetime result from exposure to antigens. Q17: Adaptive Immunity is the second line of defense involves production of antibodies and generation specialized lymphocytes against specific antigens. Q18: Innate immunity does not form a defensive memory, While Adaptive Immunity form a defensive memory. Q19: Antibody is a protein produced by the body's immune system when it detects harmful substances, called antigens. Q20: Antigens are large molecules of proteins, present on the surface of the pathogen- such as bacteria, fungi viruses, and other foreign particles. Q21: IgG, IgE, IgD, IgM, IgA are immunoglobulin produced by Plasma cell. Lec.4 Q1: Bacteria (bacterium): are prokaryotic unicellular microorganisms that were the first forms of life to appear on Earth, about 4 billion years ago. Q2: Archaebacteria are known to be the oldest living organisms on earth. They are classified as bacteria because they resemble bacteria when observed under a microscope. But they are completely distinct from prokaryotes. However, they share slightly common characteristics with the eukaryotes. Q3: Archaebacteria can easily survive under very harsh conditions such as the bottom of the sea and the volcanic vents and are thus known as extremophiles. Q4: Bacterial cells are about one-tenth the size of eukaryotic cells and are typically 0.5–5.0 micrometers (µm) in length. Q5: Thiomargarita are visible to the naked eye, up to half a millimeter long. Q6: The smallest bacteria are members of the genus Mycoplasma, which measure only 0.3 micrometers. Q7: Bacterial Classification according to Morphology: cocci, bacilli, vibrio, spirilla, tetrahedral. Q8: Most bacterial species are spherical, called cocci. Q9: Some bacterial species are rod-shaped, called bacilli. Q10: Some bacteria, called vibrio, are shaped like slightly curved rods or comma-shaped. Q11: Some bacteria can be spiral-shaped, called spirilla, or tightly coiled, called spirochaetes. Q12: A small number of bacterial species have tetrahedral or cuboidal shapes. Q13: The wide variety of shapes is determined by the bacterial cell wall, and is important because it can influence the ability of bacteria to acquire nutrients, attach to surfaces, swim through liquids and escape predators. Q14: Bacterial cells typically contain the following structures: a cell wall, cell membrane, cytoplasm, ribosomes, plasmids, flagella, and a nucleoid region. Q15: Cell Wall: Outer covering of the cell that protects the bacterial cell and gives it shape. Q16: Cytoplasm - A gel-like substance composed mainly of water that also contains enzymes, salts, cell components, and various organic molecules. Q17: Cell Membrane or Plasma Membrane: Surrounds the cell's cytoplasm and regulates the flow of substances in and out of the cell. Q18: Nucleoid Region: Area of the cytoplasm that contains the single bacterial DNA molecule. Q19: Most bacteria contain small independent pieces of DNA called plasmid that often encode for traits that are advantageous but not essential to their bacterial host. Q20: Plasmids can be easily gained or lost by a bacterium and can be transferred between bacteria. So plasmids can be described as an extra chromosomal DNA in a bacterial cell. Q21: Flagella are long, whip-like protrusion that aids in cellular locomotion. Q22: Endospores- are bacterial survival structures that are highly resistant to many different types of chemical and environmental stresses. Q23: Fimbriae - are protein tubes that extend out from the outer membrane. They are generally short in length and present in high numbers about the entire bacterial cell surface. Q24: Fimbriae usually function to facilitate the attachment of a bacterium to a surface. Q25: Pili- are similar in structure to fimbriae but are much longer and present on the bacterial cell in low numbers. Q26: Pili are involved in the process of bacterial conjugation where they are called conjugation pili or sex pili. Q27: The bacterial cell wall differs from all other organisms by the presence of peptidoglycan which is located immediately outside of the cytoplasmic membrane. Q28: Peptidoglycan is made up of a polysaccharide backbone consisting of alternating N- Acetylmuramic acid (NAM) and N-acetylglucosamine (NAG) residues in equal amounts. Q29: The major function of the cell wall is to provide rigidity, strength, structural support, protection against mechanical stress and infection. It also aids in diffusion of gases in and out of the cell. Q30: Gram-positive cell walls are thick and the peptidoglycan layer form almost 95% of the cell. Q31: The gram positive bacteria have a thick cell wall and are made up of many layers of peptidoglycan and teichoic acids. Q32: Gram-negative cell walls are thin and unlike the gram-positive cell walls, they contain a thin layer of peptidoglycan (5-10%) adjacent to the cytoplasmic membrane. Q33: The gram negative bacteria have thinner cell walls, and are made up of few layers of peptidoglycans and are surrounded by a lipid membrane containing lipopolysacccharides and lipoproteins (outer membrane). Q34: The arrangements of flagella about the bacterial cell include: A-Monotrichous : Single flagellum. B-Lophotrichous : A bunch of flagella found at one of the cell pole.  