cycle 1 bio class + class 2

What is chlamy

Eukaryote

Green algae

3 important characteristics of chlamy

Contains cell wall (like plant), eyespot, flagella (like animal)

Is chlamy a plant

NO, but it shares characteristics of plant and animal cell

Purpose of eyespot

Allows chlamy to swim toward and away from light source

Analogous to vision

Where is chlamy found

Freshwater systems in moderate temps

Chlamy division

Asexual: binary fission

Divides every 10 hrs under lab conditions

Mass doubles after division

Name the phases

Lag phase (bottom): slow growth rate

Exponential (middle): max rate of cell growth

Stationary (top): no change in cell growth (stop)

Why does the cell reach stationary phase?

Cell will stop dividing because it has run out of nutrients

AKA LIMITING NUTRIENT (can run out of any nutrient)

What is tap media

standard maintenance medium

What MACRO nutrients to focus on for tap and why

Mg: is the central atom in chlorophyll (which chlamy has)

p: crucial for atp

N (from NH4Cl): N is in amino acids which makes proteins; N is in nucleotides which makes DNA/RNA

What micronutrient to focus on for tap and why

Fe: the pigment required for photosynthesis in the photosystems

Limited iron = decreased photosynthesis

What is the likeliest explanation for humans + chlamy to have flagella when plants don’t?

Trait got lost, plants didn’t require flagella

Why do prokaryotes and eukaryotes both have flagella

Only way to move around

Side note: bacteria has flagella, but chlamy has nothing in common with it (bacteria = prokary)

Flagella is an —logous trait between bacteria and eukaryotes

Same structure + function, but evolved independently of each other

Primary purpose of cilia/flagella:

Motility, sensory, sexual reproduction

What are microtubules that are found in flagella

A protein polymer made from TUBULIN subunits

what are dynein arms

A motor protein (meaning it converts chemical energy from atp hydrolysis into mechanical energy)

How does chlamy move?

Dynein arms cause microtubule to bend

Bending action generates directional force

This allows cell motility and movement of fluids

2 types of cilia

Motile (propel) and non motile (sensory)

What are ciliopathies

Malfunctioning cilia hairs

Diseases linked to cilia mutation

Non motile cilia relay what type of info

Light, colour, smell (IT IS SENSORY!)

what is comparative proteomics

Studies changes in protein abundance between different groups

How many chlamy proteins are homologous with plants and humans

Chlamy and human = 10%

Chlamy and plants= 26%

Chlamy and human and plants = 33%

What 2 processes does chlamy use light for

Source of energy

To understand surrounding through eyespot

What is organelle? Do prokaryotic have organelles

Membrane bound

Prokary don’t have organelle : RIBOSOME IS NOT ORGANELLE

What is a basal body

A motor for the flagella

Where microtubules assemble and grow

Not in prokary cells

What is phototaxis

Movement towards (+) or away (-) from light source

Purpose: to find optimal light for photosynthesis

Why would chlamy display negative phototaxis

To avoid light damage

Prevents oxidative stress causing cellular damage

where is eyespot located

Partly in chloroplast, partly in plasma membrane

Why does this structural arrangement matter

Carotenoid granule layer in the chloroplast acts as reflective shield

Channelrhodopsin plasma membrane detects light

How do these structures work together (cell movement)

Cell is rotating in helical pattern as it moves

The rotation allows for eyespot to periodically be exposed to light, then be shaded by carotenoids layer

This causes flashing light signal

So how does light detection change flagella movement

When light hits channelrhodopsin

1. It opens up (because it is a light gated ion channel)

2. Positive Ca ions flow into cell which changes flagella beating pattern

The 2 flagella beat differently

• one is more sensitive than the other to the calcium change which causes the cell to turn

What is a carotenoid granule layer, why does it matter

Stacked array of carotenoid rich pigment granules that form a reflective shield

Purpose: it reflects and amplifies light like a mirror

It creates directional shading during rotation

What would happen without a carotenoid layer

Chlamy would only detect light intensity and not direction

(aka steering wheel would be impaired)

What is channelrhodopsin? Significance?

Light gated ion channel protein

Detects light and lets ions move across membrane

Purpose: enables phototaxis and allows cell towards mod. light and away from intense light

How does channelrhodopsin work

Light hits ops in

Protein changes shape

Pore in membrane opens

Positive ions (Ca2+) flow into cell

Electrical state of membrane changes which alters flagella beating pattern= cell turns!

Sumamry:

Carotenoid layer:

Channelrhodopsin:

Carotenoid layer= determines light direction

Channelrhodopsin= detects light and triggers movement

Explain

1. Channelrhodopsin exposed to light

2. Protein changes shape, pore in membrane opens up

3. Ca 2+ moves in, reducing polarization (inside = more +)

   outcome: membrane is depolarized, flagella beating is altered (action potential)

4. Voltage gated channel (Na+) activates an Na+ moves out

The action potential migrates along plasma membrane and once it reaches BASAL BODY, movement occurs

How does chlorophyll trap light

Chlorophyll has porphyria ring with Mg2+ at its center, this ring is a conjugated system (key to absorbing light)

1. Light absorption happens in porphyrin ring

   • where e- move around freely because of conjugated system (conjugated system= single and double bond)

2. Conjugated system allows for e- to absorb energy from RED,BLUE light

   • when e- excite, they move to higher energy state

3. Excited ex transfer their energy to other molecules in photosystems

   • this generates atp + nadph

The e- moving freely is good because otherwise energy would disperse as heat instead of being channeled towards chem reactions.

Why can’t chlorophyll absorb green light

• Blue and red light photons have right energy to excite chlorophyll e-

• Green photons have wrong energy for e- to jump to that level

Result: green light bounces off

Which photon light has more energy

Blue light has more energy

Blue light doesn’t cause plants to grow faster because higher energy state decays before it can be used

What are the 3 fates of excited red state

1. e- gets used for photosynthesis

2. e- is unstable and is lost as heat

3. Fluorescence: a little energy is lost from lower excited state, then pushes photon out (energy lost), then e- decays