Cell Structure and Function

The Cell and DNA: A Simple Guide

• Somatic and germ cells are the two types of cells
• Cytoplasm contains several organelles

The Basic Building Block: Your Cells

• The body is comprised of cells, each with specific functions
• The nucleus can be considered the city hall, and it stores all of the vital instructions, such as DNA
• The mitochondria are the power plants turning food into energy and perform apoptosis(cell death); they have their own DNA, supporting the endosymbiotic theory
• The cell membrane is like city walls, controlling what goes in and out
• The cytoplasm is similar to the streets and spaces between everything, filled with a jelly-like substance
• Lysosomes break down waste, damaged cells, and invading pathogens, and are involved in programmed cell death

Overview of Cell Organelles

• The nucleus contains genetic information, DNA, and histones and controls cell structure, function, and replication
• Genes are DNA sections containing hereditary information
• Nucleolus produces ribosomal ribonucleic acid (RNA) subunits, transcribes, processes, and assembles these subunits to form ribosomes
• Smooth endoplasmic reticulum (SER) produces phospholipids, while rough endoplasmic reticulum (RER) synthesizes lysosomal enzymes and proteins for intracellular and extracellular use
• Ribosomes aid in protein production on the RER and polysomes by interpreting messenger RNA (mRNA) with transfer RNA (tRNA)
• Golgi complex sorts, modifies, and packages proteins from the RER
• Secretory vesicles store enzymes awaiting a signal for release
• Food vacuoles store ingested material and combine with lysosomes for digestion and degradation, known as autophagy
• Lysosomes digest engulfed materials and combine with food vacuoles
• Lysosome membrane separates digestive enzymes from cytoplasm
• Peroxisomes break down intracellular molecules and develop nerve cell myelin sheath
• Mitochondria convert food into energy, completing breakdown of glucose, producing nicotine adenine dinucleotide and adenosine triphosphate (ATP)
• Cytoskeleton gives internal support and transports molecules inside the cell
• Cilia propel materials along the surface of certain cells
• Flagella provide the motile force for sperm cells
• Centrioles organize the spindle apparatus during cell division

How Cells Make More Cells: The Cell Cycle

• Cells go through four main stages:
• First Growth (G1): The cell grows and does its daily work
• DNA Copying (S): DNA is duplicated
• Second Growth (G2): Final preparations are made
• Division (M): One cell divides into two

DNA, RNA, and the Cell's Instruction Manual

• DNA stays put in the nucleus
• mRNA takes photo copies of recipes (DNA) to be used elsewhere
• tRNA brings ingredients to the ribosome
• Ribosomes help make proteins using mRNA and tRNA

Key Concepts

• Cellular Permeability: A cell membrane's ability to allow certain substances to pass through while blocking others; it regulates the internal environment
• Membrane Structure:
  • Gates: Specialized proteins in the cell membrane that open or close
  • Regulation: Gates controlled by:
    • Proteins: Channels or carriers for specific substances
    • Chemical Signals: Trigger gate opening or closing
    • Electrical Charges: change electrical potential
• Diffusion: Movement of solutes from high to low concentration, a fundamental process for transporting substances within and between cells

Key Terms

• Solutes: Substances dissolved in a solution (e.g., salts, sugars)
• Concentration Gradient: The difference in concentration of a substance across a space

Important Processes

• Passive Transport: Substance movement across the cell membrane without energy, driven by diffusion
• Facilitated Diffusion: Passive transport using proteins to move substances across the cell membrane

Replication and Differentiation

• Replication: Cells duplicate DNA before cell division
• Differentiation: Unspecialized cells develop into specialized cells with distinct functions

Proto-oncogenes

• Proto-oncogenes are normal genes that promote cell growth and division
• When mutated, proto-oncogenes can become oncogenes, leading to uncontrolled cell proliferation

Neoplasms

• Neoplasms are abnormal tissue growth from excessive cell division
• Benign Neoplasms: Non-cancerous growths that does not invade surrounding tissues
• Malignant Neoplasms: Cancerous growths that invade nearby tissues and can metastasize

Cellular Adaptation and Damage

• Cellular Adaptation: Changes in cell structure or function in response to stress or environmental changes
• Cellular Damage: Injury to cells, often caused by toxins, inflammation, or ischemia

ROS (Reactive Oxygen Species) Free Radicals

• Reactive molecules that damage cellular components, sourced from metabolism, environmental toxins, and radiation

Antioxidants

• Substances that neutralize ROS, such as Vitamins C and E, and glutathione

Inappropriate Apoptosis

• Programmed cell death that occurs inappropriately, such as in neurodegeneration or cancer

