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Bio 204 > Light > Flashcards

Light Flashcards

1
Q

Cataracts

A

The lens in the eye becomes opaque because of protein denaturation that inhibits some wavelengths entering. Decreases the blue spectrum

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2
Q

Physical nature of light

A

Provides energy (direct or indirect) and provides information about the world around us

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3
Q

How the sun works

A

Converting hydrogen into helium, which converts matter into energy (EMR)

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4
Q

EMR

A

Energy that travels in waves at the speed of light.

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5
Q

Wavelength range of EMR

A

10^-12-10^6 (cosmic to radio waves)

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6
Q

Light

A

The portion of EMR that humans can detect with their eyes. 400-700 nm

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7
Q

Physics definition of light

A

Also includes ultraviolet and infared

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8
Q

Wave particle duality

A

Has no mass, is a wave and a photon particle. Creating a wave of photons.

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9
Q

Wavelength and energy relationship

A

Inverse

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10
Q

3 options for a photon hitting something

A
  1. Reflected
  2. Transmitted through
  3. Absorbed (the only way it can be used as energy)
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11
Q

Absorption process

A

A photon is transferred to an electron in a molecule. The electron is excited out of ground state, that state can be used for energy

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12
Q

Absorption only happens if

A

The energy of the photon exactly matches the amount needed to excite the electron

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13
Q

Pigment

A

Molecules that are good at absorbing light such as chlorophyll, retinal, and indigo

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14
Q

Why is pigment a good absorber

A

Because of the conjugated system.

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15
Q

Conjugated system

A

A region where carbon atoms covalent bonds alter single and double causing a delocalization of electrons. They are not busy so they can interact with photons

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16
Q

Colors of pigments

A

Every chemical structure has a unique energy and therefore absorbs a unique wavelength. The color is the not absorbed wavelengths

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17
Q

Ultimate energy source

A

The sun

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18
Q

Photosynthesis

A

Plants use photons to make CO2 into glucose. Light enters the biosphere through this process.

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19
Q

Not all that use light as energy are photosynthetic

A

There is not always a conversion of CO2 to glucose

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20
Q

Halobacterium

A

Archaea that contain a light driven proton pump called bacteriorhodopsin. The energy is used but not to make glucose

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21
Q

Rhodopsin

A

A common photoreceptor. Made of opsin protein that is bended with retinal pigment

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22
Q

Opsin

A

Spans the membrane many times. Retinal is in its middle

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23
Q

Photons enters the eye then…

A

Retinal pigment changes shape, alters the opsin protein, eventually leading to vison by altering intracellular concentration

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24
Q

Scale of photoreceptiors

A

125 million receptors per eye, millions of rhodopsin per receptor

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25
Q

Channel rhodopsin and bacteriorhodopsin

A

Structurally similar to rhodopsin, but evolutionarily different

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26
Q

Other photoreceptors

A

Less common, but are used to see different wavelengths of light

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27
Q

Opsin and the nose

A

Proteins very similar are used for smell. Therefore they are good at sensory perception

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28
Q

Sensing light without eyes

A

Used by plants, algae, invertebrates and some bacteria

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29
Q

C. reinhartii

A

An eyespot in the chloroplast that is 2 layers thick that focus and direct light to the photoreceptors. Doesn’t play a role in photosynthesis

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30
Q

Phototaxis

A

C. Reinhartti uses flagella to swim to or from light

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31
Q

Light absorption pathway

A

Triggers rapid response in ion concentration which triggers electrical events, which lets the cell move

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32
Q

Phytochrome

A

A photoreceptor critical for photomorphogenesis. Present in the cytosol and is red light activated. Tells the nucleus to make leaves

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33
Q

Photomorphogenesis

A

The developmental process when seedlings are exposed to sunlight

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34
Q

The eye

A

An organ animals use to sense lights. Distinguished from and eye spot via vision

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35
Q

Vision

A

Requires an eye and brain (or basic nervous system). Proves the eye and brain coevolved

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36
Q

Ocellus

A

The simplest eye. A photoreceptor lined pit

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37
Q

Photoreceptor

A

Modified nerve cell from photoreceptor molecules

38
Q

Flatworms

A

Information about the ocellus-to the cerebral ganglion for orientation. How they avoid predication

39
Q

Eye advancement

A

Produce an image of desirable objects and shapes

40
Q

Compound eye

A

Common in insects and coruscations. 100’s of tightly packed ommatidia each gather a little bit of visual information. The brain gets a mosaic image.

41
Q

What are compound eyes good at?

