Lec 3: Cell Structure

What organism cell is this?

animal cell

What structures are both in animal and plant cells?

mitochondria, nucleus, smooth and rough er (endoplasmic reticulum), and ribosomes, and golgi apparatus

What organism cell is this?

plant cell

What structures are only in the plant cells?

cell wall, plasmodesmata, vacuole, and plastids

What is the function of a mitochrondia?

generates most cellular ATP

What is the func of a nucleus?

acts as the information center

What is the func of the smooth er? rough er?

• rough ER - site of protein synthesis

• smooth ER - synthesis of carbohydrates and lipids // modifies foreign substances to make them less toxic

What is the func of ribosomes?

synthesizes all cellular protein

What is the func of the golgi apparatus?

• collects, packages, and distributes molecules

• synthesis of cell-wall components

synthesis means the process of combining simpler substances to form more complex ones

What are plastids? Name the different types.

• organelles w double membrance

• chloroplasts, chromoplasts, amyloplast and etioplast

Function of chloroplasts

performs photosynthesize in order to generate ATP and sugars

function of chromoplast

makes carotenoids

examples of chromoplasts’ functions

• gives colors (yellow, orange, and red) to flower/fruit

  • attract pollinators in order to disperse their seeds

• helps plants absorb blue light

Identify the vacuole, chromoplasts, and cytoplasm. What is inside the chromoplasts?

Function of Amyloplast

stores starch

What plastid is this? What type of cell is this?

amyloplast; potato cells

Where are potatoes native to?

Peru

Explain the context of this photo.

• indigenous Peruvians bred many potatoes into different varieties.

  • crop diversity is important bc they can survive climate change

• other scientists learn from Peruvians on how to develop genotypic differences for potato survival

What are etioplasts?

plastid in plants grown in the dark

Which plant has Etioplasts?

the left one

Explain the context of this image.

• etioplast

• basketball bumps are prolamellar bodies

Explain the context of this image.

• chloroplast

• scribbles of 2nd to least darkest horizontal lines are thylakoid

What causes the white plants that grown in the dark to turn green?

light produces a hormone called cytokinin

Explain the context of this image.

• grey and purple are the transcription factors (TF) who are proteins that bind to DNA

• func: regulate gene expression by transcribing DNA into mRNA

Explain the context of this image.

• light strikes the etioplast —> stimulates the cytokinin

• cytokinin binds to the plasma membrane and releases intermediate protein inside the cell

• intermediate proteins travel into the nucleus and become TFs that bind to the DNA

• mRNA transcribe in the nucleus and travels into the cytoplasm

• tRNA translates the mRNA into a new protein

• new protein travels in the cell to the etioplast and goes inside the prolamellar bodies

• new protein stimulate the dissociation of the prolamella bodies and formation of thylakoids

Why are etioplasts important?

• quicker method to transform into chloroplast rather than assemble chloroplast from scratch

Give an example of plastids interchange. Explain its importance.

• Ripening: fruits turn from green to red

• the hormone ethlyene stimulates the chloroplasts into becoming chromoplasts

• Why? to attract seed dispersal agents.

  • Note: the hormone mechanism is similar to TFs.

What is a vacuole and its function? Explain how its function works.

• organelle that takes up 90% of the cell volume

• funcs:

  • cell growth

    • How? turgor pressure = vacuole fills with H2O + presses on cell walls

  • storage

    • sugars, proteins, ions, anthocyanins

  • digests and recycles old organelles (mitochondria + plastids)

  • store secondary metabolites (are chemicals indirectly essential for plants)

What are anthocyanins? Their function?

• water soluble pigments in the vacuole

• func

  • creates red, purple and blue

  • uv protection that almost covers the entire cell

Explain the context of this image.

anthocyanin protects the bananas from uv rays

Explain the context of this photo.

• mescaline (is a substance that make the cactus hallucinogenic) in the peyote cactus

• func:

  • anti-predation

    • How? The animals who eats it gets hallucinations and cannot remember to eat or drink water. It will die.

• fact:

  • some peyote are spineless bc their mescaline is so strong that it protects the cactus enough

Why is peyote threaten in the wild? Who does it affect?

harvested for recreational or hallucinogenic use; indigenous people using the plants for sacred ceremony

Provide examples of secondary metabolites.

1) THC in cannabis

2) caffeine in coffee plant

3) nicotine in tobacco plant

4) all spices (ex: bay, ginger, and onion

Why do plants have toxic chemicals and we do not?

1) we can run from predators while plants cannot due to their rigid cell wall