Basic Biology Reviewer PDF 25/09/2024

Basic Biology Reviewer 25/09/2024...

Basic Biology Reviewer 25/09/2024 Review Outline A. Biomolecules LET REVIEW OF BASIC B. Cell Biology BIOLOGICAL SCIENCE C. Microscopy D. Cell Cycle and Division E. Genetics © Asst. Prof. Gideon A. Legaspi Physical Sciences Department F. Photosynthesis and Respiration De La Salle University-Dasmariñas G.Taxonomy September 20, 2024 H. Ecology 1 2 A. BIOMOLECULES (PELiCaN) 1. Proteins a. Amino acids (AA) - the building blocks of proteins. There are three structural 1. Proteins – made up amino acids and comprise around 70% features in amino acids: the α-amino group, the α-carboxylic acid, and the of the cell’s dry mass. Perform diverse functions such as variable functional group (R) as illustrated below: storage, energy source, transport, and catalysis. 2. Enzymes – globular proteins that serve as biocatalysts. 3. Lipids – water insoluble (non-polar) in nature such as fats and oils. Energy reserve and cushion internal organs. 4. Carbohydrates – major energy source such as sugars and b. There are 20 standard amin acids with variable structures. starch. Made up of monosaccharides. c. Essential amino acids – cannot be synthesized by the body and must be obtained 5. Nucleic acids – stores genetic information (DNA) and serve form diet or supplementation. Deficiency may lead to certain disease. Includes as molecular machineries for protein synthesis (RNA). Made isoleucine, leucine, lysine, methionine, tyrosine, valine, tryptophan, up of nucleotides which are nitrogenous compounds phenylalanine, arginine, and histidine. 3 4 d. Peptide bond- the bond that connects amino acids together to form peptides and proteins. e. Peptides – made up of 2 or more amino acids, but typically less than 50. They perform various functions such as hormones and neurotransmitters. f. Proteins – are polypeptides with at least 50 amino acids Have a large complex structure, they are called as macromolecule = big molecule. Perform various functions in the body such as transport, storage, structural components, hormones and defense. Image Source: https://ib.bioninja.com.au/standard-level/topic-2-molecular-biology/24-proteins/amino-acids.html 5 6 © Asst. Prof. Gideon A. Legaspi, RCh, MSc 1 Basic Biology Reviewer 25/09/2024 2. Enzymes a. Enzymes – are globular catalytic proteins which speed up the rate of biochemical reactions. b. Lock and Key Model - shows the complementary between the structure of the enzyme and its substrates (reactants). The active site is a hydrophobic cleft within the enzyme where the substrate(s) fit and facilitate catalysis. Image Source: https://biology-igcse.weebly.com/lock-and-key-model.html 7 8 c. Examples of Enzymes 1. Amylase – enzyme present in saliva and pancreatic juice which aid in the 3. Lipids digestion of starch into glucose. a. Lipids- water-insoluble or non-polar biomolecules such as fats and oils. Also include lipid-soluble vitamins (A,D,E,K), phospholipids, and cholesterol. 2. Lactase – enzyme present in small intestines which digest lactose (milk sugar). Adults typically lacks sufficient lactase leading to lactose intolerance. b. Fatty acids - long-chain carboxylic acids that serve as building blocks of fats, oils, and phospholipids. They can either be saturated (all C-C bond) or unsaturated 3. Pepsin – enzyme present in stomach which breaks down proteins into smaller (with C=C bond) in nature. peptides. 4. Lysozyme – antibacterial enzyme that is present in saliva, tears, mucus, and breast milk. 5. Lipase – enzyme present in pancreatic juice which aid in the digestion of fats and other lipids. 6. Catalase – enzyme in the peroxisomes which decomposes hydrogen peroxide into water and oxygen. Image Source: https://byjus.com/biology/difference-between-saturated-and-unsaturated-fats/ 9 10 c. Phospholipids- amphipathic molecules which contain both polar and non-polar d. Cholesterol- polycyclic compound called sterol which are found in animals and components. They made-up the cell membrane of cells as phospholipid bilayer. humans. Serves as precursor for sex hormones (estrogens, progesterone, and testosterone), adrenocorticoids (aldosterone = regulates mineral balance and glucocorticoid = stress hormone), and bile acids (fat emulsifiers). 11 12 © Asst. Prof. Gideon A. Legaspi, RCh, MSc 2 Basic Biology Reviewer 25/09/2024 4. Carbohydrates Common Monosaccharides a. Monosaccharides - simple or single sugars which serve as building blocks of carbohydrates. More technically known as polyhydroxy aldoses or ketoses. 1. Glucose – also known as “dextrose” which is the sugar found in our blood. It is the product of photosynthesis in plants. 2. Fructose – also known as “fruit sugar”, sweetest among the common monosaccharides. Combines with glucose to form the disaccharide sucrose (table sugar). 3. Galactose – also known as “brain sugar” as it is abundant in nerve tissue as glycoprotein. Combines with glucose to form the disaccharide lactose (milk sugar). 4. Ribose – the sugar that makes up the backbone of the RNA and DNA. 13 14 d. Polysaccharide- made up of multiple sugar units that are joined together by c. Disaccharide- made up of two an O-glycosidic bond. monosaccharides that are joined 1. Starch– storage form of glucose in plants, mixture of amylose and together by an O-glycosidic bond. amylopectin. Detected by iodine test in which the brown solution turns into a blue-back color. 1. Sucrose – glucose + fructose, 2. Glycogen – storage form of glucose in animals and humans, present in liver common table sugar and muscles. 3. Cellulose – component of plant’s cell wall, serve as dietary fibers. 2. Lactose – galactose + glucose, milk sugar 3. Maltose – glucose + glucose, malt sugar which is a product of starch hydrolysis Image Source: https://www.biologyonline.com/dictionary/polysaccharide 15 16 5. Nucleic acids a. Nucleotides - building blocks of nucleic acids that are made up of sugar, phosphate, and nitrogenous base (N-base) 1. Sugar – ribose in RNA and deoxyribose in DNA 2. Phosphate – inorganic acid with negative charges –PO42- 3. N-base – heterocyclic nitrogenous compounds either as purine or pyrimidine 17 18 © Asst. Prof. Gideon A. Legaspi, RCh, MSc 3 Basic Biology Reviewer 25/09/2024 b. N-glycosidic bond - the connection between N-base and sugar via an to form a nucleoside. For purine and pyrimidine, the linkage is via a C1’-N9 and C1’-N1, respectively. c. Phosphoester bond - the attachment of phosphate group at 5’ hydroxyl of the sugar via a leads to the formation of nucleotides. 