Cell Division Mitosis and Meiosis PDF

LESSON 4: CELL DIVISION: MITOSIS AND MEIOSIS  VINCENTIAN PRAYER Lord Jesus, / you who willed to become poor/ give us eyes and heart directed toward the poor,/ help us to recognize you in them,/ in their thirst,/ their hunger,/ their loneliness,/ and their misfortune. //Enkindle within ou...

LESSON 4: CELL DIVISION: MITOSIS AND MEIOSIS  VINCENTIAN PRAYER Lord Jesus, / you who willed to become poor/ give us eyes and heart directed toward the poor,/ help us to recognize you in them,/ in their thirst,/ their hunger,/ their loneliness,/ and their misfortune. //Enkindle within our Vincentian Family unity,/ simplicity,/ and the fire of love/ that burned in St. Vincent de Paul and St. Louise de Marillac.// Strengthen us,/ so that, faithful to the practice of these virtues,/ we may contemplate you/ and serve you in the person of the poor/ and may one day/ be united with you and them in your kingdom.// St. Vincent de Paul & St. Louise de Marillac… Pray for us. learning objectives Describe the stages of mitosis and meiosis. Explain crossing over and recombination during meiosis. Identify disorders that result from abnormal chromosome numbers. Understand the significance and applications of mitosis and meiosis in organisms. INTRODUCTION TO CELL DIVISION Cell division is essential for all living organisms, whether they are made up of a single cell or millions of cells. Through cell division, organisms grow, repair damaged tissues, and reproduce. During cell division, the instructions for building new cells are passed equally to each new cell, ensuring the continuity of life from one generation to the next.  THE TWO MAJOR PHASES OF CELL DIVISION Cell division occurs in two major phases: 1. Interphase: This is the preparatory phase where the cell grows and its DNA is replicated. 2. Mitotic Phase: This includes both nuclear division (karyokinesis) and cytoplasmic division (cytokinesis). There are two types of nuclear division, mitosis and meiosis, based on the number of chromosomes in the daughter cells. BEFORE MITOSIS: INTERPHASE DNA is present as uncondensed chromatin (not visible under microscope) DNA is contained within a clearly defined nucleus Centrosomes and other organelles have been duplicated Cell is enlarged in preparation for division  WHAT IS CHROMATIN? Chromatin refers to a mixture of DNA and proteins that form the chromosomes found in the cells of humans and other higher organisms. BEFORE MITOSIS: INTERPHASE DNA is present as uncondensed chromatin (not visible under microscope) DNA is contained within a clearly defined nucleus Centrosomes and other organelles have been duplicated Cell is enlarged in preparation for division WHAT IS THE MAIN FUNCTION OF TELOMERES? The primary role of telomeres is to prevent the ends of chromosomes from becoming fused with each other or from being degraded. Without telomeres, the chromosomes would lose important genetic information each time a cell divides.  Designation of Chromosomes Metacentric Submetacentric A metacentric chromosome A submetacentric has a centrally located chromosome has a centromere, resulting in two centromere slightly off- arms of equal length. center, creating one longer arm and one shorter arm. Acrocentric Telocentric An acrocentric A telocentric chromosome chromosome has a has the centromere at the centromere near one end, end, with only one visible producing a very short p arm. arm and a long q arm. Interphase: This is the preparatory phase where the cell grows and makes a copy of its DNA. G1 phase (Gap 1): The cell grows in size and synthesizes proteins. S phase (Synthesis): The cell replicates its DNA to produce identical copies. G2 phase (Gap 2): The cell continues to grow and prepares for cell division. WHAT IS MITOSIS? Mitosis is the process that ensures daughter cells have the same genetic material and chromosome number as the parent cell. It plays a vital role in wound healing, tissue regeneration, and asexual reproduction. Mitosis occurs in somatic cells (body cells), and it is crucial for maintaining genetic continuity across cell generations. PHASES OF MITOSIS PHASES OF MITOSIS: PROPHASE During prophase, chromosomes condense and become visible under a microscope. The nuclear envelope disintegrates, and spindle fibers begin to form at the cell’s poles. Each chromosome consists of two chromatids connected by a centromere. In animal cells, spindle fibers form around centrioles, while in plant cells, spindle fibers emerge from the centrosomes. By the end of prophase, the cell is ready to proceed to the next stage, with 46 double-stranded chromosomes present. PHASES OF MITOSIS: METAPHASE In metaphase, the chromosomes align at the cell’s equatorial plane, or center. This alignment ensures that, during the next phase, the chromatids will separate properly. Spindle fibers attach to the centromeres of the chromosomes, pulling them into alignment along the equatorial plane. PHASES OF MITOSIS: ANAPHASE Anaphase is characterized by the separation of the sister chromatids. Once they are separated, these chromatids are considered individual chromosomes. The spindle fibers pull these daughter chromosomes toward opposite poles of the cell. By the end of anaphase, the two poles of the cell have equal sets of chromosomes. PHASES OF MITOSIS: TELOPHASE AND CYTOKINESIS During telophase, the chromosomes at each pole are enclosed within new nuclear envelopes, forming two distinct nuclei. The chromosomes uncoil back into chromatin. In cytokinesis, the cytoplasm divides, resulting in two identical daughter cells. In animal cells, a cleavage furrow forms to divide the cells, while in plant cells, a cell plate forms between the new nuclei.  