Observations, Experiments and Theory

• Observations involve watching and recording events, while experiments involve manipulating variables to test a hypothesis.

Good Observations

• Should be objective, detailed, and accurately recorded.
• Should be repeatable by others.

Good Experiments

• Should have a control group for comparison.
• Only one variable should be tested at a time.
• Should have a large sample size to ensure statistical significance.
• Should be repeatable by others, ensuring the results are reliable.

Theory in Science

• Represents a well-substantiated explanation of some aspect of the natural world.
• Is based on a body of facts that have been repeatedly confirmed through observation and experiment.
• Enables predictions.

Cell Theory

• All cells come from pre-existing cells.

Eukaryotic Cell Components & Organelles

• Cytoplasm: A gel-like fluid that suspends organelles and facilitates cellular processes.
• Cell Membrane: Outer boundary of the cell that controls what enters and exits.
• Cytoskeleton: Network of protein fibers that provide structure, support, and facilitate movement within the cell.
• Nucleus: Contains DNA, the genetic material of the cell, and controls cell activities.
• Nucleolus: Located within the nucleus, responsible for ribosome synthesis.
• Rough Endoplasmic Reticulum (RER): Studded with ribosomes, it synthesizes and modifies proteins.
• Smooth Endoplasmic Reticulum (SER): Involved in lipid synthesis, detoxification, and calcium storage.
• Ribosomes: Sites of protein synthesis, found freely in the cytoplasm or attached to the RER.
• Golgi Apparatus: Modifies, sorts, and packages proteins and lipids for transport.
• Vesicles: Membrane-bound sacs that transport substances within the cell.
• Vacuoles: Storage of water, nutrients, and waste products.
• Lysosomes: Contain enzymes for breaking down cellular waste and debris.
• Mitochondria: Carry out cellular respiration to produce ATP, the energy currency of the cell.
• Chloroplasts: Found in plant cells, carry out photosynthesis to convert light energy into chemical energy.
• Cell Wall: Provides support and protection to plant cells (made of cellulose).

Plant vs. Animal Cells

• Lysosomes are primarily found in animal cells.
• Chloroplasts, cell walls (made of cellulose), and central vacuoles are unique to plant cells.

Most Important Function of Cells

• Protein synthesis is the most important function.

Organelles Involved in Protein Synthesis

• Nucleus: Contains the DNA blueprint for proteins.
• Nucleolus: Produces ribosomes.
• Ribosomes: Synthesize proteins.
• Rough Endoplasmic Reticulum: Modifies and transports proteins.
• Golgi Apparatus: Processes and packages proteins for their final destination.

Roles of Proteins in Cells

• Enzymes: Catalyze biochemical reactions.
• Structural proteins: Provide support and shape to cells and tissues.
• Transport proteins: Carry molecules across cell membranes.
• Hormones: Chemical messengers that coordinate bodily functions.
• Antibodies: Defend against foreign invaders.
• Example: Enzymes speed up metabolism.

Mitochondria & Cellular Respiration

• Mitochondria are the site of cellular respiration.
• Glucose is broken down to produce ATP (energy), carbon dioxide, and water.
• Oxygen is required as the final electron acceptor in the process.

Chloroplasts & Photosynthesis

• Chloroplasts are the site of photosynthesis.
• Light energy, water, and carbon dioxide are used to produce glucose and oxygen.

Importance of Cellular Respiration & Photosynthesis

• Cellular respiration provides energy for living organisms by breaking down glucose.
• Photosynthesis produces glucose and oxygen, which are essential for cellular respiration and life on Earth.

Prokaryotic vs. Eukaryotic Cells

• Prokaryotic: Lack a nucleus and other membrane-bound organelles (e.g., bacteria).
• Eukaryotic: Have a nucleus and other membrane-bound organelles (e.g., animal, plant, fungi, and protist cells).
• Common Features: Both have a plasma membrane, cytoplasm, ribosomes, and DNA.

Microscope Parts & Functions

• Eyepiece: Lens for viewing the specimen (typically 10x magnification).
• Objective Lenses: Provide different magnifications.
• Stage: Platform that supports the slide.
• Condenser: Focuses light onto the specimen.
• Diaphragm: Controls the amount of light passing through the specimen.
• Coarse and Fine Focus Knobs: Adjust the clarity of the image.