19 20 d. Phosphodiester bond – the bond between nucleotides to form nucleic acids which is through the formation of 3’- and 5’- bond between the sugars of nucleotides. e. Base pairs – the purine base forms H-bonds with a complementary pyrimidine. In DNA, A base pairs with T as stabilized by 2 H-bonds while G base pairs with C as stabilized by 3 H-bonds. In RNA, A base pairs with U instead of T! 21 22 f. There are several important differences between the g. Nucleosome – the basic packaging of eukaryotic DNA where DNA and RNA as illustrated below: DNA is packed with histone proteins and then package together further into coils that eventually condenses into the chromosomes as illustrated below: 23 24 © Asst. Prof. Gideon A. Legaspi, RCh, MSc 4 Basic Biology Reviewer 25/09/2024 h. Three Types of RNA 2. Messenger RNA - serves as the template for protein 1. Ribosomal RNA - associates with various proteins to form synthesis. The nitrogenous base sequence is read as triplet of the ribosomes. There are two major types of ribosomes in the bases called the codons which encode for a specific amino acid cytoplasm namely the large ribosome subunit (50S in except for the stop codons. prokaryotes and 60S in eukaryotes) and the small ribosome subunit (30S in prokaryotes and 40S in eukaryotes). 25 26 3. Transfer RNA - involved in bringing the amino acids from the PRACTICE QUESTIONS cytoplasm to the ribosomes during protein synthesis. They have a characteristic cloverleaf or cruciform structure which is made up of 1. Proteins are made-up of what building blocks? A. Nucleotides B. Monosaccharides C. Fatty acids D. Amino acids three hairpin loops. 2. What biomolecules serves as the repository of genetic information? A. Deoxyribonucleotides C. Enzymes B. Proteins D. Carbohydrates 3. Adenine pairs with what nucleotide in RNA? A. Guanine B. Uracil C. Thymine D. Cytosine 4. All of the following are monosaccharides except? A. Glucose B. Fructose C. Lactose D. Galactose 27 28 PRACTICE QUESTIONS B. CELL BIOLOGY 1. Proteins are made-up of what building blocks? 1. Cell - the fundamental unit of structure and function of all living A. Nucleotides B. Monosaccharides C. Fatty acids D. Amino acids organisms. 2. Robert Hooke - first discovered cells in 1665 by looking at the 2. What biomolecules serves as the repository of genetic information? microscopic view of a thin slice of cork. He called the tiny box-like A. Deoxyribonucleotides C. Enzymes compartments as “cells” because it reminded him of the cells of a B. Proteins D. Carbohydrates monastery. 3. Antonie van Leeuwenhoek - revealed the existence of many kinds 3. Adenine pairs with what nucleotide in RNA? of cells including bacteria which he called as “animalcules” for little A. Guanine B. Uracil C. Thymine D. Cytosine animals. 4. All of the following are monosaccharides except? 4. Theodore Schwann and Matthias Jakob Schleiden - respectively A. Glucose B. Fructose C. Lactose D. Galactose proposed in 1839 that all animals and plants are made up of one or more cells thus cells are the basic unit of life. 29 30 © Asst. Prof. Gideon A. Legaspi, RCh, MSc 5 Basic Biology Reviewer 25/09/2024 5. Rudolf Virchow - proposed in 1858 his famous theory in Latin, “Omni cellula e cellula” which means that all cells come from pre-existing cells. 6. Cell Theory - states that the cell is the fundamental unit of structure and function of all living organisms and that all cells come from pre-existing cells by cell division. 7. Prokaryotes - lack nucleus and membrane-bound organelles. Archaea and Bacteria are the two domains of the prokaryotes. 8. Eukaryotes - have distinct membrane-bound nucleus and many other membrane- bound organelles. Include Fungi, Protists, Plants, and Animals. Image Source: https://rsscience.com/eukaryote-prokaryote/ 31 32 9. Bacteria – prokaryotic cells with basic cellular structure shown below: 33 34 10. Bacteria DNA – naked in nature because it is not packaged with proteins and 11. Bacterial Appendages not membrane-bound. a. Pili - are hair-like in appearance and utilized for surface attachment or DNA exchange of DNA with another bacterium. b. Fimbriae - are also hair-like but are shorter and more numerous. c. Flagellum (plural flagella) - is a whip-like structure that can propel a bacterium for movement. Image Source: https://quora.com/What-is-the-difference-between-genomic-DNA-and-plasmid-DNA Image Source: https://easybiologyclass.com/tag/pili/ 35 36 © Asst. Prof. Gideon A. Legaspi, RCh, MSc 6 Basic Biology Reviewer 25/09/2024 12. Gram-negative bacteria – bounded by a thin peptidoglycan cell 14. Plant versus Animal Cell - have many similar cellular structures but each wall which itself is surrounded by a lipolysachharide outer membrane. one also has some unique cellular structures as illustrated below. Stained red by Gram-stain. 