KNOWLEDGE CHECK Which phase of interphase is the longest? A. S phase B. G1 phase C. G2 phase D. M phase  KNOWLEDGE CHECK During which phase of interphase does DNA replication occur? A. S phase B. G1 phase C. G2 phase D. M phase  KNOWLEDGE CHECK What happens to the cell during the G2 phase of interphase? A. The cell grows and prepares for mitosis. B. The cell replicates its DNA. C. The cell divides its cytoplasm. D. The cell enters the G1 phase.  KNOWLEDGE CHECK Which phase of interphase follows the S phase? A. G1 phase B. G2 phase C. M phase D. Prophase  KNOWLEDGE CHECK What is the main purpose of the G1 phase of interphase? A. To replicate DNA B. To prepare for mitosis C. To grow and synthesize proteins D. To divide the cytoplasm  KNOWLEDGE CHECK During which stage of mitosis do the sister chromatids separate and move to opposite poles of the cell? A. Prophase B. Metaphase C. Anaphase D. Telophase  KNOWLEDGE CHECK Which stage of mitosis comes after prophase? A. Metaphase B. Anaphase C. Telophase D. Cytokinesis  KNOWLEDGE CHECK What happens during the prophase stage of mitosis? A. The nuclear envelope breaks down. B. The sister chromatids separate. C. The cell plate forms. D. The nuclear envelope reforms.  KNOWLEDGE CHECK Which stage of mitosis marks the end of nuclear division? A. Prophase B. Metaphase C. Anaphase D. Telophase  KNOWLEDGE CHECK What is the final stage of mitosis, where the cytoplasm divides to form two daughter cells? A. Prophase B. Metaphase C. Anaphase D. Cytokinesis  KNOWLEDGE CHECK Which phase of interphase is the longest? A. S phase B. G1 phase C. G2 phase D. M phase  KNOWLEDGE CHECK During which phase of interphase does DNA replication occur? A. S phase B. G1 phase C. G2 phase D. M phase  KNOWLEDGE CHECK What happens to the cell during the G2 phase of interphase? A. The cell grows and prepares for mitosis. B. The cell replicates its DNA. C. The cell divides its cytoplasm. D. The cell enters the G1 phase.  KNOWLEDGE CHECK Which phase of interphase follows the S phase? A. G1 phase B. G2 phase C. M phase D. Prophase  KNOWLEDGE CHECK What is the main purpose of the G1 phase of interphase? A. To replicate DNA B. To prepare for mitosis C. To grow and synthesize proteins D. To divide the cytoplasm  KNOWLEDGE CHECK During which stage of mitosis do the sister chromatids separate and move to opposite poles of the cell? A. Prophase B. Metaphase C. Anaphase D. Telophase  KNOWLEDGE CHECK Which stage of mitosis comes after prophase? A. Metaphase B. Anaphase C. Telophase D. Cytokinesis  KNOWLEDGE CHECK What happens during the prophase stage of mitosis? A. The nuclear envelope breaks down. B. The sister chromatids separate. C. The cell plate forms. D. The nuclear envelope reforms.  KNOWLEDGE CHECK Which stage of mitosis marks the end of nuclear division? A. Prophase B. Metaphase C. Anaphase D. Telophase  KNOWLEDGE CHECK What is the final stage of mitosis, where the cytoplasm divides to form two daughter cells? A. Prophase B. Metaphase C. Anaphase D. Cytokinesis WHAT IS MEIOSIS? Meiosis is a specialized type of cell division that occurs only in reproductive cells (eggs, sperm, and spores). It reduces the chromosome number by half, ensuring that when egg and sperm cells fuse during fertilization, the resulting zygote has the correct diploid chromosome number. Meiosis contributes to genetic diversity in sexually reproducing organisms through the process of recombination and crossing over.  INTERPHASE AND INTERKINESIS Meiosis is preceded by interphase, in which DNA is replicated to produce chromosomes consisting of two sister chromatids. A second growth phase called interkinesis may occur between meiosis I and II, however no DNA replication occurs in this stage. MEIOSIS I: PROPHASE I In prophase I, chromosomes condense, and homologous chromosomes pair up in a process called synapsis. During this stage, crossing over occurs between non-sister chromatids, allowing for genetic recombination. Each homologous chromosome pair consists of two chromatids from the mother and two from the father. At the end of prophase I, the cell has 46 double-stranded chromosomes (92 chromatids). MEIOSIS I: METAPHASE I, ANAPHASE I, AND TELOPHASE I Metaphase I: The homologous chromosomes (tetrads) align along the equator of the cell, with spindle fibers attaching to the centromeres. Anaphase I: The homologous pairs are pulled apart to opposite poles, but the sister chromatids remain attached. Telophase I: Two new nuclei form, and cytokinesis occurs, resulting in two daughter cells, each with half the number of chromosomes. MEIOSIS II: PROPHASE II In prophase II, the nuclear envelope dissolves again, and spindle fibers reform. The chromosomes, each still composed of two chromatids, begin to condense. Unlike in prophase I, no synapsis or crossing over occurs. The cell prepares for the second round of division. At this stage, there are 23 double-stranded chromosomes (46 chromatids) in each cell. MEIOSIS II: METAPHASE II, ANAPHASE II, AND TELOPHASE II Metaphase II: Chromosomes align along the equator of each cell, with spindle fibers from opposite poles attaching to the centromeres of each sister chromatid. Anaphase II: The centromeres split, allowing the sister chromatids to be pulled to opposite poles. Each chromatid is now an individual chromosome. Telophase II: Nuclear envelopes form around the separated chromosomes. Cytokinesis follows, resulting in four genetically distinct haploid daughter cells, each containing 23 single-stranded chromosomes.  