LEC 3: THE PLANT CELL Flashcards
True or False: Plants can produce gametes by mitosis, unlike animals like us
True
Gameotphytes are … and Sporophytes are … (diploid/haploid)
Haploid, diploid
Where is plant DNA stored?
The nucleus, the mitochondria and the plastids
What are the three distinctive features of plant cells (that animal cells do not have)
- Plastids
- Vacuoles
- Cell wall
What is an example of maternal inheritance in plant cells?
Chloroplasts/plastids in general are passed down by the egg cell. The genes encoded by the plastids are a part of maternal inheritance.
Which parent passes down the mitochondrial genome?
The mother/the female
What organelles fall under the umbrella term ‘plastid’
Chloroplasts, chromoplasts ans leucoplasts
What does a semi-autonomous plastid mean?
Plastids can synthesize some of their own proteins using their own genome.
True or False: All the proteins encoded by the nucleic genome can be translated by the plastid genome?
False, only some proteins are synthesized by the plastid genome - all other proteins are transcribed in the nucleus
How are maternal and cytoplasmic inheritance the same?
Cytoplasmic inheritance refers to the genome outside of the nucleus. Maternal inheritance refers to the genome present in plastids, which are outside the nucleus. Hence maternal and cytoplasmic inheritance can be dubbed as the same.
How many membranes do chloroplasts have
2
What pigments in chloroplasts allow light to be harvested for photosynthesis? Where are they located?
Chlorophyll A and B are located in the membrane of thyalkoids (in chloroplasts)
What colorful pigments make up the majority of chromoplasts?
Carotenoids
What causes the leaves to turn color during the fall?
Degradation of chlorophyll allow carotenoid pigments to be exposed - these pigments are red and orange.
Organize the series: chloroplast, leaf, cell, chlorophyll A and B, thylakoid from largest to smallest
leaf, cell, chloroplast, thylakoid, chlorophyll A and B
What proteins allow the chloroplasts to move towards the light?
Actin connect the chloroplasts and myosin move the chloroplasts along the actin
What is cytoplasmic streaming in plants? What induces cytoplasmic streaming?
The movement of chloroplasts can be induced by pH, light, and temperature.
How are chromoplasts similar/different to chloroplasts?
They are both plastids that contain pigments, but chromoplasts do not have chlorophyll.
What are some functions of chromoplasts? (4)
- Shield the cell from UV rays and decrease UV penetration
- Attract pollinators
- Defend the plant from pathogens like bacteria and fungi
- Health benefits for humans
What is the main function of leucoplasts?
Starch storage
I am a plastid, I have large storage units for starch, I have no pigment or internal membrane. What am I?
Leucoplasts
What are the storage organelles in leucoplasts called?
Amyloplasts
Where are all plastids derived from?
Proplastid
What are etioplasts?
Etioplasts are chloroplasts that have not been exposed to light.
Can chloroplasts/etioplasts interconvert freely?
Yes, depending on the environmental conditions all plastids are free to differentiate.
What causes the change in peel color during tomato maturation?
Conversion from chloroplast to chromoplast causes chlorophyll to be degraded and carotenoids to be built up - changing the color from green to red.
What plastids are present in the early stages and late stages of tomato maturation?
Early - chloroplasts
Late - chromoplasts
What pigments are found in the cells of tomatoes during maturation?
Early = chlorophyll (A and B)
Late = lycopene carotenoid
What causes some plants and green algae to lose their ability to photosynthesize?
The plastid genome becomes obsolete, causing photosynthesizing abilities to be lost with the genome.
What are two organisms that present the loss of a plastid genome?
- Rafflesia (parasite) still has the plastid present but no longer has a plastid genome
- Polytomella (green algae) lost their use of chloroplasts and plastid genome was degraded.
What is the single membrane of a vacuole called?
Tonoplast
What feature of vacuoles creates turgor pressure in cells?
The vacuole’s ability to store several sugar solutes creates an osmotic pressure (water flowing inward) that pushes the cell wall outward. This pressure is turgor pressure.
What are the vacuoles three main functions?
- Rigidity - created by turgor pressure
- Storage - nutrients, chemicals and solutes
- Breakdown - enzymes used to breakdown molecules
How do vacuoles PASSIVELY acquire material/accumulate compounds?
- Diffusion; material permeating across a gradient
- Channels; material passing through integrated channels on the tonoplast.
How do vacuoles ACTIVELY acquire material/accumulate compounds?
- Transporters; driven by ATP or another proton gradient (moving in the opposite direction)
- Vesicle mediated movement; engulfing material through endocytosis and pinching of the membrane
What causes osmotic pressure in cells?
Ions and sugars cause water to flow inside the cell.
What causes turgor pressure
Water molecules in the vacuole that push against the cell wall, (outward) along with osmotic pressure pushing inward create turgor pressure
What type of solution is most ideal for plants?
Hypotonic solution - greater concentration of solutes inside the cell than outside.
What is the difference between HYPO and HYPER tonic solutions?
Hypertonic = solute concentration OUTSIDE the cell is greater than inside. Water will want to flow out.
Hypotonic = solute concentration INSIDE the cell is greater than outside. Water wants to flow in.
Why is a hypertonic solution not ideal for cells?
If water wants to move outside the cell, the cell wall collapses on itself and the cell shrivels up.
What is the term that describes when a cell becomes collapsed?
Plasmolyzed
How do vacuoles deter herbivores for plants?
Toxins are released from the root into a vacuole which travels to the leaf of the plant. When herbivores attack the plant the toxin is released.
What is an example of vacuoles protecting plants from herbivores?
Nicotine release in tobacco plants begins in the root of the plant. It is deposited in a vacuole which travels up the floem and into the leaf of the plant - where it remains incase a herbivore attacks.
True or false, pigments can make up most of the vacuole in some plant species?
True
The petal epidermis contains what pigment that is stored in vacuoles?
Anthocyanins
In the Japanese Morning Glory, what pigments are responsible for the coloring of petals?
anthocyanins, flavonoids and metal ions
What causes the sudden change in color of Japanese Morning Glorys when the flower opens?
The pH of the vacuole changes
What pH is the Japanese Morning Glory when the flower is blue and when the flower is purple
Purple: pH is 7, more acidic
Blue: pH is 7.7, more basic
How does pH affect the pigments in the petals of Japanese Morning Glorys
The pH affects the composition of anthocyanins, flavonoids, and metal ions
What allows the vacuole to degrade material so well during endocytosis?
A low acidic pH
What is the pH of a regular vacuole, compared to the cytoplasm?
Vacuoles usually have pH 5 while the cytoplasm has a pH 7.
What does autophagy mean?
Disposal and recycling of worn-out organelles?
Why are bulbs a good food storage outlet during dormancy?
Because bulbs are mainly made of vacuoles, which can hold a lot of material like nutrients and sugars.
How do tulips and onions remain so resilient after harsh winters?
Their bulbs have vacuoles that store proteins, fats and carbs that will be stored until the right conditions for growth are recognized.
