Cell Structure and Function

Cell Structure and Function

• Cells are the fundamental units of life.
• All living organisms are composed of cells.
• Cells exhibit a wide range of shapes and sizes, adapted to their specialized functions.
• Prokaryotic cells, such as bacteria, lack a nucleus and membrane-bound organelles.
• Eukaryotic cells, such as plant and animal cells, possess a nucleus and membrane-bound organelles.
• Key organelles include the nucleus, mitochondria, ribosomes, endoplasmic reticulum, Golgi apparatus, vacuoles, and chloroplasts (in plant cells).
• The nucleus stores genetic information (DNA).
• Mitochondria are the powerhouses of the cell, responsible for cellular respiration and energy production.
• Ribosomes synthesize proteins.
• The endoplasmic reticulum (ER) is involved in protein and lipid synthesis.
• The Golgi apparatus processes and packages proteins.
• Vacuoles store water, nutrients, and waste products.
• Chloroplasts are responsible for photosynthesis in plant cells.

Cellular 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 convert light energy into chemical energy in the form of glucose.
• Mitosis is a type of cell division that produces two genetically identical daughter cells.
• Meiosis is a type of cell division that produces four genetically diverse daughter cells, essential for sexual reproduction.
• DNA replication is the process of copying DNA before cell division.
• Transcription is the process of creating mRNA from DNA.
• Translation is the process of using mRNA information to create proteins.
• Active transport moves molecules across a membrane against their concentration gradient, requiring energy.
• Passive transport moves molecules across a membrane down their concentration gradient, without energy.

Genetics

• Genes are segments of DNA that code for specific traits.
• Alleles are different versions of a gene.
• Genotype is the genetic makeup of an organism.
• Phenotype is the physical expression of a trait.
• Dominant alleles mask the effects of recessive alleles.
• Homozygous individuals have two identical alleles for a gene.
• Heterozygous individuals have two different alleles for a gene.
• Mendelian genetics describes the inheritance of traits based on the laws of segregation and independent assortment.
• Mutations are changes in DNA sequence that can affect the expression of traits.

Ecology

• Ecology is the study of the relationships between organisms and their environment.
• Organisms interact with each other and their abiotic environment, including factors like sunlight, water, temperature, and soil.
• Levels of organization in ecology range from individual organisms to populations, communities, and ecosystems.
• Food chains and food webs represent the flow of energy and nutrients through an ecosystem.
• Producers, such as plants, create their own food through photosynthesis.
• Consumers obtain energy by consuming producers or other consumers.
• Decomposers break down dead organisms and return nutrients to the ecosystem.
• Ecosystems are dynamic and constantly changing in response to environmental pressures.
• Biomes are large geographical areas with distinct climates and plant communities.

Biological Evolution

• Evolution is the change in 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.
• Adaptation refers to inherited traits that enhance survival and reproduction in a specific environment.
• Common ancestry is a fundamental principle of evolutionary biology, suggesting that all life forms share a common ancestor.
• Evidence for evolution comes from fossil records, comparative anatomy, embryology, and molecular biology.
• Phylogenetic trees illustrate evolutionary relationships between organisms.

Classification of Organisms

• Organisms are classified into a hierarchical system based on shared characteristics.
• The system begins with Domain, followed by Kingdom, Phylum, Class, Order, Family, Genus, and Species.
• Important types of organisms include bacteria, archaea, protists, fungi, plants, and animals.
• Binomial nomenclature is the system used to name organisms using their genus and species names.

Human Anatomy and Physiology

• Human anatomy is the study of the structure of the human body.
• Human physiology is the study of the functions of the human body.
• Important organ systems include the circulatory, respiratory, digestive, nervous, endocrine, skeletal, muscular, and immune systems.
• The circulatory system transports blood and oxygen throughout the body.
• The respiratory system facilitates gas exchange between the body and the environment.
• The digestive system breaks down food for nutrient absorption.
• The nervous system coordinates body functions through nerve impulses.
• The endocrine system regulates body processes through hormones.
• The skeletal system provides support and protection.
• The muscular system enables movement.
• The immune system defends the body against pathogens.