Macromolecules: Carbohydrates, Lipids, and Nucleic Acids

• When unsure, carbon is the most important element to select for life-related questions.
• Besides Carbon, Hydrogen, Nitrogen, Oxygen, Phosphorus, and Sulfur are vital to living things.

4 Macromolecules of Life

• Carbohydrates, lipids, proteins, and nucleic acids make up the four macromolecules of life.

Carbohydrates

• Carbohydrates are sugars (e.g., glucose), often appearing as hexagon-shaped ring molecules.
• Breaking down one glucose molecule yields 36 to 38 ATP molecules, which provide energy for the cell.
• Photosynthesis equation: 6CO2 + 6H2O + Light Energy → C6H12O6 + 6O2
• Cellular respiration is the reverse of photosynthesis and releases energy as ATP, done by all living things.

Lipids

• Lipids are fats with a water-loving end and a water-hating end.
• Lipids are crucial in the cell membrane, forming the phospholipid bilayer.

Nucleic Acids

• Nucleic acids (DNA and RNA) are the building blocks of living organisms, aiding in cell replication and protein synthesis.
• Nucleic acids consist of a five-carbon sugar, a phosphate group, and a nitrogen-containing base.
• DNA (deoxyribonucleic acid) stores genes in the cell nucleus in a double-helix shape.
• DNA includes a phosphate group, the sugar 2-deoxyribose, and the bases adenine, thymine, cytosine, and guanine.
• In DNA, adenine pairs with thymine (A-T), and cytosine pairs with guanine (C-G).
• RNA (ribonucleic acid) carries DNA's instructions for protein creation from the nucleus to the ribosome.
• RNA is single-stranded and comprises a phosphate group, the sugar ribose, and the bases adenine, uracil, guanine, and cytosine.
• In RNA, adenine pairs with uracil (A-U), and cytosine pairs with guanine (C-G).

Proteins

• Proteins consist of folded amino acids, used by every cell to build necessary proteins.
• Enzymes are proteins that accelerate chemical reactions in living organisms.
• Words ending in "ase" or "yme" often indicate enzymes.
• Enzymes can be deactivated by heat.
• Chemical reactions begin with reactants and end with products.

Homeostasis

• Living things maintain internal balance (e.g., temperature) to stay alive, known as homeostasis.
• Feedback loops halt conditions when they change too much.

Cells

• All living things are composed of cells.
• Animals can be multicellular or unicellular.
• Organelles form cells, which form tissues, organs, organ systems, and organisms.
• The nucleus is the cell's control center, containing DNA that codes for proteins.
• Bacterial cells lack a nucleus.
• Mitochondria store energy within the cell.
• All cells have a cell membrane that separates them from their environment.
• Plant cells have chloroplasts for photosynthesis and cell walls for structural rigidity.
• Photosynthesis equation: 6CO2 + 6H2O → C6H12O6 + 6O2

Classification

• Organisms are classified into six kingdoms: Archaebacteria, Bacteria, Protista, Fungi, Plantae, and Animalia.

Prokaryotes vs Eukaryotes

• Prokaryote cells lack a nucleus, exemplified by Archaebacteria and Eubacteria.
• Eukaryotes possess a nucleus and membrane-bound organelles, including Protista, Fungi, Plantae, and Animalia.

Cellular Transport

• Cellular transport maintains homeostasis by balancing substance movement in and out of the cell membrane.
• Passive transport moves molecules with the concentration gradient (high to low) without energy (ATP).
• Active transport moves molecules against the concentration gradient (low to high) and requires energy.

Mitosis and Meiosis

• PMAT: Prophase, Metaphase, Anaphase, Telophase are the stages of chromosome separation in mitosis.
• Mitosis supports growth, repair, and replacement.
• Meiosis produces gametes (sex cells).
• Viruses are non-living entities that invade living cells, utilizing the cell's DNA to reproduce.

Genetics

• Asexual Reproduction: one parent, a cloned copy, many offspring that develop quickly
• Sexual Reproduction: two parents, variation of parents, few offspring that develop slowly
• Heredity is the passage of traits from one generation to the next.
• Traits are coded as genes in DNA and stored on chromosomes.
• Alleles are different versions of the same genes.
• Dominant alleles are always expressed over recessive alleles.
• Genotype is the genetic makeup (e.g., Bb), while phenotype is the observable trait (e.g., brown eyes).
• Homozygous means the same alleles (GG or gg), and heterozygous means different alleles (Gg).
• Dominant alleles (GG or Gg) override recessive alleles (gg).
• Punnett squares display genotypes and phenotypes of parents and offspring.
• Humans have 46 chromosomes (23 pairs), with 23 from each parent.
• 22 pairs are autosomes, and 1 pair are sex chromosomes (X and Y).
• Dominant alleles usually win over recessive, but incomplete dominance mixes traits.
• Co-dominance shows both traits separately, polygenic traits are controlled by multiple genes.
• Sex-linked traits are controlled by the X chromosome.
• Multiple alleles mean more than two possible choices, but each person gets two (one from each parent).
• Replication copies DNA, transcription copies mRNA from DNA, and translation decodes mRNA to make proteins (Protein Synthesis).

Evolution

• Evolution is the change in organisms over generations.
• Adaptations are inherited traits beneficial to an organism’s environment.
• FAME summarizes evolutionary evidence: fossil, anatomical, molecular, and embryological.
• Natural selection is survival of the fittest organisms in any given environment.

Ecology

• Living things consume food for energy.
• Food webs illustrate energy transfer through consumption.
• Only about 10% of energy transfers from one level to the next.
• Organisms are arranged in food chains, webs, or pyramids.
• Producers use sunlight to make their own food (plants).
• Consumers eat other organisms for food.
• Herbivores eat only producers, carnivores eat only consumers, and omnivores eat both.
• Decomposers consume dead organisms.

Symbiosis

• Symbiosis is a relationship between two or more living things.
• Mutualism benefits both organisms.
• Commensalism benefits one, leaving the other unaffected.
• Parasitism benefits the parasite, harming the host.
• Competition harms both, forcing a struggle for survival.

Human Anatomy and Physiology

• Digestive system converts food into smaller molecules for cell use.
• Circulatory system transports nutrients and oxygen to cells, removing wastes.
• Respiratory system exchanges oxygen and carbon dioxide.
• Nervous system receives and sends messages via the brain, spinal cord, nerves, and neurons.