Biology Chapter: Cell Division and Genetics

General Concepts

• Life's properties include order, reproduction, growth, development, energy processing, regulation, response to the environment, and evolutionary adaptation.
• Life's diversity is organized into three domains: Bacteria, Archaea, and Eukarya. Bacteria and Archaea are prokaryotic, meaning they lack a nucleus and membrane-bound organelles. Eukarya includes organisms with a nucleus and membrane-bound organelles, like plants, animals, fungi, and protists.
• Humans are classified in the domain Eukarya and the kingdom Animalia.
• Science uses an evidence-based process of inquiry to investigate the natural world. This involves observations, hypotheses, predictions, tests of hypotheses (experiments or additional observations), and analysis of data.
• A scientific theory is a well-supported explanation of a natural phenomenon based on evidence and repeated testing.

The Process of Science

• Researchers often manipulate one component of a system and observe the effects.
  • Independent variable: the factor being manipulated.
  • Dependent variable: the factor being measured to gauge the outcome.
  • Controlled experiment: compares an experimental group (with the manipulated variable) to a control group (without the manipulated variable).

Five Unifying Themes in Biology

• Life is distinguished by unity and diversity.
• Evolution is the unifying explanation for this unity and diversity.
• Darwin synthesized the theory of evolution by natural selection. Natural selection is the process where organisms with traits better suited to their environment are more likely to survive and reproduce, passing those traits to their offspring.

Notes for Chapter 2

• DNA provides the blueprint for proteins and directs cellular activities.
• Flow of information: DNA → RNA → protein
• Ecosystems involve matter cycling through producers, consumers, and decomposers. The process starts and ends in the environment.
• The study of life extends from molecular to global scales.
• All systems have emergent properties that are the result of interactions between components.
• Scientists analyze these interactions using systems biology.

Notes for Chapter 3

• Matter is composed of elements and elements are made up of atoms.
• About 25 elements are essential for human life.
• Four elements (oxygen, carbon, hydrogen, nitrogen) make up approximately 96% of the weight of most organisms.
• Atoms are composed of subatomic particles: protons (in the nucleus), neutrons (in the nucleus), and electrons (orbiting the nucleus).
• The unique number of protons defines an element's atomic number.
• Atomic mass is approximately equal to the sum of protons and neutrons.
• Isotopes are variations of an element with different numbers of neutrons.
• Radioactive isotopes can be used as tracers to monitor atoms in living organisms.
• Electrons fill electron shells around the nucleus, and interactions between electrons of different atoms result in chemical bonds.
  • Ionic bonds: result from the transfer of electrons (one atom gains an electron, one atom loses).
  • Covalent bonds: result from the sharing of electrons.
  • Nonpolar covalent bond: electrons are shared equally
  • Polar covalent bond: electrons are not shared equally (one atom is more electronegative)
  • Hydrogen bonds: relatively weak bonds between a hydrogen atom (covalently bonded to an electronegative atom like oxygen or nitrogen) and another electronegative atom.
• Water's unique properties are due to its polarity and ability to form hydrogen bonds. These properties include cohesion, adhesion, surface tension, high specific heat, evaporative cooling, versatility as a solvent, and density differences.
• The study of life extends from the microscopic scale to the global scale.

Notes for Chapter 4

• Microscopes reveal cell structures.
• Cell theory states that all organisms are composed of cells and that all cells arise from pre-existing cells.
• Cell size is related to its surface area-to-volume ratio, which is critical for efficient material exchange (the larger the area, the better).
• The plasma membrane is a phospholipid bilayer with embedded proteins that regulates transport
• Prokaryotic cells lack a nucleus and membrane-bound organelles and are generally smaller.
• Eukaryotic cells have membrane-bound organelles and are larger.
• Eukaryotic cells are grouped by function into four categories: genetic control (nucleus), manufacturing, distribution, breakdown (endomembrane system), energy processing (mitochondria, chloroplasts), and structural support, movement, and communication (cytoskeleton).

Notes for Chapter 5

• Cellular respiration is a process of breaking down sugars for energy in the presence of oxygen.
• ATP is the primary energy source for cells.
• Brown fat cells produce heat without ATP through a specialized respiration process.
• All life depends on energy, ultimately sourced from the sun.
• Photosynthesis converts carbon dioxide and water into organic molecules while releasing oxygen, a process that is the opposite of cellular respiration.