13. Gram-positive bacteria - lack an outer membrane but with thick peptidoglycan layer. Stain purple by Gram stain. Image Source: https://byjus.com/biology/difference-between-gram-positive-and-gram-negative-bacteria/ Image Source: https://www.thinglink.com/scene/886054660429840385 37 38 15. Regions of the Cell Plasma membrane Cytoplasm Nucleus 39 40 16. PLASMA MEMBRANE – made up of phospholipid bilayer with embedded proteins. -Protection -Regulates passage of materials in & out the cell -Maintains cell shape -Proteins serve as channels or Fluid Mosaic Model receptors Fluid Mosaic Model 41 42 © Asst. Prof. Gideon A. Legaspi, RCh, MSc 7 Basic Biology Reviewer 25/09/2024 17. MEMBRANE PROJECTIONS- outer extension of the plasma membrane 18. CYTOPLASM CILIA – numerous hair-like projections for sweeping -Aqueous region between motion the plasma membrane MICROVILLI- numerous and nucleus finger-like projections that increases surface area for nutrient absorption -Contains the dissolved solutes, various FLAGELLUM- whip-like inclusions, and organelles projection for propelling motion 43 44 19. CYTOSKELETON – network of fibrous proteins that provide structural support and assist in cell movement (1) Microfilaments – fine filaments of contractile actin protein (2) Intermediate filaments- cell-specific heterogeneous filaments that include keratin, desmin, vimentin, lamins, neurofilaments, and glial fibrillary acidic protein (3) Microtubules- hollow tubes constructed of tubulin proteins Cytoskeleton 45 46 20. Centrioles 21. Endoplasmic Reticulum (ER) – network of internal membranes that extend throughout the cytoplasm -Pair of hollow cylinders each Smooth ER - tubular sacs that consists of nine lack ribosomes; involves in lipid triplets of and drug metabolism, releases microtubules Ca2+ for cell signaling -Form spindle fibers for the Rough ER - flattened sacs that movement of are studded with ribosomes; chromosomes process and transport proteins during cell division that are synthesized by the ribosomes 47 48 © Asst. Prof. Gideon A. Legaspi, RCh, MSc 8 Basic Biology Reviewer 25/09/2024 22. Ribosomes 23. Golgi Bodies -Particles of RNA and proteins, free or attached to -Layers of flattened rough ER sacs, arranged like -Site of protein synthesis stacked bowls -Package and modify proteins 49 50 24. Lysosomes 25. Peroxisomes -Membrane-bound vesicles that contain acidic -Membrane-bound vesicles that contain oxidative digestive enzymes (acid hydrolases) enzymes (oxidases) -Digestion of worn intracellular parts and -Site of detoxification reactions especially the biomolecules (autophagy) and those from break down of hydrogen peroxide (H2O2) by outside the cell (heterophagy) the enzyme catalase 51 52 26. Mitochondria 27. NUCLEUS - control center of the cell; transmits genetic information and provides the instructions for synthesis of proteins and enzymes. -Elongated or ovoid double- membrane sacs Matrix Nuclear membrane -The inner membrane folds to form cristae -Powerhouse of the cell Nucleolus where ATP is synthesized -ATP is the energy currency Chromatin of the cell 53 54 © Asst. Prof. Gideon A. Legaspi, RCh, MSc 9 Basic Biology Reviewer 25/09/2024 a. Nuclear Membrane b. Nucleolus -Phospholipid bilayer membrane that is continuous -Dense spherical bodies with the rER, contains proteins inside the nucleus that form the nuclear pore complex - Site of ribosomal RNA -Separates the nucleoplasm synthesis from the cytoplasm, regulates passage of substances to and from the nucleus 55 56 c. Chromatin - granular, threadlike materials composed of DNA and 28. VACUOLE histone proteins; Site of ribosomal RNA synthesis; repository of genetic materials - Plant cells have a large central vacuole which may be absent in animal cells or present only in smaller size but multiple number. - It stores nutrients and waste products in the cells and maintains the hydrostatic or turgor pressure in plants. DNA Packaging 57 58 PRACTICE QUESTIONS 29. CHLOROPLAST 1. The mitochondria are called the powerhouses of the cell. Why is this so? A. They are responsible for the production of adenosine triphosphate in the cell. - A double-membrane organelle B. They are responsible for protein synthesis in the cell. C. They are responsible for the degradation of lipids in the cell. that contains chlorophyll – the D. They are responsible for the degradation of deoxyribonucleic acid in the cell. green pigment in plants that 2. What cell organelles are found in plant cells but not in animal cells? absorbs energy from sunlight A. Cell wall and ribosomes C. Chloroplasts and mitochondria and uses it for manufacturing B. Chloroplasts and centrioles D. Cell wall and chloroplasts sugar from carbon dioxide and 3. Prokaryotes can be best distinguished from eukaryotes by which feature? water in the process called A. Absence of ribosomes C. Presence of ribosomes photosynthesis. B. Absence of nucleus D. Presence of nucleus 4. The plasma membrane are made up of what biomolecules? A. Protein fibers C. Carbohydrate chains B. Phospholipid bilayer D. DNA double helix 59 60 © Asst. Prof. Gideon A. Legaspi, RCh, MSc 10 Basic Biology Reviewer 25/09/2024 PRACTICE QUESTIONS C. MICROSCOPY 1. The mitochondria are called the powerhouses of the cell. Why is this so? A. They are responsible for the production of adenosine triphosphate in the cell. 1. Hans Jansen and Zaccharias Jansen – invented the first compound microscope B. They are responsible for protein synthesis in the cell. by this father-and-son tandem of Dutch spectacle makers; who constructed a C. They are responsible for the degradation of lipids in the cell. viewing tube with several lenses. D. They are responsible for the degradation of deoxyribonucleic acid in the cell. 2. Robert Hooke - In 1665, the English inventor published his book Micrographia 2. What cell organelles are found in plant cells but not in animal cells? in which he described the structure of a thin slice of cork using a microscope that A. Cell wall and ribosomes C. Chloroplasts and mitochondria he devised himself. B. Chloroplasts and centrioles D. Cell wall and chloroplasts 3. Antonie van Leeuwenhoek - made a more powerful and useful version of the 3. Prokaryotes can be best distinguished from eukaryotes by which feature? compound microscope with a magnifying power of up to 270X. One of his many A. Absence of ribosomes C. Presence of ribosomes notable microscopic discoveries is the first known observation of bacteria which B. Absence of nucleus D. Presence of nucleus he called as “animalcules” for “tiny animals”. He was later recognized as the “Father of Microbiology” 4. The plasma membrane are made up of what biomolecules? A. Protein fibers C. Carbohydrate chains B. Phospholipid bilayer D. DNA double helix 61 62 4. Compound microscope – most common modern microscope which has four Parts Description and Functions main structural components – the head, base, stage, and arm as illustrated below. 1. Head The upper part that houses the optical systems of the microscope. 