Discovering the Plant Cell

Advanced Biotechnology c 5 (C)

Objectives

• The student will be able to:– Identify the parts of a plant cell– Describe the functions of each organelle– Compare plant cells to other cells

Intro to Plant Cells• Plants cells have some unique structures– In particular, chloroplasts allow the plant to

capture energy from the Sun• Eukaryotic cells– Means membrane-bound nucleus

• Some organelles are similar between other types of cells.

Types of Specialized Plant Cells• Parenchyma Cells– Synthesize and store organic products, “filler”

tissue; e.g., the soft part of the plant.• Collenchyma Cells– Extra structural support, esp. in areas of new

growth• Sclerenchyma Cells– Provide main structural support

Plant Cell Characteristics

• Plant cells generally larger than animal• Plant cells more consistent in size and shape• Unique structures:– Cell wall– Large vacuole– Plastids• chloroplasts

Plant Cell vs Animal Cell

Animal Cell• Various sizes and shapes• Smaller than plant cells• Organelles typically not

found in plant cells:– Centrioles– Lysosomes– Cilia/flagella

Plant Cell• Consistent shape and size

– Typically “cube-ish”

• Organelles typically not found in animal cells:– Cell wall– Large vacuole– Plastids

• Chloroplasts

Organelles• Cell (Plasma)

Membrane• Cell Wall• Chloroplast• Cytoplasm• Cytoskeleton• Endoplasmic

Reticulum (ER)• Golgi Complex

• Microtubules• Mitochondria• Nucleus

• Nucleolus• Nucleopore

• Peroxisomes• Plasmodesmata• Ribosomes• Vacuole

Plasma Membrane

• Plasma Membrane:– Similar to other cell type plasma membranes– Phospholipid bilayer acts as a permeability barrier.– Location for transport of molecules into the cell.

Cell Wall

Plant Cell

• Mostly composed of cellulose

Animal Cell

• No cell wall

Bacteria Cell

• Prokaryotic cells made up of murein aka peptidoglycan.

The cell wall is a rigid layer on the outside of the plasma membrane. The cell wall offers structural support, filtration, and protection.

Chloroplasts• Only found in plants• Contain chlorophyll– Green pigment that makes plants

green• Main function is photosynthesis• Chloroplasts contain their own

DNA• Chloroplasts can host transgenes –

better isolated than nuclear transformation

Cytoskeleton

• Supports cell shape and function.• Composed of proteins which can assemble or

disassemble as the needs of the cell change.• Found in cells of all domains of life.

Endoplasmic Reticulum• Two types:– Rough (RER)

• System of sacks found in cell’s cytoplasm• Rough is covered with ribosomes that give it a rough

appearance.• Functions as transport through the cell, produces proteins• Transport vesicles take proteins from RER to Golgi apparatus

– Smooth• System of tubes located in cytoplasm.• Function as transport through the cell. • Contains enzymes to assist in digestion of lipids proteins• Smooth ER buds off of rough ER.

Golgi Complex

• Also known as Golgi body or apparatus.• Flattened and layered organelle. Resembles a

stack of pancakes.• Receives the vesicles from RER and converts

proteins and lipids to various useable products• Transports out vesicles

Microtubules

• Component of the cytoskeleton

• Helps maintain structure of a cell

• Involved in cellular processes and

intracelluar transporthttp://images.nigms.nih.gov/index.cfm?event=viewDetail&imageID=3611

Mitochondria• Found in most eukaryotic cells.• The “powerhouse of the cell”.– Generate most of the cell’s adenosine

triphosphate (ATP) chemical energy– Maintains control over the cell cycle/growth.

• Mitochondria has it’s own DNA (mtDNA).

Nucleus

• Contains most of the cell’s genetic material

Cell is undergoing

mitosis

Blausen.com staff. "Blausen gallery 2014". Wikiversity Journal of Medicine. DOI:10.15347/wjm/2014.010. ISSN 20018762.

Nucleus continued• Contains chromosomes which house the DNA• Nuclear pores around the nuclear membrane

allow molecules to move across the membrane.

• Movement is needed for gene expression and chromosome maintenance

Nucleolus• Inside the nucleus is the nucleolus• Ribosomes are made inside the nucleolus

Peroxisome• Produces enzymes for the breakdown of fatty

acids• Assist in photorespiration of leaves and

germination of seeds.

Plasmodesmata

• Microscopic channels traversing cell walls of plant cells

• Transport proteins, mRNA, viral genomes from cell to cell– Viral movement example: tobacco mosaic virus

MP-30

Ribosomes

• Ribosomes are technically NOT an organelle as they are non-membrane bound.

• Free-floating and attached to rough endoplasmic reticulum.

• Site of protein synthesis.– RNA translated into protein

Vacuole• Present in all plant and fungal cells– Some protist, animal, and bacterial cells

• Enclosed compartments filled with water

• Functions:– Containing waste products– Containing water– Maintaining internal hydrostatic pressure– Support structures such as leaves and

flowers

Vacuoles

Identification Game

• http://www.sheppardsoftware.com/health/anatomy/cell/plant_cell_game.htm