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Cell Structure
Essential Question:
How do cells maintain homeostasis?

Focus Questions:
1
...

o When you throw a ball at the target in the yard, is it easier to hit the target, or just the wall in
general?

Cell Types


Prokaryotic
2



Eukaryotic

Characteristics of All Cells





Cell membrane: the layer that covers the cell, separates the cell from the environment, and controls what
moves in and out of the cell
Cytoplasm – area of cell inside cell membrane
Ribosomes – organelles where proteins are made
Control center with DNA

Prokaryotic Cells
3




First cell type on earth
Cell type of Bacteria and Archaea





No nucleus
Nucleoid = region of DNA concentration
Organelles not bound by membranes

Eukaryotic Cells




Has a nucleus: holds DNA
In addition to the characteristics that all cells have, Eukaryotic cells also contain organelles
...


Cell Parts



Cells – the basic unit of life
Organelles - small structures inside a cell with specific functions
...

Structure: Two layers of phospholipids, proteins

5

Cytoplasm
1
...

(organelles + cytosol)
a
...

2
...
” Regulates DNA & RNA actions
...

• Structure: Surrounded by membrane called nuclear envelope
...

Structure: Double Membrane

DNA – Deoxyribonucleic acid


Function: information on how to make proteins
...
Uses mRNA to carry a copy of the instructions from the DNA to the ribosomes
...

o “Free” Ribosome: Make proteins that remain inside the cell (can switch to bound)

o

Bound Ribosome: Make proteins that are exported from the cell (can switch to free)

8

Endoplasmic Reticulum
1
...

a
...
Smooth ER: no ribosomes
2
...

2
...

Structure: Pancake-shaped layered organelle

9

Vacuoles & Vesicles
1
...
(In plants, a Central Vacuole also helps to make the
plant rigid and stiff)
...
Structure: small membrane-bound organelle
...
Function: packets of enzymes that break down materials in a cell
...
Structure: Small membrane-bound organelles

Mitochondria
1
...
“The Powerhouse”
11

2
...


Cytoskeleton
1
...

a
...
Microtubules
2
...
Function: microtubules that help divide the cell during cell division
...
Structure: Tubules

Cilia & Flagella
1
...
Structure:
a
...
Cilia – many short fibers

Chloroplasts (Plants only)
1
...

2
...
Function: Provides support for the cell and the plant
...
Structure: Made of cellulose
Review Questions
o Why is the nucleus important?
o What does it contain?
o Why is what it contains important?

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