Biology Chapter: Cell Organelles and Functions

Cells

• Basic unit of life
• Animal cells have a cell membrane, nucleus, cytoplasm, mitochondria, ribosomes, endoplasmic reticulum (rough and smooth), Golgi apparatus, and lysosomes.
• Plant cells have a cell wall, cell membrane, nucleus, cytoplasm, mitochondria, ribosomes, endoplasmic reticulum, Golgi apparatus, chloroplasts, vacuole, and amyloplasts.

Plant vs Animal Cells

• Cell wall: Present in plant cells, absent in animal cells.
• Vacuole: Larger central vacuole in plant cells, small and numerous vacuoles in animal cells.
• Chloroplasts: Present in plant cells, absent in animal cells.
• Centrioles: Present in animal cells, absent in plant cells (generally).

Parts & Their Functions

• Nucleus: Contains DNA, controls cell activities; includes nucleolus and chromatin.
• Cytoplasm: Site of chemical reactions, contains water, dissolved proteins, sugars, enzymes, and organelles, mostly water.
• Mitochondria: Rod-shaped, carry out cellular respiration, release energy for cell activities.
• Plasma membrane: Surrounds the cell, partially permeable, controls passage of substances.
• Cell wall: Provides support and protection for plant cells, made of cellulose.

Specialized Cells, Tissues, Organs and Systems

• Specialized cell: A cell with a specific function determined by its structure
• Tissue: A group of similar cells performing a specific function
• Organ: A structure composed of several types of tissues working together.
• System: Multiple organs working together

Nutrients

• Importance: Provide energy, raw materials for new cells, and help organisms stay healthy.
• Functions of water: Solvent for chemical reactions, key component of cells, tissues, and fluids, regulates blood temperature, transports dissolved substances.
• Carbohydrates: Monosaccharides, disaccharides, and polysaccharides (e.g., glucose, fructose, galactose, sucrose, maltose, starch, glycogen, cellulose).

Food Tests

• Benedict's Test: Tests for reducing sugars (e.g., glucose).
• Iodine Test: Tests for starch.
• Biuret Test: Tests for protein.
• Ethanol Emulsion Test: Tests for fats.

Enzymes

• Biological catalysts that speed up chemical reactions by lowering activation energy.
• Characteristics: Speed up reactions, required in minute amounts, specific in action.
• Lock-and-key hypothesis describes how enzymes and substrates interact.

Factors Affecting Enzyme Activity

• Temperature: Optimum temperature exists where the enzyme’s activity is maximum.
• pH: Optimum pH exists where the enzyme’s activity is maximum.
• Enzyme concentration: Increasing enzyme concentration increases the rate of reaction until substrate concentration becomes the limiting factor.
• Substrate concentration: Increasing substrate concentration increases the rate of reaction until enzyme concentration becomes the limiting factor.

Nutrition in Humans

• Processes: Ingestion, digestion, absorption, assimilation, and egestion.
• Alimentary canal: Mouth, salivary glands, esophagus, stomach, duodenum, pancreas, gallbladder, liver, ileum, colon, rectum, anus.

Digestive System

• Mouth: Chewing, saliva (salivary amylase)
• Esophagus: Peristalsis
• Stomach: Gastric juice, hydrochloric acid, pepsin; chyme
• Small intestine: Pancreatic juice, bile, intestinal enzymes; absorption
• Large intestine: Water and mineral absorption; feces

Photosynthesis

• Process where light energy is converted to chemical energy (glucose) using water and carbon dioxide.
• Word equation: Carbon dioxide + water + light energy → glucose + oxygen.

Factors Affecting Rate of Photosynthesis

• Light intensity: Rate increases proportionally with light intensity up to a point, then plateaus.
• Carbon dioxide concentration: Rate increases proportionately with CO2 concentration up to a point, then plateaus.
• Temperature: Optimum temperature exists where the rate of photosynthesis is maximum; rate decreases outside that temperature.

Respiration in Humans

• Aerobic respiration: Complete breakdown of glucose in the presence of oxygen.
• Word equation: Glucose + oxygen → carbon dioxide + water + energy
• Anaerobic respiration: Partial breakdown of glucose in the absence of oxygen.

Transport in Humans

• Structure of blood: Plasma, red blood cells (RBCs), white blood cells (WBCs), platelets
• Composition of blood: Dissolved substances (nutrients, wastes), proteins, salts, and water
• Function of blood: Transport of oxygen, nutrients, hormones, waste products, and heat.
• Blood vessels: Arteries, veins, capillaries (different structures and functions)

Circulation

• Path of blood: Heart → arteries → arterioles → capillaries → venules → veins → heart
• Blood pressure and flow: Difference in pressure drives flow; valves prevent backflow
• Transport in plants: Xylem (water and minerals) and phloem (sugars and amino acids)
• Transpiration pull, root pressure, capillary action

Respiration in Humans

• Aerobic respiration: complete breakdown of food in the presence of oxygen, lots of energy
• Anaerobic respiration: partial breakdown of food without oxygen, less energy

Respiratory System

• Nose, trachea, bronchi, bronchioles, alveoli; gas exchange
• Inspiration: intake of air
• Expiration: output of air
• Mechanisms: diaphragm, intercostal muscles

Reproduction in Plants

• Asexual reproduction: Offspring genetically identical to parent (e.g., budding, runners)
• Sexual reproduction: Offspring genetically different from parent (e.g., flowers, seeds)
• Parts of a flower: Flower stalk, petals, sepals, stamens (anthers and filaments), carpels (stigma, style, ovary)
• Pollination: Transfer of pollen to stigma
• Fertilization: Fusion of sperm and egg

Reproduction in Humans - Male

• Male reproductive system: Testes, epididymis, vas deferens, seminal vesicles, prostate gland, urethra, penis
• Sperm production: Testes; testosterone production
• Sperm structure: Head, mid-piece, tail

Reproduction in Humans - Female

• Female reproductive system: Ovaries, oviducts (fallopian tubes), uterus, vagina, labia
• Egg production and release: Ovaries produce eggs; ovulation
• Parts of the female reproductive system: ovaries, fallopian tubes, uterus, vagina
• Fertilization: meeting of egg and sperm within the fallopian tube

Diseases

• Coronary heart disease: Blockage of coronary arteries reduces blood flow to heart, potentially leading to death
• COPD: Lung diseases (e.g., bronchitis, emphysema) affect air flow
• Lung cancer: Cancer in lung tissues
• Sexually transmitted infections (STIs): Infections transmitted through sexual contact