KEY DIFFERENCES Prophase I involves synapsis and crossing over, while Prophase II does not. In Metaphase I, homologous chromosome pairs align, but in Metaphase II, individual chromosomes align. Anaphase I separates homologous chromosomes, whereas Anaphase II separates sister chromatids.  COMPARISON MITOSIS MEIOSIS Produces genetically identical cells Produces genetically unique cells Results in diploid chromosome number Results in haploid chromosome number Results in diploid cells Results in haploid cells Produces two new cells Produces four new cells Takes place throughout the Takes place only during the reproductive organism's life years of the organism Involved in asexual reproduction Involved in sexual reproduction  GAMETOGENESIS Gametogenesis is the process by which diploid cells undergo meiosis to form mature haploid gametes (sperm in males, eggs in females). Spermatogenesis occurs in the testes, producing sperm cells. Oogenesis occurs in the ovaries, resulting in egg cells. Both processes ensure the proper chromosome number is maintained during sexual reproduction. GAMETOGENESIS SPERMATOGENESIS Occurs in the testes starting at puberty. Spermatogonia (immature cells) develop into sperm cells through stages: primary spermatocytes → secondary spermatocytes → spermatids → sperm. Sertoli cells provide nourishment during development. Each sperm is haploid (22 autosomes + 1 sex chromosome, X or Y). OOGENESIS Takes place in the ovaries. Oogonia develop into primary oocytes during fetal development, then mature into secondary oocytes and finally an ovum after puberty. The process results in one large ovum and smaller polar bodies (which do not contribute to fertilization). The ovum is haploid (22 autosomes + 1 X chromosome).  The study of mitosis and meiosis is essential for understanding how organisms grow, repair tissues, and reproduce. Abnormalities in these processes can lead to genetic disorders, such as Down syndrome, which is caused by an abnormal number of chromosomes. By understanding these processes, we gain insight into cell function, reproduction, and genetic diversity. LESSON: NUCLEIC ACID AND PROTEIN  VINCENTIAN PRAYER Lord Jesus, / you who willed to become poor/ give us eyes and heart directed toward the poor,/ help us to recognize you in them,/ in their thirst,/ their hunger,/ their loneliness,/ and their misfortune. //Enkindle within our Vincentian Family unity,/ simplicity,/ and the fire of love/ that burned in St. Vincent de Paul and St. Louise de Marillac.// Strengthen us,/ so that, faithful to the practice of these virtues,/ we may contemplate you/ and serve you in the person of the poor/ and may one day/ be united with you and them in your kingdom.// St. Vincent de Paul & St. Louise de Marillac… Pray for us. learning objectives Describe the functions of proteins. Identify the different types of proteins. Describe the functions of nucleic acids. Describe the two types of nucleic acids.  LESSON OVERVIEW Proteins and nucleic acids are essential biomolecules in living organisms. They play key roles in various biological processes, enabling life to exist and thrive. Proteins are required for diverse biological functions across the body. Nucleic Acids store, transmit, and express hereditary information. Life would be impossible without these two biomolecules.  PROTEINS Proteins consist of long chains of amino acids, called polypeptides, which serve as the building blocks of protein structure and function. Amino Acids: Monomers of proteins, typically arranged in chains of 100 to 10,000 amino acids. Each amino acid contains a central carbon atom bonded to an amino group, hydrogen, carboxyl group, and a unique side chain (R-group). There are 20 common amino acids, each with distinct side chains that contribute to protein diversity. STRUCTURE OF AN AMINO ACID  LEVELS OF PROTEIN ORGANIZATION The functionality of a protein structure depends on the following four hierarchical organizations: primary, secondary, tertiary, and quaternary structures. The interactions that take place between the different protein structures give them three-dimensional arrangements that enable them to facilitate different functions in the body.  LEVELS OF PROTEIN ORGANIZATION Primary structure is simply a linear chain of amino acids in a polypeptide strand. The amino acid sequence is the main determinant of the overall structure of the protein. This sequence also determines the amino acid chain's ultimate biological function.  LEVELS OF PROTEIN ORGANIZATION Secondary structure refers to the local three- dimensional folding of the polypeptide chain in the protein. The alpha helix (spiral) and the beta sheet (beta strand forming an accordion- like pleated sheet) are the two more common secondary structure motifs. Varying arrangements of weak hydrogen bonds are responsible for these configurations.  LEVELS OF PROTEIN ORGANIZATION Tertiary structure is formed when the distant segments of a primary structure and the relationships of the side chains are bound in a three-dimensional folding of the entire polypeptide chain. This structure is stabilized both by non- covalent (hydrophobic interactions, electrostatic bonds, hydrogen bonding, Van der Waals forces), and covalent (disulfide) bonds.  