General Biology (Q1) PDF

GENERAL BIOLOGY (Q1) - In 1858, Rudolf Virchow said Lesson 1 “Omnis cellula e cellula” meaning new cells came from pre-existing Cell Theory...

GENERAL BIOLOGY (Q1) - In 1858, Rudolf Virchow said Lesson 1 “Omnis cellula e cellula” meaning new cells came from pre-existing Cell Theory cells History Three (3) postulates of cell theory - In 1665, Robert Hooke 1. All living things are made up of discovered the cell while looking cells at a piece of cork under the 2. All cells came from pre-existing microscope. cells - In 1674, Anton Van Leeuwenhoek 3. Cells are the basic units of life became the first to observe live cells made possible by an Lesson 2 improvement in the microscope. - In 1838, Matthias Jakob Cell Organelles - The word “organelle” means “little Schleiden, a German Botanist organ” said that cells are the building - All cells share three common blocks of plants that arose from components. - Cell Membrane a single cell. - Cytoplasm - In 1839, Theodor Schwann said - DNA that cells are the fundamental units of animals. Three Common Cell Organelles - Schleiden and Schwann’s Cell Membrane discovery led to the “cell theory” - All cells have a cell membrane, a where cells are the basic unit of phospholipid bilayer with all living things. This failed to embedded proteins that separates the internal contents explain how new cells arose of the cell from its surrounding environment. Updated as of September 20, 2024 All rights reserved | 12-Gauss 2024-2025  GENERAL BIOLOGY (Q1) - Cell membranes that specialize in - Pili(or pilus) are used to absorption are folded into exchange genetic material fingerlike projections called during a type of reproduction microvilli. called conjugation. Cytoplasm - Bacteria use Fimbriae(or fimbria) - The cytoplasm is the entire to attach to a host cell. region of the cell within the - In terms of size prokaryotic cells plasma membrane. are significantly smaller than - In eukaryotes, it comprises eukaryotic cells with prokaryotic organelles suspended in the gel- cells being 0.1 to 5 nm in like cytosol, the cytoskeleton, diameter to a eukaryotic cell’s 10 and various chemicals. to 100 nm diameter. - Consists of 70% to 80% water, - However, the prokaryotic cell’s maintaining a semi-solid smaller size ensures that ions consistency due to the proteins and organic molecules quickly within it diffuse throughout the cell. Prokaryotic vs Eukaryotic Cells Eukaryotic Cells - Unlike prokaryotic cells, Prokaryotic Cells eukaryotic cells have: - A prokaryote is a simple, single- - a membrane-bound celled unicellular organism that nucleus lacks a nucleus, or any other - numerous membrane- membrane-bound organelle. bound organelles - Prokaryotic DNA is found in a - several-rod shaped region within the cell called the chromosomes nucleoid. - Most prokaryotes have a Other Cell Organelles peptidoglycan cell wall and many have a polysaccharide capsule. The Nucleus - Some prokaryotes have flagella, - Typically, the nucleus is the most pili, or fimbriae. prominent organelle in a cell. - Flagella(or flagellum) is used for - The nucleus houses the cell’s locomotion. DNA and directs the synthesis of ribosome subunits and proteins. Updated as of September 20, 2024 All rights reserved | 12-Gauss 2024-2025  GENERAL BIOLOGY (Q1) unwound, jumbled bunch of Nuclear Envelope threads. These unwound protein- - Double-membrane structure that DNA complexes are called constitutes the outermost portion chromatin. of the nucleus. - Both the inner and outer Nucleolus membranes of the nuclear - The nucleolus is organized envelope are phospholipid around regions of some bilayers. chromosomes containing DNA - The nuclear envelope is that encode ribosomal RNA. punctuated with pores that - A darkly stained area within the control the passage of ions, nucleus, the nucleolus molecules, and RNA between the aggregates the ribosomal RNA nucleoplasm and cytoplasm. with ribosomal subunits that are - The nucleoplasm is the semi-solid transported out through the fluid inside the nucleus, where we pores in the nuclear envelope to find the chromatin and the the cytoplasm. nucleolus. - The nucleus is considered a ribosome production factory. Chromatin and Chromosomes - Chromosomes are structures Ribosomes within the nucleus that are made - Ribosomes are the cellular up of DNA. organelles responsible for - In eukaryotes, chromosomes are protein synthesis and are linear structures consisting of considered the protein factories linear DNA and proteins. of the cell. - Every eukaryotic species has a - They may be attached to the specific number of chromosomes cytoplasmic side of the cell in the nuclei of its body cells. As membrane or the cytoplasmic an example, a human being has side of the endoplasmic 46. reticulum and the outer - When the cell is in the growth membrane of the nuclear and maintenance phases of its envelope. life cycle, proteins are attached to DNA, and they resemble an Mitochondria Updated as of September 20, 2024 All rights reserved | 12-Gauss 2024-2025  GENERAL BIOLOGY (Q1) - Mitochondria are often called the - The membranes of vacuoles, on powerhouse of the cell the other hand, do not fuse with - They are responsible for making the membranes of other cellular Adenosine Triphosphate(ATP). components. - The process used for making ATP produces oxygen