CETs Science - 🧬

• ORGANIC COMPOUNDS

  Carbohydrates -

  • are made up of carbon, hydrogen, and oxygen atoms.
  • sugar, starches, and cellulose atoms. They have the general formula CnH2nOn.
  • Their sizes range from the small simple sugars like glucose and fructose to the large and complex forms like starch and glycogen.
  • Only the simple sugars (monosaccharides) can easily pass across cell membranes. Most

  carbohydrates serve as energy molecules or energy reserves in living organisms.
• Cellulose - gives strength and protection to plant cells.
• Lipids –

  • are macromolecules such as fats, oils and waxes.
  • They are made up of carbon, hydrogen, and oxygen.
  • The building blocks used to form fats are fatty acids and glycerol.
  • Some excess food in the body is stored as fats. * that are liquid at room temperature are known as oils.
  • Waxes serves as protective body covering to organisms. They make plant and animal tissues water-resistant.
• Proteins - are made up of repeating units of amino acids. They are a component of the muscles

  and all other tissues. In the form of enzymes, they control the rate of chemical reactions inside

  the cell. Without the enzymes, such chemical processes hardly occur.
• Enzymes - are proteins that act as catalysts (substances that can increase or speed up chemical reaction).
• Nucleic Acids - are carriers of hereditary information in living organisms.
• Vitamins - are substances necessary in very small amount for body growth and activity.
• Water - is the most abundant inorganic compound. About 65% to 95% of the substances of every living thing is water. It is the medium of transport for food, minerals and other substances in living system.
• Carbon dioxide - supplies the carbon found in substances made by living things.

  • are chemical elements or compounds occurring naturally. They may come from the soil maybe dissolved in water, or maybe found as salt in seawater. Minerals are absorbed by plant roots in the form of ions
• LIFE FUNCTIONS

  1. Nutrition is the process of ingesting and absorbing food to provide the energy for life, promote growth, and repair or replace damages tissues.
• Transport involves movement of nutrients water, ions, and other materials into and out of the various cells and tissues of organisms. Circulatory system plays a major role in transport.
• Metabolism includes the process by which nutrients and simple molecules are used to form more complex molecules for growth, repair, and reproduction (anabolism).
• 2 Types of metabolism

  • Catabolism - Catabolism refers to the set of metabolic pathways that break down molecules into smaller units and release energy. This energy is stored in molecules of adenosine triphosphate (ATP) and is used to drive various cellular processes. Catabolic reactions are generally exergonic, meaning they release energy.
  • Anabolism - is the set of metabolic pathways that construct molecules from smaller units. These reactions require an input of energy, typically in the form of ATP, and are thus endergonic.
• An internal balance in all aspects of metabolism and biological function is called homeostasis.
• Digestion is a special form of catabolism that breaks food down into smaller molecules and releases energy.
• Absorption allows small molecules to pass through cell membranes throughout the body tissues. This allows for a gas exchange and in some species such as plants and fungi, nutrients are obtained by absorption from soil and water.
• Excretion is the elimination of waste products.
• Reproduction is the process by which an organism produces offspring either sexually or asexually.

  1. Asexual - is the reproduction without the use of gametes or sex cells. One parent organism ran reproduces by itself.

  • Fission - is the splitting of the body of an organism into two identical parts. (e.g., Paramecia and planaria)
  • Budding - is the growing of bud out of the parent cells of bodies which when detached can grow into another organism that resembles the appearance of parent (e.g., sponges, and yeast)
  • Sporulation - is the spore formation as in fern plant and mushrooms.
• 2. Sexual - requires the union of male and female gametes called "fertilization". Male gametes are called sperm cells and female gametes are called egg cells. Fertilization is classified into two types, namely:

  • External Fertilization - the union of sperm cells and egg cells

  happen outside the body of the female organisms. (e.g., seashells,

  starfishes, frogs, fishes)

  • Internal Fertilization - the union of sperm cells and egg cells

  happen inside the body of a female organism (e.g., higher forms of

  animals and human)
• PROKARYOTIC CELL

  • found only in bacteria and archaebacteria, all the components, including the DNA, mingle freely in the cell’s interior, a single compartment.
  • can be rod like, spherical, or spiral in shape
  • live in a watery environment, whether it is soil moisture, a pond, or the fluid surrounding cells in the human body.
• Parts of a Simple bacterium

  Cell Wall:

  • Function: Provides shape and protection to the cell.
  • Structure: Made of peptidoglycan in most bacteria, which is a polymer consisting of sugars and amino acids.
• Parts of a Simple bacterium

  Cell Membrane:

  • Function: Acts as a barrier, controlling the entry and exit of substances.
  • Structure: A phospholipid bilayer with embedded proteins.
• Parts of a Simple bacterium

  Cytoplasm

  • Function: Contains the cell's components and is the site for most cellular activities.
  • Structure: A gel-like substance composed mainly of water, salts, and proteins.
• Parts of a Simple bacterium

  Nucleoid:

  • Function: Contains the bacterial chromosome, which is the cell's genetic material.
  • Structure: An irregularly-shaped region within the cell, not surrounded by a membrane.
• Parts of a Simple bacterium

  Ribosomes:

  • Function: Sites of protein synthesis.
  • Structure: Composed of RNA and proteins, they are smaller than eukaryotic ribosomes (70S in size).
• • Plasmids:
  • Function: Carry additional genetic information, often including genes for antibiotic resistance.
  • Structure: Small, circular DNA molecules separate from the chromosomal DNA.
• • Flagella:
  • Function: Provide motility, allowing the bacterium to move toward or away from stimuli (chemotaxis).
  • Structure: Long, whip-like appendages made of protein (flagellin).
• • Pili (Fimbriae):
  • Function: Help in attachment to surfaces and in conjugation (transfer of genetic material between bacteria).
  • Structure: Hair-like structures made of protein (pilin).
• Capsule:

  • Function: Protects the bacterium from desiccation and from being engulfed by eukaryotic cells (phagocytosis).
  • Structure: A gelatinous layer composed of polysaccharides or polypeptides
• Mesosome

  • Function: Historically thought to increase the surface area of the cell membrane, aiding in cellular processes like respiration and DNA replication. However, modern research suggests that mesosomes might be artifacts created during the preparation of bacterial cells for electron microscopy.
  • Structure: Folded invaginations of the plasma membrane.
• EUKARYOTIC ANIMAL CELLS

  • are typically about ten times larger than prokaryotic cells. In animal cells, the plasma membrane, rather than a cell wall, forms the cell’s outer boundary.
  • With a design similar to the plasma membrane of prokaryotic cells, it separates the cell from its surroundings and regulates the traffic across the membrane.
• Plasma Membrane

  The plasma membrane that surrounds eukaryotic cells is a dynamic structure composed of two layers of phospholipid molecules interspersed with cholesterol and proteins. Phospholipids are composed of a hydrophilic, or "water-loving", head and two tails, which are hydrophobic, or "water-hating". Tiny gaps in the membrane enable small molecules such as oxygen (upper right) to diffuse readily into and out of the cell.
• Nucleus of a Cell


  The largest organelle in an animal cell
• Nucleus


  • Contains numerous strands of DNA, the length of each strand being many times the diameter of the cell
  • Present in eukaryotic cells
  • A discrete structure containing chromosomes, which hold the genetic information for the cell
  • Separated from the cytoplasm of the cell by a double-layered membrane called the nuclear envelope
  • Contains a cellular material called nucleoplasm
  • Nuclear pores, present around the circumference of the nuclear membrane, allow the exchange of cellular materials between the nucleoplasm and the cytoplasm