LEVELS OF PROTEIN ORGANIZATION Quaternary structure involves the fitting together of two or more polypeptide chains, eventually forming a functional protein. This structure is stabilized by the same bonds as those in the tertiary structure. An example of a protein with a quaternary structure is hemoglobin. Subunit or domain is the term used to denote each chain in a protein. HIERARCHICAL ORGANIZATIONS OF PROTEIN TWENTY ESSENTIAL AMINO ACIDS  TYPES OF PROTEINS ACCORDING TO FUNCTION Structural proteins are proteins involved in maintaining the shape and framework of the cell. An example is collagen. Collagen is the most abundant protein found in the human body It is a type of structural protein that is fibrous in nature. It gives strength and support to tissues that undergo continual wear and tear such as skin and bone.  TYPES OF PROTEINS ACCORDING TO FUNCTION Transport proteins carry other substances in and out of cells. These are involved in cal transport as discussed in Chapter 1. Regulatory proteins control numerous cell processes. These are proteins that bind to segments of DNA and control the replication of DNA in mitosis and meiosis.  TYPES OF PROTEINS ACCORDING TO FUNCTION Enzymes facilitate many chemical reactions. They do this by lowering the amount of energy needed to start the reaction while not being permanently altered in the process. The induced fit model describes how enzymes work. There is an active site in the enzyme with which specific molecules, called substrates, interact. This interaction causes the enzyme to change shape, which favors a chemical reaction. Enzymes are affected by pH and temperature. TYPES OF PROTEINS ACCORDING TO FUNCTION  TYPES OF PROTEINS ACCORDING TO FUNCTION Defense proteins such as antibodies are highly specific proteins that are responsible for detecting a foreign substance or "antigen." The body produces a specific antibody to respond to an antigen to inactivate it. A good example to see how antibodies work is to know how vaccines work in the body. This is especially important in times of a pandemic, when vaccines are very much in demand to fight diseases such as COVID-19.  TYPES OF PROTEINS ACCORDING TO FUNCTION Proteins play a critical role in immune defense, especially antibodies that detect and neutralize foreign substances, such as viruses and bacteria. Antibodies: Proteins that identify and neutralize specific antigens. Vaccines introduce weakened or inactivated antigens to stimulate antibody production, helping build immunity. Upon re-exposure, memory cells trigger a rapid antibody response, offering long-term protection.  TYPES OF PROTEINS ACCORDING TO FUNCTION Fluid balance is also regulated by proteins, primarily albumin in blood plasma. Proteins exert oncotic pressure on capillary pores, and through the process of osmosis, pull fluid from the interstitial space back into the intravascular space to prevent significant loss of fluid volume. When protein levels are low, fluid escapes the blood vessels and collects in the lungs (pulmonary edema), abdomen (ascites), or in other parts of the body.  NUCLEIC ACIDS Nucleic acids are larger organic molecules that carry the “code/blueprint of life”. They carry the instructions both for the characteristics passed on to the offspring and for translating the hereditary message into proteins that will be built into new cell structure, cell and organism. There are two main types of nucleic acid: Deoxyribonucleic acid (DNA) and ribonucleic acid (RNA). these nucleic acids are polymers of nucleotides- their building blocks. DNA exists as a double helix, while RNA as a single helix.  NUCLEIC ACIDS Each nucleotide consists of three components: a purine or pyrimidine nucleobase (sometimes termed nitrogenous base), a pentose sugar, and a phosphate group.  NUCLEIC ACIDS Each nucleotide consists of three components: a purine or pyrimidine nucleobase (sometimes termed nitrogenous base), a pentose sugar, and a phosphate group. The substructure composed of a nucleobase plus sugar is termed a nucleoside.  NUCLEIC ACIDS Nucleic acid types differ in the structure of the sugar in their nucleotides such that RNA contains ribose, while DNA contains 2'-deoxyribose (a derivative of ribose where the hydroxyl group at the 2' position was replaced by hydrogen, leading to a net loss of oxygen).  NUCLEIC ACIDS Four different nitrogen-containing bases are found in DNA: adenine, guanine, cytosine, and thymine. RNA also contains adenine, guanine, and cytosine, but instead of thymine, it has uracil as its fourth base. These are the bases that make up the nucleic acid alphabet. The nitrogenous bases in DNA pair specifically with each other: thymine pairs with adenine, while cytosine pairs with guanine. This base pairing rule is important in the following: (1) DNA replication in mitosis/meiosis, (2) protein sythesis, and (3) maintaining the molecular stability of DNA as a double helix molecule.  NUCLEIC ACIDS In addition, the sugars and phosphates in nucleic aids are linked to each other in an alternating chain via phosphodiester linkages. DNA consists two chains of nucleotides twisted around each other in a double helix and held together by hydrogen bonds. On the other hand, RNA is composed of single chains that fold into complex shapes or remain stretched out as long threads. The sequence of the nucleotides in the DNA determines the structure of every protein in an organism.  