Notes for Chapter 6

• Cellular respiration occurs through a series of reactions, from glycolysis to the Krebs cycle to oxidative phosphorylation, leading to ATP production.
• NADH and FADH2 are electron carriers that transport electrons to the electron transport chain in oxidative phosphorylation, a crucial part of ATP creation.
• The process of oxidative phosphorylation creates most of the ATP in cellular respiration.

Notes for Chapter 7

• Anaerobic respiration (fermentation) occurs in the absence of oxygen
• NAD+ is regenerated during fermentation, allowing glycolysis to continue.
• Cellular respiration (in the presence of oxygen) has higher ATP yields compared to fermentation.

Notes for Chapter 8

• Cell division is essential for reproduction and growth and development in multicellular organisms.
• Prokaryotes divide through binary fission.
• Eukaryotes divide through the cell cycle, including mitosis (nuclear division) and cytokinesis (cytoplasmic division).
• Cell division is a tightly regulated process. Checkpoints within the cell cycle ensure accuracy during each stage.
• Cancer results from uncontrolled cell division. There are many factors that promote or restrict cell growth, and issues relating to their control impact on the cell cycle.

Notes for Chapter 9

• Genes are the fundamental units of heredity
• The chromosome theory of inheritance explains how traits are passed down through genes' location on chromosomes. This was pioneered by Mendel, whose research led to the discovery of important principles and patterns in inheritance, including the law of segregation and the law of independent assortment.

Notes for Chapter 10

• Genes are physically located on chromosomes.
• Linked genes tend to be inherited together because they are close together on the same chromosome
• Crossing over contributes variation and recombining genes during the formation of gametes
• In many species, sex is determined by sex chromosomes like X and Y.
• X-linked traits have different inheritance patterns than those on autosomal chromosomes.

Notes for Chapter 11

• DNA and RNA are nucleic acids composed of nucleotides.
• DNA has a double helix structure, while RNA is single-stranded.
• DNA's bases are adenine, thymine, cytosine, and guanine.
• RNA's bases are adenine, uracil, cytosine, and guanine
• DNA replication is a semiconservative process. Each new DNA molecule is composed of one original strand and one new complementary strand.
• DNA synthesis is facilitated by enzymes like DNA polymerase and ligase.
• Transcription is the synthesis of RNA under the direction of DNA. Translation is the synthesis of protein under the direction of RNA.

Notes for Chapter 13

• Evolution explains the diversity of life, and the environment has a large influence on evolutionary changes.
• Darwin's theory of evolution posits that species descend from common ancestors and adapt to their environment over time
• Natural selection is the key mechanism of evolution. In this process, individuals with traits suited to their environment are more likely to survive and reproduce, passing on those advantageous traits.
• Fossils provide evidence of past life forms and transitions between species.
• Homologies (similarities in traits due to common ancestry) provide further evidence of evolution. Analogous structures are examples of similar traits used for the same purpose, but are not due to shared ancestry.
• Evolutionary trees depict the relationships and branching sequences among species based on shared characteristics.

Notes for Chapter 14

• Microevolution is the change in gene frequencies within a population over time. It's a smaller scale of evolutionary change, while speciation refers to the formation of new species from existing ones.
• Speciation occurs when a population of a species becomes reproductively isolated from other populations of the same species. This isolation can occur by geographic separation (allopatric speciation), or by other mechanisms (sympatric speciation).
• Reproductive barriers are mechanisms that prevent interbreeding between different species or populations, maintaining their separation.

Notes for Chapter 15

• Natural selection occurs through the process of variations in heritable characteristics, and the favoring of those characteristics that increase reproductive success within an environment.
• Some examples of selection patterns include stabilizing selection (favoring intermediate phenotypes), directional selection (favoring one extreme phenotype), and disruptive selection (favoring both extreme phenotypes).
• Sexual selection is a form of natural selection that focuses on traits that increase reproductive success, such as attracting a mate or competing with rivals.
• Microevolution is concerned with change within a species, while macroevolution describes the larger picture of speciation and the broader diversity of life.
• The process of speciation can happen gradually or through fast changes. The exact mechanism of speciation is very complex and occurs alongside other evolutionary processes or constraints.