Gene Mutation

• Permanent alterations in the DNA sequence that can lead to protein function changes and diseases

Malignant Neoplasms

• Characteristics: Rapid growth, invasion of surrounding tissues, and potential to metastasize

Genetic Disorders

• Marfan Syndrome: Affects connective tissue, leading to cardiovascular, skeletal, and ocular issues
• Neurofibromatosis: Causes tumors on nerve tissues, resulting in skin changes and potential neurological issues
• PKU (Phenylketonuria): Metabolic disorder due to deficiency in the enzyme phenylalanine hydroxylase, leading to intellectual disability (if untreated)
• Lupus: Autoimmune disease where the immune system attacks healthy tissues, causing damage to multiple organ systems

Substances Crossing the Cell Membrane

• Passive Transport:
  • Diffusion: Molecules move from high to low concentration
  • Facilitated Diffusion: Molecules move via transport proteins
  • Osmosis: Water diffuses across a selectively permeable membrane
• Active Transport: -Movement of substances against their concentration gradient, requiring energy (ATP). -Example: Sodium-potassium pump
• Endocytosis and Exocytosis:
  • Endocytosis: Engulfing substances into the cell
  • Exocytosis: Expelling materials from the cell

Cellular Energy Source and Production

• ATP (Adenosine Triphosphate): The primary energy currency of the cell
• Energy Production:
  • Glycolysis: Produces ATP in the cytoplasm
  • Krebs Cycle (Citric Acid Cycle): Occurs in the mitochondria, producing electron carriers (NADH and FADH2)
  • Electron Transport Chain: In the inner mitochondrial membrane, where ATP is produced through oxidative phosphorylation

Process of Protein Synthesis

• Transcription:
  • DNA is transcribed into messenger RNA (mRNA) in the nucleus
• Translation:
  • mRNA is translated into a protein at the ribosome
• Transfer RNA (tRNA) transfers amino acids to the ribosome, which undergo Post-Translational Modifications for function and activity

Cellular Organization

• Cell Types:
  • Prokaryotic Cells: Simple cells without a nucleus (e.g., bacteria)
  • Eukaryotic Cells: Complex cells with a nucleus and organelles (e.g., plant and animal cells)
• Tissue Organization: -Cells group into tissues (e.g., epithelial, connective, muscle, and nervous tissues). -Tissues combine to form organs, which work together in organ systems.

Genetics, Epigenetics, and Environment in Disease Development

• Genetics: Heredity study and the variation, including mutations that may lead to diseases
• Epigenetics: Gene expression Changes due to environmental factors (e.g., diet, stress) that can be passed to offspring
• Environmental Factors: Toxins, lifestyle, and socioeconomic status affect disease risk

Mitosis vs. Meiosis

• Mitosis produces two identical cells
• Meiosis produces reproductive cells with varied gene combinations

Mutations and Errors

• Mutation: Permanent change to DNA
• Replicaiton Error: Mistake that happens when copying DNA
• Hypertrophy: Increase in cell size
• Hyperplasia: Increase in cell number
• Atrophy: Decrease in cell size
• Metaplasia: Change in cell type
• Dysplasia: Disorganized cell growth
• Neoplasia: Cancerous cell growth

Genes and Alleles: The Family Recipe Book

• Gene: The complete instructions for a protein (complete recipe)
• Allele: Variation of a gene (chewy vs, crisp cookies)

How Traits Pass Down: Inheritance

• Dominant Traits: Will appear if there is one copy
• Recessive Traits: Will only appear if there are two copies
• X-linked traits: Inheritance that work differently in males and females

Cell Division and Body Balance

• Balance is maintained by replacing old cells, growing new and injured cells

Quality Control: Cell Checkpoints

• DNA must copy correctly
• Cell should be big enough
• Everything is ready for vision or something things can go wrong and lead to cancer

Direct Contact Signaling

• Cell touches directly
• Exchanges molecular informaiton
• Uses protein channels and surface receptors

Chemical Signaling

• Release of signaling molecules
• Different communication ranges: -Autocrine cell signals itself -Paracrine: Nearby cells -Endocrine: Distant cells via hormones

Molecular Messengers

• Hormones
• Neurotransmitters
• Growth Factors
• Cytokines

Signaling Pathways

• Receptor activation
• Intracellular signal transmission
• Gene expression modification

Key Molecular Players

• Receptors detect external signals and trigger internal responses (surface membrane, intracellular)
• Second messengers amplify and transmit signals (cyclic AMP, calcium ions, inositol triphosphate)

Signaling Cascade

• Signal reception (ligand binds to receptor)
• Signal transduction (molecular chain reaction, protein kinase activation, phosphorylation events)
• Cellular response (gene expression changes, protein synthesis, metabolic adjustments)

MicroRNA Communication

• Genetic information exchange
• Intercellular messaging
• Epigenetic regulation

Extracellular Vesicles

• Membrane-enclosed packages
• Transport molecular information
• Facilitate long-distance communication

Communication Breakdown: Disease Implications

• Cancer: Uncontrolled cell proliferation/Miscommunicated growth signals
• Neurological disorders: Impaired neurotransmitter signaling/Miscommunication between neurons
• Autoimmune conditions: Misinterpreted cellular signals/Inappropriate immune responses

What is Epigenetics?