C-Amphitrichous : Single flagellum found at each of two opposite poles. D-Peritrichous : Multiple flagella found at several locations about the cell. Q35: Asexual reproduction of bacteria: Bacterial reproduction most commonly occurs by a kind of cell division called simple binary fission. Binary fission results in the formation of two bacterial cells that are genetically identical. Budding: external buds from the parent cell. Q36: Sexual reproduction of bacteria: In sexual reproduction there is no meiosis (formation of gametes and zygote). Instead, it involves transfer of a portion of genetic material (DNA) from a donor cell to a recipient cell. This process called as genetic recombination, it is occur in the following three ways: Q37: Genetic recombination occurs in three ways: Transformation (the liberated DNA from a destroyed cell penetrates another one) Transduction (when a bacteriophage carries DNA fragments from one cell to another) Conjugation (sexual contact between two bacterial cells) bacterial conjugation occurs through which a donor cell transfers plasmid to recipient cell through a conjugation tube formed between both cells. Q38: Bacterial growth follows four phases: Lag Phase Log Phase Stationary phase Decline Death Phase Q39: Bacteria can also be biochemically defined by how they produce energy. Bacteria that produce energy with oxygen are aerobic, while bacteria that make energy without oxygen are anaerobic. Q40: Aerobic Bacteria: The bacteria that grow in the presence of oxygen are called aerobic bacteria. They have the ability to detoxify oxygen with the help of enzymes. The final electron acceptor is molecular oxygen. Water is produced from the final electron acceptor. In the liquid medium, they are seen on the surface of the medium.  Example: Bacillus. Q41: Anaerobic Bacteria: The bacteria that grow in the absence of oxygen are called anaerobic bacteria. It does not have the ability to detoxify oxygen. The final electron acceptor is carbon dioxide or sulfur. Acetate- like substances, methane, nitrate and sulfide are produced by these bacteria. In the liquid medium, they are seen at the bottom of the medium. Example: Clostridium. Q42: Compare between aerobic and aerobic bacteria: AEROBIC ANAEROBIC Need oxygen to survive Do not require oxygen to survive Produce more energy Produce less energy Bacteria are seen on the surface of Bacteria are settled at the bottom of the liquid the liquid Example: Bacillus Example: Clostridium Q43: Bacteria feed themselves in a variety of ways. Heterotrophic bacteria (heterotrophs) are an organism that cannot fix carbon, and uses organic carbon for growth. Autotrophic bacteria (autotrophs) microorganisms that are able to make their own food, from simple substances present in its surroundings (They synthesize their own organic food from inorganic substances). Q44: Heterotrophs can be divided based on how they obtain energy; If the heterotroph uses light for energy, then it is considered a photoheterotroph, While if the heterotroph uses chemical energy, it is considered a chemoheterotroph. Q45: Autotrophic bacteria (autotrophs) microorganisms that are able to make their own food, from simple substances present in its surroundings (They synthesize their own organic food from inorganic substances). Q46: There are two major classes of autotrophs:  Chemoautotrophs Photoautotrophs. Q47: Chemoautotrophs are bacteria that use chemical energy. They are able to take in carbon dioxide and water and convert those substances into carbohydrates and sugars. Carbohydrates and sugar are the main energy sources for bacteria. Q48: Photoautotrophs are autotrophs that obtain their energy from sunlight; these organisms can turn light energy into chemical energy that will fuel the bacteria’s processes. These organisms contain a green pigment called cyanobacteria (like the chlorophyll in plants). Q49: The oral cavity has the second largest and diverse microbiota after the gut harboring over 700 species of bacteria. Q50: The oral cavity is invaded mainly by aerobes by the 1st year and may include Streptococcus, Lactobacillus and Actinomyces. Q51: Streptococcus mutans is a facultative anaerobic, gram-positive coccus commonly found in the human oral cavity and is a significant contributor to tooth decay. Lec.5 (Part I) Q1: Genetics is a branch of biology, the study of heredity. This study is largely based on genes. Q2: Genes are structures found in every single cell that contain information about traits that an organism has or carries. Q3: Type of nucleic acid includes: DNA (deoxyribonucleic acid) RNA (ribonucleic acid). Q4: Nucleic acids are polymers of nucleotides linked in a chain through