and produces Endoplasmic Reticulum carbon dioxide as a waste - The endoplasmic reticulum is a product. series of interconnected membranous sacs and tubules Peroxisomes that modify proteins and - Peroxisomes are small, round synthesize lipids. organelles enclosed by single - However, these two functions are membranes. performed in different areas of - Peroxisomes carry out oxidation the endoplasmic reticulum: the reactions that break down fatty rough endoplasmic reticulum acids. and the smooth endoplasmic - They also detoxify many poisons reticulum. that may enter the body. - Many of these poisons release Rough Endoplasmic Reticulum hydrogen peroxide, which is - The rough endoplasmic reticulum damaging to cells; however, is so named because the when these reactions are ribosomes attached to its confined to peroxisomes, cytoplasmic surface give it a enzymes safely break down the studded appearance when hydrogen peroxide. viewed through an electron microscope. Vesicles and Vacuoles - Ribosomes transfer their newly - Vesicles and vacuoles are synthesized proteins into the membrane-bound sacs that lumen of the rough endoplasmic function in storage and reticulum where they undergo transport. structural modifications, such as - The membranes of vesicles can folding or the acquisition of side fuse with either the plasma chains. membrane or other membrane systems within the cell. Updated as of September 20, 2024 All rights reserved | 12-Gauss 2024-2025  GENERAL BIOLOGY (Q1) - The rough endoplasmic reticulum be sorted. These newly modified also creates phospholipids for proteins and lipids are then cellular membranes. tagged with phosphate groups or - The rough endoplasmic reticulum other small molecules so that is abundant in cells that secrete they can be routed to their protein for example cells in the proper destinations. liver. - Finally, the modified and tagged proteins are packaged into Smooth Endoplasmic Reticulum secretory vesicles that bud from - The smooth endoplasmic the trans face of the Golgi. reticulum is continuous with the - In plant cells, the Golgi rough endoplasmic reticulum but apparatus has the additional role has few or no ribosomes on its of producing polysaccharides. cytoplasmic surface. - Functions of the smooth Cytoskeleton endoplasmic reticulum include - A network of protein fibers that the synthesis of carbohydrates, help maintain the shape of the lipids, and steroid hormones; cell, secure some organelles in detoxification of medications specific positions, allow and poisons, and storage of cytoplasm and vesicles to move calcium ions. within the cell, and enable cells within multicellular organisms to The Golgi Apparatus move. - Sorting, tagging, packaging and - Collectively, this network of distribution of lipids and proteins protein fibers is known as the take place in the Golgi cytoskeleton. apparatus, a series of flattened - There are three types of fibers membranes. within the cytoskeleton: - The receiving side of the Golgi microfilaments, intermediate apparatus is called the cis face. filaments, and microtubules. The opposite side is called the trans face. As the proteins and lipids travel through the Golgi, they undergo further Flagella (ACCESSORY ORGANELLE) modifications that allow them to Updated as of September 20, 2024 All rights reserved | 12-Gauss 2024-2025  GENERAL BIOLOGY (Q1) - Flagella are long, hair-like their centrioles removed can still structures that extend from the divide. plasma membrane and are used to move an entire cell. Lysosomes - Nicknamed “janitor of the cell” or Cilia (ACCESSORY ORGANELLE) “garbage disposal of the cell” - Many of them extend along the - Lysosomes have the role of the entire surface of the plasma digestive component and membrane. organelle-recycling facility of - Are short hair-like structures that animal cells. are used to move entire cells or - Enzymes within the lysosome aid substances along the outer the breakdown of proteins, surface of the cell polysaccharides, lipids, nucleic acids, and even worn-out Specialized Cell Structures organelles. - Uses hydrochloric enzymes Centrosomes - Lysosomes also use their - Centrosomes are microtubule- hydrochloric enzymes to destroy organizing centers found near pathogens that might enter the the nuclei of animal cells. It cell. contains a pair of centrioles, two structures that lie perpendicular Cell Wall to each other. Each centriole is a - The cell wall is a rigid covering cylinder of nine triplets of that protects the cell, provides microtubules. structural support, and gives - The centrosome replicates itself shape to the cell. before the cell divides. The - The chief component of centrioles appear to have some prokaryotic cell walls is role in pulling duplicated peptidoglycan, the major organic chromosomes to opposite ends molecule in the plant cell wall is of the dividing cell. cellulose, a polysaccharide made - However, the exact function of up of glucose units. centrioles in cell division is still not clear, as cells that have had Updated as of September 20, 2024 All rights reserved | 12-Gauss 2024-2025  GENERAL BIOLOGY (Q1) Chloroplasts Types of cell modifications - Chloroplasts are plant cell organelles that carry out Apical Modifications photosynthesis. - Apical modifications are cell - Photosynthesis is a series of modifications found on the