Biology 12U - Chapter 2 Parts of the cell

Cell/Plasma Membrane

• Also called the “plasma membrane”

• A double-layered membrane made of phospholipids with proteins embedded within it

• Surrounds the cell

• Semi-permeable to allow the passage of materials in and out of the cell

Cytosol and Cytoplasm

• Cytosol: Liquid portion of the cell

• Cytoplasm: All the internal portions of the cell, except the nucleus

Nucleus

• “Control centre” of the cell

• Contains DNA, the hereditary material of the cell

• RNA is transcribed here

• Consists of the nuclear envelope, chromatin and the nucleolus

Nuclear envelope/membrane

• A double membrane that surrounds the nucleus

• Contains pores that allow the passage of materials in and out of the nucleus

Chromatin

• Long, thread-like strands of DNA

• There are a set number of these strands for each species (i.e. in humans, there are 46)

Chromosomes

Condensed DNA- only present in this form during cell division

Nucleolus

• Densely packed ball of DNA, RNA and protein

• Visible in the cell only when the cell is not dividing

• Used to make ribosomes

Ribosome

• Small, spherical organelles that can be free floating in the cytosol, or found attached to the endoplasmic reticulum

• Manufacture proteins within the cell

Rough Endoplasmic Reticulum

• A network of tubes, made by one continuous membrane (an extension of the nuclear membrane)

• Rough- ribosomes attached to surface, inside folds proteins

Smooth Endoplasmic Reticulum

• A network of tubes, made by one continuous membrane (an extension of the nuclear membrane)

• Smooth- contains enzymes to produce lipids for cell

Golgi Apparatus/Body

• Composed of a stack of flattened sacs

• Made up of a series of double membranes

• Responsible for packaging proteins for storage or export out of the cell

Vesicle

• Membrane-bound sacs 

• Transport proteins

• May contain enzymes to break down molecules

• Examples: peroxisomes

Vacuole (animal cell)

Vesicles that isolate and dispose of waste and toxic materials

Vacuole (plant cell)

Large central vacuole where amino acids, sugars, ions and wastes accumulate.  Helps to keep plant firm

Lysosome

• vesicles that contain digestive enzymes

Mitochondria

• “Powerhouse” of the cell

• double-membrane structure that converts glucose into cellular energy (adenosine triphosphate)

Cytoskeleton

• Filaments that provide cell structure and helps with cell division

Microfilaments

• Structures made of the protein actin, located on the inside of cells- can change the shape of the cell (ex: contraction of muscles)

Microtubules

• Protein cylinders that aid in cellular processes (ex: Spindle fibres during mitosis)

Chloroplast (plant cell)

• Double membrane bound organelle used for photosynthesis

Cell wall (plant cell)

• Outer barrier of a plant cell, gives structure

Cilia

• Hair-like structures used to move water, mucus or for movement

Flagellum

• Whiplike tail used to move cells

Extracellular matrix

• Mixture of proteins and polysaccharides surrounding a cell, attaches to the cell membrane.  Anchors cells, functions in cell signaling.

Cell junctions

• Structures that connect cells together.  Can send and receive ions and other signals.