Cell Structure

Organelles

Recall the Characteristics of Life

All Living things share the following:CellsOrganizationEnergy useHomeostasisGrowth/DevelopmentReproduction

The Cell Theory Cells are the only characteristic that cannot be found in

non-living things. Because of their importance, much cell research has taken place and been compiled into the cell theory:

1. All living things are composed of one or more cells.

2. Cells are the basic units of structure and function in an organism.

3. Cells come only from the reproduction of existing cells.

2 Levels of Organization

Molecular and CellularMacromolecules are organized into structures

called organelles. Organelles working together make up a cell.

One cell has all it needs to carry out all life processes.

The organelles carry out all of the functions of life.

How is a single, tiny little cell able to do so much?

Each organelle in the cell performs a specific function.

Remember, all cells haveA cell membraneDNA (genetic information)cytoplasm

Only eukaryotic cells have a nucleus and other membrane-bound organelles.

Macromolecules

Four macromolecules make up all the organelles:ProteinsLipids (fats)Nucleic AcidsCarbohydrates

CELL MEMBRANE

STRUCTURE: Organized in a bilayer. Outer portion is hydrophilic and inner is hydrophobic. Mostly made of lipids (phospholipids) and proteins.

FUNCTION: the cell membrane surrounds the cytoplasm of a cell and physically separates the inside of the cell from the outside environment. Allows needed materials to pass through.

Analogy: security guard or border control

Found in: ALL cells (prokaryotic and eukaryotic)

Cell Membrane

Nucleus

Nuclear membrane

Cheek Cell

CELL WALLFunction: Gives cells

Rigidity and Strength, and offers protection and overall provides skeletal support.

Structure: Composed of cellulose, a type of carbohydrate. The structure is rigid, yet flexible, and it will bend rather than hold a shape, like when a plant wilts.

Analogy: Brick walls of a builiding

Found in: Prokaryotic and Plant cells

Cell Wall

The cytoplasm contains the organelles of a cell Structure: The cytoplasm is the region of the

cell between the membrane and the nucleus. It consists of a gelatin-like fluid which “bathes” the organelles. It is a solution with dissolved salts, minerals,

etc.Function: Region where most of the cell’s

activities are carried out.

Analogy: Jell-O with fruit pieces in it

Found in: ALL Cells

Cytoplasm

Cytoplasm

MitochondriaStructure: Mitochondria has two membranes. The outer membrane is smooth. The inner membrane is folded to allow more room for chemical reactions to occur.

Function: Mitochondria break down compounds from food to release usable energy for the cell

Analogy: Power Plant- converts energy to a usable form.

Found in: Plant and Animal Cells

Cytoplasm

Mitochondria Cell Membrane

RibosomesFunction-Ribosomes are responsible for

translating code from mRNA and making proteins.

Structure- Ribosomes are made up of proteins and RNA and consist of two parts, a large subunit and a small subunit. Some are attached to the endoplasmic reticulum; others float freely in the cytoplasm.

Found in: ALL cells Analogy: Construction workers

Ribosome

Ribosomes

•Function: Transports materials within cells (an intracellular highway)-Rough ER has a role in protein synthesis-Smooth ER synthesizes (makes) lipids, breaks down toxic substances

Analogy: factory; conveyor belts, machines, etc.

Structure: Membranous network of sac-like structures that are connected by cytoskeleton (Rough ER has ribosomes on it)

Found in: Plant and Animal Cells

Golgi Body

Analogy: shipping department, Post Office

•Structure: It is a network of flattened and stacked membrane-bound sacs found within cells

•Function: The golgi body stores, packages, and distributes the proteins and lipids made in the endoplasmic reticulum

Found in: Plant and Animal Cells

Smooth ER

Rough ER

Ribosome

Golgi Body

Structure- lysosomes are spherical organelles contained by a single-layer membrane containing digestive enzymes inside

Function- Lysosomes contain the enzymes for breakdown of worn out cell parts.

Analogy: garbage/waste disposal.

Found in: Plant and Animal Cells

Lysosomes

CytoskeletonFunctions- It maintains the cell’s

shape and helps in the movement of the organelles.

Structures- Flexible scaffold-like structure made up of microfilaments, microtubules, and proteins.

Analogy: frame of a car/house.

Found in: ALL cells

Cytoskeleton

NucleusStructure: It has a double-layered membrane. It has large pores through which materials pass back and forth.

•Function: The nucleus directs all activity in the cell, controls the growth and reproduction of the cell, and contains the blueprints of the cell in the DNA.

•Analogy: county office that stores the original building blueprints. “Brain”, stores info and sends out messages.

•Found in: Plant and Animal Cells

Nucleus

Nuclear membrane

Cilia

FUNCTION: The cilia generate water

currents

STRUCTURE: In eukaryotic cells, cilia and

flagella contain proteins and microtubules, which are composed of linear polymers of globular proteins called tubulin.

Analogy: cilia are like fans

Cilia found in: Animal Cells

Cilia

Flagella

FUNCTION: Flagella are used primarily for

movement of single cells.

STRUCTURE: In eukaryotic cells, cilia and

flagella contain proteins and microtubules, which are composed of linear polymers of globular proteins called tubulin.

Analogy: flagella are like boat rudders

Flagella found in: Animal and Prokaryotic Cells

Flagella

Animal Sperm Cell Prokaryotic Bacterial Cell

Animal and Plant Cells Share Many Structures in Common

Animal Cell Plant Cell

Plant cells and Animal cells have some key differences:

A cell wallVacuolePlastids (Chloroplasts)

VacuoleStructure: Large sac surrounded by a membrane

Function: Stores salts, minerals, nutrients, water, etc. and plays an important structural role for plants

Analogy: Warehouse Found in: Plant cells and animal cells (very tiny)

Plastids (Chloroplasts)

Structure: Surrounded by double-membrane, contains chlorophyll

Function: contain pigments, capture energy from the sun to make organic compounds (food), may store food (starch)Analogy: solar panelsFound in: Plant cells

Cell Wall

Chloroplast

Cell WallNucleus