NUCLEIC ACIDS James Watson, an American molecular biologist, and Francis Crick, a British molecular biologist, published in 1953 the classic paper that describes DNA as a double helical structure. Their groundbreaking conclusion was also drawn from the studies of different scientists such as the Swiss chemist Friedrich Miescher, American chemist Phoebus Levene, American biochemist Erwin Chargaff, and the English chemist Rosalind Franklin. In 1962, Francis Crick and James Watson, together with Maurice Wilkins (a New Zealand-bom British physicist who also studied DNA structure) were awarded the Nobel Prize in Physiology or Medicine. NUCLEIC ACIDS LESSON _: CELLULAR TRANSPORT  VINCENTIAN PRAYER Lord Jesus, / you who willed to become poor/ give us eyes and heart directed toward the poor,/ help us to recognize you in them,/ in their thirst,/ their hunger,/ their loneliness,/ and their misfortune. //Enkindle within our Vincentian Family unity,/ simplicity,/ and the fire of love/ that burned in St. Vincent de Paul and St. Louise de Marillac.// Strengthen us,/ so that, faithful to the practice of these virtues,/ we may contemplate you/ and serve you in the person of the poor/ and may one day/ be united with you and them in your kingdom.// St. Vincent de Paul & St. Louise de Marillac… Pray for us. learning objectives Explain transport mechanisms in cells. Differentiate between exocytosis and endocytosis. INTRODUCTION TO CELLULAR TRANSPORT Living cells exist in a liquid environment, and the plasma membrane plays a crucial role in regulating the movement of molecules into and out of the cell. It is selectively permeable, allowing essential substances such as nutrients and oxygen to enter, and removing waste products. Different transport processes facilitate these movements, ensuring cellular function.  IMPORTANCE OF MEMBRANE REGULATION For cells to function properly, the plasma membrane must selectively allow certain substances like sugars and amino acids to enter, while expelling harmful metabolic waste. The cell’s ability to control this exchange depends on the size, chemical structure, and cellular conditions of the molecules that need to cross the membrane.  FACTORS AFFECTING MEMBRANE TRANSPORT Whether a molecule can pass through the plasma membrane depends on several factors: Size of the molecule: Larger molecules often need assistance from carrier proteins. Chemical composition: Some molecules pass freely, while others require energy or specific channels. State of chemical balance: The current ion or solute concentration inside the cell affects transport rates.  WHAT IS PASSIVE TRANSPORT? Passive transport is the movement of substances across the plasma membrane without energy expenditure. Molecules move naturally from areas of higher concentration to lower concentration, following the concentration gradient. The three key types of passive transport are diffusion, osmosis, and facilitated diffusion.  DIFFUSION Diffusion involves the movement of solute molecules from an area of high concentration to an area of low concentration. This process occurs spontaneously and does not require cellular energy. The overall movement is referred to as "net diffusion" because molecules are moving randomly, but the result is a spread from concentrated areas to less concentrated areas. DIFFUSION  DIFFUSION An example of diffusion can be observed when you spray air freshener in a room. Initially, the concentration of the air freshener is high in the area where it was sprayed. Over time, the molecules spread out evenly throughout the room, moving to areas where the concentration is lower.  OSMOSIS Osmosis, another means of passive transport, is the diffusion of water molecules across a selectively permeable membrane from a region of lower solute concentration (hypotonic) to a region of higher solute concentration (hypertonic). Osmosis balances water content on both sides of the membrane, crucial for maintaining cellular stability.  OSMOSIS A cell in different environments reacts based on osmosis: Hypotonic environment: Water enters the cell, potentially causing it to swell or burst. Hypertonic environment: Water leaves the cell, causing it to shrink or shrivel. Isotonic environment: Water moves equally in and out, maintaining the cell's balance. OSMOSIS  OSMOSIS Osmosis is critical for cellular survival. If a cell is placed in a hypotonic solution (low solute concentration outside the cell), water enters, causing the cell to expand. In contrast, a hypertonic solution draws water out, shrinking the cell. Cells are most stable in an isotonic solution, where the solute concentration is equal inside and outside.  OSMOSIS In marine environments, organisms must adapt to their surroundings. Some thrive in seawater because it is isotonic to their cells, while others live in freshwater, which is isotonic to them. Exposure to a different environment can disrupt the balance, leading to cell damage or death. Plants, fungi, and some protists have rigid cell walls. When placed in a hypotonic solution, water enters the cell, causing it to become turgid (firm). This turgor pressure is essential for plant structure. Conversely, in a hypertonic solution, water exits the cell, causing the plasma membrane to shrink away from the cell wall, a process known as plasmolysis.  