Section 3: Parts the Cell

Definition of Cell
A cell is the smallest unit that is capable of performing life functions.

Definition of Organelle
1.
Organelle : membrane-bound structure within a cell that has a specific shape and function. a) “little organs” b) Examples: Nucleus, Mitochondria,
Chloroplast

Structure and Function of Organelles
1.
The Structure and Function of the following organelles will be discussed:
– Cell Wall – Golgi Apparatus
– Cell (Plasma) Membrane
– Nucleus
– Nuclear Envelope
– Nucleolus
– Ribosomes
– Cytoplasm
– Endoplasmic Reticulum
– Vacuoles
– Lysosomes
– Mitochondria
– Chloroplasts
– Cytoskeleton
– Centrioles
– Cilia and Flagella

Surrounding the Cell

Cell Wall – Rock Wall around Burlington
1.
Structure: rigid wall made up of cellulose (plants), proteins, carbohydrates, chitin (fungi)
2.
Function: boundary around the plant cell, outside of the cell membrane that provides structure, support, and protection
3.
Eukaryotic & Prokaryotic

Cell Membrane/Plasma membrane –
Burlington City Limits
Structure: Two layers of phospholipids and proteins
Function: Regulates materials entering and exiting the cell

Inside the Cell

Nucleus – Burlington City Hall
1.
Structure: Separated from cytoplasm by nuclear envelope; contains nucleolus; contains DNA
2.
Function: Controls cells activities. Regulates DNA and RNA actions
3.
Eukaryotic

Nucleus – Burlington City Hall

Nuclear Envelope – Walls &
Doors of City Hall
1.
Double layer of lipids surrounds nucleus
2.
Regulates what enters or exits the nucleus

DNA – Burlington’s Laws & City Code
1.
Structure: Made up of nucleotides, locked in the nucleus
2.
Function: information how to make proteins a) Chromatin – unorganized
DNA (normal state) b) Chromosomes – organized
DNA (present before cell division)

13

Chromosomes
1.
Inside nucleus
2.
Made of DNA
3.
Contain instructions for traits & characteristics
4.
46 total in each cell**

Nucleolus – Burlington Mayor
1.
Structure: inside the nucleus, separate from
DNA
2.
Function: Produces RNA and ribosomes, which are used to make all proteins
3.
Eukaryotic

Ribosomes – Factories, Builders
1.
Structure: not membrane-bound; consist of two subunits made of protein and RNA a) Found attached to rough
ER or floating free in cytoplasm
2.
Function: location of protein synthesis
3.
Eukaryotic & Prokaryotic

Cytoplasm – All air, water, life that are in Burlington, except City Hall
1.
Structure: gelatin-like fluid that lies inside the cell membrane except for nucleus a) A human cell system is approximately 75% water
2.
Function: All cell contents that lie between the cell membrane and nucleus
3.
Eukaryotic & Prokaryotic

Endoplasmic Reticulum –
Roads & Sidewalks
1.
Structure: a system of membranous tubules and sacs
2.
Function: site of chemical reactions involving protein synthesis. Transportation route for proteins
3.
Two types: a) Rough Endoplasmic Reticulum b) Smooth Endoplasmic Reticulum
4.
Eukaryotic

Rough Endoplasmic Reticulum
1.
Rough Endoplasmic
Reticulum (rER): make large amounts of proteins to be exported from the cell or inserted into the cell membrane a) Ribosomes attached to the surface

Rough Endoplasmic Reticulum

Smooth Endoplasmic Reticulum
1.
Smooth Endoplasmic
Reticulum (sER): involved in the synthesis of lipids and breakdown of toxic substances a) Not covered with ribosomes

Golgi Apparatus – Post Office
1.
Structure: stacked flat sacs
2.
Function: receives proteins from the rER and distributes them to other organelles or out of the cell a) receives, processes, packages, and ships proteins
3.
Eukaryotic

Golgi Apparatus – Post Office

Golgi Apparatus Function
1.
Molecules come in vesicles
2.
Vesicles fuse with Golgi membrane
3.
Molecules may be modified by Golgi
4.
Molecules pinched-off in separate vesicle
5.
Vesicle leaves Golgi apparatus
6.
Vesicles may combine with plasma membrane to secrete contents

