33 Things Every Biology Student Should Know!

Chemistry of Life

• Carbon is the most important element for life.
• CHNOPS: Hydrogen, Nitrogen, Oxygen, Phosphorus, and Sulfur are other key elements.
• The four macromolecules of life: carbohydrates, lipids, proteins, and nucleic acids.
• Carbohydrates are sugars; glucose is an example.
• Breaking down one glucose molecule yields 36-38 ATP molecules.
• Photosynthesis makes sugar using the following equation: 6CO2 + 6H2O + Light Energy → C6H12O6 + 6O2
• Cellular respiration is the reverse of photosynthesis and releases energy as ATP.
• All living things perform cellular respiration.
• Lipids are fats with a water-loving end and a water-hating end.
• Lipids are important in the cell membrane (phospholipid bilayer).
• Nucleic acids (DNA and RNA) are building blocks of living organisms that help cells replicate and build proteins.
• Nucleic acids consist of 1) a five-carbon sugar, 2) a phosphate group, and 3) a nitrogenous base.
• DNA stores genes in the cell nucleus
• DNA has a double-helix with a phosphate group, a five-carbon sugar (2-deoxyribose), and four nitrogenous bases: adenine, thymine, cytosine, and guanine.
• Base pairing in DNA: adenine links to thymine (A-T), and cytosine links to guanine (C-G).
• RNA carries out DNA blueprints for protein creation, from the nucleus to the ribosome and is single-stranded.
• RNA comprises a phosphate group, a five-carbon sugar (ribose), and four nitrogenous bases: adenine, uracil, guanine, and cytosine.
• Base pairing in RNA: adenine links to uracil (A-U), and cytosine links to guanine (C-G).
• Proteins are made of folded amino acids, which are used to build proteins for every cell.
• Enzymes are proteins that speed up chemical reactions in living things; reactions start with reactants and end with products.
• Living things maintain balance called homeostasis that is maintained by feedback loops.

Cells

• All living things are made of cells, either multicellular or unicellular.
• Organelles make up cells, which make up tissues, which make up organs, which make up organ systems, which make up organisms.
• The nucleus is the control center of the cell because it contains DNA that codes for functions.
• Bacterial cells lack a nucleus.
• Mitochondria store energy in the cell.
• All cells have a cell membrane to separate them from environment.
• Plant cells have chloroplasts for photosynthesis and cell walls for structure; the equation is: 6CO2 + 6H2O → C6H12O6 + 6O2.
• Organisms are classified into six kingdoms: Archaebacteria, bacteria, Protista, fungi, plantae, and animalia.
• Prokaryotes = "NO nucleus" and are Archaebacteria and Eubacteria.
• Eukaryotes "carry a nucleus" and include Protista, Fungi, Plantae, and Animalia.
• Cellular transport maintains homeostasis by balancing substances moving in/out of the cell membrane.
• Passive transport moves molecules WITH the concentration gradient (high to low) and doesn't require energy (ATP).
• Active transport moves molecules AGAINST the concentration gradient (low to high) and requires energy.
• PMAT is the order of phases in cell division (mitosis): Prophase, Metaphase, Anaphase, Telophase.
• Mitosis is for growth, repair, and replacement (GRR), while meiosis makes gametes (sex cells).
• Viruses are non-living things that attack cells to reproduce.

Genetics

• Asexual Reproduction: one parent, cloned copy, many offspring quickly.
• Sexual Reproduction: two parents, variation, few offspring slowly.
• Heredity is the passage of traits from one generation to the next.
  • Traits are coded in DNA as genes and stored on chromosomes.
  • Different versions of genes are alleles.
  • Dominant alleles are always expressed over recessive alleles.
• Genotype is what the genes say (example: Bb), phenotype is what is seen (example: brown eyes).
• Homozygous is the same (GG or gg), heterozygous is different (Gg).
• Dominant (GG or Gg) always wins over recessive (gg).
• Humans have 46 chromosomes (23 pairs): 23 from the mother, 23 from the father; 22 pairs are autosomes, 1 pair are sex chromosomes (X and Y).
• Dominant alleles win over recessive BUT incomplete dominance mixes traits, co-dominance shows both traits separately.
• Polygenic traits are controlled by more than one gene.
• Sex-linked traits are controlled by the X chromosome.
• Multiple alleles mean more than two choices, but each person only gets two.
• Replication is the copying of DNA.
• Transcription is mRNA copied from DNA.
• Translation is the decoding of mRNA by tRNA to collect amino acids to make proteins.

Evolution

• Evolution is the change in organisms through generations.
  • Adaptations are inherited traits that benefit an organism's environment.
• FAME summarizes evolution evidence that can be traced to a common ancestral lineage:
  • F - fossil evidence
  • A - anatomical structures (homologous, vestigial and analogous)
  • M - molecular evidence (DNA, RNA and proteins)
  • E - embryological evidence
• Natural selection states the best-adapted organisms survive and reproduce.

Ecology

• Living things eat to get energy.
• Only a little energy (10%) flows from one level to the next.
• Organisms follow food chains, food webs, or food pyramids.
  • Producers make their own food.
  • Consumers eat other organisms.
  • Herbivores eat producers, carnivores eat consumers, and omnivores eat both.
  • Decomposers eat dead organisms.
• Symbiosis is a relationship between two or more living things.
  • Mutualism: good for both.
  • Commensalism: good for one, unaffected for the other.
  • Parasitism: good for one (parasite), bad for the other (host).
  • Competition: bad for both.

Anatomy & Physiology

• The digestive system converts food into smaller molecules for cells.
• The circulatory system transports nutrients and oxygen to cells and removes cell wastes.
• The respiratory system swaps oxygen and carbon dioxide.
• The nervous system receives and sends messages.