reviewer

• DNA replication is the process by which a cell makes an identical copy of its DNA
• Occurs in the nucleus of eukaryotic cells
• Steps of DNA replication:

  • Initiation: DNA molecule unwinds and separates into two strands facilitated by helicases
  • Elongation: DNA polymerase adds new nucleotides in 5' to 3' direction, leading and lagging strands replicated differently
  • Termination: Replication completed when entire DNA molecule duplicated
• Transcription involves the synthesis of mRNA from a DNA template
• mRNA carries genetic information from nucleus to ribosomes
• Translation determines sequence of amino acids in a polypeptide chain based on mRNA information
• Rosalind Franklin contributed to understanding DNA structure by capturing X-ray photo of DNA
• Watson and Crick used Franklin's X-ray photo to describe DNA double helix structure
• Discovery of DNA double helix revolutionized understanding of genetics and heredity
• Cell respiration:

  • Anaerobic respiration occurs in absence of oxygen, produces small amount of ATP
  • Aerobic respiration occurs in presence of oxygen, produces large amount of ATP
  • Krebs Cycle takes place in mitochondria, breaks down acetyl CoA to produce carbon dioxide, ATP, NADH, and FADH2
• Major classes of biological molecules:

  • Carbohydrates, lipids, proteins, and nucleic acids
  • Carbohydrates used for energy storage and structural components
  • Carbon in biological molecules allows formation of diverse shapes
• Elements in biological molecules:

  • Carbon, hydrogen, oxygen, nitrogen, phosphorus, and sulfur
  • Combination of smaller molecules through dehydration synthesis forms larger biological molecules
• Organic vs. inorganic molecules:

  • Organic molecules contain carbon, include carbohydrates, lipids, proteins, and nucleic acids
  • Inorganic molecules do not contain carbon, except CO2, include water, salts, metals, and minerals
• Monosaccharides and polysaccharides:

  • Monosaccharides are simple sugars with 3 to 6 carbons, building blocks of complex carbohydrates
  • Polysaccharides are long chain molecules made of repeating monosaccharide units
• Triglycerides and phospholipids:

  • Triglycerides function as energy storage molecules and provide insulation
  • Phospholipids are crucial for cell membrane structure
• Proteins functions:

  • Enzymatic activity, defense, transport, support, motion, regulation, storage
  • Peptide bond links amino acids to form polypeptide chain, primary structure of protein
• Mitosis:

  • Cell nucleus divides into two identical cell nuclei
  • Phases: Prophase, Metaphase, Anaphase, Telophase, Cytokinesis
• Meiosis:

  • Two rounds of division: Meiosis I and Meiosis II
• Cell cycle stages:

  • Interphase: Cell grows and DNA is replicated
  • Mitosis: Short period compared to interphase, 93% of a cell's life is spent in interphase
• • Anaphase II: Centromeres split, sister chromatids separate and move to opposite sides
  • Telophase II: Nuclei reform, cytoplasm divides into four daughter cells with reduced chromosomes
• Stages of meiosis:

  • Interphase: Chromosomes replicate, each consisting of 2 identical sister chromatids
  • Prophase I: Homologous chromosomes form tetrads with overlapping chromatids
  • Metaphase I: Homologous chromosomes line up on the metaphase plate
  • Anaphase I: Homologous chromosomes separate and move to opposite sides
  • Telophase I: Nuclei reform, cytokinesis results in two daughter cells with haploid chromosomes
  • Prophase II: Chromosomes line up, spindle fibers form
  • Metaphase II: Chromosomes line up on the metaphase plate
• Functions of epithelial tissue:

  • Protecting underlying structures like skin and oral mucosa
  • Acting as barriers against pathogens and toxins
  • Permitting passage of substances, e.g., in the lungs
  • Secreting substances for bodily function maintenance
  • Absorbing nutrients from the digestive tract
• Four primary tissue types in animals:

  • Epithelial tissue
  • Connective tissue
  • Muscle tissue
  • Nervous tissue
• Embryonic tissue:

  • Derived from endoderm, mesoderm, and ectoderm germ layers
  • Endoderm forms digestive tract lining
  • Mesoderm forms muscle, bone, and blood vessels
  • Ectoderm forms skin and nervous system
• Functions of connective tissue:

  • Enclosing and separating tissues
  • Connecting tissues
  • Supporting and moving
  • Storing, cushioning, and insulating
  • Transporting and protecting
• Functions of muscle tissue:

  • Specialized for contraction
  • Skeletal muscle for voluntary movement
  • Cardiac muscle for involuntary heart pumping
  • Smooth muscle for involuntary movements in organs
• Functions of glial cells in the nervous system:

  • Support and protect neurons
  • Surround neurons, supply nutrients, and insulate
  • Regulate chemical environment and remove pathogens
• Functions of membranes in animal tissues:

  • Mucous membranes line cavities and secrete mucus
  • Serous membranes line trunk cavities and secrete serous fluid
  • Synovial membranes line movable joints
• Basic functions of cells:

  • Metabolize and release energy
  • Synthesize molecules
  • Provide communication
  • Reproduction and inheritance through mitosis and meiosis
• Plasma membrane functions:

  • Selective barrier regulating cell interactions
  • Support cell contents and enclosure
  • Communication between cells
• Functions of membrane proteins:

  • Marker molecules
  • Attachment proteins
  • Transport proteins
  • Receptor proteins
  • Enzymes
• Cell components and structures:

  • Plasma membrane
  • Cellular organelles
  • Nucleus
  • Cytoplasm
  • Nuclear envelope, chromatin, chromosomes, microtubules, actin filaments, intermediate filaments
• Phagocytosis:

  • Engulfing and internalizing solid materials by cells
  • Formation of a vesicle around material for ingestion
• Endoplasmic reticulum (ER) functions:

  • Rough ER: Major site of protein synthesis
  • Smooth ER: Involved in lipid and carbohydrate synthesis
  • Various metabolic processes and molecule synthesis
• Functions of centrioles and spindle fibers:

  • Organizing microtubules during cell division
  • Forming bases of cilia and flagella
  • Aiding in chromosome separation during cell division
• Microvilli:

  • Increase cell surface area
  • Aid in absorption and secretion