2. Eyepiece or Ocular This is where you look through at the head of a lens microscope. Standard magnifying power is 10x. 3. Eyepiece holder It holds the eyepieces in place above the objective lens. 4. Objective lenses They serve as the main optical lenses of a microscope and has a magnifying range from 4x- 100x. 5. Nosepiece The revolving head that houses the objective lenses and makes it possible to switch from one objective lens to another. 63 64 Parts Description and Functions 6. Stage It is where the specimen is placed for Parts Description and Functions microscopic viewing. 11. Coarse adjustment It is rotated to move the stage up and down 7. Stage clip or It is used to hold the specimen in place and can knob and bring the specimen into initial focus. Mechanical Stage be adjusted manually or mechanically. 12. Fine adjustment It is rotated to sharpen the image of the knob specimen. 8. Condenser Located beneath the stage which controls the lighting focus on the specimen in conjunction with an iris diaphragm. 13. Illuminator It is found on the base of the microscope and 9. Iris diaphragm It is made up of thin opaque plates with an serves as the light source for viewing of the adjustable hole in the center that controls the specimen. amount of light reaching the specimen. 14. Base It supports the microscope by serving as stand 10. Arm It connects all the main components together and houses the illuminator or light source. and is also used as handle for carrying the microscope. 65 66 © Asst. Prof. Gideon A. Legaspi, RCh, MSc 11 Basic Biology Reviewer 25/09/2024 5. Different Objective Lenses 6. Two general methods of specimen mounting a. Scanning objective (SO) - the shortest one with a magnifying power of 4x a. Dry mount method - involves viewing the sample without the use of a and has a red ring mark for standard identification. It is used for getting liquid medium. The sample is placed between the glass microscope slide an overview of the specimen. and the cover slip then pressed firmly to flatten it. b. Low power objective (LPO) - has a magnifying power of 10x and has a b. Wet mount method - the specimen is viewed under a liquid medium like yellow ring mark. This is the most used objective for specimen viewing. water or staining agent. The cover slip is then placed at a right angle on the outer edge of the liquid and pressed using a paper towel to absorb any c. High power objective (HPO) - has a magnifying power of 40x and with a excess fluid. light blue ring mark. It is used for observing the finer details in a specimen. 7. Staining – uses stains or dyes to visualized specific structures in a biological sample. An example of this stain is iodine which useful for staining of plant d. Oil immersion objective (OIO) - the longest objective with a magnifying cells. Dyes like eosin and methylene blue reacts with proteins and nucleic acids power of 100x and white ring mark. It is used for maximum magnification of in cells to give a reddish and bluish stain, respectively. the specimen but requires the use of synthetic or natural oil to prevent spherical aberration of the image formed. 8. Microtome – a mechanical tool used for more precise cutting of thin slices or sections of a sample. 67 68 9. Total magnification (TM) - calculated by multiplying the magnifying power of the eyepiece and objective lens. a. SO – 4 x 10 = 40x TM b. LPO – 10 x 10 = 100x TM c. HPO – 40 x 10 = 400x TM d. IOI – 100 x 10 = 1000x TM 10. Electron microscope (EM) - uses a beam of electrons instead of light to visualize a specimen. This powerful microscope is capable of a magnification power of up to 10,000,000x. a. Scanning electron microscope (SEM) - used for surface morphology analysis. b. Transmission Electron Microscope (TEM) - used for probing the ultrastructure of cells. Image source: https://scoop.eduncle.com/comparision-between-optical-microscope-sem-and-tem-together 69 70 PRACTICE QUESTIONS PRACTICE QUESTIONS 1. What parts of the microscope serve to magnify the specimen? 1. What parts of the microscope serve to magnify the specimen? A. Eyepiece and iris diaphragm C. Objectives lens and eyepiece A. Eyepiece and iris diaphragm C. Objectives lens and eyepiece B. Objectives lens and light source D. Eyepiece and stage B. Objectives lens and light source D. Eyepiece and stage 2. A specimen was viewed under the high-power objective, what is the total magnification 2. A specimen was viewed under the high-power objective, what is the total magnification of viewing? of viewing? A. 100x B. 200x C. 300x D. 400x A. 100x B. 200x C. 300x D. 400x 3. The view of a specimen under a microscope is blurred. Which parts should be 3. The view of a specimen under a microscope is blurred. Which parts should be manipulated to get a better view of the specimen? manipulated to get a better view of the specimen? A. Iris diaphragm and condenser A. Iris diaphragm and condenser B. Coarse and fine adjustment knobs B. Coarse and fine adjustment knobs C. Mechanical stage and clips C. Mechanical stage and clips D. Light source and objective lens D. Light source and objective lens 71 72 © Asst. Prof. Gideon A. Legaspi, RCh, MSc 12 Basic Biology Reviewer 25/09/2024 D. CELL CYCLE AND DIVISION 4. Synthesis phase (S) - the DNA content of the cell is duplicated and 1. Cell cycle - a series of physiologic events in eukaryotic cells that may last for 6-8 hours. The DNA content of the cell is duplicated so ultimately leads to growth and cell division. that when it divides into two daughter cells later, each one will contain the same number of chromosomes or DNA content. 2. G0 phase - The quiescent or resting stage of the cell. 5. Second gap phase (G2) - the cell continues its growth, synthesizes proteins and enzymes needed for cell division, and completes the 3. First gap phase (G1) - the cell becomes metabolically active in replication of its centrosomes. preparation for DNA replication. The cell undergoes physical growth, duplicates its organelles and cytosolic components, and starts replicating its centrosomes for about 8-10hours. 