• Epigenetics determines whether cells become heart cells, nerve cells, or skin cells
• It controls how DNA is read and expressed, but not the actual DNA text

The Environment-Gene Connection

• The lifestyle and environment can influence genes -Diet and nutrition -Stress levels -Physical activity -Environmental exposures -Early life experiences

Gene Editing and CRISPR: The Ethics Debate

• Potential ethical concerns regarding gene editing include: -Safety and unintended consequences -Access and equality -Future generations

Genetic Testing

• Types: -Diagnostic testing -Predictive testing -Carrier testing

Inheritance Patterns

• Dominant Traits: Are always seen even if only one copy is present, such as with brown eyes
• Recessive Traits: Are only seen when two copies are present, such as with blue eyes
• X-Linked Inheritance: Instructions travel on the x chromosome so it differs by gender

Punnett Squares

• It calculates Genetic Inheritance

The Future of Genetics

• Personalized medicine, disease prevention, and ethical consideration
• Genetic medicine is set to reach $8.1b by 2025

The Role of Genetic Counseling

• Interprets genetic results, make informed decisions, navigate ethical considerations and plan for future health needs

The Human Immune System: A Comprehensive Guide

• The body has two lines of defence -Innate immunity (outer wall) -Adaptive immunity (the elite guards)

Innate Immunity

• Physical barriers (skin, mucous membranes)
• Chemical barriers (stomach acid, enzymes)
• Cellular defenders of the quick response, but it is less specific

Adaptive Immunity

• Highly specific responses take long to activate, but they create immunological memory and exposure

Innate and Adaptive Immunity

• Innate: -Immediate, non-specific (Physical and chemical barriers) (inflammation, fever) -Natural killer cells and dendritic cells take part
• Adaptive: -Specific response (T and B cells and and antigen-presenting cells take part) (antibody production) (cell-mediated immunity)

The Cellular Army's Innate Immune Cells

• Neutrophils: First responders
• Macrophages: The clean up crew
• Natural killer cells: Virus hunters
• Dendritic cells: The messengers

Adaptive Immunes Cells

• B lymphocytes: Antibody factories
• T lymphocytes: The commanders, who comprise strategy planners, assassins and record keepers

IgG

• The most common, provides long-term immune defense

IgA

• Guards mucous membrane

IgM

• First responder in new infections

IgE

• Allergy and parasite fighter

IgD

• The mysterious sentinel

Chemical Signals

• Interleukins coordinate immune responses
• Interferons provide anti-viral messages
• The tumor necrosis factor triggers inflammation

The Complement System

• Cascade like dominies -Tag invaders -Attract immune cells -Create holes in bacterial infections -Clear away infection

Inflammation

• Causes -Redness (Rubor) -Heat: (Calor) -Swelling (Tumor) -Pain (Dolor) -Loss of function (Functio laesa)

Key Mediators

• Histamine: Blood vessel dilator
• Prostaglandins: Pain and fever inducers
• Cytokines. Immune cell recruiters

Hypersensitivity Reactions

• Type I (Immediate) -Minutes to react -Caused by allergies, asthma -Mediated by IgE
• Type II (Cytotoxic) -Antibodies attack cells -Caused by blood transfusion reactions -Mediated by IgG/IgM
• Type III (Immune Complex) -Caused by antibody-antigen deposits that result in lupus, rheumatoid arthritis and complement activation
• Type IV (Delayed) -Takes 24-72 hours -T-cell mediated and results in contact dermatitis

The Immune Response in Action

• Recognition: Pathogen detection and danger signal release
• Activation: Immune cell recruitment and antibody production
• Resolution: Pathogen elimination and memory cell formation

Disorders of the Immune System

• Autoimmune: Body attacks itself, causing diabetes and rheumatoid arthritis
• Immunodeficiencies: Weakened defense like HIV
• Allergies and hypersensitivities range from mild to life-threatening

Clinical Application of the Immune System

• Vaccinations and immunotherapy. Also, diagnostic tools

Role of the Body's Normal Defenses in Preventing Disease

• Physical Barriers: Acts as first line of defense
• Chemical Barriers: inhibits pathogen growth
• Cellular Defenses: such as white blood cells as phagocytes and natural killer cells to destroy pathogens

Vaccine Types and their use in clinical settings

• Live Attenuated Vaccines:Weakened forms of the virus or bacteria (e.g., MMR vaccine)
• Inactivated Vaccines: Killed pathogens (e.g., polio vaccine.)