Rules for Using a Microscope

• Start with the lowest power objective lens.
• Focus using the coarse adjustment knob first, then the fine adjustment knob.
• Adjust the diaphragm for optimal light.
• Properly prepare slides to minimize artifacts.

Total Magnification

• Calculated by multiplying the magnification of the eyepiece by the magnification of the objective lens.

Magnification, Resolution, & Contrast

• Magnification: Increases the apparent size of the object.
• Resolution: Clarity of the image, ability to distinguish between two close objects.
• Contrast: Difference in light intensity between the specimen and the background.

Field of View

• The diameter of the area visible through the microscope.
• It decreases as magnification increases.

Length of Specimen

• Estimate how many specimens can fit across the Field of View.
• Divide the Field of View value by that number.

Magnification of a Drawing

• Calculated by dividing the size of the image by the actual size of the specimen.

Light vs. Electron Microscopes

• Light Microscopes: Use light to view specimens, lower magnification (up to 1000x), can observe live specimens.
• Electron Microscopes: Use electron beams to view specimens, higher magnification (up to 1,000,000x), specimens must be dead.

Interphase

• The period of the cell cycle when the cell grows and prepares for division.
• It is significantly longer than mitosis/cytokinesis.

Phases of Interphase

• G1 (Gap 1): Cell grows and performs normal functions.
• S (Synthesis): DNA is replicated.
• G2 (Gap 2): Cell prepares for mitosis.

Importance of S Phase

• Ensures that each daughter cell receives a complete set of chromosomes.

Sister Chromatids vs. Chromosomes

• Sister Chromatids: Two identical copies of a chromosome, joined at the centromere.
• Chromosomes: Organized structures of DNA and proteins that carry genetic information.

Phases of Mitosis

• Prophase: Chromosomes condense, nuclear envelope breaks down, spindle fibers form.
• Metaphase: Chromosomes line up at the metaphase plate.
• Anaphase: Sister chromatids separate and move to opposite poles.
• Telophase: Chromosomes decondense, nuclear envelope reforms, spindle fibers disappear.

Chromatin vs. Chromosomes

• Chromatin: DNA is loosely packed and accessible for transcription (occurs during interphase).
• Chromosomes: DNA is tightly coiled and condensed for cell division (occurs during mitosis).

Mitosis vs. Cytokinesis

• Mitosis: Division of the nucleus and chromosomes.
• Cytokinesis: Division of the cytoplasm and the rest of the cell.

Cytokinesis in Plant vs. Animal Cells

• Animal Cells: Cell membrane pinches off to form two separate cells.
• Plant Cells: Cell plate forms between the two new nuclei, eventually becoming the new cell wall.

Cancer

• Uncontrolled cell growth and division due to mutations in genes regulating the cell cycle.

Carcinogen

• A substance or agent capable of causing cancer.

Mutations, Carcinogens, & Cancer

• Carcinogens can cause mutations in DNA, which can lead to uncontrolled cell growth and cancer.

Cancer Cells vs. Regular Cells

• Similarity: Both undergo cell division.
• Differences: Cancer cells divide uncontrollably, ignore signals to stop dividing, and can invade other tissues.

Stem Cells

• Undifferentiated cells that can differentiate into specialized cell types.

Adult vs. Embryonic Stem Cells

• Adult Stem Cells: Found in specific tissues and can differentiate into a limited range of cell types.
• Embryonic Stem Cells: Found in early embryos and can differentiate into any cell type in the body.

Example of Adult Stem Cells

• Bone marrow stem cells can differentiate into different blood cell types.

Levels of Complexity in Body Systems

• Cells are the basic units of life, they work together to make tissues
• Tissues are groups of similar cells performing a specific function
• Organs are made of different tissues working together
• Organ systems consist of multiple organs working together to perform complex functions
• Tissues, organs, and organ systems can be made up of one or several types of cells.

Animal Tissues

• Epithelial Tissue: Covers surfaces for protection, secretion, and absorption.
• Connective Tissue: Supports, connects, and separates tissues and organs (e.g., bone, cartilage, blood).
• Muscle Tissue: Contracts to produce movement.
• Nervous Tissue: Transmits electrical signals for communication and coordination.

Plant Tissues

• Meristematic Tissue: Responsible for growth and development through cell division.
• Dermal Tissue: Outer protective layer of the plant.
• Vascular Tissue: Transports Water Nutrients throughout the plant (Xylem & Phloem).
• Ground Tissue: Performs various functions, including photosynthesis, storage, and support.