6. Interphase - the collective term for the period of G1, S, and G2 phases. 73 74 The Cell Cycle 7. Mitosis phase (M) - the somatic or body cell divides into two daughter cells with equal DNA content and is the shortest phase at up to 2 hours. 8. Equational division - the cell division wherein the daughter cells will have the same chromosome number as their parent cell (diploid cell) which characterized mitosis. 9. There are four phases in mitosis namely prophase, metaphase, anaphase, and telophase (PMAT) Image Source: https://d2gne97vdumgn3.cloudfront.net/api/file/DHethAqRfKaXriyENwLY 75 76 10. Prophase – 1st stage where chromatin condenses into 13. Anaphase - characterized by the disjunction of the sister chromosomes, nuclear membrane starts to disappears, spindle chromatids and their movement towards the opposite poles of the fibers forms, and the centrioles migrate towards the opposite poles cell due to spindle fiber contraction. of the cells. 14. Telophase - the chromosomes have reached the opposite poles 11. Late prophase (prometaphase) - the spindle fibers start to and uncoil, the spindle fibers disappear, and the nuclear membrane capture the chromosomes by attachment to the kinetochore, the reforms. disc-shaped protein complex in the centromere, which is essential for the movement of the chromosomes later. 15. Cytokinesis - the cell divides into two daughter cells. In animal cells cytokinesis occurs by invagination of the cell membrane while in 12. Metaphase - distinguished by the alignment of the plant cells it is via the formation of cell plate. chromosomes on the equatorial plate of the cell. In addition, the nuclear membrane has completely dissolved by this point. 77 78 © Asst. Prof. Gideon A. Legaspi, RCh, MSc 13 Basic Biology Reviewer 25/09/2024 16. Meiosis - cell division in germ or sex cells wherein the chromosome number of the parent cell is reduced by half, hence, it is known as reductional division which forms haploid cells. There are two stages in meiosis called meiosis I and meiosis II, just like mitosis, each stage has four phases namely prophase, metaphase, anaphase, and telophase. 17. Meiosis I - the reductional stage because it is where the chromosome number of the cell is halved. a. Prophase I - unique because it has 5 substages that are not found during mitosis: i. Synapsis - the pairing up of homologous chromosomes in the process called. The homologous pair forms the bivalent or tetrad chromosomes. ii. Crossing-over stage - the non-sister chromatids begin to exchange genetic segments through the help of recombinase enzyme, resulting to genetic variability. Image source: https://d2gne97vdumgn3.cloudfront.net/api/file/DHethAqRfKaXriyENwLY 79 80 b. Metaphase I - characterized by the complete dissolution of the nuclear membrane, full formation of the spindle fibers, and the alignment of the bivalents along the equatorial plate of the cell. c. Anaphase I - the homologous chromosome pairs separate to the opposite poles of the cell due to the contraction of the spindle fibers. which is the reductional stage. d. Telophase I - the chromosomes have reached the poles and start to uncoil. The nuclear membrane reappears while the spindle fibers disappear. e. Cytokinesis - will divide the parent cell into two daughter cells. f. Meiosis II - the daughter cells will then enter the second round of cell division which is like the stages of mitosis. The result is the formation of four haploid daughter cells. Image source: https://i1.wp.com/ramneetkaur.com/wp-content/uploads/2016/10/78587-036-221D6479.jpg?w=796&ssl=1 81 82 Differences Between Mitosis and Meiosis PRACTICE QUESTIONS 1. The onion root tips cells have visible disjunction of the chromosomes into the opposite poles of the cell. The cells are already in which phase of the cell division? A. Prophase C. Anaphase B. Metaphase D. Telophase 2. A human cell has 46 chromosomes. How many chromosomes are there in the human egg cell? A. 23 B. 46 C. 69 D. 92 3. All of the following are features of meiosis, except? A. It occurs only in gametes or sex cells. B. It results to the formation of diploid daughter cells. C. It has two stages called meiosis I and meiosis II. D. It is considered as a reductional cell division. Image source: https://pw.live/chapter-cell-cycle/diffrence-between-mitosis-and-meiosis 83 84 © Asst. Prof. Gideon A. Legaspi, RCh, MSc 14 Basic Biology Reviewer 25/09/2024 PRACTICE QUESTIONS E. GENETICS 1. The onion root tips cells have visible disjunction of the chromosomes into the 1. Gregor Johann Mendel - the Austrian monk who began breeding studies in pea opposite poles of the cell. The cells are already in which phase of the cell division? plants (Pisum sativum) which led him to the discovery of the laws that govern A. Prophase C. Anaphase genetic inheritance for which he was recognized as the “Father of Genetics”. B. Metaphase D. Telophase 2. Genetics – the study of how traits are passed from parents to offspring. It involves 2. A human cell has 46 chromosomes. How many chromosomes are there in the human the study of genes and their variation and inheritance. egg cell? A. 23 B. 46 C. 69 D. 92 3. Gene - a small segment of the DNA that is made-up of a specific base sequence which encodes for a particular protein, including enzyme. 3. All of the following are features of meiosis, except? A. It occurs only in gametes or sex cells. 4. Locus - the location of a gene in the chromosome (plural loci). B. It results to the formation of a diploid daughter cells. C. It has two stages called meiosis I and meiosis II. 5. Genome - the totality of all genetic materials of an organism. In humans, our D. It is considered as a reductional cell division. genome is the entirety of the genes in 46 chromosomes that occur in 23 homologous pairs. 