Cell Biology: Levels of Organization, Biomolecules, and Functions
Levels of Organization in Biology
Levels of organization: Atom > Molecule > Organelle > Cell > Tissue > Organ > Organ system > Organism
Bioelements and Biomolecules
Bioelements: Chemical elements that make up living things. Bioelements join together to form biomolecules. Two types:
Inorganic Biomolecules
Inorganic biomolecules include water and mineral salts.
Water is the most abundant substance found in living things, making up about 65% of the human body. Mineral salts can be found in living things in the form of dissolved ions or as crystals.
Organic Biomolecules
Organic biomolecules are unique to living things and contain significant amounts of the chemical element carbon. There are four main types:
Carbohydrates
Monosaccharides: Composed of one molecule. Example: glucose
Disaccharides: Formed when two monosaccharides are joined together. Examples: sucrose and maltose.
Polysaccharides: Formed when many monosaccharides are joined together. Examples: Cellulose and glycogen.
Lipids
Lipids include fats, phospholipids, and cholesterol. Fats are the simplest lipids and can be broken down into fatty acids and glycerol (a sugar alcohol).
Proteins
Proteins are composed of many smaller molecules called amino acids. Examples: collagen, haemoglobin, and antibodies.
Nucleic Acids
These macromolecules are composed of smaller ones called nucleotides. Examples: DNA and RNA.
Types of Cells
Muscle cell / Bone cell / Brain cell / Blood cell / Intestine cell
Catabolism and Anabolism
Catabolism: Complex organic substances → simple substances + energy. (The destructive phase of metabolism. The energy produced is used to synthesize new molecules for reproduction and for cell function).
Anabolism: Simple substances + energy → complex organic substances. (The constructive phase of metabolism. The complex molecules produced are used in growth and structural repairs.)
Cells: The Basic Units of Life
The cell is the simplest living unit that can carry out the life functions of nutrition, interaction, and reproduction.
A cell is the basic, structural, functional, and biological unit that makes up all living things.
Living things can be made of one cell (unicellular organisms) or many cells (multicellular organisms).
Life Functions in Cells
Cells perform three life functions: nutrition, interaction, and reproduction.
Once inside the cell, the nutrients undergo a series of chemical processes, known together as cellular metabolism.
According to the purpose and type of reaction that occurs, there are two types of metabolic reactions: catabolism and anabolism.
Cell Parts and Their Functions
- Nucleus: Contains the genetic material that controls cellular functions.
- Smooth Endoplasmic Reticulum: No ribosomes; lipids are synthesised.
- Mitochondria: Through cellular respiration, mitochondria produce most of the energy of a cell.
- Ribosomes: They are found free in the cytoplasm or attached to the rough endoplasmic reticulum. They are involved in protein synthesis.
- Cytoskeleton: It maintains the shape of the cell and facilitates the movement of the cell.
- Lysosome: Have enzymes (proteins) that carry out cell digestion.
- Golgi Body: Stores, processes, and packages substances received from the rough endoplasmic reticulum.
- Rough Endoplasmic Reticulum: Many ribosomes; synthesis and transport of proteins to the Golgi body.
- Nucleolus: To produce ribosomes.
- Centrosome: 2 centrioles → Participate in cell division. They move DNA to the sides of the cell.
- Plasmatic Membrane: Surrounds the cell and enables the exchange of substances.
Microscope Parts
Eyepiece lens, revolving nosepiece, objective lenses, stage clips, stage, condenser lens, diaphragm, light source, base, fine adjustment knob, coarse adjustment knob, arm, body tube.