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Biology Unit 2: Cells Cheat Sheet by

Includes cell structure, Prokaryotic and Eukaryotic cells, Animal cells and Plant cells, Cell Theory [history], specialised cells and stem cells.

The Cell Theory

1. All Organisms are composed of one or more cells.
2. The cell is the basic unit of structure and organi­sation in organisms.
3. All cells come from preexi­sting cells.


Permeable Membrane:
A membrane that lets everything through
Semipe­rmeable Membrane:
A membrane that lets some/c­ertain thing [mater­ials] through
Imperm­eable Membrane:
A membrane that does not let things [mater­ials] through


Where cellular reactions take place
Has a thick jelly-like structure
Allows protein respir­ation in the [Mitoc­hon­dria]
Where Mitosis and Meiosis occurs

Cell Wall

Porus to let things through
Rigid (100x thicker than the cell membrane)
Maintains shape and protects cells
Attaches to other cell walls to form strong structures (plants need to be strong but don't have skeletons)

Golgi Body

Golgi apparatus
Port of the cell
Where items are collected, packed and exported
Receives proteins from the Rough Endopl­asmic Reticulum [rER]
Modifies proteins by adding lipids or carbs or by changing shapes
Sends proteins to damaged cell parts for recovery

Cell Structure Of A Leaf

The lamella is the broad flat surface of a leaf. [The large surface area allows for maximum absorption of light.] The thin lamella also allows for light to get to deeper portions of the leaves.
Thin cells in the upper epidermis allow sunlight to reach the mesophyll
Palisade cells are packed with Chloro­plasts. Have large vacuoles or stores.
The spongy mesophyll have large air spaces between it's cells for gaseous exchange
Xylem vessels start a series of plant cells. At a certain point the carboh­ydrate lignin forms within the cell walls. Lignin in imperm­eable. Living contents of the cell die; The end walls between the cells break down. Continuous tubes are formed.


Group of cells with a common function.
Note: Cells (similar) to tissues to organs to organ systems to organisms


The powerhouse of the cell
Provides energy to all parts of the cell
Where cellular respir­ation takes place
[Gluco­se+­O2=­ATP­+CO2] transports to other cells


Skeleton of the cell
Some cells can move using:
Flagella: a few long whip-like structures outside the cells
Cillia: Hundreds of short hairlike structures outside the cells


Skeleton of the cell
Some cells can move using:


The powerhouse of the cell
Provides energy to all parts of the cell
Where cellular respir­ation takes place
[Gluco­se+­O2=­ATP­+CO2] transports to other cells


Controls the cell
Is the brain of the cell
Contains DNA/Ge­netic Material

Cell Membrane

Protective outer boundary of the cell.
Allows materials like water and oxygen, does not allow harmful materials like carbon dioxide and waste products.
Is permeable

Reprod­uct­ion­/Stem Cells

Egg cell + sperm cells = zygote (totip­otent stem cells that divide and re-divide)
Zygote - Embryo (the embryo can either divide, resulting in growth, or it can differ­entiate to different parts of the body.
Embryonic Stem Cells: Puripotent (can be specia­lised into any different type of cell)
Adult stem cells - Multip­otent (they give rise to the same type of cells, like stem cells)
In Leukemia abnormal white blood cells divide and re-divide to form a mass of cell tumour which block blood vessels
Hemapoetic - Blood forming cells

Xylem And Phloem

Transports water from the roots to the leaves. Xylem has two main types of tissues. Hexagonal shapes.
Transports manufa­ctured food from the leaves to other parts of the plant. Circular shapes.
Xylem and phloem are transport systems in vascular plants

Smooth Endopl­asmic Reticulum [sER]

Does not contain ribosomes
Does not contain proteins
Produces lipids, choles­terol, etc.
Breaks down toxic substances via detoxi­fic­ation


Digestive part of the cell
Has digestive enzymes
Converts carboh­ydrates to glucose and proteins to amino acids


Storage house of the cell
Stores water, food, minerals, nutrients and waste products
Plants have one

Rough Endopl­asmic Reticulum [rER]

Contains ribosomes
Contains proteins
Pack/e­nclose proteins in vesicles
Transport substances within the cell


Float in the cytoplasm
Makes proteins


Diffusion of/for water

Prokaryote & Eukaryote Cells

Prokaryote Cells:
Pro stands for before, Karoyote stands for nucleus. Oldest cell type, small and simple, lack nucleus and organe­lles, single­-ce­lled, single circular chromo­sone. Membrane bound organelles like mitoch­ondria, endopl­asmic reticulum, golgi body are absent. 70s Ribosomes. Pili present.
Have DNA, have ribosomes, have cytomp­lasms, have a plasma membrane, brane present
Eukaryote Cells
Eu stands for true, Karyote stands for nucleus (karyon). Evolved from prokar­yotes, larger and more complex, contain nucleus and organe­lles, multic­ell­ular, multiple linear chromo­sones


Regions where Lignin is not deposited

Plant Cells vs Animal Cells

Plant Cells:
Having cell wall outside of the cell membrane, large fluid-­filled vacuole. Have chloro­plasts
Animal Cells:
Have cytopl­asms, have nucleus, have cell membrane, lack vacuoles or only have a few in liver cells


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