AP Biology Module 6

6.1 The Cell is the Fundamental Unit of Life

What are the 8 characterisitics of life?

  1. Growth and development

  2. Ability to reproduce

  3. Maintain homeostasis

  4. Responds to stimuli

  5. Taking Energy from environment/Metabolizing

  6. Having Cells

  7. Organization

  8. Ability to Evolve/Evolution

  • The cell is the simplest biological entity that can exist independently

    • Every living organism is either unicellular or multicellular

    • The invention of the microscope helped with understanding the structure of cells

    • The cell is the simplest entity we can define as living

  • The cell theory states that organisms consist of cells; cells are the basic unit of life; and cells come from preexisting cells

    • The cell theory:

      • All organisms are made up of cells

      • The cell is the fundamental unit of life

      • cells come from preexisting cells

    • Cell Theory is powerful because it unites all forms of life, and provides a way for biologists to study and understand life

  • Life is hard to explain but has a few key features

    • Ability to reproduce

    • respond to the environment

    • harness energy from the environment

    • evolve over time

6.2 All cells maintain homeostasis, store and transmit information, and transfer energy

  • The cell membrane is the boundary that separates the cell from its environment

    • There is an active and dynamic interplay between cells and their surroundings that plays out at the cell membrane

    • The internal state of a cell is quite stable while the outside of a cell is constantly changing

    • This is why the cell membrane is important because it helps the inside of the cell to remain stable and main its functions to survive and produce life

  • The cell membrane maintains homeostasis for the cell

    • Homeostasis is a critical feature of cells and of life itself, especially important for multicellular organisms

      • Can even extend to ecosystems where different elements all independently work together to maintain a stable environment

      • Homeostasis is an active process

  • An essential part of a cell is its ability to store, use, and transmit information

  • Information in a cell is stored in the form of the nucleic acid DNA

    • The arrangement of nucleotides within a strand of DNA is what stores information

    • This information stored in DNA helps with reproduction, directs the formation of proteins

      • Proteins form and do almost everything in a cell

    • To make proteins, the information in DNA is used to make RNA, the RNA is then used to make proteins

    • A ribosome is a structure that is the site of protein synthesis

    • DNA is easily copied, which allows for easy reproduction

  • The central dogma describes the usual flow of information in a cell, from DNA to RNA to protein

  • Metabolism is the set of chemical reactions in cells that build and break down macromolecules and harness energy

    • All organisms use chemical reactions to break down molecules, and in the process releasing energy that is stored in a chemical from called ATP (adenosine triphosphate)

    • Metabolism occurs in catabolism and annabolism

      • catabolism breaks down molecules into smaller units and releases energy and annabolism builds molecules from smaller units and requires an input of energy

6.3 The structure and function of cells are closely related.

  • There is a close and intimate relationship between the shape of biological structures and their function

    • Primary structure determines how a protein folds into its final shape (tertiary structure)

  • The close relationship between form and function can be seen at all levels of scale including molecules, cells, and organs

6.4 Prokaryotes eukaryotes differ in internal organization

  • Prokaryotic cells lack a nucleus and extensive internal membrane-enclosed compartments

  • Prokaryotes include bacteria and archaea

  • Prokaryotic cells are typically much smaller than eukaryotic cells

  • DNA is circular in Prokaryotes

  • No membrane bound organelles within Prokaryotes

  • The three domains of life are Bacteria, Archaea, and Eukarya

  • Prokaryotes often contain muh smaller ciriclur molecules of DNA known as plasmids

  • Prokaryotes have a cell wall

  • Plasmids can be transferred between cells through threadlike structures known as pili

    • Bacteria - One of the three domain of life, consisting of unicellular organisms that differ from archea in many aspects of their cell molecular biology

    • Archea - One of the three domains of life, consisting of unicellular organisms that differ from bacteria in many aspects of their cell and molecular biology

    • You can calculate how big the bacteria is

  • Single celled eukaryotes move by motile cilia

  • Eukaryotes evolved much later than prokaryotes in the history of life

  • Eukaryotes include animals, plants, fungi, and protists

  • Eukaryotic cells have a nucleus and other internal compartments called organelles

  • nucleus - The compartment of the cell that houses the DNA in chromosomes

  • cytoplasm - The region of the cell outside of the nucleus

  • prokaryotic - Describes a cell that does not have a nucleus; used to refer collectively to archaeons and bacteria

  • eukaryotic - Describes a cell that has a nucleus; used to refer collectively to animals, plants, fungi, and protists