85 86 6. Allele - the variant form of a specific gene. For example, in pea plant the allele for 9. Mendel’s Laws of Heredity – governs the expression of genetic traits as its height is either tall or dwarf. Mendel discovered that a trait is controlled by an discovered by Gregor Mendel. allelic pair and that can either be: a. Dominant allele - masks the expression of another allele. a. Law of Segregation - states that during the formation of gametes, the alleles for b. Recessive allele – allele whose expression is masked by a dominant allele. each gene segregate from each other such that each one carries only one allele for a c. To simplify the representation of alleles, the dominant and recessive traits are gene. represented by capital and lower-case letter such “Y” for yellow and “y” for green. 7. Genotype - the specific allelic combination for a certain gene. a. Homozygous allele - an allelic pair is made up of the same allele, such as YY and yy. b. Heterozygous allele - an allelic pair is made up of each alternative gene form, such as Yy. 8. Phenotype - the observable trait that results from the expression of the genotype. Law of Segregation. During gametes formation, the alleles for each gene, such as those for The dominant allele determines the observable trait. seed color, segregate from each other such that each one carries only one allele. 87 88 10. Punnett square - a square diagram designed by Reginald C. Punnett which is b. Law of Independent Assortment - states that the alleles for different traits segregate independently during gametes formation. used to determine the probability of an offspring having a particular genotype and predicting its corresponding phenotype. For example, the alleles for seed shape in pea plants, round (R) and wrinkled (r), and the 11. Monohybrid cross - the parents are crossed for a single trait only. For example, alleles for seed color yellow (Y) and green (y) if heterozygous yellow peas (Yy) were test crossed, the resulting Punnett square would separate independently and at random analysis is below. from each other. For homozygous round yellow pea (RRYY), the only type of gametes formed is RY. Meanwhile, for heterozygous round yellow peas (RrYy), there are four different types of gametes that were formed namely RY, Ry, rY, and ry. Lastly, for homozygous wrinkled green pea (rryy), the only type of gametes formed is ry. 89 90 © Asst. Prof. Gideon A. Legaspi, RCh, MSc 15 Basic Biology Reviewer 25/09/2024 12. Dihybrid cross - the parents are crossed for two traits. For example, if 13. Non-Mendelian Inheritance - refers to any pattern of inheritance that does not heterozygous round yellow peas (RrYy) were test crossed, the resulting Punnett follow one or two laws of the Mendelian genetics. square analysis is given below. a. Incomplete dominance - occurs when one allele is not completely dominant over the other allele such that the heterozygous phenotype is the blend of the two homozygous phenotypes. For example, the gene for red flower color (R) is not completely dominant over white flower color (r). The heterozygote (Rr) will have a pink color because of the blending of red and white colors. 91 92 b. Co-dominance - occurs when both alleles are simultaneously expressed in the c. Sex-linked traits - those that are found only in the X chromosome and absent heterozygote. In cows, the roan coat color is a result of co-dominance of red coat in the Y chromosome. These traits are therefore linked to the gender of an and white coat colors. In humans, a typical example of co-dominance is the ABO individual. blood type where blood type A and B are co-dominant. i. Since males only have a single X chromosome, they are more prone to X-linked recessive disorders like red-green color blindness, male pattern baldness, hemophilia and Duchenne muscular dystrophy. ii. Hemophilia - a sex-linked recessive disorder that results to the inability of the blood to clot, making someone susceptible to life-threatening incidence of hemorrhage. A carrier mother and a normal father have a 25% chance of having a male child that will be hemophiliac and a 25% chance of having a carrier daughter. 93 94 14. Molecular Biology - the branch of Biology that deals with the study of proteins and nucleic acids. 15. Central dogma - of Molecular Biology describes how the genetic information in our DNA is transmitted into proteins through a two-step process called transcription and translation. 16. Transcription - the process by which the genetic information contained in the DNA is transferred into the ribonucleic acid (RNA) which occurs in the nucleus. 17. Translation - the process by which the genetic information in the RNA is converted to protein which occur in the cytoplasm, particularly the ribosomes. 95 96 © Asst. Prof. Gideon A. Legaspi, RCh, MSc 16 Basic Biology Reviewer 25/09/2024 PRACTICE QUESTIONS PRACTICE QUESTIONS 1. What do you call the observed traits in an organism as determined by its genes? 1. What do you call the observed traits in an organism as determined by its genes? A. Genotype C. Recessive trait A. Genotype C. Recessive trait B. Dominant trait D. Phenotype B. Dominant trait D. Phenotype 2. What is the maximum probability that the child of a couple with blood types A and 2. What is the maximum probability that the child of a couple with blood types A and B will have a blood type O? B will have a blood type O? ? A. ½ B. ¼ C. 1/8 D. 1/16 A. ½ B. ¼ C. 1/8 D. 1/16 3. Which genetic law states that the alleles in a gene separates during gametes 3. Which genetic law states that the alleles in a gene separates during gametes formation? formation? A. Law of Segregation A. Law of Segregation B. Mendel’s Law B. Mendel’s Law C. Law of Independent Assortment C. Law of Independent Assortment D. Murphy’s Law D. Murphy’s Law 97 98 F. PHOTOSYNTHESIS AND RESPIRATION 1. Photosynthesis - the process by which light energy is converted to chemical 6. Xylem – the vascular channel that conducts water and other nutrients from the energy by plants and other autotrophic organisms. soil to the leaves. 2. Chlorophyll - the green pigment in plants that absorbs light energy which is 7. Phloem – the vascular channel that transports food from the leaves to other used to combine water and carbon dioxide to produce glucose during parts of the plant. photosynthesis. 3. Mesophyll – the cells of the leaves where chlorophyll are found which are parenchymal cells in the upper and lower epidermis. 