Biology Chapter: Cells and Enzymes

Organization of Cells

• Cells are the fundamental building blocks of life
• Tissues are formed from groups of similar cells working together
• Organs are made up of different tissues working together to perform a specific function
• Organ systems are groups of organs that work together

Enzymes

• Enzymes are biological catalysts
• Catalysts speed up the rate of chemical reactions without being used up
• Enzymes work via the "lock-and-key" theory
• The enzyme acts as the lock, and the substrate acts as the key
• The substrate fits into the active site of the enzyme, which is a specific region on the enzyme's surface
• The enzyme breaks down the substrate into products
• Each enzyme is specific to a particular substrate

Enzyme Conditions

• Enzymes have an optimum pH and temperature where they work best
• If the temperature or pH deviates too much from the optimum, the enzyme can denature
• Denaturation means the active site of the enzyme changes shape, making it unable to bind to the substrate

Examples of Enzymes

• Carbohydrates are broken down into simple sugars like glucose by the enzyme carbohydrase
• Proteins are broken down into amino acids by the enzyme protease
• Lipids (fats) are broken down into glycerol and fatty acids by the enzyme lipase

Digestive System

• The digestive system breaks down food into smaller molecules that can be absorbed by the body
• The order of food travel is: Mouth, esophagus, stomach, small intestine, large intestine, rectum
• The mouth begins mechanical digestion with teeth and chemical digestion with salivary amylase
• The esophagus transports food from the mouth to the stomach
• The stomach churns food and adds gastric juices for chemical digestion
• The small intestine is where most absorption of nutrients takes place
• The large intestine absorbs water from undigested food
• The rectum stores waste before expulsion

Food Tests

• Starch test: Add iodine solution to a sample. A blue/black color indicates the presence of starch
• Sugars test: Add Benedict's solution to a sample and heat it. A brick red color indicates the presence of sugars.
• Proteins test: Add biuret solution to the sample. A purple/lilac color indicates the presence of proteins.
• Lipids test: Add Sudan III stain solution to the sample and shake it. If two distinct layers form, lipids are present.

Lungs

• The lungs are responsible for gas exchange, taking in oxygen and releasing carbon dioxide.
• Oxygen enters the lungs through the trachea, bronchi, bronchioles, and finally the alveoli.
• The alveoli are tiny air sacs where gas exchange occurs.
• They are surrounded by a network of blood capillaries for efficient gas exchange.

Heart

• The heart is a double pump system responsible for circulating blood throughout the body.
• The left ventricle pumps oxygenated blood to the body.
• The right ventricle pumps deoxygenated blood to the lungs.
• The heart is made of a thick muscular wall to enable forceful blood pumping

Blood Vessels

• Arteries carry oxygenated blood away from the heart at high pressure. They have thick, muscular walls and a small lumen (central space).
• Veins carry deoxygenated blood back to the heart at lower pressure. They have thinner walls, a larger lumen, and valves to prevent backflow of blood.
• Capillaries are tiny blood vessels with thin, permeable walls that allow for exchange of substances between blood and tissues.

Plant Organization

• A leaf is a complex structure adapted for photosynthesis
• Upper epidermis: Protects the leaf and allows light to pass through
• Palisade mesophyll: Contains chloroplasts for photosynthesis
• Spongy mesophyll: Contains air spaces for gas exchange
• Lower epidermis: Contains stomata for gas exchange and transpiration
• Xylem: Transports water and minerals up the plant
• Phloem: Transports sugars produced during photosynthesis down the plant.

Explore the fundamental concepts of cell organization and enzyme function in this quiz. Understand how cells form tissues and organs, as well as the specific roles that enzymes play as biological catalysts. Test your knowledge on enzyme conditions and the significance of optimum pH and temperature.