reactions that use carbon apical surface of a cell. dioxide, water, and light energy to make glucose and oxygen. - Chloroplasts contain a green pigment called chlorophyll - Chlorophyll captures the light energy that drives the reaction to photosynthesis. Central Vacuole - Plant cells contain a large central vacuole that occupies most of Examples of Apical modifications the area of the cell. - Cilia - The central vacuole plays a key - Cilia(singular: cilium) are role in regulating the cell’s usually short hair-like concentration of water in structures that move in changing environmental waves to generate fluid conditions. movement. - The central vacuole also supports - Usually found in the the expansion of the cell. respiratory system. - Works together with goblet cells that secrete mucus to Lesson 3 remove debris and microbes out Cell Modifications - Formed from microtubules - Cells are modified to perform different specialized functions - Flagella - Flagella(singular: flagellum) are whiplike Updated as of September 20, 2024 All rights reserved | 12-Gauss 2024-2025  GENERAL BIOLOGY (Q1) structures used for propulsion - There are different names for different numbers and locations of flagella - Pseudopods - Pseudopods are temporary, irregular lobes formed by amoeba and some other eukaryotic cells. - Villi and Microvilli - Bulge outward to engulf - Villi are small fingerlike prey. projections that help increase surface area for easier absorption of nutrients. - Microvilli are even smaller fingerlike projections that arise in the surface of villi to increase the surface area for easier absorption AND adsorption of - Extracellular Matrix (ECM) nutrients. - Compound secreted by the cell on its apical surface - The cell wall is the extracellular structure in plant cells that distinguishes them from animal cells Updated as of September 20, 2024 All rights reserved | 12-Gauss 2024-2025  GENERAL BIOLOGY (Q1) - Glycoprotein is the main ingredient of ECM in animal cells Lateral Modifications - Modifications found on the lateral surface of the cell - Tight Junctions - Act as barriers that regulate the movement of water and solutes between epithelial layers - Prevents leakage of extracellular fluid Examples of Lateral Modifications - Gap Junctions - Also known as communicating junctions - Closable channels that connect the cytoplasm of adjoining animal cells - The presence of connexon that allows a direct exchange of chemicals between the cytoplasm of two cells's basement membrane - Adhering Junctions Updated as of September 20, 2024 All rights reserved | 12-Gauss 2024-2025  GENERAL BIOLOGY (Q1) - Anchoring junctions on the - Desmosomes/ lateral surface of the cell Hemidesmosomes - Fastens cells to one - Anchoring junctions on the another basal surface of the cell - Very similar to Adhering Junctions - Rivet-like links between cytoskeleton and extracellular matrix components such as the basal lamina that underlie epithelia - Primarily composed of keratin, integrins, and cadherins Basal Modifications - Hemidesmosomes are - Modifications on the basal desmosomes that are surface of the cell found on the lateral surface of the cell Examples of Basal Modifications Updated as of September 20, 2024 All rights reserved | 12-Gauss 2024-2025  GENERAL BIOLOGY (Q1) Lesson 4 replicating each chromosome in the nucleus. Cell Cycle S phase - In the S phase, DNA replication occurs through the mechanisms that result in the formation of identical DNA molecules — sister chromatids — that are joined at a point by the centromeric region. - The centrosome is duplicated during the S phase. - The two centrosomes will give Phases of the Cell Cycle rise to the mitotic spindle, the Interphase apparatus that orchestrates the - During interphase, the cell movement of chromosomes undergoes normal growth during mitosis. processes while also preparing for cell division. For the cell to G2 Phase undergo the mitotic phase, many - In the G2 phase, the cell internal and external conditions replenishes its energy stores and must be met. The stages of synthesizes the proteins interphase are G1 , S, G2. necessary for chromosome manipulation. G1 Phase - In this phase, the cell makes final - During the G1 phase, the cell preparations for the mitotic grows and more organelles are phase. produced. - During this phase, the cell The Mitotic Phase accumulates the building blocks - In the mitotic phase, a multistep of chromosomal DNA and the process is undergone during associated proteins as well as which the duplicated accumulates sufficient energy chromosomes are condensed, reserves to complete the task of aligned, separated, and moved to opposite poles of the cell, and Updated as of September 20, 2024 All rights reserved | 12-Gauss 2024-2025  GENERAL BIOLOGY (Q1) then divided into two new cell cycle at which the identical daughter cells. progression of a cell to the next stage in the cell cycle can be halted until conditions are Control of the Cell Cycle favorable. - The length of the cell cycle is - These checkpoints occur near the highly variable, even among cells end of G1, at the G2/M transition, of a single organism. and during metaphase. - There is variation in the time a cell spends in each phase of the Cell Cycle Checkpoints cell cycle. - In rapidly dividing human cells, G1 checkpoint the cell cycle lasts about 