Digestive System Purpose

• Breaks down food into smaller molecules that can be absorbed into the bloodstream.

Digestive Tract vs. Accessory Organs

• Digestive Tract: A continuous tube through which food passes (mouth, esophagus, stomach, small intestine, large intestine, rectum, anus).
• Accessory Organs: Assist in digestion but are not part of the digestive tract (liver, gallbladder, pancreas).

Main Organs of the Digestive Tract

• Mouth: Mechanical and chemical digestion begins with saliva breaking down carbohydrates.
• Esophagus: Transports food from the mouth to the stomach.
• Stomach: Churns food, secretes acid and enzymes for protein digestion.
• Small Intestine: Main site of nutrient absorption, enzymes digest carbohydrates, proteins, and fats.
• Large Intestine: Absorbs water and electrolytes, forms and stores feces.
• Rectum: Stores feces until elimination.
• Anus: Eliminates feces from the body.

Accessory Organs in Digestion

• Liver: Produces bile, which emulsifies fats.
• Gallbladder: Stores and concentrates bile.
• Pancreas: Secretes digestive enzymes and bicarbonate to neutralize stomach acid.

Mechanical vs. Chemical Digestion

• Mechanical Digestion: Physical breakdown of food into smaller pieces (e.g., chewing, churning in the stomach).
• Chemical Digestion: Breakdown of food by enzymes (e.g., amylase breaking down starch, pepsin breaking down proteins).

Macromolecule Digestion

• Carbohydrates: Digested into simple sugars. Begins in the mouth with amylase, continues in the small intestine.
• Proteins: Digested into amino acids. Begins in the stomach with pepsin, continues in the small intestine.
• Lipids: Digested into fatty acids and glycerol. Occurs primarily in the small intestine with the help of bile and lipases.

Circulatory System Functions

• Transports oxygen, nutrients, hormones, and waste products throughout the body.

Circulatory System

• Closed circulatory system: Blood is confined to vessels.

Blood Components

• Cells: Red blood cells, white blood cells, and platelets.
• Plasma: The liquid portion of blood, consisting of water, proteins, and other solutes.
• Plasma is the greater portion.

Blood Cells & Functions

• Red Blood Cells: Transport oxygen.
• White Blood Cells: Immune defense.
• Platelets: Blood clotting.

Circulatory System Components

• Heart: Pumps blood throughout the body.
• Arteries: Carry blood away from the heart.
• Veins: Carry blood back to the heart.
• Capillaries: Tiny vessels where exchange of nutrients and gases occurs.

Arteries vs. Veins vs. Capillaries

• Arteries: Thick walls, carry blood away from the heart.
• Veins: Thinner walls, carry blood back to the heart, have valves to prevent backflow.
• Capillaries: Thin walls, facilitate exchange of substances between blood and tissues.

Heart Role

• Pumps blood throughout the body.

Path of Blood Through the Heart

• Deoxygenated blood enters the right atrium through the superior and inferior vena cava.
• Blood passes through the tricuspid valve into the right ventricle.
• Blood is pumped through the pulmonary valve into the pulmonary artery, which carries it to the lungs.
• Oxygenated blood returns to the left atrium through the pulmonary veins.
• Blood passes through the mitral valve into the left ventricle.
• Blood is pumped through the aortic valve into the aorta, which carries it to the body.

Respiratory System Purpose

• Facilitates the exchange of oxygen and carbon dioxide between the body and the environment.

Respiratory System Structures & Roles

• Nose/Mouth: Entry point for air.
• Trachea: Windpipe that carries air to the lungs.
• Bronchi: Branches of the trachea that lead to each lung.
• Lungs: Main organs of gas exchange.
• Alveoli: Tiny air sacs in the lungs where oxygen and carbon dioxide exchange occurs.
• Diaphragm: Muscle that helps control breathing.

Gas Exchange at Alveoli

• Oxygen diffuses from the alveoli into the blood.
• Carbon dioxide diffuses from the blood into the alveoli.

Digestive, Respiratory, & Circulatory Systems

• Digestive System: Provides glucose (fuel for cellular respiration).
• Respiratory System: Provides oxygen for cellular respiration and removes carbon dioxide.
• Circulatory System: Transports glucose and oxygen to cells and carries away waste products.