Plant Cell Biology

What type of cells are plant cells?

Eukaryotic cells (have membrane-bound organelles)

What structures make up a plant cell?

Protoplast (cytoplasm, nucleus, organelles) + cell wall

What is the main adaptation of plant cells?

Adapted for photosynthesis, structural support, and water regulation

How much of a mature plant cell is occupied by the vacuole?

Up to 90% of the cell volume

What membrane surrounds the vacuole?

Tonoplast

What is the role of the tonoplast?

Maintains acidic conditions and controls transport into the vacuole

How does turgor pressure form?

K⁺ ions accumulate → water enters by osmosis → vacuole expands → presses on cell wall

Why is turgor pressure important?

Keeps plants upright and drives cell elongation

What substances are stored in the vacuole?

Water, ions, pigments, toxins, defense chemicals

What are secondary metabolites?

Organic molecules not directly involved in growth or reproduction

What are functions of secondary metabolites?

Pigmentation, UV protection, defense against herbivores and pathogens

What is the vacuole’s role in secondary metabolites?

Stores them safely away from cytoplasm and prevents metabolic disruption

What are anthocyanins?

Pigments producing red, purple, and blue colors

Where are anthocyanins synthesized and stored?

Synthesized in cytoplasm, stored in vacuoles

What are functions of anthocyanins?

Attract pollinators, UV protection, oxidative stress protection

What are plastids?

Plant-specific organelles with a common ancestral plastid

What are the main functions of plastids?

Photosynthesis, pigmentation, storage

What are proplastids?

Undifferentiated plastids in meristematic tissue

Why are proplastids important?

They can differentiate into other plastid types

What is the function of chloroplasts?

Site of photosynthesis

What pigments do chloroplasts contain?

Chlorophyll and carotenoids

What is the main product of photosynthesis?

Glucose

What are chromoplasts specialized for?

Pigment synthesis and storage

What pigments are found in chromoplasts?

Carotenoids

What colors do chromoplasts produce?

Red, orange, and yellow

How do chromoplasts often form?

From chloroplasts

What are leucoplasts?

Non-pigmented plastids specialized for storage

Where are leucoplasts commonly found?

Roots, seeds, and underground tissues

What is an amyloplast?

A type of leucoplast

What do amyloplasts store?

Starch

Where are amyloplasts commonly found?

Roots, tubers, and seed endosperm

What stain is used to detect starch?

Iodine potassium iodide (IKI)

What is the first step of autumn leaf color change?

Chlorophyll breakdown

Why does chlorophyll break down in autumn?

Shorter days and cooler temperatures

What pigments become visible after chlorophyll loss?

Carotenoids

What causes red and purple leaf colors in autumn?

Anthocyanin production

What plastid change can occur in autumn leaves?

Chloroplasts convert to chromoplasts

What is the plant cell wall made of?

Cellulose-rich extracellular matrix

What are functions of the plant cell wall?

Maintains shape, provides support, prevents osmotic bursting

How does the cell wall work with the vacuole?

Generates and maintains turgor pressure

What is the function of the nucleus?

Controls gene expression

What is the function of mitochondria?

Aerobic respiration and ATP production

What is the function of rough ER?

Protein synthesis

What is the function of smooth ER?

Lipid synthesis

What is the function of the Golgi apparatus?

Modifies and packages proteins for transport

What are plasmodesmata?

Cytoplasmic channels connecting adjacent plant cells

What do plasmodesmata allow?

Direct transport of ions, sugars, and signaling molecules