24 - The G1 checkpoint, also known as hours. the restriction point in - The G1 lasts approximately 9 mammalian cells and the start hours, the S phase lasts point in yeast, is the point at approximately 10 hours, the G2 which the cell becomes phase lasts about 4.5 hours, and committed to entering the cell the M phase lasts for about 0.5 cycle. hours. - As the cell progresses through G1, depending on internal and Regulation at the Internal external conditions, it can either Checkpoints delay G1, enter a quiescent state - Mistakes in the duplication or known as G0, or proceed past distribution of the chromosomes the restriction point. lead to mutations that may be - DNA damage is the main passed on to every new cell indication for a cell to "restrict" produced from an abnormal cell. and not enter the cell cycle. - To prevent a compromised cell from continuing to divide, there G2 checkpoint are internal control mechanisms - Following DNA replication in the that operate at three main cell S phase, the cell undergoes a checkpoints. growth phase known as G2. - A checkpoint is one of the - During this time, necessary several points in the eukaryotic mitotic proteins are produced Updated as of September 20, 2024 All rights reserved | 12-Gauss 2024-2025  GENERAL BIOLOGY (Q1) and the cell is once more - The nucleolus disappears. subjected to regulatory - The centrosomes begin to move mechanisms to ensure proper to opposite poles of the cell. status for entry into the - Microtubules that will form the proliferative Mitotic (M) phase. mitotic spindle extend between the chromosomes, pushing them Metaphase Checkpoint farther apart as the microtubule - The metaphase or mitotic spindle fibers lengthen. checkpoint occurs at the point in - The sister chromatids begin to metaphase where all the coil more tightly with the aid of chromosomes should/have condensin proteins and become aligned at the mitotic plate and visible under a light microscope. be under bipolar tension. The tension created by this bipolar Late Prophase attachment is what is sensed, - Many processes from the early which initiates the anaphase prophase continue to advance. entry. - The remnants of the nuclear envelope fragment Lesson 5 - The mitotic spindle continues to develop as more microtubules Mitosis assemble and stretch across the Karyokinesis length of the former nuclear area. - Karyokinesis (a division of the - Chromosomes become more nucleus) also known as mitosis, is condensed and discrete. divided into different phases — - Each sister chromatid develops a prophase, metaphase, anaphase, protein structure called a and telophase. kinetochore in the centromeric region. The proteins of the Phases of Mitosis kinetochore attract and bind Early Prophase mitotic spindle microtubules. - The nuclear envelope starts to disassociate into small vesicles, Metaphase and the membranous organelles - During metaphase, all the fragment and disperse towards chromosomes align in a plane the periphery of the cell. Updated as of September 20, 2024 All rights reserved | 12-Gauss 2024-2025  GENERAL BIOLOGY (Q1) called the metaphase plate, or - Nuclear envelopes form around the equatorial plane, midway the chromosomes. between the two poles of the cell. - The sister chromatids are still Cytokinesis tightly attached by cohesion - During cytokinesis, cell division is proteins. completed via the physical - At this time, the chromosomes separation of the cytoplasmic are maximally condensed. components into two daughter Anaphase cells. - During anaphase, the cohesion - The division is not complete until proteins degrade, and the sister the cell components have been chromatids separate at the apportioned and completely centromere. separated into two daughter - Each chromatid now called a cells. chromosome, is pulled rapidly - Stages of mitosis are different toward the centrosome to which for eukaryotes that have cell its microtubule is attached. walls, such as plant cells. - The cell becomes visibly - In cells such as animal cells that elongated as the polar lack cell walls, cytokinesis follows microtubules slide against each the onset of anaphase. A other at the metaphase plate, contractile ring composed of where they overlap. actin filaments forms just inside the plasma membrane at the Telophase former metaphase plate. The - During telophase, the actin filaments pull the equator chromosomes reach the opposite of the cell inward, forming a poles and begin to decondense fissure. This fissure, or “crack”, is (unravel), relaxing into a called the cleavage furrow. The chromatin configuration. furrow deepens as the actin ring - The mitotic spindles are contracts, and eventually, the depolymerized into tubulin membrane is cleaved in two. monomers that will be used to - In plant cells, a new cell wall assemble cytoskeletal must form between the daughter components for each daughter cells. During interphase, the cell. Golgi apparatus accumulates Updated as of September 20, 2024 All rights reserved | 12-Gauss 2024-2025  GENERAL BIOLOGY (Q1) enzymes, structural proteins, and the unique characteristics of glucose molecules (which will be living organisms. used to make the cellulose component of the cell wall) before breaking into vesicles and dispersing throughout the dividing cell. During telophase, these Golgi vesicles are Parts of a Chromosome