phosphodiester bonds. Q5: DNA: Occurs in nucleus as well as cell organelles like chloroplast and mitochondria. Q6: RNA: May be found in nucleus but mainly occurs in cytoplasm carry out protein synthesis. Q7: Functions of Nucleic Acids: Transmission of hereditary Characters (DNA) Synthesis of Proteins (RNA) Q8: Nucleotides are the building blocks of all nucleic acids. Q9: Nucleotides have a distinctive structure composed of three components bound together:  A nitrogen-containing "base" - either a pyrimidine (one ring) or purine (two rings) A 5-carbon sugar - ribose or deoxyribose A phosphate group Q10: The combination of a base and sugar is called a nucleoside. Q11: A nitrogenous base is an organic molecule with a nitrogen atom. The main biological function of a nitrogenous base is to bond nucleic acids together. There are two kinds of nitrogen-containing bases - purine and pyrimidine. Q12: Purines consist of a six-membered and a five-membered nitrogen-containing ring. Q13: Pyridmidines have only a six-membered nitrogen-containing ring. Q14: Most DNA is located in the cell nucleus (where it is called nuclear DNA), but a small amount of DNA can also be found in the mitochondria (where it is called mitochondrial DNA). Q15: The information in DNA is stored as a code made up of four chemical bases: adenine (A), guanine (G), cytosine (C), and thymine (T). Q16: Human DNA consists of about 3 billion bases, and more than 99 percent of those bases are the same in all people. Q17: An important property of DNA is that it can replicate, or make copies of itself. Q18: A always pairs with T through two hydrogen bonds, and G always pairs with C through three hydrogen bonds. Q19: RNA nucleotide contains a nitrogenous base, a ribose sugar, and a phosphate. Q20: There are actually three types of RNA: messenger RNA, ribosomal RNA, transfer RNA Q21: Messenger RNA: is a copy of a section of DNA. Q22: When a section of DNA is copied to RNA; this is called transcription. Q23: The process of protein synthesis from RNA is called translation. Q24: Ribosomal RNA: Part of the ribosome and helps build the protein. Q25: Transfer RNA: it brings the correct amino acid to the ribosome. Q26: The Human Genome Project has estimated that humans have between 20,000 and 25,000 genes. Lec.5 (Part II) Q1: DNA replication is the biological process of producing two identical replicas of DNA from one original DNA molecule. This process occurs in all living organisms and is the basis for biological inheritance. Q2: The three steps in the process of DNA replication are initiation, elongation and termination. Q3: Mutation is the changing of the structure of a gene, resulting in a variant form which may be transmitted to subsequent generations, caused by the alteration of single base units in DNA, or the deletion, insertion, or rearrangement of larger sections of genes or chromosomes. Q4: Gene mutations can be classified in two major ways: Hereditary mutations Acquired mutations Q5: Hereditary mutations are inherited from a parent and are present throughout a person’s life in virtually every cell in the body. These mutations are also called germ line mutations because they are present in the parent's egg or sperm cells. Q6: Acquired (or somatic) mutations occur at some time during a person's life and are present only in certain cells, not in every cell in the body. These changes can be caused by environmental factors such as ultraviolet radiation from the sun, or can occur if an error is made as DNA copies itself during cell division. Q7: Acquired mutations in somatic cells (cells other than sperm and egg cells) cannot be passed to the next generation. Q8: The most common Genetic Dental Abnormalities is clefting of the lip and palate. Clefting, the incomplete fusion of the lip and/or palate, can appear alone or as part of a hereditary syndrome. Q9: Malocclusion: Also called a bad bite, is caused by crowded, extra or missing teeth, or jaws out of alignment. Most malocclusions are inherited genetically and can lead to temporo-mandibular jaw (TMJ) disorders that can result in problems chewing and speaking. Q10: Periodontal (Gum) Disease: refers to bacterial infection and inflammation causing damage to soft and hard tissues supporting the teeth. In its early stages (gingivitis), gums become red, swollen and bleed easily, but the disease is reversible. In advanced stages of periodontal disease (periodontitis), gums and bone supporting the teeth become seriously damaged, resulting in loose teeth that may fall out or need removal by a dentist. Q11: Oral Cancer: Often starting as a tiny, inconsequential white or red spot or sore anywhere in the mouth, most cases often occur in people who use tobacco and alcohol. Q12: Mutation in an oncogene may convert ordinary body cells into cancer cells. Mutations of normal tumor suppressor genes which are anticancer genes that slow down or stop the growth of normal body cells also can give rise to oral cancers.