OSMOSIS The principles of osmosis have practical uses, especially in food preservation. For example: Salting fish: The salt draws out water from the fish through osmosis, preventing microbial growth. Sugaring fruits: Water is drawn out of the fruit, preserving it by reducing microbial activity.  OSMOSIS Plasmolyzed Flaccid Turgid  FACILITATED DIFFUSION Facilitated diffusion is a form of passive transport where molecules move down the concentration gradient with the help of protein channels or carrier proteins. This process allows larger or hydrophilic molecules to pass through the membrane without energy input. There are two main types of proteins involved in facilitated diffusion: 1. Channel proteins: Open and close in response to stimuli, allowing specific molecules to pass through. 2. Carrier proteins: Change shape to carry molecules across the membrane. FACILITATED DIFFUSION  ACTIVE TRANSPORT Active transport moves substances across the membrane against the concentration gradient, from areas of low concentration to areas of high concentration. This process requires energy, usually in the form of ATP, and is crucial for maintaining cellular homeostasis. ACTIVE TRANSPORT  ACTIVE TRANSPORT Active transport is vital for several reasons: 1. It allows cells to absorb nutrients even when they are in higher concentrations inside the cell. 2. It helps in removing waste products even when the external concentration is higher. 3. It maintains essential ion concentrations like potassium, sodium, calcium, and hydrogen inside the cell.  ACTIVE TRANSPORT The sodium-potassium pump is a well-known example of active transport. This process moves sodium (Na+) out of the cell and potassium (K+) into the cell, both against their concentration gradients. This pump uses energy from ATP and is essential for processes like nerve impulse transmission. ACTIVE TRANSPORT  BULK TRANSPORT Bulk transport moves large molecules, such as proteins and polysaccharides, in and out of the cell via vesicles. This process requires energy and can occur through two main mechanisms: exocytosis and endocytosis. Exocytosis involves the removal of materials from the cell. Vesicles within the cell fuse with the plasma membrane, releasing their contents outside. This process is important for cells that secrete substances, such as digestive enzymes in the digestive system. EXOCYTOSIS  ENDOCYTOSIS Endocytosis is the process where the cell engulfs materials from its surroundings. The plasma membrane wraps around the material, forming a vesicle that is then brought into the cell. Endocytosis is crucial for cells to take in large particles or fluids that cannot pass through the membrane by other means.  ENDOCYTOSIS There are two main types of endocytosis: 1. Phagocytosis ("cell eating"): The cell engulfs large, undissolved particles. For example, white blood cells use phagocytosis to engulf bacteria. 2. Pinocytosis ("cell drinking"): The cell engulfs dissolved substances from its surroundings, often seen in the uptake of nutrients by egg cells. ENDOCYTOSIS  SUMMARY · Passive transport is the movement of substances across membranes without energy expenditure. · Diffusion is the net movement of substances from an area of higher concentration to an area of lower concentration (down the concentration gradient). · Osmosis is the diffusion of water molecules across a selectively permeable membrane. · A hypertonic solution has a stronger tendency to cause water movement from another solution. If a cell is placed in this type of solution, it will shrink because water of the cytoplasm will be drawn out.  SUMMARY · A hypotonic solution has a lower tendency to gain water from another solution. If a cell is placed in this type of solution, water will enter the cell, causing it to bulge or become turgid and could lead to cell rupture. · Isotonic describes two solutions that have equal amounts of water and solutes. If a cell is placed in this type of solution, it can maintain its equilibrium; therefore, there will be no change in the cell. · Plasmolysis occurs when a plant wilts after it has been deprived of water. · Facilitated diffusion is the passive movement of solutes through protein channels down the concentration gradient.  SUMMARY · Active transport is the movement of solutes across a membrane (up the concentration gradient) which requires the expenditure of energy through transport proteins called carrier proteins. · Exocytosis is the process of removing materials from the cell. · Endocytosis is the reverse process of exocytosis, in which cells engulf materials. · Phagocytosis ("cellular eating") is the most common form of endocytosis. It occurs when undissolved materials enter the cell. · Pinocytosis ("cellular drinking) occurs when dissolved substances enter the cell. LESSON: CARBOHYDRATES AND LIPIDS  VINCENTIAN PRAYER Lord Jesus, / you who willed to become poor/ give us eyes and heart directed toward the poor,/ help us to recognize you in them,/ in their thirst,/ their hunger,/ their loneliness,/ and their misfortune. //Enkindle within our Vincentian Family unity,/ simplicity,/ and the fire of love/ that burned in St. Vincent de Paul and St. Louise de Marillac.// Strengthen us,/ so that, faithful to the practice of these virtues,/ we may contemplate you/ and serve you in the person of the poor/ and may one day/ be united with you and them in your kingdom.