transported on microtubules to form a phragmoplast a vesicular structure) at the metaphase plate. There, the vesicles fuse and coalesce from the center toward the cell walls; this structure is called a cell plate. As more vesicles fuse, the cell plate enlarges until it merges with the cell walls at the periphery of the cell. Enzymes use the glucose p and q arms that has accumulated between - The centromere divides the the membrane layers to build a chromosome into two regions the new cell wall. The Golgi p arm(short) and the q arm(long) membranes become parts of the plasma membrane on either side Telomeres of the new cell wall. - At the ends of each chromosome are stretches of DNA called Chromosomes telomeres. Telomeres help - Chromosomes are thread-like protect the ends of structures found in the nucleus of chromosomes from damage or cells, made of DNA and proteins, fusing with nearby carrying genetic information. chromosomes. They play a crucial role in cell division, ensuring DNA is Centromeres accurately copied and - The centromere links a pair of distributed, and are essential for sister chromatids together Updated as of September 20, 2024 All rights reserved | 12-Gauss 2024-2025  GENERAL BIOLOGY (Q1) during cell division. This where the spindle fibers attach constricted region of the during cell division to pull sister chromosome connects the sister chromatids apart. (extra note: chromatids, creating a short arm Kinetochores are located directly (p) and a long arm (q) on the next to the centromeres.) chromatids. During mitosis, spindle fibers attach to the centromere via the kinetochore. Additional Information - DNA is wrapped around proteins Sister Chromatids called histones - A sister chromatid refers to the - The egg cell produced through identical copies (chromatids) ovulation produces one X formed by the DNA replication of chromosome while the sperm cell a chromosome, with both copies can either be an X or a Y. joined together by a common - A human being has 23 pairs of centromere. In other words, a chromosomes, if a human is born sister chromatid may also be with more or less it is considered said to be 'one-half' of the a genetic mutation and causes duplicated chromosome. various health issues. - A pair of sister chromatids is called a dyad. - A full set of sister chromatids is Lesson 6 created during the synthesis (S) phase of interphase when all the Meiosis chromosomes in a cell are - Meiosis is a special type of cell replicated. division necessary for sexual - The two sister chromatids are reproduction in eukaryotes. separated from each other into - Meiosis begins with one diploid two different cells during mitosis cell containing two copies of or the second division of meiosis. each chromosome. - One from the organism’s mother Kinetochores and one from its father - is a disc-shaped protein structure associated with duplicated chromatids in eukaryotic cells Updated as of September 20, 2024 All rights reserved | 12-Gauss 2024-2025  GENERAL BIOLOGY (Q1) Prophase I Zygotene (Zygonema) - Prophase I is the first stage of - Chromosomes line up and pair Meiosis with the main purpose of with their homologous partners Genetic change. forming bivalents. - DNA is exchanged between - The paired homologous homologous chromosomes in a chromosomes begin to associate process called homologous with one another. recombination. This often results Pachytene (Pachynema) in chromosomal crossover. - The homologous chromosomes - The paired and replicated become tightly associated chromosomes are called through synapsis, forming a bivalents or tetrads tetrad (4 chromosomes) - The process of pairing the - Crossing over can occur at this homologous chromosomes is stage, though it becomes more called synapsis. visible in later stages. - At this stage, non-sister chromatids may crossover at Diplotene (Diplonema) points called chiasmata (plural; - The homologous chromosomes singular chiasma) begin to separate slightly - The chromosomes uncoil, allowing limited transcription of Leptotene (Leptonema) DNA - 1st stage of Prophase I - Chromosomes begin condensing Diakinesis into long strands inside the - Chromosomes condense further, nucleus and the four chromatids in each - The two sister chromatids are tetrad become visible. tightly bound and - Homologous chromosomes indistinguishable from each separate further and the other as they are both chiasmata become more evident homologous. as they terminalize. Updated as of September 20, 2024 All rights reserved | 12-Gauss 2024-2025  GENERAL BIOLOGY (Q1) - Sister chromatids are still attached Meiosis II - Some species enter a brief interphase called interkinesis - Interkinesis lacks an S phase so chromosomes are not duplicated - Forms four haploid gametes Metaphase I - In the 2nd phase of meiosis I - The tetrads from prophase I line Prophase II up in the middle of the dividing - Chromosomes condense cell randomly. - New spindles are formed and - Spindle fibers attach to the engage the individual tetrads from both ends of the kinetochores of the sister cell. chromatids. - Nuclear envelope fragments and breaks Anaphase I - Microtubules pull homologous chromosomes apart Metaphase II - Sister chromatids remain tightly - Chromosomes line up at the bound together at the metaphase plate. centromere - Chiasmata are broken as Anaphase II