Neo-Darwinism vs. Saltationism: Evolution Theories
Neo-Darwinism vs. Saltationism (Punctuated Equilibria)
Neo-Darwinism:
- The variability of populations is genetic and is due to two processes: mutation and genetic recombination.
- The gene pool is defined as the sum of all genes (each with their different alleles) present in all individuals of a population.
- Natural selection acts on genetic variability. Each individual in a population carries different alleles responsible for their phenotype.
- Natural selection leads to changes in the set of alleles of the
Nucleic Acids, DNA Replication, and Protein Synthesis
Nucleic Acids
DNA Functions: Stores genetic information, transmits information to other molecules and between generations. 10 base pairs per turn.
Nucleotides: Sugar and phosphate make the backbone; bases give chemical identity. Bases: Adenine + Thymine (2 H-bonds), Guanine + Cytosine (3 H-bonds). Has 1-3 phosphate groups attached. A, G = purines. T, C = pyrimidines.
Chargaff’s Base Pairing Rule: A-T, C-G (helped discover the helical shape of DNA). Pair because of base distance, H-bond pattern, and
Read MorePhotosynthesis: Pigments, Light, and Carbon Fixation in Plants
Photosynthesis: Pigments, Light, and Carbon Fixation
Over 90% of a plant’s weight is water. CO2 in the atmosphere moves by diffusion through the ostiole, then the walls of the mesophyll, and finally reaches the chloroplasts. This process is proportional to the concentration of CO2 in the atmosphere (0.03%).
Chlorophyll: The Green Pigment
Chlorophyll is the green pigment that allows plants to absorb light, primarily in the violet, blue, and red spectrum, while reflecting green light. Chlorophylls are
Read MoreCellular Nutrition: Autotrophs, Heterotrophs, and Respiration
Cells need organic substances for two main purposes:
- Building and Repair: To rebuild structures, grow, and reproduce.
- Energy Production: To carry out activities such as movement and exchanging substances with the environment.
Living organisms obtain nutrition in two primary ways:
Autotrophic Nutrition
Autotrophs are able to capture energy from sunlight and use it to produce organic matter from inorganic substances. They take in raw materials to construct their own nutritional matter.
Heterotrophic Nutrition
Heterotrophs
Read MoreGenetic Engineering and Selective Breeding Techniques
DNA Polymerase: Sequencing vs. Cellular Function
Contrast the role of DNA polymerase in determining a DNA sequence with its role in normal cells.
In DNA sequencing, DNA polymerase replicates small pieces of DNA using normal bases and some bases that are tagged with dye. Each base can be tagged with a different color dye. The dye-tagged bases stop replication. After running the bases on a gel, scientists can determine the sequence of the DNA by reading the order of the colored bands on the gel. In
Read MoreDigestive and Respiratory Systems: Anatomy and Functions
Larynx: Anatomy and Function
The larynx is a tubular organ that connects the pharynx to the trachea, located in the front of the neck. During swallowing, communication is intercepted by a layer of cartilage (epiglottis) that prevents food from passing into the airways. It consists of the hyoid bone and the following cartilages:
- Cricoid: It is superimposed on the trachea, forming a ring with an anterior arch and a posterior seal.
- Thyroid: Forms the laryngeal prominence (Adam’s apple).
- Epiglottis: When