4. Cuticle - the upper epidermis of the leaves which is covered with the waxy substance cutin, that prevent water loss through transpiration. 5. Stoma (plural stomata) - an opening on the lower epidermis that allows the passage of gases into and out of the leaves as regulated by guard cells. 99 100 6. Chloroplast – the plastid in plants that contains the chlorophyll which has an outer and inner membrane separated by an intermembrane space. 7. Stroma - the alkaline aqueous space inside the chloroplasts that contains various proteins, DNA, ribosomes, and starch granules. 8. Thylakoid - disc-shaped membranous sacs that contain the chlorophylls. 9. Granum – formed by stacks of 10-20 thylakoids. 10. stroma lamellae - membranous structures that connect the thylakoid within one granum to another Image Source: https://micro.magnet.fsu.edu/cells/chloroplasts/chloroplasts.html 101 102 © Asst. Prof. Gideon A. Legaspi, RCh, MSc 17 Basic Biology Reviewer 25/09/2024 11. Light harvesting complex (LHC) – formed by chlorophyll along with 14. Light-independent phase (Calvin cycle) - also referred to as dark reaction carotenoids and proteins, that channels energy from sunlight into the because it occurs even in the absence of light particularly in the stroma. It starts photosynthetic reaction center (PRC). when the enzyme complex ribulose bisphosphate carboxylase/oxygenase or RuBisCO fixes CO2 with ribulose bisphosphate (RuBP) (carbon fixation). 12. During photosynthesis, six moles of carbon dioxide gas react with six moles of water to produce one mole of glucose and six moles of oxygen gas. This reaction is summarized by the chemical equation below: 15. Respiration - the oxidative breakdown of glucose molecule through a complex series of reactions in the mitochondrion to yield energy in the form of 6CO2(g) + 6H2O(l)  C6H12O6(aq) + 6O2(g) adenosine triphosphate (ATP). 16. Mitochondrion - is called the “powerhouse of the cell” because of such 13. Light-dependent phase – the phase of photosynthesis that only occur in the energy yielding function. It is an organelle with outer and inner membranes presence of light, and it takes place on the thylakoid membrane within the that are separated by an intermembrane space. The inner membrane is chloroplast. During this phase light energy is converted to adenosine convoluted forming partial partitions called cristae where membrane proteins triphosphate (ATP) and reduced nicotinamide adenine dinucleotide phosphate are embedded including the ATP synthase complex. The inner space enclosed (NADPH) which serves as chemical energy and reducing power, respectively. by the inner membrane is called the mitochondrial matrix. 103 104 17. Glycolysis - occurs in the cell’s cytoplasm, where glucose is split into two pyruvate molecules by a series of reactions that also yield two molecules each of ATP and reduced nicotinamide adenine dinucleotide (NADH). 18. Pyruvate oxidation – undergoes oxidative decarboxylation to yield acetyl- CoA and two molecules of NADH in the mitochondrial matrix. 19. Kreb’s cycle (citric acid cycle) - acetyl-CoA is combined with oxaloacetate to form citric acid which is the starting reaction for this cyclical reaction which involves a series of reactions that yields a total of 6 NADH, 2 reduced flavin adenine dinucleotide (FADH2), and 2 ATP molecules. 20. Electron transport chain (ETC) – the electrons and hydrogen cations carried by NADH and FADH2 are shuttled through a series of protein complexes, resulting to proton gradient. Image Source: https://news-medical.net/life-sciences/ What-are-Mitochondria.aspx 105 106 21. Oxidative phosphorylation – the coupling of the proton gradient with ATP synthesis by the ATP synthase complex. 22. The over-all reaction of respiration involved is that one of glucose is oxidized with 6 moles of oxygen gas to yield 6 moles of carbon dioxide, 6 Pyruvate moles of water, and 36-38 moles of ATP which is the opposite reaction of oxidation photosynthesis: C6H12O6(aq) + 6O2(g)  6CO2(g) + 6H2O(l) 107 108 © Asst. Prof. Gideon A. Legaspi, RCh, MSc 18 Basic Biology Reviewer 25/09/2024 PRACTICE QUESTIONS PRACTICE QUESTIONS 1. The process by which ATP is produced from glucose inside the mitochondria is 1. The process by which ATP is produced from glucose inside the mitochondria is called? called? A. Oxidation C. Respiration A. Oxidation C. Respiration B. Reduction D. Condensation B. Reduction D. Condensation 2. What pigment in plants enable them to manufacture their own food? 2. What pigment in plants enable them to manufacture their own food? A. Carotene C. Chloroplast A. Carotene C. Chloroplast B. Xanthophyll D. Chlorophyll B. Xanthophyll D. Chlorophyll 3. Which of the following are the products of photosynthesis? 3. Which of the following are the product of photosynthesis? A. Carbon dioxide and water A. Carbon dioxide and water B. Oxygen gas and glucose B. Oxygen gas and glucose C. Glucose and carbon dioxide gas C. Glucose and carbon dioxide gas D. Water and oxygen gas D. Water and oxygen gas 109 110 5. Plant Taxonomy G. Taxonomy a. Non-vascular plants (bryophytes) - do not have lignified conducting structures 1.Taxonomy - the branch of Biology that deals with the called xylem and phloem. Incudes mosses, liverworts, and hornworts. hierarchical classification of organisms based on their b. Vascular plants (tracheophytes) - have lignified conducting structures called shared characteristics. xylem and phloem. 2. Carl Linnaeus - recognized as the “Father of Taxonomy” because of his work in establishing the binomial nomenclature system. 3. Binomial nomenclature - an organism is given a scientific name that consists of its genus and species name in Latin. For example, the scientific name of a cat is Felis catus, Felis is the genus that should be written with a capitalized first letter while catus is the species name that should be written in lower case letters. 4. Taxonomic hierarchy - from highest to lowest is domain, kingdom, phylum, class, order, family, genus, and species. Image source: https://courses.lumenlearning.com/boundless-biology/chapter/seedless-vascular-plants/ 111 112 c. Pteridophytes - seedless vascular plants such as ferns. 