microtubules attached to the - Sister chromatids are pulled fused kinetochores pull the apart by the shortening of the homologous chromosomes apart kinetochore microtubules. - Nonkinetochore microtubules Telophase I and Cytokinesis lengthen the cell. - Separated chromosomes arrive at opposite poles Telophase II and Cytokinesis - First meiotic division results in - Chromosomes arrive at the poles two haploid cells of the cell and decondense. Updated as of September 20, 2024 All rights reserved | 12-Gauss 2024-2025  GENERAL BIOLOGY (Q1) - Nuclear envelopes surround the four nuclei - Separates the two cells into four unique haploid cells Lesson 7 Mutations Mutations - Alterations or changes in the genetic material - In a clinical context, it's usually Definition of terms (for convenience) harmful - Aneuploidy (change in number of - Inherited chromosomes) if the number of - Can originate from exposure to chromosomes ain’t 46 it is an mutagenic agents but arise more aneuploidy. spontaneously through errors in - Hypo = lower amount, Hyper = DNA replication/repair. higher amount - More likely to be recognized if - Euploidy refers to the amount of effects are detrimental SETS of chromosomes n=23 Chromosomes in context with referring to 23 chromosomes. mutations Nondisjunction - A chromosome anomaly, - Failure of bivalents to separate abnormality, or aberration during Meiosis I, the gametes reflects an atypical number of get both homologous of 1 pair. chromosomes or a structural - Sometimes in meiosis II when abnormality in one or more sister chromatids fail to separate chromosomes. one gamete gets 2 copies of the Karyotype homologous - Refers to a full set of - it can also occur during the early chromosomes from an individual mitotic division of the zygote - which can be compared to a there will be the presence of 2 or “normal” karyotype for the more cell lines. species via genetic testing Updated as of September 20, 2024 All rights reserved | 12-Gauss 2024-2025  GENERAL BIOLOGY (Q1) 3 Types of Aneuploidy - Monosomy when missing a chromosome from a pair - Trisomy is a genetic abnormality in which there are 3 copies of a chromosome instead of the normal 2 of a certain chromosome - Tetrasomy is the presence of 4 Causes copies, instead of the normal 2 of - Aging effect on primary oocyte a particular chromosome - Radiation - Delayed fertilization after ovulation Chromosome variation in number Aneuploidy Monosomy - Is an abnormal number of chromosomes - It occurs when an individual is missing either a chromosome from a pair or has more than Trisomy two chromosomes from a pair. Examples of Syndromes involving - It occurs during Cell division Aneuploidy when the chromosomes do not Down syndrome ( Trisomy 21 or separate properly between two Trisomy G) cells. - is a chromosomal disorder caused by the presence of all or part of an extra 21st chromosome - Named after John Langdon Down, the British physician who described the syndrome in 1866 - The disorder was identified as a chromosome 21 trisomy by Jerome Lejeune in 1959. Updated as of September 20, 2024 All rights reserved | 12-Gauss 2024-2025  GENERAL BIOLOGY (Q1) Physical features include Edward’s Syndrome (Trisomy 18 or - Micronesia (Abnormally small Trisomy E) chin) - is a genetic disorder caused by - An unusually round face the presence of all or part of an - Macroglossia (Protruding or extra 18th chromosome. oversized tongue) - It is named after John H. - An almond shape to the eyes Edwards, who first described the caused by an Epicanthic Fold of syndrome in 1960. the eyelid - The syndrome has a very low - Upslanting Palpebral Fissures rate of survival, resulting from - Shorter limbs heart abnormalities, kidney - a single transverse palmar malformations, and other crease internal organ disorders. - poor muscle tone, and a larger - Children with this syndrome may than normal space between the have mental retardation, big and second toes. developmental delays, growth - Health concerns for individuals deficiency, feeding difficulties, with Down syndrome include a breathing difficulties, and higher risk for congenital heart arthrogryposis(a muscle disorder defects, gastroesophageal reflux that causes multiple joint disease, recurrent ear infections, contractures at birth). obstructive sleep apnea, and - Some physical malformations thyroid dysfunctions. associated with this include a small head (microcephaly) accompanied by a prominent back portion of the head (occiput); low-set, malformed ears; abnormally small jaw (micrognathia); cleft lip/cleft - Down syndrome is observed in 1 palate; upturned nose; narrow in 1250 births eyelid folds (palpebral fissures); - 47 chromosomes XY or XX widely spaced eyes (ocular - #21 Trisomy Nondisjunction hypertelorism. Updated as of September 20, 2024 All rights reserved | 12-Gauss 2024-2025  GENERAL BIOLOGY (Q1) (abdominal defect) abnormal palm pattern, overlapping of fingers over thumb cutis aplasia (missing portion of the skin/hair), cleft palate - UROGENITAL: abnormal Patau syndrome (Trisomy 13 or genitalia and kidney defects Trisomy D) - OTHER: heart defects - A syndrome in which a patient (ventricular septal defect) and has an additional chromosome single umbilical artery 13 due to a nondisjunction of chromosomes during meiosis. - Patau syndrome can also occur when part of chromosome 13 