Plan Bio section (3 lectures) Flashcards
Plant cell general features
- lots of conserved features when comparing to animal cells or fungal cells (conserved organelles, structures, metabolism+process, genes)
- Plant cells are glued together by the cell wall (no cell migration)
- Aren’t as many cell types compared to animal cells (~50 diff types of plant cells)
Individual plant cells can
de-differentiate, divide, and form a complete plant
DNA particle gun
what is it used to make+ step + blast
- Used to make transgenic plants
- After bombardment, cells that contain the transgene are selected and induced to form complete plants with each of their cells containing the transgene
- Take DNA of interest and blast it into the plant cell
Root hair cytoplasmic streaming (3)
purpose+ organelles +cytoplasm
- Theres a lot of cytoplasmic streaming inside root hair to transport materials
- Organelles within the root hair are acting on actin filaments
- These organelles are moving the cytoplasm and moving nutrients.
Organization of vesicular transport at the plant Golgi stacks
- The myosin motors bind to actin filaments and utilize ATP hydrolysis to generate the necessary force for movement. This movement is directional and can transport vesicles towards specific regions within the cell.
The plant Golgi stacks move along —- that are associated with ER
- actin filaments
- Plant Golgi stacks are mobile organelles that can travel along actin filaments.
Model for ER-to-Golgi vesicle transport in plant cells
Move throughout the cytoplasm near the plasma membrane
Plant myosin XI
The fastest myosin (takes 35 nm steps)
movement drives cytoplasmic streaming
Chloroplast move in response to light in leaf cells (3):
dim+ bright+ movement is directed by
- Dim light Chloroplasts align perpendicular to the direction of light. In the dim light, want to use as much sunlight as possible.
- Bright light Chloroplasts align parallel to the direction of light. In bright light, chloroplasts hide behind their neighbours because light is too intense
- Chloroplast movement is directed by light intensity
Chloroplast movement is triggered by blue wavelengths of light (2)
move on….
- Chloroplasts avoid the blue light, causing it to move
- Organelles move on actin filaments using myosin motors
Plant cytoskeleton
- MTs and actin filaments are conserved
- No intermediate filaments
- Motors: myosin and kinesins (no dyneins)
- Kinesins are plus and minus ended
- There are no centrioles or centrosomes. The microtubial (MTOC) organizing centers are on the surface of the plasma membrane and on the nuclear envelope
Four plant microtubule arrays: interphase cortical array (3)
found in + amount + location
- found in interphase
- found up against to the plasma membrane
- only 1 present in interphase
Four plant microtubule arrays: Per-prophase band (4)
What it is + what it does x 2+ where it forms
- a transient band of microtubules in pre-prophase that predicts the plane and position of the new cell wall
- forms right under (touches) the plasma membrane
- the preprophase band also functions in properly orienting the mitotic spindle, and contributes to efficient spindle formation during prometaphase
Four plant microtubule arrays: Mitotic spindle
involved in pulling of sister chromatids
Four plant microtubule arrays: Phragmoplast (2)
during…+ what it does
- a plant cell specific structure that forms during late cytokinesis.
- This complex assembly of microtubules, actin filaments and associated molecules acts as a framework for cell plate assembly and subsequent formation of the future cell wall separating the two daughter cells
Plant cell wall (4)
who has it+ weight%+ all plants have what/loca+many have a ….
- All plants have a cell wall
- Make up about 15-30% of dry weight of a plant cell
- All plant cells have a primary wall, synthesized just outside the plasma membrane (extracellular)
- There are many plant cells that have a secondary wall, this is made after the primary wall, and it lies internal to the primary wall (still extracellular)
secondary cell walls are composed of
lignin and cellulose
Middle lamella (2)
What it does + made of
- a cementing layer between the primary walls of adjacent cells
- composed of pectic polysaccharide
Cell turgor pressure (3)
What it is + important for+ high solute concen means
- Turgor pressure is the internal pressure (caused by water) within plant cells
- Within the cell, between the vacuole and the rest of the cell , there’s high solute concentration. Therefore water will move (osmosis) into the cell (high internal pressure)
- Important in maintaining leaf shape
4 components of a cell wall: Cellulose microfibrils (3)
what is it made of+ structure
- Long polymers of glucose
- Held together by beta(1-4) linkages
- These bundle together to form a microfibril
4 components of a cell wall: Hemicellulose (3)
Function (does it by..)+ composed of +made in+length
- Function to crosslink adjacent microfibrils. Does this by using hydrogen bonding because they are reversible and easier to break
- They are composed of glucose and another sugar (can be xylose or arabinose)
- Made in Golgi bodies
- not as long as cellulose
4 components of a cell wall: Pectins (4)
what it is + function x2 + made in
- Branched polysaccharide
- Functions to determine the porousity of the wall, more pectin= more pourous
- Also binds proteins in the wall
- Made in Golgi bodies
4 components of a cell wall: proteins (4)
important for stable+important for loose+ made in + move thru
- Important for wall stability (stablize H-bonds between hemi and CMF)
- Important for loosening the wall (loosening H-bonds between hemi and CMF)
- Proteins made in the RER
- Move through Golgi and then to plasma membrane through vesicles
Synthesis of the wall: cellulose
- Cellulose microfibrils are made in the plasma membrane by cellulose synthase (rosette)
Rosettes formation
movement determined by+ what it does
- Important for making the microfibril, take glucose from inside of the cell, to produce cellulose microfibrils on the outside
- Rosette moves through membrane, this is determined by the cortical microtubules
cells cannot grow —- but can grow —-
laterally
vertically
Cytokinesis of plant cell
phragmoplast
- phragmoplast is the complex arrangement of microtubules, microfilaments and it along with golgi derived vesicles make the cell plate
- phragmoplast job is to transport Golgi derived vesicles to newly developed cell plate
Interphase
Non dividing cell
Prophase
Chromosomes begin to condense
METAPHASE
condensed chromosomes line up at the equator
Anaphase
sister chromatids seperate
Telophase
New nuclear envelopes begin to form
MT and phragmoplast arrangement (2)
arrangement + how vesicles are moved
- Arranged so the + end of the MT are towards the center of the phragmoplast
- Uses kinesin motors to move vesicles to the + end of the MT
Plasmodesmata (3)
formed during+ structure/function+ trapped
- Form during cell division
- microscopic channels (small tubes that connect plant cells to each other, providing living bridges between cells) which traverse the cell walls of plant cells and some algal cells, enabling transport and communication between them.
- ER trapped between in the new cell wall
The standard lytic vacuole (3)
- Role in regulating pH
- Has low pH
- degrading role
Protein storage vacuoles
- store protein that can be used as food reserves for budding seeds
Functions of plant vacoules (5):
- Important for storage of ions, organic acids, sugars, proteins etc.
This is important in turgor pressure because you have high solute concentration - Digestion (similar role to lysosomes in animal cells)
Turnover of cellular components - In pH and ion homeostasis, pH is less than 5.5 within the vacuole
These have proton pumps that regulate pH of the cytoplasm - Defence
vacuole can accumulate toxic compounds (ex: phenolics and alkaloids) to release in face of pathogen - Storage
store ions, organic acids, sugars, proteins
