Cell Structure and Function

Cell Structure and Function

• Cells are the basic units of life.
• All living organisms are composed of one or more cells.
• Cells vary in size and shape, reflecting their diverse functions.
• Cells share fundamental structures and processes.
• Prokaryotic cells lack a nucleus and membrane-bound organelles.
• Eukaryotic cells possess a nucleus and membrane-bound organelles.
• Key organelles include the nucleus (controls cell activities), mitochondrion (powerhouse of the cell), endoplasmic reticulum (protein and lipid synthesis), Golgi apparatus (modifies and packages proteins), ribosomes (protein synthesis), lysosomes (degrade waste), vacuoles (storage), and chloroplasts (photosynthesis in plant cells).
• Cell membranes are selectively permeable, regulating the passage of substances into and out of the cell.
• Cell walls provide structural support and protection for plant cells.

Cell Processes

• Cellular respiration is the process by which cells break down glucose to release energy in the form of ATP.
• Photosynthesis is the process by which plants and other autotrophs convert light energy into chemical energy in the form of glucose.
• Mitosis is the process of cell division that results in two identical daughter cells.
• Meiosis is the process of cell division that results in four genetically diverse daughter cells, crucial for sexual reproduction.
• DNA replication is the process by which a DNA molecule is copied to produce two identical DNA molecules.
• Transcription is the process by which genetic information from DNA is copied into RNA.
• Translation is the process by which the information in RNA is used to synthesize proteins.

Biological Molecules

• Four major types of biological molecules are: carbohydrates, lipids, proteins, and nucleic acids.
• Carbohydrates are composed of carbon, hydrogen, and oxygen. They provide energy and structural support.
• Lipids are composed primarily of carbon and hydrogen. They store energy, form cellular membranes, and act as hormones.
• Proteins are polymers of amino acids. They perform a wide array of functions, including catalyzing reactions (enzymes), providing structural support, and transporting molecules.
• Nucleic acids (DNA and RNA) store and transmit genetic information.

Ecology

• Ecology is the study of the interactions between organisms and their environment.
• Organisms interact with each other and their physical surroundings (abiotic factors) through various relationships like competition, predation, and symbiosis (mutualism, commensalism, parasitism).
• Ecosystems are composed of biotic (living organisms) and abiotic (non-living components) factors.
• Energy flows through ecosystems in a one-way direction from producers to consumers to decomposers.
• Nutrients cycle within ecosystems.
• Different trophic levels exist in a food chain or web, depicting the flow of energy.

Genetics

• Genetics is the study of heredity and variation in organisms.
• Genes are segments of DNA that contain the instructions for building and maintaining organisms.
• Alleles are different forms of a gene.
• Homozygous and heterozygous genotypes refer to the presence of identical or different alleles for a gene.
• Phenotypes are the observable physical characteristics of an organism.
• Mendelian genetics describes patterns of inheritance for single traits.
• Chromosomes are structures containing DNA and proteins that carry genes. They are organized into pairs in diploid organisms.

Evolution

• Evolution is the process of change in the heritable characteristics of biological populations over successive generations.
• Natural selection is a key mechanism of evolution where organisms with advantageous traits are more likely to survive and reproduce.
• Adaptations are traits that enhance an organism's survival and reproduction in its environment.
• Common ancestry is a key concept in evolutionary theory, all life on Earth derives from shared ancestors.
• Speciation is the process by which new species arise over time from existing species.

Classification

• Organisms are classified into hierarchical categories reflecting their evolutionary relationships.
• The major taxonomic categories in order from broadest to narrowest are domain, kingdom, phylum, class, order, family, genus, and species.
• Binomial nomenclature is the system of giving each organism a unique scientific name composed of genus and species.

Physiology

• Physiology is the study of how living organisms function.
• Organ systems work together to maintain homeostasis.
• Examples of organ systems include the digestive, respiratory, circulatory, nervous, and endocrine systems.
• Each organ system has specialized structures and functions that work together.