becomes attached to another chromosome (translocated) before or at conception. Of those fetuses that do survive to Turner Syndrome or Ullrich-Turnet gestation and subsequent birth, syndrome “Gonadal Dysgenesis” common abnormalities include: - It is a chromosomal abnormality - NERVOUS SYSTEM: mental & in which all or part of one of the motor challenged, microcephaly, sex chromosomes is absent. holoprosencephaly (failure of the - There are characteristic physical forebrain to divide properly). abnormalities, such as short - STRUCTURAL EYE DEFECTS: stature, swelling, broad chest, microphthalmia, Peters anomaly, low hairline, low-set ears, and cataract, iris and/or fundus webbed necks. (coloboma), retinal dysplasia or - Girls with Turner syndrome retinal detachment, sensory typically experience gonadal nystagmus, cortical visual loss, dysfunction, which results in and optic nerve hypoplasia amenorrhea and sterility. - MUSCULOSKELETAL AND - Concurrent health concerns are CUTANEOUS: polydactyly (extra also frequently present, including digits), low-set ears, prominent congenital heart disease, heel-deformed feet known as hypothyroidism, diabetes, vision rocker-bottom feet, omphalocele Updated as of September 20, 2024 All rights reserved | 12-Gauss 2024-2025  GENERAL BIOLOGY (Q1) problems, hearing concerns, and - The term hypogonadism in XXY many autoimmune diseases. symptoms is often - Finally, a specific pattern of misinterpreted to mean "small cognitive deficits is often testicles" or "small penis". It observed, with particular means decreased testicular difficulties in visuospatial, hormone/endocrine function. mathematical, and memory - Microorchidism (i.e. small areas. testicles). - 1 in 5,000 births - 45 chromosomes - X only - #23 Monosomy Nondisjunction 96-98% do not survive to birth - No menstruation - No breast development Jacob’s syndrome - Narrow hips - Broad shoulders and Euploidy - is the condition in which changes in the number of chromosomes in Klinefelter’s syndrome (47, XXX or the living cells occur in multiples XXY Syndrome) of odd numbers. - is a condition in which human - The change in number could males have an extra X sex occur as a single set chromosome. (monoploidy) or in many - the syndrome was named after multiples of the basic set of Dr. Harry Klinefelter chromosomes. - infertile Types of Euiploidy - Rounded body type with some 1. Monoploidy degree of gynecomastia - the condition is termed (increased breast tissue). monoploidy if among Updated as of September 20, 2024 All rights reserved | 12-Gauss 2024-2025  GENERAL BIOLOGY (Q1) diploid organisms due to strawberry plants, and certain reasons wheat. irregularities occurring in chromosomal number result in the individual having only a single basic set of chromosomes ( haploid ) 2. Diploidy - it is a condition in which due to certain reasons the chromosomes occur as Chromosome Aberrations twice the haploid number. 1. Deletion: Genetic material is It is possible in living missing organisms that are haploid 2. Duplication: Genetic material is like the lower group of present twice (2x the normal) plants. Higher living 3. Inversion: Genetic material is organisms cannot be flipped (orientation wise.) considered diploid Deletion (gene deletion deficiency, or because normally they deletion mutation) have twice the basic - is a mutation in which a part of a number of chromosomes chromosome or a sequence of (2n). DNA is missing. 3. Polyploidy (Multiple Set of - A portion of the chromosome is Chromosomes) missing or deleted. - it is the condition in which - Deletions can be caused by euploidic organisms have errors in chromosomal crossover multiple sets of organisms during meiosis. 3n, 4n, or 5n or more. - Causes include the following: - This phenomenon is Losses from translocation, commonly observed Chromosomal crossovers within among plants. Polyploidy a chromosomal inversion, has been induced in Unequal crossing over, and tomatoes, apples, Breaking without rejoining. chickoos, grapes, Types of deletion include Updated as of September 20, 2024 All rights reserved | 12-Gauss 2024-2025  GENERAL BIOLOGY (Q1) the following: - 46 Chromosomes XY or XX - Terminal Deletion: Deletion that - Deletion of the Upper arm of occurs towards the end of a chromosome 11 chromosome (near the telomeres location-wise.) - Intercalary Deletion/Interstitial Deletion: a deletion that occurs from the interior of a chromosome. Pi Cri-du-chat syndrome Thirteen Q Deletion Syndrome - 1 in 216000 births - 1 in 500000 Birth - 46 chromosomes - 46 Chromosomes XY or XX - Deletion of the lower arm of - Deletion of the lower arm of Chromosome number 5. Chromosome 13 Symptoms include: - Effects include: - Moon-shaped face - Mentally retarded - Heart disease - Deformed face - Mentally Retarded - No thumbs - Malformed Larynx - Heart disease - Normal lifespan - Short lifespan Prader-Willi Syndrome - 1 in 5000000 births The yellow box highlights the lost - 46 Chromosomes portion. - XY=97% of people with PWS - XX=3% of people with PWS - Deletion of the lower arm of Aniridia-Wilms Tumor Chromosome 15 Syndrome - Effects include: - 1 in 50000000 Births (50 mil) - Small penis Updated as of September 20, 2024 All rights reserved | 12-Gauss 2024-2025  GENERAL BIOLOGY (Q1) - Mentally retarded - It can cause intellectual - Respiratory problems disabilities, a