Unit 1 Objectives – Diversity, Chemistry of Life and Cells

Also, competencies 1, 5, and 6.

Competency 1:  Process of Science

●        Explain the process by which science seeks to understand the world around us. 

●        Design of a hypothetical experiment to test a hypothesis either given to the student or derived by the student from observations provided. 

●        Identify the role of observation in this process.

●        Define independent and dependent variables

Competency 5:  Structure and Function

●        Give examples of how structure and function are interrelated in organisms at molecular, cellular, and organismal levels. 

Competency 6:  A Systems Approach to Biology

●        Explain how the parts of the system interact to make the functioning system a whole entity. 

●        Describe the emergent properties in biological systems. 

Overview of Biology: (A)

Objective A1: List the shared characteristics of living systems

1. Cellular Structure: All living things are composed of one or more cells.

2. DNA: Stores the genetic information necessary for an organism to develop, function, and reproduce. “Blueprint for all living things.”

3. Reproduce: Organisms reproduce their own kind.

4. Grow/Develop: Organisms grow and develop as a result of genes providing specific instructions that will direct cellular growth and development.

5. Use Energy: All organisms use a source of energy for their metabolic activities. 

6. Homeostasis: The environment outside an organism can change, but the organism can adjust its internal environment/conditions.

7. Respond: All organisms respond to environmental stimuli. 

8. Evolve: Mutations allow the possibility for organisms to adapt to a changing environment, a process of gradual change in a population or species over time, life on Earth has evolved from three lineages / “domains”: bacteria, archaea, and eukarya.

Objective A2: Differentiate basic science from applied science

Basic Science: “pure” science seeks to expand knowledge regardless of the short-term application of that knowledge. It is not focused on developing a product or a service of immediate public or commercial value. The immediate goal of basic science is knowledge for knowledge’s sake, although this does not mean that, in the end, it may not result in a practical application. Sometimes referred to as “useless science.”

Applied Science: In contrast, “technology” science aims to use science to solve real-world problems, making it possible, for example, to improve a crop yield, find a cure for a particular disease, or save animals threatened by a natural disaster. In applied science, the problem is usually defined for the researcher. Sometimes referred to as “useful” science.

Objective A3: Deductive vs. Inductive Reasoning

Deductive: Top down approach, general premises→specific conclusions

Inductive: Bottom up approach, specific premises→general conclusions

Objective A4: Summarize the steps in the scientific method

• First documented by Sir Francis Bacon

The scientific method is a research method that has been developed overtime and has defined steps. Some of these steps consist of observation, formulation of a hypothesis, testing, and confirming or falsifying the hypothesis.

Step 1- Make an observation (Ex: There is something wrong with the electrical outlet)

Step 2- Ask a question

Step 3- Form a hypothesis that answers the question 

Step 4- Make a prediction based on a hypothesis 

Step 5- Do an experiment to test the hypothesis

Step 6- Analyze the results 

Either the hypothesis is supported or the hypothesis is not supported

Objective A5: Describe the levels of biological organization 

Organelles → Cells → Tissues → Organs → Organ Systems → Organisms, Populations, and Communities → Ecosystems → The Biosphere

Objective A6: List the three biological domains and briefly describe the characteristics of the organisms in each domain.

Archaea: Single-celled organisms lacking intracellular organelles (like Bacteria), usually extremophiles.

Bacteria: Prokaryotic cells with microbes that lack membrane-enclosed nuclei and organelles.

Eukarya: Contains eukaryotes, unicellular microorganisms (protists) and plants, fungi, and animals.

Chemistry of Life: (B8) 

• Isotopes: one or more forms of an element that have different numbers of neutrons

• Ions: atom or chemical group that does not contain equal numbers of protons and electrons

• Molecules: a chemical structure consisting of at least two atoms held together by one or more chemical bonds

• Compounds: substance composed of molecules consisting of atoms of at least two different elements

Organic v Inorganic: (B9)

Organic: Contain C-H covalent bonds, derived from other living organisms

Inorganic: Ionic bonds, no C-H bonds, rarely contain C but occasionally can

Chemistry of Life: (B10)

• Covalent bond: type of strong bond formed between two atoms of the same or different elements; forms when electrons are shared between atoms

• Ionic bond: chemical bond that forms between ions with opposite charges (cations and anions)

• Hydrogen bond: weak bond between slightly positively charged hydrogen atoms and slightly negatively charged atoms in other molecules

Chemistry of Life: (C11)

Objective C11: Discuss how the properties of water impact the characteristics of life

States of water: Solid, Liquid, Gas

• Hydrogen bonds form and break in liquid water as the molecules slide past each other.

• Kinetic energy causes the bonds to break because of high heat in the system (water vapor), allowing the water molecules to escape as gas

• When the temperature reduces, water molecules form crystalline structure, forming hydrogen bonds that make ice less dense due to no kinetic energy (no bonds breaking)

  • Water molecules are pushed farther apart 

  • ICE FLOATS BECAUSE OF THE DENSITY COMPARED TO LIQUID WATER (see hydrogen bonding)

  • When ice forms at the surface of a lake, it protects water organisms from freezing and dying

  • One way cells can survive freezing is if another liquid (ex: glycerol) replaces the water in the cell.