A

Detecting movement

42
Q

Single lens eye (camera-like eye)

A

Humans, other vertebrates. Light enters one lens, hits the retina that sends the signal to the optic nerve

43
Q

Darwin

A

Didn’t think the eye was from natural selection

44
Q

Eyes today

A

Started with oight sensitive cells 500 million years ago. They have evolved from over 1000 species

45
Q

Most eyes

A

Are fundamentally the same. Gene Pax6 is the master for eye formation. Rapid eye improvements are critical for survival

46
Q

Why do we use visible light

A

It is the most plentiful on earth, and has the right amount of energy to break the bonds

47
Q

Shorter wavelengths

A

Absorbed by the ozone layer

48
Q

Longer wavelengths

A

Absorbed by carbon dioxide and water

49
Q

What light is damaging

A

Ultra violet radiation that comes with visible light photons

50
Q

Photo-oxidative damage

A

Too much light absorption by the retina. Excited electron react with oxygen causes water to become hydrogen peroxide

51
Q

Plants and photo-oxidative damage

A

Often experience this damage. It can be repaired quickly

52
Q

Ultraviolet light

A

200-400nm. Higher and therefore more damaging energy. Longer waves reach earth’s surface

53
Q

Ozone layer

A

Protects the earth from short EMR wavelengths. O2 + ultraviolet photon— O3

54
Q

Ionizing radiation

A

Photons are energetic enough to remove electrons and form ions. DNA is very susceptible to this

55
Q

Dimer

A

When 2 neighboring bases covalently bons altering the DNA’s shape. Hinders replication and gene transcription.

56
Q

Dimer outcomes

A

It can be fixed by enzymes or lead to skin cancer

57
Q

Melanin

A

A pigment that absorbs ultraviolet light. Protects the human skin and is in squid ink

58
Q

Spectrophotometer

A

A tool to detect the wavelengths of light that are not absorbed by something. Used to make a absorption spectrum

59
Q

Absorption spectrum

A

A graph of absorbance vs wavelength

60
Q

Melanocytes

A

Skin cells where melanin is produced

61
Q

Why skin color

A

A balance of ultraviolet protection and vitamin D absorbtion

62
Q

Circadian rhythms

A

Internal clock controlled by sleep/wake schedule, body temperature, metabolism, cell division, and mating.

63
Q

Circadian rhythms set

A

Is set by the light pattern outside, but once done is good to go for a while

64
Q

How were circadian rhythms discovered

A

In 1729 someone put plants is a dark room for a while and found they reacted the same as the did in the light

65
Q

The clock gene

A

Transcription is controlled on a 24 hour cycle. Leads to circadian rhythms

66
Q

All organisms studied

A

Have a circadian rhythm therefore it must have a purpose. Lets organisms predict and act preemptively on events

67
Q

Photoperiod

A

Day length

68
Q

Organisms clocks track…

A

Seasons by tracking the photoperiod. Tells them when to flower, fur, mate, migrate

69
Q

Periperal clocks

A

Set by the suprachiasmatic nucleus (SCN). A small part in the brain.

70
Q

SCN

A

Releases melatonin from the pineal gland for sleep

71
Q

Jet lag

A

Day light and circadian rhythms are out of synch. Shows that biological clocks are not easily reset

72
Q

Jet lag symptoms

A

Lack of appetite, fatigue, insomnia, or mild depression

73
Q

Color as a signal

A

Use as a signal for mating and a sign of good health. Males are more colorful often to attract women.

74
Q

Carotenoid in animals

A

Allows for pigment to be made, and shows a healthy diet. Breaks down harmful oxygens

75
Q

Color in plants

A

Used to attract pollinators

76
Q

Pollination

A

Movement of the pollen from anthers (male) to the female stigma

77
Q

Animals and pollination

A

They are there for the food the pollen produces and pollination happens as a result

78
Q

Flower-pollinator associations

A

Coevolution of plants and animals to have the right amount of food and pollination

79
Q

Coevolution

A

A change in 1 leads to a change in the other. Shape, size, colour of a plant to attract the evolving animals

80
Q

Bee pollination

A

Blue, yellow and ultraviolet plants are targeted as bees can’t see red

81
Q

Camouflage

A

Hiding using similar appearances to the environment. Can be color, patters and behaviors.

82
Q

Camouflage example

A

Peppered moths

83
Q

Light pollution

A

Bad for nocturnal animals as their hunting advantage is gone. Turtles can’t find the ocean, and birds keep running into lights

84
Q

Life in the dark

A

Our eyes loose color then shape because rods don’t see color and are active at night.

85
Q

Nocturnal vision

A

Often have bigger eyes to get more light in. They have specially designed compound eyes

86
Q

Eye evolution

A

Animals always in the dark (underwater or underground) have lost eye function. They still have functional receptors to set circadian rhythms

87
Q

Bioluminescence

A

The process of animals making their own light.

88
Q

How does bioluminescence work

A

The opposite of photosynthesis. ATP excites an electron into an excited state. When if falls back down a photon of light is released

89
Q

Bioluminescence efficiency

A

95% compared to the 5% of a lightbulb

90
Q

Why bioluminescence

A

Attract a mate or prey. Camouflage or communicate

91
Q

Dinoflagellate

A

Bioluminescence buddies. When they are shook they release light which then makes the predators visible to their predators

92
Q

Quorum sensing

A

Communication through light. Behind the phenomenon of milk seas. Mostly occurs in the deep sea where they is no natural light.

Bio 204 (23 decks)

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