distinctive facial - Obesity appearance, and a variety of - Short lifespan physical problems including heart defects and a bleeding disorder. Duplication (chromosomal duplication or gene amplification) - A portion of the chromosome is duplicated, resulting in extra Eighteen Q Deletion Syndrome genetic material. - 1 in 10000000 Births - Duplications arise from an event - 46 Chromosomes XY or XX termed unequal crossing over - Deletion of the lower arm of that occurs during meiosis Chromosome 18 between misaligned homologous - Mentally retarded chromosomes. - Heart disease - Duplication is the opposite of a - Abnormal hands and feet deletion. - Large eyes - The chance of this happening is a - Large ears function of the degree of sharing - Normal lifespan of repetitive elements between two chromosomes. Jacobsen Syndrome (11Q Deletion, CHARCOT-MARIE-TOOTH DISEASE XYY) (CMT) - is a rare congenital disorder - maybe caused by duplication of resulting from the deletion of a the gene encoding peripheral terminal region of chromosome myelin protein 22 (PMP22) on 11 chromosome 17. Updated as of September 20, 2024 All rights reserved | 12-Gauss 2024-2025  GENERAL BIOLOGY (Q1) - Presently incurable, this disease 2. Translocation: Genetic material is is one of the most common swapped from another inherited neurological disorders, chromosome with 36 in 100,000 affected. Translocation - Physical signs include Lack of - When a portion of one muscle, high arching, and chromosome is transferred to hammer toes present on the foot. another chromosome. Inversions - In a reciprocal translocation, - A portion of the chromosome has segments from two different broken off, turned upside down, chromosomes have been and reattached, therefore the exchanged. genetic material is inverted. - Is a chromosome rearrangement in which a segment of a chromosome is reversed end to end. - An inversion occurs when a single chromosome undergoes breakage and rearrangement within itself. - An inversion Inversions are of two types: paracentric and pericentric. - 2 break rearrangement - Segment is reversed - 1. Pericentric inversion: when the centromere is involved - 2. Paracentric inversion: when only one arm is involved Two chromosome disorders Robertsonian Translocation (Both types are called translocation.) - In a Robertsonian translocation, 1. Insertion: Genetic material is an entire chromosome has added from another attached to another at the chromosome Centromere - in humans, these Updated as of September 20, 2024 All rights reserved | 12-Gauss 2024-2025  GENERAL BIOLOGY (Q1) only occur with chromosomes 13, the chromosome 21 long arm 14, 15, 21, and 22. onto the long arm of chromosome 14. Insertions - Rare nonreciprocal type of translocation - A segment of a chromosome gets inserted into another chromosome Ring chromosome - a chromosome whose arms have fused to form a ring. - A ring chromosome is denoted by the symbol r. - Ring chromosomes may form in cells following genetic damage by mutagens like radiation, they may also arise spontaneously during development. Conditions caused by translocations include: - Cancer: several forms of cancer are caused by translocations; this has been described mainly in leukemia (acute myelogenous leukemia and chronic myelogenous leukemia). - Infertility: one of the would-be parents carries a balanced translocation, where the parent - Disorders arising from the is asymptomatic but conceived formation of a ring chromosome fetuses are not viable. Down include ring chromosome 20 syndrome is caused in a minority syndromes where a ring formed (5% or less) of cases by a by one copy of chromosome 20 is Robertsonian translocation of associated with epilepsy Updated as of September 20, 2024 All rights reserved | 12-Gauss 2024-2025  GENERAL BIOLOGY (Q1) - ring chromosome 14 and ring Mutagenesis is the process of DNA chromosome 13 syndrome are change. associated with mental retardation and dysmorphic Mutagenic Agents facial features. - Causes DNA damage that can - Ring chromosome 15 is result in Genetic mutations associated with mental retardation, dwarfism, and Physical Mutagens microcephaly. - High energy Ionizing Radiation: - Ring formation of an X X-rays and Gamma rays can chromosome causes Turner damage Strands and DNA syndrome. bases/sugars (Basically targets Isochromosome either the base holding the T, A, - Formed by the mirror image C, G or targets the TA and CG copy of a chromosome segment bonds themselves.) including the centromere. - Nonionizing radiation: UV rays - A chromosome that has lost one cause Pyrimidine Dimers of its arms and replaced it with (prevent T or C from properly an exact copy of the other arm. bonding with their opposites.) - This is sometimes seen in some Chemical Mutagens females with Turner syndrome or - Base analogs: Directs in tumor cells. mutagenesis - Nitrous Acid: Deaminates C to produce U - Alkylating Agents and Intercalating Agents: Lesions- indirect mutagenesis Pathway to mutation: Mutagens to Mutagenesis to Mutation Replication Fidelity to Mutation Updated as of September 20, 2024 All rights reserved | 12-Gauss 2024-2025  GENERAL BIOLOGY (Q1) Mutagenic Agents present in Cigarettes. (more reasons not to smoke) Oncogenes: Mutated genes that could cause cancer. Updated as of September 20, 2024 All rights reserved | 12-Gauss 2024-2025