Cell Structure and Function

Cell Structure and Function

• Cells are the fundamental units of life, exhibiting diverse shapes and sizes, tailored to their functions.
• All cells share basic traits: a plasma membrane, cytoplasm, and genetic material (DNA).
• Prokaryotic cells (e.g., bacteria) lack membrane-bound organelles and a nucleus; eukaryotic cells (e.g., animal and plant cells) possess these.
• The plasma membrane regulates substance passage, maintaining internal balance (homeostasis).
• Cytoplasm, the cellular fluid, houses organelles and facilitates cellular processes.
• Nucleus, a key eukaryotic organelle, holds DNA, directing cell activities.
• Mitochondria are the cell's energy producers, generating ATP via cellular respiration.
• Ribosomes, free or bound to the endoplasmic reticulum, synthesize proteins.
• Endoplasmic reticulum (ER) is involved in protein and lipid synthesis and modification. Rough ER has ribosomes, while smooth ER lacks them.
• The Golgi apparatus modifies, sorts, and packages proteins and lipids for secretion or intracellular use.
• Lysosomes contain digestive enzymes, breaking down waste and cellular debris.
• Vacuoles store water, nutrients, and waste products, and maintain turgor pressure in plant cells.
• Cytoskeleton (microtubules, microfilaments, intermediate filaments) provides support and intracellular transport.
• Chloroplasts, unique to plant cells, perform photosynthesis, converting light energy to chemical energy.

Biological Molecules

• Four main biological molecule types: carbohydrates, lipids, proteins, and nucleic acids.
• Carbohydrates (C, H, O) are a primary energy source.
• Lipids (e.g., fats, oils, steroids) are hydrophobic molecules that store energy, form membranes, and act as signals.
• Proteins, amino acid polymers, have diverse roles: catalyzing reactions (enzymes), transporting molecules, providing structure, and coordinating cellular responses.
• Nucleic acids (DNA and RNA) store and transmit genetic information. DNA holds an organism's genetic code; RNA plays varied roles in protein synthesis.

Cellular Respiration

• Cellular respiration breaks down glucose to produce ATP, the primary cellular energy.
• Stages include glycolysis, the Krebs cycle, and the electron transport chain.
• Glycolysis, anaerobic, occurs in the cytoplasm, breaking down glucose to pyruvate.
• The Krebs cycle, in the mitochondria, further breaks down pyruvate, producing ATP, CO2, and electron carriers.
• The electron transport chain, also in the mitochondria, uses electron carriers to generate ATP from ADP.
• Cellular respiration is essential for life, converting food energy to cellular energy.

Photosynthesis

• Photosynthesis converts light energy into chemical energy (glucose) in plants and some organisms.
• Photosynthesis occurs in chloroplasts, specifically the thylakoid membranes.
• Stages include light-dependent and light-independent reactions.
• Light-dependent reactions capture light energy to produce ATP and NADPH.
• Light-independent reactions (Calvin cycle) use ATP and NADPH to convert CO2 into glucose.
• Photosynthesis is crucial for plant food production and global carbon cycling.

Genetics

• DNA carries the genetic code for all life.
• Genes are DNA segments coding for traits.
• DNA replication ensures accurate genetic duplication for cell division.
• Transcription converts DNA's information into RNA; translation converts RNA into proteins.
• Mutations are DNA sequence changes, potentially altering traits.
• Mitosis produces two identical daughter cells from a parent cell.
• Meiosis produces gametes with half the chromosomes of the parent cell.

Ecology

• Ecology studies organism-environment relationships and interactions.
• Ecologists study energy flow, nutrient cycling, and community dynamics.
• Ecosystems involve living organisms interacting with the abiotic environment (e.g., climate, soil).
• Populations are all species in a given area.
• Communities are all populations in a given area.
• Biomes are large ecosystems with specific climate and plant life.
• Biodiversity encompasses life variety at all levels (genes to ecosystems).
• Ecological succession describes species changes over time.

Evolution

• Populations of organisms change over time (evolution).
• Natural selection drives evolution by favoring advantageous traits.
• Genetic variation is crucial for evolution.
• Evidence for evolution includes the fossil record, comparative anatomy, embryology, biogeography, and molecular biology.
• Evolution is an ongoing process shaping life's diversity.

Human Biology

• Human biology studies the human body's anatomy, physiology, genetics, and diseases.
• The body's organization ranges from cells to systems.
• The skeletal system supports and protects; the muscular system enables movement.
• Digestive, respiratory, circulatory, and excretory systems maintain homeostasis and nutrition.
• The nervous system controls bodily functions via nerve impulses.
• The endocrine system regulates functions with hormones.
• The immune system defends against disease.
• Human reproduction involves gamete formation, fertilization, and development.

This quiz explores the key characteristics and components of cells, including comparisons between prokaryotic and eukaryotic cells. You will learn about essential organelles like the nucleus, mitochondria, and ribosomes, as well as the functions they serve within the cell. Test your knowledge of cellular biology and the functions that sustain life.