Water Heat Capacity:

• Water has the highest heat capacity of any liquid

• Heat capacity = the amount of heat that one gram of a substance must absorb or lose to change the degree by one (Celcius)

  • Amount for water - calorie

  • Takes water a long time to heat and cool

  • Water's heat capacity is 5x more than sand

• Warm-blooded animals use water to disperse heat in their bodies evenly

  • Transport heat from warm to cool places

    • Maintain even body temp

Water Heat Vaporization:

• How much energy it takes to transform a unit of liquid water into a u/nit of gas

• Turns at 100 degrees Celsius, 212 degrees Fahrenheit

• The evaporation of sweat, which is 90 percent water, allows the organism to cool so that it can maintain homeostasis of body temperature

  • An animal will sweat, burn the water off their body via their skin, and transfer the heat/energy used to evaporate the water into the gaseous state of water, therefore cooling them

Properties of water:

• Polarity

  • Polar

  • Hydrogen positivity (+1 times 2) and oxygen’s negativity (-2 times 1)

• Acidity/Basicness

  • Completely neutral 

    • Makes it the UNIVERSAL SOLVENT

  • Dissociates into H+ (pure acid) and OH- (pure base)

  • Acid: substance increasing hydrogen ions concentration in solutions (usually because one of the hydrogen atoms dissociate)

  • Base: OH- concentration within a solution or OH- in a molecule

• Hydrogen bonding

  • Intermolecular force

    • dipole-dipole

  • Hydrogens in water will attract highly electronegative atoms (F, O, Cl)

  • Cause for the high density of water 

  • Cause for the “stickiness of water”

• Hydrophilic vs Hydrophobic: 

  • Hydrophilic is when polar substances interact readily or dissolve in water (water loving) + in membranes the ligands are on the cell membrane. 

  • Hydrophobic are non polar compounds (afraid of water) + the receptors can be inside the cell. 

• Cohesive and Adhesive:

  • Cohesion: water molecules are attracted to each other because of hydrogen bonding which keeps the molecules in a liquid-gas interface. 

  • Surface tension: Occurs because of cohesion. How a substance will withstand rupturing when placed under tension or stress. Allows for water molecules to ‘float’ to the top. 

  • Adhesion: attraction between water and other molecules. 

• Solvent Properties: 

  • Solvent: Substance capable of dissolving other polar molecules and ionic compounds.

  • Sphere of Hydration: charges of molecules allowing for forming of hydrogen bonds with water (hydration shells). 

  • Dissociation: Separation of atoms from molecules resulting in formation of ions. 

Objective C12: Identify the building blocks of the macromolecules and their role in living organisms  

Macromolecules role in living organisms

Carbohydrates: The body's primary source of energy and the brain's preferred energy source.

Lipids: Help control what goes in and out of your cells.

Proteins: Structural support, biochemical catalysts, hormones, enzymes, building blocks, and initiators of cellular death.

Nucleic acids: Storage and expression of genomic information.

D(13) Cell: Discuss the cell theory and list its provisions

Three Main Ideas of Cell Theory

-All living things are composed of one or more cells.

-The cell is the most basic unit of life.

-New cells are not spontaneous generated; they are created from existing cells. 

Cell (D14)

Differentiate between prokaryotic and eukaryotic cells:

• Prokaryotic Cell: A simple, most single-celled (unicellular) organism that lacks a nucleus, or any other membrane-bound organelle. Most prokaryotes have a cell wall for an extra layer of protection, and some have a flagella or pili for locomotion. Prokaryotes are 10 to 100 times smaller than eukaryotes.

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• Eukaryotic Cell: Cells that have a membrane-bound nucleus and numerous membrane-bound organelles (endoplasmic reticulum, Golgi apparatus, chloroplasts, etc). Eukaryotes are 10 to 100 times larger than prokaryotes.  

Objective E16: Describe the processes by which substances cross the plasma membrane 

Transport

Types of transport:

• Simple diffusion

• Facilitated Diffusion

• Active Transport

• Osmosis

Simple Diffusion:

• Does NOT use energy

• Small non polar molecules or gasses that are permeable and pass through without help

• High → Low concentration  

Facilitated Diffusion:

• Does NOT use energy

• Because Ions and polar molecules are impermeable to the membrane, a carrier/embedded protein lets them through

• Embedded/transport/carrier protein: membrane protein that facilitates a substance's passage across a membrane by binding it

• The inside of the carrier/embedded protein is polar, allowing polar molecules through

• High → Low concentration

Active Transport:

• Requires energy (ATP)

• Uses protein pump & ATP to cross

• Protein pump: active transport mechanism that works against electrochemical gradients

• Low -> High concentration 

Sodium Potassium Pump

Active transport of Na+ to extracellular fluid and K+ ions to the intracellular fluid across the cell membrane re-establishes an electrochemical gradient which has potential energy.

5 steps: 

1. 3 sodium ions (Na+) bind to the pump

2. A phosphate from ATP is donated to the pump (Energy used)

3. The pump changes shape and releases Na+ outside of the cell

4. 2 potassium ions (K+) bind to the pump and a transferred into the cell

5. The phosphate group is released and the pump returns to its original shape

Osmosis:

• Water movement across the membrane

• Water diffuses across cell membrane towards a lower water amount and higher solution concentration

Osmolarity:

• Describes the solute in a water solution

• Solutes that dissociate, increase osmolarity 

• A solution with more water molecules than solute particles has low osmolarity 

Tonicity:

• Hypertonic solution= higher osmolarity (higher solute particle, lower water) in extracellular fluid vs cytoplasm 

• Hypotonic solution= lower osmolarity (lower solute partial, higher water) in extracellular fluid vs cytoplasm, plants cells prefer 

• Isotonic solution= relatively equal osmolarity in extracellular fluid and cytoplasm, animal cells prefer

Water Potential:

Objective D15: Discuss the fluid mosaic model 

The fluid mosaic model describes the plasma membrane structure as a mosaic of components—including phospholipids, cholesterol, proteins, and carbohydrates—that gives the membrane a fluid character. Plasma membranes range from 5 to 10 nm in thickness.