6. Animal Taxonomy d. Spermatophytes - seed-bearing plants. a. Invertebrates - animals without backbone. 1. Gymnosperms - have naked or exposed seeds that are found mostly in cones with 1. Poriferans - commonly known as sponges, are asymmetric aquatic animals with more than 1,000 species such as conifers, cycads, and Gingko. unspecialized cells. 2. Angiosperms - bear flowers and have seeds enclosed in a fruit. They are the most 2. Echinoderms - radially asymmetric marine animals that include sea cucumbers, diverse phylum of plants with almost 300,000 species. starfishes, sea urchins, and brittle stars. a. Monocotyledons (monocots) - , have seed in one cotyledon, fibrous root system, 3. Cnidarians - stinging aquatic animals that include corals, sea anemones, and scattered vascular bundles, parallel leaf venation, and petals in multiple of 3’s. jellyfishes. b. Dicotyledons (dicots) - have seed in two cotyledons, taproot system, radial 4. Mollusks - soft-bodied invertebrates with around 85,000 known species that vascular bundles, net-like leaf venation, and petals in multiple of 4’s or 5’s. include gastropods (snails and slugs), bivalves (such as oyster and mussel), and cephalopods (such as squids and octopuses). 5. Annelids - also known as segmented or ringed worms including earthworms and leeches. 6. Nematodes - round worms like the parasitic worms filarias, Ascaris, pinworms, and hook worms. 7. Platyhelminths - flatworms that include the parasitic flukes and tapeworms, and the mostly free-living planarians. 113 114 © Asst. Prof. Gideon A. Legaspi, RCh, MSc 19 Basic Biology Reviewer 25/09/2024 8. Arthropods - the largest phylum of animals in our planet including arachnids (spiders and scorpions), myriapods (millipedes and centipedes), crustaceans ( crabs H. Ecology – the study of the relationships between living organisms and and shrimps), and hexapods (insects). their physical environment. b. Vertebrates – animals with backbone. a. Abiotic factors - physical and chemical components of the environment that 1. Fishes - cold-blooded aquatic vertebrates with gills for breathing and fins and support and affect living things. Abiotic factors can be subdivided into climactic tails for swimming. factors, edaphic factors, and physiographic factors. 2. Amphibians - cold-blooded vertebrates with metamorphic life cycle like frogs and toads. 1. Climatic factors - affect weather conditions like sunlight, temperature, 3. Reptiles - cold-blooded vertebrates with four limbs (except snakes) and thick, precipitation, and wind, among others. horny epidermis that make them capable of thriving on dry land. Include turtles, snakes, crocodiles, and lizards. 2. Edaphic factors - the physico-chemical factors of the soil in an ecosystem which 4. Birds – warm-blooded, winged and feathered vertebrates belonging to class include soil type, composition, water content, mineral content, and organic matter Aves. content. 5. Mammals - warm-blooded vertebrates with female that have mammary glands which produce milk for the nourishment of their young offspring 3. Physiographic factors - refer to topography or over-all features of a place such as the presence of rivers, lakes, mountains, or plains. 115 116 b. Biotic factors - are the living things found in an ecosystem. c. Ecological relationship - refers to the interactions between individuals of various 1. Autotrophs - can manufacture their own food either by photosynthesis or species that can either be symbiotic or non-symbiotic in nature. producers (photoautotrophs) like plants and algae or chemical synthesis 1. Symbiotic relationships - close interactions over a long period of time which (chemoautotrophs) like Archaea. They serve as the ultimate food source for all have an impact on the survival of the associated species. living things. a. Commensalism - one organism benefits from the relationship without harming the other one. Example of commensalism is the growth of orchids on tree trunks and 2. Heterotrophs - or consumers cannot manufacture their own food and must eat the nesting of birds on a tree. producers or other consumers for nourishment. b. Mutualism - both organisms benefit from their interaction. Examples of this are a. Primary consumers - eat producers as their food source. the relationship between coral and the algae that they harbor and the remora fish on b. Secondary consumers – eat primary consumers as their food source. manta rays or sharks. c. Tertiary consumers - feed on secondary consumers. c. Parasitism - one organism benefits at the expense of another in their interaction. d. Herbivores - animals that feed exclusively feed on plants. The parasite is the one that benefits while the one being harmed is the host. Parasites e. Carnivores – animals that feed exclusively on other animals. that dwell outside the host are called ectoparasites like ticks in dogs, fleas in cats, f. Omnivores - animals that feed on both plants and other animals. and lice in humans. Parasites that dwell inside an organism are called endoparasites like worms inside the intestines of animals and humans. 3. Saprotrophs - derive their nourishment from decaying organic matter such as bacteria, fungi, and some protozoa. 117 118 2. Non-symbiotic relationships - are relationships that do not involve close d. Trophic level - the position of an organism in a association between food chain depending on its mode of nourishment, a. Predation - the relationship wherein one animal kill another for food. The killer whether as producer or various kinds of consumer. is called the predator, and the killed organism is the prey. Example of this is a lion 1. Productivity - of an ecosystem is measured by the percentage of energy that enters the ecosystem that is and all animals that it hunts as prey like deer and zebra. converted into biomass in each trophic level. b. Competition - the rivalry between species for the same resource that is of limited quantity. If the competition is between individuals of the same species, then 2. Biomass - defined as the total mass in a unit area i