BI108 Cell Structure and Function

Prokaryotic cell

small, simple, and lack a nucleus or membrane-bound organelles

• Plasma membrane and cell wall (most)

• No membrane-bound nucleus or other compartments

Cell wall

Functions in structural support and protection

• Primarily made of cellulose (polymer of monosaccharide glucose)

Eukaryotic cell

larger, complex, contain a nucleus harboring linear DNA, and possess specialized organelles

• Membrane -bound nucleus and other organelles

Extracellular matrix

• Present in animal cells

• Holds cells in tissues

• Contributes to the physical properties of cartilage, skin, etc

• Filter materials

• Orients cell movements

Cytoskeleton

• Supports and maintains cell shape

• Holds organelles in position

• Moves organelles

• Interacts with extracellular structures to hold cell in place

• Proteins

Actin filaments

help stiffen the membrane; critical in most types of cell movement

Intermediate filaments

structural support

• Made of proteins that intertwine to form fibers

Microtubules

long, hollow cylinders

• Establishing cell shape, providing structural support

Cytoplasm

the material within the cell (except the nucleus)

Nucleus

largest organelle within a cell; feature of eukaryotic cells

• Contains DNA

• Site of DNA replication

• Site of gene expression (transcription)

• Surrounded by nuclear membrane

Nucleoid

contains the bacterial chromosome

Endomembrane system

network of interconnected membranes in the cytoplasm

Nuclear envelope

surrounds nucleus; has an inner and outer membrane (double membrane system)

Smooth Endoplasmic Reticulum

does NOT have ribosomes

Chemically modifies small molecules

Rough Endoplasmic Reticulum

has ribosomes attached

Proteins enter from ribosomes

Proteins are modified, folded, and transported

Golgi apparatus

receives proteins from the Rough ER and concentrates, packages, and sorts proteins

Vesicles

sacs that shuttle substances between various components

Ribosome

a molecular machine consisting of RNA and proteins that is the site of protein synthesis

Mitochondria

an organelle found in all eukaryotes that functions providing energy for the cell (in eukaryotes)

Cellular respiration results in ATP production

Double membrane

Chloroplasts

site of photosynthesis

Light is converted to chemical bond energy

Double membrane

Vacoule

Present in plant and protist cells

Stores waste products and toxic compounds

Provides structure for plant cells (turgor pressure)

Store color pigments in flowers and fruits, attracts pollinators (reproduction)

Chromosome

a DNA molecule (circular or linear, depending on the species) usually associated with specific proteins that bind to the DNA