// St. Vincent de Paul & St. Louise de Marillac… Pray for us. learning objectives Describe the structure and functions of carbohydrates. Identify the different types of carbohydrates. Describe the structure and functions of lipids. Identify the different types of lipids.  LESSON OVERVIEW Atoms to Macromolecules: Atoms can join to form molecules, which in turn can be assembled into larger structures known as macromolecules. In biological systems, these macromolecules play essential roles and are typically composed of smaller building blocks called monomers. Types of Biomolecules: The four major categories of biomolecules are proteins, carbohydrates, lipids, and nucleic acids. These macromolecules are primarily composed of the elements carbon (C), hydrogen (H), oxygen (O), and nitrogen (N), but they also require key elements like calcium, sodium, potassium, and magnesium to perform various biological functions.  LESSON OVERVIEW Carbon plays a crucial role in the composition of organic compounds because it can form bonds with four other atoms, allowing for complex molecular structures. Carbon is the backbone of life, and most biomolecules—such as carbohydrates, lipids, proteins, and nucleic acids— are carbon-based. Organic compounds contain carbon and are foundational to all living organisms. A few exceptions, such as carbonates, are not considered organic despite containing carbon. MACROMOLECULES FOUND IN LIVING THINGS MACROMOLECULES CARBOHYDRATES LIPIDS NUCLEIC ACIDS PROTEINS such as such as such as such as sugars and starches fats and oils nucleotides amino acids which contain atoms of which contain atoms of which contain atoms of which contain atoms of carbon, hydrogen, carbon, hydrogen, carbon, hydrogen, carbon, hydrogen, oxygen, nitrogen, oxygen oxygen oxygen, nitrogen phosphorus  CARBOHYDRATES Carbohydrates are the most abundant organic compounds on Earth, essential for both energy storage and structural functions in organisms. Composed of carbon, hydrogen, and oxygen in a 1:2:1 ratio (CH₂O), carbohydrates are also referred to as “hydrates of carbon.” Carbohydrates are categorized into four main groups based on their structure and complexity: monosaccharides, disaccharides, oligosaccharides, and polysaccharides. TYPES OF CARBOHYDRATES  MONOSACCHARIDES Monosaccharides are the simplest form of carbohydrates and serve as the basic building blocks for more complex carbohydrates. These simple sugars consist of a single sugar molecule, and their general chemical formula is C₆H₁₂O₆. The universal cellular fuel, glucose, is a six-carbon monosaccharide. It can easily be degraded to yield stored energy or readily assembled into large storage polymers. When the body's glucose levels are low, such as during fasting or intense exercise, the liver can produce glucose from other substances like amino acids (from protein breakdown) and glycerol (from fat breakdown). This process is called gluconeogenesis.  MONOSACCHARIDES Examples: Glucose: The main source of energy in the body, glucose is essential for cellular respiration. Foods like rice, bread, and pasta are rich in glucose, which is broken down during digestion to release energy. Fructose: Known as fruit sugar, fructose is naturally present in fruits like mango, honeydew, and pineapple. Galactose: Another simple sugar, galactose, combines with glucose to form lactose, the sugar found in milk.  DISACCHARIDES Disaccharides are formed when two monosaccharide molecules are bonded together through a glycosidic bond. This bond is formed via a condensation reaction, which results in the release of a water molecule. Examples: Sucrose (table sugar) consists of one glucose molecule and one fructose molecule. It is commonly found in sugar cane, sugar beets, and certain fruits. Lactose (milk sugar) is made up of glucose and galactose and is found in milk and other dairy products. Maltose consists of two glucose molecules and is present in malted foods and corn syrup.  OLIGOSACCHARIDES Oligosaccharides consist of three to nine monosaccharide units linked together by glycosidic bonds. They are less common than monosaccharides and disaccharides but are found in certain plants and used as food additives. Uses: These mildly sweet compounds are often used to improve the texture of foods and are seen as partial substitutes for fats and sugars. Sources: Onions, garlic, and legumes are naturally rich in oligosaccharides.  POLYSACCHARIDES Polysaccharides are large carbohydrate molecules consisting of hundreds to thousands of monosaccharide units linked together. These macromolecules serve either as storage molecules or structural components in living organisms. Examples: Starch: Plants store energy in the form of starch, a polysaccharide composed of glucose monomers. Starch is a major component of foods like potatoes and grains.  POLYSACCHARIDES Glycogen: In animals, excess glucose is stored as glycogen, primarily in the liver and muscles. Glycogen can be quickly broken down to release glucose when energy is needed. Cellulose: The most abundant organic molecule on Earth, cellulose, provides structural support in plant cell walls. Unlike starch, humans cannot digest cellulose, but it plays an important role as dietary fiber. Chitin: Found in the exoskeletons of insects and crustaceans, chitin provides structural strength to these organisms.  