Light and Vision

Question 1

What is light?

Answer 1

The visible region of the electromagnetic spectrum that humans can detect with their eyes

Question 2

How can we tell that the light we can’t see exists?

Answer 2

We can feel and see the affects that the lights can have

Ex. Sunburn

Question 3

What are photons?

Answer 3

A particle of light energy

Question 4

What does the molecular structure of pigment molecules allow them to do?

Answer 4

Absorb light energy

Question 5

What is the structural similarity between pigments?

Answer 5

Have alternating single double bond structure which allows them to absorb light

Question 6

What is the pigment in our eyes that helps us see called?

Answer 6

Retinal

Question 7

What are the cells in the retina linked to? What does this allow?

Answer 7

They are linked to the optic nerve and this allows us to see

Question 8

What are photoreceptors?

Answer 8

Specialized neurons found in the retina that convert light into electrical signals

Question 9

What pigment do rods and cones have?

Answer 9

Retinal

Question 10

What are cone cells responsible for?

Answer 10

They are responsible for colour vision and they function best in bright light

Question 11

What are rod cells responsible for?

Answer 11

Perceiving the size, shape, and brightness of images and function better in dim lighting

Question 12

What is rhodopsin composed of?

Answer 12

The protein opsin and retinal

Question 13

What happens to a retinal molecule when it absorbs light?

Answer 13

A conformational change occurs, goes from cis-retinal to trans-retinal (inactive to active)

Question 14

What happens to opsin when retinal absorbs light?

Answer 14

Opsin changes shape as well

Question 15

What happens after a photon is absorbed for vision to occur?

Answer 15

1. Retinal absorbs the photon which causes it to change shape
2. Opsin then changes shape as well
3. This causes a signal to be sent to the brain which then translates that signal into vision

Question 16

Why is being colour blind more common in males?

Answer 16

It is an x related condition and because men only have one X chromosome they only need to have one copy of the defective gene while women would need two

Question 17

Is dichromatic or trichromatic vision colour blindness?

Answer 17

Dichromatic

Question 18

What proteins result in trichromatic vision?

Answer 18

1. Opsin S, short wavelength blue light
2. Opsin M, medium wavelength green light
3. Opsin L, long wavelength red light

Question 19

What cells in the body contain the colour opsin gene?

Answer 19

All of them, but only eye cells have this gene expressed

Question 20

What wavelength is dichromatic vision missing?

Answer 20

Missing long wavelength sensitive