FINAL EXAM Flashcards
Light can be used as a source of ______ and _________.
A source of energy and information.
Energy that directly or indirectly supports sustains all organism. Information is used to gain knowledge about the physical world that surrounds the organism.
Can organisms use light both as energy and information?
Yes, organisms have evolved to exploit both.
Light is a ______ of discrete particles called ________. What is the called?
WAVE of discrete particles called PHOTONS.
The particle-wave duality.
What do the wave-like properties of light determine?
The wave-like properties reflect the type of energy making up the light. Using the wavelength, we perceive this energy in different colors based on their strength.
How does light interact with our world?
Light interacts with matter like a particle. For light, the photons interact with matter and have 3 possible fates:
1) REFLECTED OFF OBJECT
2) TRANSMITTED THROUGH OBJECT (passes through object)
3) ABSORBED BY OBJECT
Define the particle-wave duality?
The particle-wave duality states that light can act as both particles (photons) or waves.
What are Cataracts?
It is a vision deteriorating disease which changes the lens of the eye, making it more opaque. Our lenses are made of proteins, water, and absorb certain wavelengths of light. Due to Cataracts the protein in the lens gets denatured, which decreases the transmittance (spreading) of clue light.
What does denature mean?
It is the process modifying the molecular structure of a protein.
How far away is the Earth from the Sun?
150 million kilometers, this distance keeps the water in liquid state.
When a photon hits an object, what happens?
When a photon hits an object is can be absorbed, reflected, or transmitted. If it is absorbed, the photon is transferred into an electron and used for energy.
When are photons allowed to be absorbed?
A photon can only be absorbed if the accepting electron has the same energy as the photon. The energy of the electron is defined as the distance between the electron’s ground state and excited state. If the energy is not equal the photon is transmitted or reflected.
What is a pigment?
When the photon is absorbed, we call the matter that it interacts with a pigment. Pigments are able to absorb only certain types of color, and the color represents the amount of energy in the wavelengths of light. In this figure, you can see the relationship of energy, wavelength and color.
How do we see colors?
We see the color that is not absorbed. For example, plants absorb wavelengths of red and blue light. However, they do not absorb green light, which is then reflected or transmitted into our eyes.
How does a pigment absorb light?
Chemically speaking, they often have alternating double and single bonds. These are called conjugated double bonds.It results in delocalization of electrons. Therefore, they are not closely associated with any atoms and thus are more available to interact with a photon of light. When a photon interacts with these, their chemical nature can be altered. The photon is essentially absorbed, and no longer exists.
What is the central dogma?
The central dogma of molecular biology describes the two-step process, transcription and translation, by which the information in genes flows into proteins: DNA → RNA → protein. Transcription is the synthesis of an RNA copy of a segment of DNA. RNA is synthesized by the enzyme RNA polymerase.
A molecule with _______ bonds are insoluble in water.
Non-Polar
What is a hydrophilic molecule?
A hydrophilic molecule or portion of a molecule is one whose interactions with water and other polar substances are more thermodynamic ally favorable than their interactions with oil or other hydrophobic solvents.
What are the major characteristics of life?
Major Characteristics of Life o Basic Building Blocks Carbohydrates Lipids Proteins Nucleic Acids
o Information System
DNA and genetic information.
Information flows through central dogma.
o Energy Use and Metabolism
All cells need a source of carbon and a source of energy.
All cells use energy and carbon to build macromolecules and carry out the processes of life.
All cells use ATP as the main energy carrier
Absorption Spectrum
A spectrum of EM radiation transmitted through a substance that tells you how much of each type of radiation is absorbed by the substance
Photoreceptor
Specialized cells on the back of the retina that absorb light and process it into neural impulses for interpretation in the brain.
Two Major Functions of Light in Living Systems
o Vision
In animals, light is used primarily for vision. Light allows us to see the world around us which can help us identify different aspects of our surrounding environment such as food or shelter or predators.
o Energy
Plants and some bacteria have the ability to carry out photosynthesis. They use light energy to drive a reaction that makes glucose. They use light as an energy source to make food.
What are opsins?
o Opsins are a group of proteins found in the eye that are made sensitive to light via the pigment retinal. When an opsin protein binds to retinal, it forms a protein complex called rhodopsin. o Different opsins bind to different conformations of retinal which allows us to see a variety of different colours. o Retinal consists of a conjugated system that allows delocalized electrons to bounce around. When retinal absorbs light, the delocalized electrons get “excited” momentarily. This causes a conformational change in the retinal which starts a chain reaction that actives the rhodopsin complex and turns the light energy into neural impulses.
Cell Theory
All organisms are made of cells. (Unity) (Pattern)
Cells are the basic unit of life. (Unity)
All cells come from other cells. (Unity) (Mechanism)
Evolution
All organisms come from other organisms and all organisms have descended from a common ancestor. (Unity) Characteristics of a population change over time. (Diversity) (Pattern) Evolution requires genetic variation. (Diversity) Individuals with certain heritable traits produce more offspring and these traits get passed on more which causes evolution. (Mechanism)