Pathogenesis of Hypersensitivity

• Type I (Allergic Reactions): IgE-mediated response (e.g., pollen allergies) Types of Hypersensitivity Reactions
• Type II (Cytotoxic Reactions): IgG or IgM antibodies bind to cell surface antigens (e.g., autoimmune hemolytic anemia).Types of Hypersensitivity Reactions
• Type III (Immune Complex-Mediated): Antigen-antibody complexes deposit in tissues (e.g., lupus).Types of Hypersensitivity Reactions
• Type IV (Delayed-Type Hypersensitivity): T-cell mediated (e.g., contact dermatitis).Types of Hypersensitivity Reactions

Altered Immune Responses and Common Disorders

• Systemic Lupus Erythematosus (SLE): An autoimmune disorder
• HIV/AIDS: HIV attacks CD4+ T cells, leading to a weakened immune system

Factors Enhancing and Impairing the Body's Defense

• Enhancing Factors: Healthy diet, regular exercise, adequate sleep, vaccination, good hygiene practices
• Impairing Factors: Chronic stress, conditions

Diagnostic and Treatment Considerations for Immune Disorders

• Diagnostic Approaches: Blood tests, imaging and skin test for allergies
• Treatment Options: Vaccines or immunotherapy

Main Interleukins Involved with Inflammation

• IL-1: Promotes inflammation and activates T cells
• IL-6: Stimulates immune response
• IL-8: Attracts neutrophils to sites of inflammation
• IL-12: Enhances the activity of natural killer (NK) cells and T cells

Interleukins Associated with Autoimmune Diseases

• IL-17: Promotes inflammation and is associated with autoimmune conditions
• IL-21: autoimmune diseases e.g. lupus erythematosus

Allergy and Hypersensitivity Reactions

• Lab values include elevated Serum IgE Levels for allergic response
• Lab values with elevated Eosinophilia- allergic reaction

PAMPs and DAMPs

• PAMPs (Pathogen-Associated Molecular Patterns): molecules recognized by the innate immune system
• DAMPs (Damage-Associated Molecular Patterns and it's released by stressed or damaged cells that trigger immune responses

Inflammation and Chronic Diseases

• Chronic inflammation can lead to tissue damage and is implicated in the development of various chronic diseases such as:

Chain of Infection

• Pathogen: The infectious agent (e.g., bacteria, virus)
• Reservoir: The natural habitat of the pathogen (e.g., humans, animals)
• Portal of Exit: The way the pathogen leaves the
• Portal of Entry: The way the pathogen enters a new host
• Susceptible Host: An individual who can become infected

Gram-Negative & Gram-Positive

• Gram negative: -Thin peptidoglycan layer -Outer membrane -Stain pink _ Gram Postive: -Thick peptidoglycan layer -No outer membrane -Stain Purple -Body response

Comparing Viruses vs bacteria

• Viruses - are non-cellular
• Bacteria are cellular

Stages of HIV

• Stage 1: Attachment
• Stage 2: Fusion
• Stage 3: Reverse Transcription
• Stage 4: Replication

HIV Lab Values

• CD4+ T cell count >200 cells/mm³ indicates HIV infection

Aids Labs

• CD4+ T cell count <200 cells/mm³
• Presence of opportunistic infections or certain cancers

A Fire Alarm

• Inflammation a double-edged sword that can protect or damage
• Acute can respond repidly to injury, but chronic is long term and low-grade that result in cardiovascular disease

Bio Markers

• C-creative protein (CRP)
• Interleukin-6 (IL-6)
• Erythrocyte Sedimentation Rate

Bacteria

• Bacterial infections transmitted by touching someone or airborne

Tiny and Hijacking

• Viruses are infectious agents that cause cells to replicate them

Infections with Fungi

• Athletes foot and other single-celled

Life, Eating, and Vectors

• Parasites are organisms that cause malaria, for example, and the diseases are passed by vectors

Gene, Structure, Infection and Transmission

• Prions are the misfolded proteins known as CJD

Childhood Specific Mutations

• Likely to affect developmental genes
• Often relation to congenital conditions

Immunosenescence's impact

• Infections over time will reduce a body's immune system strength