Science Biology

• Organic compounds contain carbon and are found in all living things
• Organic molecules


  • Carbohydrates
  • Proteins
  • Lipids
  • Nucleic Acids
• Carbohydrates


  Major source of energy, include sugars and starches, made up of carbon, hydrogen, and oxygen with a 2:1 ratio of hydrogen to oxygen, plants and animals use carbohydrates for maintaining structure within the cells
• Proteins


  Nitrogen-containing compounds made up of chains of amino acids, 20 amino acids can combine to form a great variety of protein molecules, can compose enzymes, hormones, antibodies, and structural components
• Lipids


  Water-insoluble (fats and oils), made up of carbon, hydrogen and oxygen, composed of glycerol and fatty acid, provide insulation, store energy, cushion internal organs, found in biological membranes, saturated (with hydrogen, single bonds) and unsaturated (double bonds)
• Nucleic Acids


  Direct the instruction of proteins, genetic information an organism receives from its parents, two types: DNA (deoxyribonucleic acid) and RNA (ribonucleic acid)

  
• Cell Organelles


  • Chloroplast
  • Golgi Body
  • Lysosomes
  • Mitochondria
  • Nucleus
  • Ribosome
  • Vacuole
  • Cell (plasma) membrane
  • Cell wall
  • Cytoplasm
  • Endoplasmic Reticulum

  
• Cell Types


  • Unicellular
  • Multicellular
  • Prokaryote
  • Eukaryote
• Cell Theory


  • The cell is the basic unit of life
  • All organisms are composed of cells
  • All cells come from pre-existing cells
• Cell specialization: cells >>>> tissues >>>> organs >>>> organ systems >>>> organism, each cell performs a specific function for each tissue or organ, as cells mature, they shape and contents change, as cells become specialized they may contain organelles that are NOT common to all cells, design and shape of a cell is dictated by its function and the conditions under which it works, multicellular organisms exhibit greater cellular specialization, such as red blood cells, nerve cells, and gland cells
• Cell Transport


  • Passive Transport
  • Active Transport
• Passive Transport


  Movement of substances across the plasma membrane without the use of the cell's energy (with the concentration gradient), includes diffusion, osmosis, and facilitated transport
• Active Transport


  Movement of substances across the plasma membrane that requires the use of the cell's energy and carrier molecules, substances are moving from an area of low concentration to an area of higher concentration (against the concentration gradient), includes endocytosis and exocytosis
• Homeostasis


  Internal equilibrium, the plasma membrane regulates what enters and leaves the cell, a selectively permeable membrane only allows certain substances to pass through
• Effect of Concentration on a Cell

  • Hypotonic - water moves in, cell bursts
  • Hypertonic - water moves out, cell shrivels
  • Isotonic - no net movement, cell maintains equilibrium
• Homeostasis: Self-regulating mechanism that maintains internal conditions (with individual cells and within organs, systems), example: body temperature, respiration, nutritional balance, etc., cells communicate their needs to each other mainly through their cell membranes by releasing chemical messengers that, ultimately, tell the hypothalamus gland in the brain that a change needs to be made in the interstitial fluid, since it is the ruler of homeostasis, the hypothalamus sends neural and chemical signals to other glands, tissues, organs, and organ systems to adjust the internal environment, the interstitial fluid, so that it is more suitable for all the cells at that particular time, and since we are always changing what we are doing, homeostasis needs to change along with our activities, both day and night, this constantly changing internal environment is the process of homeostasis
• Negative Feedback


  Glucose / Insulin levels in cells
• Positive Feedback


  Blood platelets / Blood clotting
• Cellular Respiration


  1. Glycolysis (anaerobic)

  2. Citric acid cycle (aerobic)

  3. Electron transport chain (aerobic)
• Photosynthesis


  Carbon dioxide + water + energy from sunlight -> glucose + oxygen
• ATP


  A molecule that stores and releases the energy in its bonds when the cell needs it, removing a phosphate group (P) releases energy for chemical reactions to occur in the cell and ATP becomes ADP, when the cell has energy, the energy is stored in the bond when the phosphate group is added to the ADP
• Fermentation


  1. Lactic Acid Fermentation (muscle cells): glucose -> lactic acid + 2ATP

  2. Alcoholic Fermentation (plant cells): glucose -> carbon dioxide + alcohol + 2ATP
• Enzymes


  • Special proteins that regulate nearly every biochemical reaction in the cell, different reactions require different enzymes, they function to provide energy to cells, build new cells, aid in digestion, break down complex molecules, act as catalysts (speed up chemical reactions without being used up or altered), factors that affect enzymes: pH, temperature, and quantity
• Cell division: process of copying and dividing the entire cell, allows unicellular organisms to duplicate in a process called asexual reproduction, allows multicellular organisms to grow, develop from a single cell into a multicellular organism, make other cells to repair and replace worn out cells, three types: binary fission, mitosis, and meiosis

  
• Protein Synthesis: Transcription and Translation

  
• Key molecules required for life

  • DNA
  • Protein Synthesis: Transcription and Translation

  
• Mitosis


  1. Interphase

  2. Mitosis

  3. Cytokinesis

  
• Meiosis


  1. Two cell divisions, one chromosome replication

  2. First meiosis division produces cells with half the number of double-stranded chromosomes

  3. Second meiosis division results in formation of four haploid cells

  
• Sperm


  Each primary sperm cell develops into four haploid cells of equal size
• Egg


  Each primary egg cell develops into one large haploid cell and three smaller haploid cells called polar bodies
• Genetics


  Branch of biology that deals with heredity
• Gregor Mendel experimented with sweet pea plants in the 1800s
• Trait


  Characteristic an individual receives from its parents
• Gene


  Carries instructions responsible for expression of traits; a pair of inherited genes controls a trait
• Homozygous


  Two alleles of a pair are identical
• Heterozygous


  Two alleles of a pair are different
• Dominant


  Controlling allele
• Recessive


  Hidden allele
• Genotype


  Genetic makeup of an organism
• Phenotype


  Physical appearance of an organism