Cell Structure and Function: A Detailed Look
Cell Structure and Function
All living things are composed of cells, the fundamental units of life. Cells are the anatomical (structural), physiological (functional), and genetic (inheritance) units of living beings. They are capable of nutrition, interaction, and reproduction.
Cell Types
- Prokaryotes: Cells with no nucleus, DNA is spread throughout the cytoplasm. Example: Bacteria.
- Eukaryotes: Cells with a nucleus where DNA is contained. Examples: Animal and plant cells.
Cell Parts
- Plasma membrane: The
Cellular Organization: Structure, Function, and Interactions
The Cell: The Basic Unit of Life
The cell is the minimum reproductive unit and the hereditary basis of information that defines a species. It has the capacity for self-replication.
Plasma Membrane: Defining the Cell
The plasma membrane defines the cell and its interaction with the external environment. It facilitates cellular compartmentalization and interaction with the extracellular environment and other cells. The nuclear membrane differentiates “eukaryotic” from “prokaryotic” cells.
Organelles:
Read MoreNeo-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
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