Key Concepts in Biology
Characteristics of Living Organisms
- Living things have motion; they move. Plants move in order to catch sunlight for photosynthesis.
- Living things respire. Respiration is a chemical reaction which occurs inside cells to release energy from the food consumed.
- Living things are sensitive to stimuli and have the ability to sense changes in their environment.
- They grow. Living things mature and grow through different stages of development.
- They acquire and fulfill nutritional requirements to survive through the process of nutrition and digestion, which involves engulfing and digesting food.
- Some living organisms are autotrophic, meaning they can harness the sun’s energy to make their food (also known as autotrophs).
- Digested food is eliminated from the body through the process of excretion.
Genetics and Molecular Biology
Genetic Engineering Applications
Used to mass-produce insulin, human growth hormone, follistim (for treating infertility), human albumin, monoclonal antibodies, antihemophilic factors, vaccines, and other drugs.
Restriction Enzymes
Enzymes that cut double-stranded DNA molecules at specific sequences. They are commonly used in molecular cloning, DNA sequencing, and genetic engineering to create recombinant DNA molecules.
DNA
DNA is a molecule that contains the instructions to develop, live, and reproduce. It is made up of four different molecules: Adenine, Thymine, Guanine, and Cytosine. These are arranged into sequences that store and transmit information.
Genes
Genes are units of heredity found within each cell that transmit information from one generation to the next. Genes are made up of DNA, a chemical code that carries instructions for the development, functioning, and behavior of all living organisms.
Gel Electrophoresis
Used to separate mixtures of DNA, RNA, or proteins according to molecular size.
PCR Amplification Purpose
It allows rapid amplification of a specific segment of DNA, which aids in the identification of gene sequences.
Watson-Crick DNA Model
Describes DNA as a double helix containing two long, helical strands wound together.
Protein Synthesis
Essential for creating vital components like hormones, enzymes, and new tissues such as muscle.
Cell Biology
Cell Specialization
Cell specialization is the process by which generic cells change into specific cells that perform tasks in the body. Cells are organized into tissues, then organs, then organ systems, and finally an organism.
Stem Cell Therapy
Stem cell therapy is the use of stem cells to treat or prevent a disease or condition.
Unipotent, Multipotent, Pluripotent Cells
Pluripotent stem cells can differentiate into all cell types in an organism, while multipotent and unipotent cells are restricted to specific cell lineages or tissues.
Stem Cell Therapy Applications
In stem cell transplants, stem cells replace cells damaged by chemotherapy or disease.
Prokaryotic vs. Eukaryotic Cells
Prokaryotes are always unicellular, while eukaryotes are often multicellular organisms.
Cellular Organelle Roles
They maintain homeostasis within the cell, for example, through energy production.
Using Light Microscopes for Cell Size
Divide the diameter of the field of view by the number of cells that fit across it to estimate cell size.
Making and Observing a Wet Mount Slide
Collect your sample and place one drop on the microscope slide to observe the size and shape of individual organisms.
Fluid Mosaic Model of Cell Membrane
It describes the cell membrane as a tapestry of various molecules (phospholipids, cholesterol, and proteins) that are fluid and constantly moving.
Passive vs. Active Transport: Diffusion & Osmosis
Passive transport does not require energy, while active transport requires energy. Both diffusion and osmosis are types of passive transport as substances move down the concentration gradient.
Transcription and Translation
Proteins are synthesized through two main steps: Transcription, where DNA is transcribed into mRNA, and Translation, where mRNA is translated into chains of amino acids that fold into functional proteins.
Factors Influencing Diffusion Rate
Factors include temperature, concentration gradient, molecule size, and the presence of a membrane.
Hypertonic, Isotonic, Hypotonic Solutions
When a cell is placed in a hypertonic solution, water leaves the cell, causing it to shrink. In an isotonic environment, there is no change in cell size. When a cell is placed in a hypotonic environment, water enters the cell, causing it to swell.
Metabolism and Energy
Role of ATP in Cell Energy
ATP provides the energy needed for essential processes in organisms and cells.
Photosynthesis: Light-Dependent & Independent
Photosynthesis is vital for life. The light-dependent reactions capture light energy from the sun and split water molecules to produce ATP and NADPH.
Factors Influencing Photosynthesis Rate
Factors include light intensity, carbon dioxide concentration, and temperature.
Aerobic vs. Anaerobic Respiration
Aerobic respiration releases significantly more energy than anaerobic respiration.
Stages of Cellular Respiration
- Glycolysis
- The Citric Acid Cycle (Krebs Cycle/TCA Cycle)
- The Electron Transport Chain