Download CHEAT SHEET – CELLS

Name:
Class:
Date:
CHEAT SHEET – CELLS
Cell Theory

Cell theory is a scientific theory which describes the properties of cells. It has several statements:

The cell is the basic unit of life.

All organisms are composed of cells

All cells come from pre-existing cells.
Cell Types
Unicellular

Multicellular
organism that exists as a
singular, independent cell

organism that exists as
specialized groups of cells;
cells are organized into
tissues that perform the same
function; tissues form organs
and organs make up an organ
system
Prokaryotic

Eukaryotic
has nuclear material in the
center of the cell, but is not
enclosed by a nuclear
membrane; no membranebound organelles; found in
bacteria and blue-green
bacteria

contain a clearly defined
nucleus enclosed by a
nuclear membrane and
membrane-bound organelles;
found in plants, animals,
fungi, and protists.
Plant vs. Animal Cells
Plant Cells
Animal Cells
 Rigid shape
 Flexible shape
 Has a cell wall
 No cell wall
 Has chloroplasts
 No chloroplasts
 One large central vacuole
 Many small vacuoles
Cell Organelles

Even though there are different kinds of cells, they all contain similar parts inside of them, called organelles. Organelle means “little
organ”. Just as organs like the lungs and heart have unique jobs to do, each organelle has its own unique job to do inside the cell.

Cell membrane is the outer covering of all cells. The two main jobs of the cell membrane are to hold the cell together and to control what
comes in and goes out of the cell.

Cell wall is a rigid layer of material that surrounds plant cells only; animal cells do not have cell walls. The cell wall is made out of a tough
substance called cellulose, which makes it very hard and rigid. The main job of the cell wall is to protect and support the plant cell.

Cytoplasm is the gel-like fluid inside the cell. The main job of the cytoplasm is to hold all of the components of a cell in one place.

Nucleus is a large oval structure found in both plant and animal cells. The main job of the nucleus is to act as “brain” of the cell: it directs
all of the cells activities. The nucleus contains large molecules called DNA, which act like instruction manuals for the cell.
Sometimes, a dark spot can be seen inside the nucleus. This is called the nucleolus, and its job is to produce ribosomes for the cell.


Mitochondria are organelles in all cells that look like jellybeans with wavy lines inside. They are known as the “powerhouses” of the cell
because their main job is to make energy for the cell. They do this by breaking down sugars in the food that we eat to generate energy.

Endoplasmic reticulum (ER for short) is a maze of tiny passageways found throughout the cytoplasm. The main job of the ER is to carry
materials from one part of the cell to another. The ER is like the water pipes in your house: they allow materials to move around quickly.

Vacuoles are tiny sacs that float throughout plant and animal cells. Their main job is to store things for the cell, such as food, water, and
wastes. Animal cells have many tiny vacuoles, but plant cells have one large vacuole, called the central vacuole, that mainly holds water.

Golgi bodies looks like several flattened tubes stacked on top of each other. The main job of Golgi bodies is to receive materials from the
ER, package them inside vacuoles, and send them to other parts of the cell or outside of the cell.

Ribosomes are tiny organelles in all cells that look like pepper grains. They can be found floating freely in the cytoplasm or attached to
the ER. The main job of ribosomes is to produce new proteins for the cell.

Lysosomes are small round structures found inside both plant and animal cells. They contain strong chemicals called enzymes and their
main job is to break down waste materials inside the cell.

Chloroplast –large green organelles found only in plant cells. The main job of chloroplasts is to capture energy from sunlight and use it to
produce food for the cell. Chloroplasts are what make leaves green.
Cell Specialization
- Cells often become adapted to perform different functions. We say that they have become specialized to do a particular job.
- The design and shape of a cell is dictated by its function and the conditions under which it works
- As cells become specialized they may develop a particular shape, have different numbers of certain organelles or contain organelles that
are NOT common to all cells (for example: plastids, cell wall, vacuole, centrioles)
- Multicellular organisms exhibit greater cellular specialization,
- Examples of specialized cells include: epithelial cells, nerve cells, muscle cells, red blood cells, white blood cells, egg cell (ovum), sperm
cell, and in plants, root hair cell, guard cell
Cells, Tissues, Organs, Organ Systems
cells  tissue  organ  organ system

In multicellular organisms, cells are not only specialized, but many of them are work together in tissues.

A tissue is a group of two or more cells working together to do a specific job. For example, if you look at your hand, the top layer of
tissue is your skin. It is made up of millions of individual skin cells working together to provide protection for your body.

Humans are made up of many kinds of tissues. The main types of tissue include epithelial tissue (includes skin and organ linings), muscle
tissue, nerve tissue, blood tissue and connective tissue (includes bone, cartilage and tendons).

An organ is a collection of 2 or more different tissues working together to do a certain job.

An organ system is a collection of 2 organs together to do a certain job.
Organ Systems in Plants
roots
Organ Systems in Humans/Animals
stem
leaves
Respiratory
Circulatory
Nervous
Digestive
Reproductive
Skeletal
Muscle
Endocrine
Excretory
Cell Transport

Two different types: passive transport and active transport



Passive Transport – movement of substances across the plasma membrane without the use of the cell’s energy
Substances are moving from an area of high concentration to low concentration (with the concentration gradient).
Three different types of passive transport:
Diffusion

movement of substances across the
plasma membrane from an area of high
concentration to an area of low
concentration


Osmosis

Facilitated Transport
Movement of water ONLY across the
plasma membrane from areas of high
concentration to areas of lower
concentration

Active Transport – movement of substances across the plasma membrane that requires the use of the energy and carrier molecules;

Substances are moving from an area of low concentration to an area of higher concentration (against the concentration gradient)
Two different types of active transport:
Endocytosis

a carrier molecule embedded in the
plasma membrane transports a
substance across the plasma
membrane following the high-to-low
concentration gradient
Exocytosis
Large particles are brought into the cell through cell membrane

Large particles leave the cell through cell membrane
Effect of Concentration on Cells
Hypotonic
Hypertonic
Isotonic

Greater concentration of substance
inside the cell

Greater concentration of substance
outside of the cells

Same concentration inside and outside
of cell

Meaning: less water inside the cell

Meaning: less water outside the cell

Meaning: water concentration same

Water moves in; cell bursts

Water moves out; cell shrivels

No net movement of substance