Cell Structure

Chapter 5

Typical Animal Cell

Cell Membrane

• What separates the cell from the outside environment

• “Fluid Mosaic” model • Functions – Transportation of materials in and out of cell– Cell recognition – Cell communication – Homeostasis

Please Label this Diagram

Fluid Mosaic Model • Cell membrane has both solid and liquid properties • Membrane made of lipid and protein • Phospholipid bilayer – fluid part

– Hydrophobic tail – Hydrophilic head

• Proteins, carbohydrates, cholesterol, etc embedded in bilayer – mosaic part

• Membrane is selectively permeable

Please Label this Diagram

Cell Wall

• Surrounds cell membrane in plant, algae, and some bacterial cells

• More protection and support • Is very porous – Allows water, oxygen, carbon dioxide, and other

substances to pass through • Made of cellulose

Nucleus • Information center of the cell– Controls metabolism, growth, differentiation,

structure and reproduction of the cell • Contains DNA (in chromosomes)• Controls actions of the

cell including cell reproduction

Parts of The Nucleus • Nuclear Envelope – 2 membranes that surround the nucleus

• Nuclear Pores – Openings in the nuclear envelope that allow molecules to move

in and out of the nucleus • Nucleolus – Small region made up of RNA and proteins – Where ribosomes are made

• Chromosomes – DNA in the nucleus – Contains genetic information

Organelles

• Small bodies with specific structures and functions within the cell

Cytoplasm

• Liquid substance between the nucleus and the cell membrane

• Contains organelles of the cell

“Mighty” Mitochondria – energy makers • Largest organelle (after nucleus) • Double membrane • Change energy stored in food into compounds that can be used by

the cell • Cristae – folds of inner membrane to increase SA for cellular

respiration • Matrix - inner part, similar to cytoplasm of cell • Contain some of their own DNA and ribosomes • Can self replicate • Other functions

– Control water/ion concentration • Cellular Respiration

– C6H1206 + 6 O2 ATP + 6 C02 + 6 H20

Chloroplasts – food makers for the world

• In plant cells only • Trap energy from sunlight and convert it into

energy that can be used by the cell• Photosynthesis (reverse cell respiration)– 6 C02 + 6 H20 + ATP C6H1206 + 6 O2

Ribosomes

• Structures where proteins are made• Made of rRNA and protein• One of the smallest organelles

• Polysomes: free floating groups of ribosomes

Endoplasmic Reticulum (ER)

• Complex network of sacs• Begins just outside the nucleus • Function: transports materials through the inside of

the cell • 2 types – Smooth ER: no ribosomes on the walls

• Lipid (hormone and steroid) synthesis• Detoxifies drugs and chemicals in the cell

– Rough ER: ribosomes on walls• Protein synthesis

Golgi Body (Apparatus)

• Proteins are sent to Golgi (from RER) for more modifications

• Proteins then used in other parts of cell or transported out of cell

• Golgi functions – Modifier – Collector – Packager – Distributer

Lysosomes – “clean up crew” • Contain chemicals and enzymes • Formed by Golgi • Not found in plants • Functions

– Cellular digestion – Auto-digestion/disposal of cell components– Breakdown of whole cells – Destroy bacteria

• Endocyctosis – cells that “engulf” other material – Process that allows larger items

to enter the cell

Vacuoles – “storage tanks”

• Saclike structures formed from other membranes within the cell

• Store/transport water, salts, proteins, carbs • Plants usually have a single large vacuole • Vesicles are small vacuoles

Cytoskeleton

• Made of filaments and fibers – Microtubules – support for

cell shape, form centrioles (used in cell division)

– Cilia/flagella – made of multiple microtubules • Used for cell movement

– Microfilaments – long fibers for movement and support

Centrioles

• Near the nucleus • 2 cylinder shapes • Are part of cell division

Prokaryotic vs Eukaryotic

Prokaryotes• Single celled organisms • Lack nucleus• Lack membrane bound

organelles

Eukaryotes • Multi- celled organisms • Have a nucleus • Have membrane bound

organelles