Introduction to Life and Macromolecules Unit 1 Notes Introduction to Life and Macromolecules

Characterisitics of Life

All living things share some basic properties. Cellular Organization—Made of Cells Reproduction Metabolism (Obtain and Use Energy) Heredity Responsiveness Growth and Development Adapt to the Environment Homeostasis

All Living Things are Made Up of Cells Smallest unit capable of all life functions Unicellular Organisms Entire organism is made up of one single cell Bacteria and protists

Multicellular Organisms The organism is made up of many cells Cells have specialized functions within the organism

All Living Things Reproduce Reproduction is the process of producing new organisms of the same type Sexual Reproduction Two different parent organisms contribute genetic information Involves the combination of male and female sex cells Asexual Reproduction A single parent organism reproducing by itself

All Living Things Obtain and Use Energy Living organisms need energy to grow, develop, repair damage, and reproduce Metabolism is the sum of all chemical reactions in an organism

All Organisms Pass Along Hereditary Traits Genes carry hereditary information Genes are composed of DNA Heredity is the reason children resemble their parents Mutations change DNA code and can be passed from generation to generation

All Living Things Respond to Their Environment An example is a plant’s leaves and stems growing toward light Organisms react to stimuli: Light Temperature Odor Sound Gravity Heat Water Pressure

All Living Things Grow and Develop Growth means to get bigger in size Development involves a change in the physical form or physiological make-up of an organism

All Living Things Adapt to Their Environment Adaptation-A process that enables organisms to become better suited to their environment Desert plants have succulent waxy leaves and stems to store water and reduce water loss

All Organisms Maintain Homeostasis A stable state of conditions in the body that are necessary for life Body temperature Blood volume pH balance Water balance

Levels of Organization

CELLS The cell is the basic unit of structure and function of a living thing. Cells are specialized by size and shape for the job they do. Unicellular organisms have only one cell. The amoeba above is made of only one cell and it must perform all the jobs of the organism.

T I S S U E S Tissues are made of the same type of cells grouped together to do a specific job. Examples: These ciliated lung cells work together to push mucous and debris out of the respiratory system. The blue Man-o-war has tissues but no organs.

Organs Organs are made up of different tissues that work together to do a job. Example: a heart is an organ made of tissues such as connective, muscle, adipose, etc. A leaf is a plant organ.

Organ Systems An organ system is a group of organs working together for a specific function.

Organ Systems (Body Systems)

Organ Systems (Body Systems)

Organisms An organism is a living thing. Sum of all cells, tissues, organs and organ systems makes an organism.

Homeostasis: maintaining a stable internal environment, despite internal and external change

Stimulus: a change to the level Control center: gets the message from the receptor that the level is off, so the control center ‘designs a plan’ to fix the level Ex: Brain (hint-the control center is usually the brain unless it is a reflex) Receptor: usually part of your nervous system, senses that the level is ‘off’ Ex: your nervous system detects that your body temperature has dropped Effector: receives a message from the brain to do something to change the level. Ex: your muscles get a message from the brain to contract, which causes shivering and goosebumps because muscle contractions release heat Stimulus: a change to the level Ex: if you go outside in the cold your body temp drops Factors stay within a ‘normal’ range due to homeostasis Ex: Body temperature

This process is called a feedback loop Most feedback loops are ‘negative feedback loops’, which means that the effector produces the opposite effect of the stimulus (ex: stimulus=lower body temp, effector=shivering to warm body) Positive feedback loops cause an increase in the stimulus (ex: stimulus=a nursing baby, effector=hormones to increase milk production)

Cell Transport Cells are constantly monitoring levels inside and outside of the cell and they let molecules move through the cell membrane in response to differences to try to ‘balance’ the solutions.

Solvent + Solute = Solution Solutions A solution is a solute dissolved in a solvent. In biology, the solvent is usually water and the solute is usually sugars, salts, etc. Solvent + Solute = Solution The more solute, the stronger the solution. The less solute, the weaker the solution.

Movement of Molecules The cell membrane does not allow most molecules to pass through, so to try to reach a balance, usually WATER (the solvent) is passed through the membrane. Ask yourself: “Which solution has the most solute?” Water moves toward that solution. If water moves into a cell, it will swell and if water moves out of a cell, it will shrink.

Passive Transport Examples: diffusion and osmosis (which is the diffusion of water) Molecules naturally move through the cell membrane to try to ‘balance’ with the external environment Happens without any energy from the cell

Active Transport Requires energy from the cell Sometimes goes against the cell’s natural effort to create a balance/homeostasis (makes the strong solution stronger)

Organic Macromolecules There are four types of large molecules that are needed by all living things. They all contain Carbon, Hydrogen, and Oxygen. They are made of smaller molecules called monomers.

Rewind…. What are molecules? Why are they important? Atoms bonded together (What are atoms?-those tiny particles made of protons, neutrons, and electrons—different types of atoms are called elements) Why are they important? They are used in all chemical reactions—things like your genetic code and the energy your body uses are stored in molecules. Your cells are built of lots of molecules working together.

Back to the organic macromolecules… CARBOHYDRATES Monomer: simple sugars (called monosaccharides—ex: glucose) Function: Main energy source for cells. Also, structural molecule for plant cell wall. Source in diet: plant products

LIPIDS Monomer: fatty acids Function: stored energy and cell membranes Source in diet: fats, oils

NUCLEIC ACIDS Monomer: nucleotides Function: genetic material (DNA/RNA) Source in diet: your body doesn’t get these molecules from eating—your cells make these molecules

PROTEINS Monomer: amino acids Function: structural molecule for animals, regulates cell and body processes, fight diseases Source in diet: meats, nuts/seeds, eggs, dairy