Cycle 1 BMP Workshop

Question 1

What model system will be used in this course?

Answer 1

Chlamydomonas reinhardtii (AKA Chlamy)

Question 2

What makes Chlamydomonas the ideal model system?

Answer 2

• Green algae
• Photosynthetic
• Unicellular eukaryote

Question 3

How does Chlamy grow?

Answer 3

Binary fission

Question 4

State the:

Generation/doubling time for Chlamy

Answer 4

~10 hours

Question 5

What does TAP Media comprise off?

Answer 5

Macronutrients and micronutrients

Question 6

Define:

Macronutrients

Give an example

Answer 6

Nutrients required in large quantities

Phosphate (required in DNA, RNA, component of ATP)

Question 7

True or False:

Chlamy can be grown in liquid cultures and agar plate

Answer 7

True

Question 8

Define:

Micronutrients

Give an example

Answer 8

Nutrients required in lesser quantities

Iron (Important in electron transport chain)

Question 9

In a growth curve:

What does the x-axis and y-axis represent?

Answer 9

X-axis = Independent variable (time)
Y-axis = Dependent variable (# cells)

Question 10

Define and describe:

Lag phase

Answer 10

Cells do not grow much, as culture is adapting to new environment

Question 11

Define and describe:

Exponential phase

Answer 11

Exponential cell growth (steepest part of slope)

Question 12

Why do cells growth fast in the exponential phase?

Answer 12

There are nutrients available for growth

Question 13

Define and describe:

Stationary Phase

Answer 13

Cells stop dividing, due to a depletion in a nutrient

Question 14

What is the depleted nutrient called in stationary phase?

Answer 14

Limiting nutrient

Question 15

Define:

Homologous structures

Answer 15

Similar physical features in organisms that share a common ancestor

Question 16

Describe:

Analogous structures

Answer 16

Features that have similar functions but are different structurally (e.g. proteins and genes involved) because these structures do not result from shared ancestry

Question 17

Give an example of:

Homologous structures

Answer 17

Chlamy and animal flagella

Question 18

Give an example of:

Analogous structures

Answer 18

Bacteria and Chlamy flagella

Question 19

Describe:

Cilia/Flagella Structure

Answer 19

Dynein, walks towards the end causing the microtubules to bend, allowing a whip like motion
Microtubule: Protein polymer (protein chain) of tubulin

Question 20

What types of cilia are there?

Answer 20

Motile cilia
Non-Motile (Sensory Cilia)

Question 21

Describe:

Motile Cilia

Answer 21

Cilia that move, have dynein

Question 22

Describe:

Non-Motile Cilia

Answer 22

Function as sensory receptors and don’t move (no dynein), have membrane proteins that interact with stimulus

Question 23

Define:

Ciliopathies

Answer 23

Genetic mutations that affect cilia structure and/or function, causing disease

Question 24

What does it mean to have a genetically heterogeneous disease?

Answer 24

Same ciliopathy (phenotype) caused by different genetic mutations (genotype)

Question 25

In terms of ciliopathies, why is Chlamy a good model system?

Answer 25

Chlamy can be used to study human ciliopathies

Question 26

# State: The appearance of proteins in human, chlamy, and plants

Answer 26

* Human-Chlamy: 10% * Human-Chlamy-Plant: 33% * Chlamy Plant: 26% * Only Chlamy: 2000ish proteins

Question 27

# State the functions of: Human-Chlamy Proteins

Answer 27

Flagella (dynein etc.)

Question 28

# State the functions of: Chlamy-Plant

Answer 28

Photosynthesis (chloroplasts etc.)

Question 29

# State the functions of: Human-Chlamy-Plant

Answer 29

Eukaryotic Processes (nucleus, mitochondria etc.)

Question 30

# State: How Chlamy is a Model System

Answer 30

* Eyespot is similar to eye * Shares genes with humans * Eukaryotic, like humans * Has flagella homologous to human cilia * Known genome sequence (can find genetic basis of mutations) * Fast and easy to grow * Can be used for plants and humans

Question 31

# Define: Phototaxis

Answer 31

Ability of cell to move in relation to light

Question 32

What are the two types of phototaxis?

Answer 32

Positive Phototaxis: Cells move toward light Negative Phototaxis: Cells move away from light

Question 33

# True or False: The eyespot is involved in photosynthesis

Answer 33

False

Question 34

What does the eyespot do? What gives it the ability to achieve this?

Answer 34

Gives Chlamy a sense of direction (know where light is coming from ) Channelrhodopsin

Question 35

What is channelrhodopsin and how does it work?

Answer 35

Light-gated ion channel Light causes channel to open, positive ions (calcium ions) rush in

Question 36

What is the the positive ions rushing in known as?

Answer 36

Depolarization

Question 37

What does depolarization trigger?

Answer 37

Action potential

Question 38

What is the pumping out of sodium ions known as?

Answer 38

Repolarization

Question 39

Where are sodium ions pumped through?

Answer 39

Voltage-gated ion channel

Question 40

What does channelrhodopson comprise of?

Answer 40

Opsin (protein) + Retinal (pigment)

Question 41

# True or False: Opsin can interact with light

Answer 41

False, opsin is a protein and has no ability to interact with light

Question 42

Why can chlorophyll absorb light/photons?

Answer 42

Chlorophyll has a conjugated system of double bonds (alternating single and double), electrons are available for light absorption

Question 43

# Define: Absorption

Answer 43

Occurs when energy from the photon is transferred to an electron within a molecule, moving the electron into the excited state

Question 44

# State the notation for: Excited state chlorophyll

Answer 44

Chl*

Question 45

What are the two colors/wavelengths of light chlorophyll can absorb?

Answer 45

Blue Red

Question 46

Why can't chlorophyll use blue light?

Answer 46

Blue photons of light have more energy, making it too unstable and decays as heat to red energy level

Question 47

Why can't chlorophyll absorb green light?

Answer 47

Doesn't match energy gap between ground and excited state, must match in order to absorb

Question 48

# Describe: Photoisomerization

Answer 48

Trans-Retinal absorbs light and turns into Cis-Retinal, causing a change in opsin conformation

Question 49

What is rhodopsin?

Answer 49

Found in human eyes Enables rod cells to be sensitive to light

Question 50

# State the differences and similiarities: Rhodopsin and Channelrhodopsins

Answer 50

Similarities * Both involve an ion channel * Both systems absorb light Differences * Rhodopsin is not the ion channel itself - triggers further downstream reactions (G-protein coupled receptor)

Question 51

# True or False: Channelrhodopsin and rhodopsin are analogous structures

Answer 51

True, they are NOT evolutionarily related

Question 52

What are the two types of photochemistry in Chlamy?

Answer 52

Photosystem (during photosynthesis) * Using light for energy * Oxidation of chlorophyll * Electron is lost Photoreceptor (during light perception) * Using light for information * Isomerization of retinal * No electron lost, retinal shape changes

Question 53

How is the brain mapped using optogenetics?

Answer 53

* Using channelrhodopsin, the opsin gene into virus * Distributes across neurons * Activate the neuron you want by exposing to blue light * See outcomes

Question 54

The action potential is triggered when...

Answer 54

Positively charged ions move into the cell

Question 55

# True or False: Bacteria flagella have dynein

Answer 55

False, bacteria flagella move by spinning not waving and thus don't have dynein