POLYSACCHARIDES In plants, the most important nutrient reserve is the polysaccharide starch. It is a mixture of amylase and amylopectin. An amylase molecule is usually composed of about a thousand units of glucose, and amylopectin about 20,000 units of glucose. Starch serves as food for the young plant. During growth and development, the enzymes in the seed hydrolyze the glycosidic bonds in starch, releasing the disaccharide maltose, which in turn becomes glucose monomers that fuel the energy needs of the growing plant.  LIPIDS Lipids are a diverse group of hydrophobic molecules that play critical roles in energy storage, cell membrane structure, and signaling. Like carbohydrates, they contain carbon, hydrogen, and oxygen, but lipids have a much lower proportion of oxygen relative to carbon and hydrogen. Lipids make certain food oily. Lipids are divided into several types, including fats, oils, phospholipids, and steroids. Each type of lipid has a unique structure and function in biological systems.  LIPIDS Three main types of lipids include: 1. Fats and Oils: These are energy reserves found in both plants and animals. At room temperature, fats are solid (e.g., butter, lard) while oils remain liquid (e.g., olive oil, corn oil). 2. Phospholipids: Essential for forming cell membranes, phospholipids have a hydrophilic (water- attracting) head and hydrophobic (water-repelling) tails. 3. Steroids: These include cholesterol and hormones, which are involved in cellular signaling and membrane fluidity.  TYPES OF LIPIDS LIPIDS COMPOUND DERIVED SIMPLE LIPIDS LIPIDS LIPIDS Esters of fatty acids Esters of fatty acids Composed of Fat Waxes and alcohol contain hydrocarbon rings other groups also and a long hydrocarbon side Esters of fatty Esters of long chain acids and chain fatty acids glycerol and long chain alcohols FATS AND OILS Fats and oils are essential macromolecules that serve as nutrient reserves in animals and plants. They play a crucial role in energy storage and are involved in various biological processes. Plant-based oils, such as corn oil, canola oil, and olive oil, are typically yellowish and liquid at room temperature. In contrast, animal fats, like lard and butter, are solid or semisolid at room temperature and are generally whitish in color.  FATS AND OILS Fats and oils consist of two main components: glycerol and fatty acids. Glycerol is a three-carbon alcohol that is highly soluble in water due to its hydroxyl groups. Fatty acids are long chains of carbon atoms attached to a carboxyl group, giving them acidic properties. Fatty acids can be classified based on their chain length, dietary importance (essential or nonessential), or the presence of double or triple bonds (saturated or unsaturated).  TRIGLYCERIDES Triglycerides are formed by one glycerol molecule and three fatty acids. Found in adipose tissue, butter, lard, and olive oil. Serve as the main form of stored energy in the body. Animal triglycerides contain high levels of saturated fatty acids, where all carbon atoms are bonded to hydrogen atoms. These straight-chain polymers are packed closely together, resulting in fats that are solid or semisolid at room temperature. Examples include bacon fat and lard. TRIGLYCERIDES Plant triglycerides, on the other hand, have higher proportions of unsaturated fatty acids, such as oleic acid and linoleic acid. This prevents close packing, leading to lower melting points and liquid forms at room temperature. Olive oil and peanut oil are good examples of plant triglycerides.  TRIGLYCERIDES Health Considerations Saturated Fats: Found in cheese, butter, coconut oil, and red meat. Can cause plaque buildup in arteries, leading to heart disease. Trans Fats: Found in processed foods. Increase bad cholesterol (LDL) and raise risk of cardiovascular issues. Healthier Options: Unsaturated fats (from plants) improve heart health and reduce the risk of obesity. SATURATED AND UNSATURATED FATS  PHOSPHOLIPIDS Phospholipids consist of a glycerol molecule, a phosphate group, and two fatty acid chains. The phosphate head is hydrophilic, while the fatty acid tails are hydrophobic, creating a unique amphipathic molecule. Phospholipids form the basic structure of all cell membranes. They organize into a bilayer, with hydrophobic tails facing inward and hydrophilic heads facing outward, creating a barrier that regulates what enters and exits cells. STRUCTURE OF A PHOSPHOLIPID  STEROIDS Steroids are organic compounds characterized by a four-ring structure. They are found in cell membranes, where they help maintain membrane fluidity and play a role in cellular signaling. Sterols, such as cholesterol, androgens, estrogens, and adrenal corticosteroids, are key examples of steroids that contribute to cellular structure, metabolism, and communication. Terpenes, which are found in essential oils and plant pigments like carotene and lycopene, are related to fat-soluble vitamins (A, D, E, K) that are essential for processes like blood clotting and tissue maintenance.  SUMMARY Carbohydrates provide energy and structural support in both plants and animals. They come in various forms, from simple sugars to complex polysaccharides. Lipids are crucial for energy storage, cell membrane integrity, and signaling. Fats and oils provide energy, while phospholipids and steroids support cellular structure and communication. Choosing the right balance of carbohydrates and lipids in the diet can promote better health and prevent diseases like heart disease and obesity.