Biology Chapter on Cell Structure and Functions

Cell Structure and Function

• Prokaryotic cells lack a nucleus and membrane-bound organelles, while eukaryotic cells have them.
• Cellular organelles have specific functions: nucleus (genetic material), mitochondria (ATP production), ribosomes (protein synthesis), ER (protein and lipid synthesis), Golgi apparatus (protein modification).

Cell Membrane and Transport

• Cell membranes are phospholipid bilayers with embedded proteins.
• Passive transport includes diffusion, osmosis, and facilitated diffusion.
• Active transport requires ATP and includes endocytosis and exocytosis.

Cellular Respiration

• Glycolysis breaks down glucose into pyruvate.
• The Krebs cycle produces electron carriers and ATP.
• The electron transport chain uses oxygen to produce ATP.
• Aerobic respiration uses oxygen; anaerobic respiration (fermentation) does not.

Photosynthesis

• Light-dependent reactions in thylakoids produce ATP and NADPH.
• The Calvin cycle in the stroma converts CO2 into glucose.

Enzymes

• Enzymes are biological catalysts that lower activation energy for reactions.
• Temperature, pH, and substrate concentration affect enzyme activity.

DNA Structure and Function

• DNA is a double helix with nucleotides (A, T, G, C).
• Replication is semi-conservative, each new DNA molecule containing one old and one new strand.

RNA and Protein Synthesis

• Transcription produces mRNA from DNA in the nucleus.
• Translation uses mRNA to produce proteins in the cytoplasm.

Mendelian Genetics

• Law of Segregation: alleles separate during gamete formation.
• Law of Independent Assortment: genes for different traits assort independently.
• Dominant and recessive traits; Punnett squares predict offspring genotypes.

Non-Mendelian Genetics

• Incomplete dominance results in blended traits.
• Codominance expresses both traits.
• Polygenic traits are controlled by multiple genes.

Mutations

• Mutations are changes in DNA.
• They can be beneficial, neutral, or harmful.

Biotechnology

• Biotechnology techniques include gel electrophoresis, CRISPR, and genetic engineering.
• Applications include medicine, agriculture, and forensics.

Levels of Organization

• Levels include organism, population, community, ecosystem, biome, and biosphere.
• Energy flows through food chains and webs.
• Only 10% of energy is typically transferred between trophic levels.

Biogeochemical Cycles

• Biogeochemical cycles include the water cycle (evaporation, condensation, precipitation).
• The carbon cycle balances CO2 through photosynthesis and respiration.
• The nitrogen cycle includes processes like nitrogen fixation and nitrification.

Ecosystem Dynamics

• Ecosystem dynamics involve biotic and abiotic factors.
• Succession occurs in both primary and secondary environments.

Population Ecology

• Population growth models include exponential and logistic growth.
• Factors affecting population size include birth rate, death rate, immigration, and emigration.

Human Impact

• Human activities affect ecosystems through pollution, deforestation, and climate change.
• Conservation efforts and sustainable practices are crucial.

Natural Selection

• Natural selection is a process where better-adapted organisms survive and reproduce.
• Principles include overproduction, genetic variation, struggle for existence, and differential survival.
• Evidence of evolution includes fossils, comparative anatomy, and molecular comparisons.

Analogous Structures

• Analogous structures show different structures but same function.

Vestigial Structures

• Vestigial structures are reduced or unused structures.

Mechanisms of Evolution

• Mechanisms include genetic drift, gene flow, mutations, and sexual selection.

Speciation

• Speciation occurs when new species are formed from existing ones.
• Mechanisms include geographic and reproductive isolation.

Human Evolution

• Human evolution shows common ancestors with primates.
• Evidence includes fossil evidence of bipedalism and increasing brain size.

Misconceptions of Evolution

• Evolution does not happen within an individual's lifetime.
• It is not goal-directed.