Vacuoles & Vesicles – Grocery stores, water tanks
1.
Structure: a sac of fluid surrounded by a membrane a) Very large in plants and very small in animals
2.
Function: used for temporary storage of wastes, nutrients, and water
3.
Eukaryotic

Vacuole

Lysosomes – Recycling Center
1.
Structure: spherical organelles that contain hydrolytic enzymes a) Formed by the Golgi
2.
Function: breaks digest down: a) food particles b) invading objects c) worn out cell parts (digestion) d) Transports undigested material to cell membrane for removal
3.
Eukaryotic

Lysosomes – Recycling Center

Mitochondria – Power Plants
1.
Structure: folded membrane within an outer membrane a) The folds of the inner membrane are called cristae
2.
Function: Produces energy ATP through chemical reactions by breaking down fats and carbohydrates (glucose) a) A.K.A - cellular respiration
3.
Eukaryotic

Mitochondria – Power Plants

Mitochondria – Power Plants

Chloroplasts – Solar Panels
1.
Structure: stacked sacs
(thylakoids) that contain chlorophyll surrounded by a double membrane
2.
Function: site of photosynthesis
(converting sun and
CO2 into glucose)
3.
Eukaryotic

Photosynthesis –Restaurants
1.
Takes place in the chloroplast
2.
Makes cellular food – glucose

Cytoskeleton – Wood, cement, steel beams
1.
Structure: a network of thin, fibrous elements made up of microtubules and microfilaments
2.
Function: Provide support and structure for the cell. Anchors organelles
3.
Eukaryotic

Microfilaments and Microtubule
1.
Helps to maintain shape of the cell.
2.
Aid in cell division (mitosis and meiosis)

Centrioles –
Cummings High vs. Western High
1.
Structure: composed of microtubules arranged in a ring a) Exist in pairs
2.
Function: help divide the cell during cell division (mitosis)
3.
Eukaryotic

Centrioles
 Short tubes necessary for cell division
(reproduction)

Cilia & Flagella – Cars or bicycles
1.
Used for movement
(animal cells only)
2.
Cilia a) Many short fibers b) Used to move substances outside human cells
3.
Flagella a) 1 long fiber b) Whip-like extensions c) Found on sperm cells

Cell Parts Analogy Homework
1.
Create an analogy (besides the city analogy) for the cell and its parts
2.
Possible ideas: a) Stadium b) School c) Country d) Restaurant e) House f) Mall

Stadium Example:
1.
Cell membrane: wall of stadium, gates
2.
Cytoplasm: everything inside the stadium.
3.
Nucleus: the control room for the stadium.
4.
Etc…

Plant Cells vs. Animal Cells
1.
Animal cells are very similar to plant cells except for the following major differences: a) Animal cells do not contain chloroplasts b) Animal cells are not surrounded by cell walls c) The vacuoles in plants are much larger than those of animals

Animal Cell

Plant Cell

Comparison of Cells

Microscope Pictures of a
Plant Cell and an Animal Cell
Elodea Human Cheek Cells

Section 4: Functions of Cells

Functions of the Cell
1.
Each living cell carries out the tasks of: a) digesting food b) transforming food into energy c) getting rid of wastes d) reproducing.

Functions of the Cell - Exocytosis
1.
Materials are exported out of the cell via secretory vesicles. In this process, the Golgi complex packages macromolecules into transport vesicles that travel to and fuse with the plasma membrane.
2.
This fusion causes the vesicle to spill its contents out of the cell.
3.
Important in expulsion of waste materials out of the cell and in the secretion of cellular products such as digestive enzymes or hormones.

Exocytosis

Exocytosis

Functions of the Cell - Endocytosis
1.
P rocess by which materials move into the cell.
2.
In phagocytosis or “cellular eating,” the cell’s plasma membrane surrounds a macromolecule and buds off to form a food vacuole.
3.
Then it fuses with a lysosome whose hydrolytic enzymes digest the “food” inside.