Cycle 1 BMP Workshop Flashcards
What model system will be used in this course?
Chlamydomonas reinhardtii (AKA Chlamy)
What makes Chlamydomonas the ideal model system?
- Green algae
- Photosynthetic
- Unicellular eukaryote
How does Chlamy grow?
Binary fission
State the:
Generation/doubling time for Chlamy
~10 hours
What does TAP Media comprise off?
Macronutrients and micronutrients
Define:
Macronutrients
Give an example
Nutrients required in large quantities
Phosphate (required in DNA, RNA, component of ATP)
True or False:
Chlamy can be grown in liquid cultures and agar plate
True
Define:
Micronutrients
Give an example
Nutrients required in lesser quantities
Iron (Important in electron transport chain)
In a growth curve:
What does the x-axis and y-axis represent?
X-axis = Independent variable (time)
Y-axis = Dependent variable (# cells)
Define and describe:
Lag phase
Cells do not grow much, as culture is adapting to new environment
Define and describe:
Exponential phase
Exponential cell growth (steepest part of slope)
Why do cells growth fast in the exponential phase?
There are nutrients available for growth
Define and describe:
Stationary Phase
Cells stop dividing, due to a depletion in a nutrient
What is the depleted nutrient called in stationary phase?
Limiting nutrient
Define:
Homologous structures
Similar physical features in organisms that share a common ancestor
Describe:
Analogous structures
Features that have similar functions but are different structurally (e.g. proteins and genes involved) because these structures do not result from shared ancestry
Give an example of:
Homologous structures
Chlamy and animal flagella
Give an example of:
Analogous structures
Bacteria and Chlamy flagella
Describe:
Cilia/Flagella Structure
Dynein, walks towards the end causing the microtubules to bend, allowing a whip like motion
Microtubule: Protein polymer (protein chain) of tubulin
What types of cilia are there?
Motile cilia
Non-Motile (Sensory Cilia)
Describe:
Motile Cilia
Cilia that move, have dynein
Describe:
Non-Motile Cilia
Function as sensory receptors and don’t move (no dynein), have membrane proteins that interact with stimulus
Define:
Ciliopathies
Genetic mutations that affect cilia structure and/or function, causing disease
What does it mean to have a genetically heterogeneous disease?
Same ciliopathy (phenotype) caused by different genetic mutations (genotype)
In terms of ciliopathies, why is Chlamy a good model system?
Chlamy can be used to study human ciliopathies
State:
The appearance of proteins in human, chlamy, and plants
- Human-Chlamy: 10%
- Human-Chlamy-Plant: 33%
- Chlamy Plant: 26%
- Only Chlamy: 2000ish proteins
State the functions of:
Human-Chlamy Proteins
Flagella (dynein etc.)
State the functions of:
Chlamy-Plant
Photosynthesis (chloroplasts etc.)
State the functions of:
Human-Chlamy-Plant
Eukaryotic Processes (nucleus, mitochondria etc.)
State:
How Chlamy is a Model System
- 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
Define:
Phototaxis
Ability of cell to move in relation to light
What are the two types of phototaxis?
Positive Phototaxis: Cells move toward light
Negative Phototaxis: Cells move away from light
True or False:
The eyespot is involved in photosynthesis
False
What does the eyespot do? What gives it the ability to achieve this?
Gives Chlamy a sense of direction (know where light is coming from )
Channelrhodopsin
What is channelrhodopsin and how does it work?
Light-gated ion channel
Light causes channel to open, positive ions (calcium ions) rush in
What is the the positive ions rushing in known as?
Depolarization
What does depolarization trigger?
Action potential
What is the pumping out of sodium ions known as?
Repolarization
Where are sodium ions pumped through?
Voltage-gated ion channel
What does channelrhodopson comprise of?
Opsin (protein) + Retinal (pigment)
True or False:
Opsin can interact with light
False, opsin is a protein and has no ability to interact with light
Why can chlorophyll absorb light/photons?
Chlorophyll has a conjugated system of double bonds (alternating single and double), electrons are available for light absorption
Define:
Absorption
Occurs when energy from the photon is transferred to an electron within a molecule, moving the electron into the excited state
State the notation for:
Excited state chlorophyll
Chl*
What are the two colors/wavelengths of light chlorophyll can absorb?
Blue
Red
Why can’t chlorophyll use blue light?
Blue photons of light have more energy, making it too unstable and decays as heat to red energy level
Why can’t chlorophyll absorb green light?
Doesn’t match energy gap between ground and excited state, must match in order to absorb
Describe:
Photoisomerization
Trans-Retinal absorbs light and turns into Cis-Retinal, causing a change in opsin conformation
What is rhodopsin?
Found in human eyes
Enables rod cells to be sensitive to light
State the differences and similiarities:
Rhodopsin and Channelrhodopsins
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)
True or False:
Channelrhodopsin and rhodopsin are analogous structures
True, they are NOT evolutionarily related
What are the two types of photochemistry in Chlamy?
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
How is the brain mapped using optogenetics?
- Using channelrhodopsin, the opsin gene into virus
- Distributes across neurons
- Activate the neuron you want by exposing to blue light
- See outcomes
The action potential is triggered when…
Positively charged ions move into the cell
True or False:
Bacteria flagella have dynein
False, bacteria flagella move by spinning not waving and thus don’t have dynein
