CELL ORGANELLES
BACKGROUND INFORMATION

Cells are made up of organelles which means
“little organs”


Organelles: specialized structures that performs
important cellular functions.
There are two main parts of a eukaryotic cell
Nucleus
 Cytoplasm

PARTS
OF THE CELL
Nucleus
 Ribosomes
 Endoplasmic Reticulum
 Golgi Apparatus
 Lysosomes

Vacuoles
 Mitochondria
 Centrioles
 Cell Membrane
 Cell Wall
 Chloroplasts
 Cytoskeleton

NUCLEUS
Controls most of cell processes and contains the
hereditary information of DNA
 BRAIN of the cell
 Contains:

Nucleolus: where assembly of proteins begin
 Nuclear envelope: Double membrane with pores that
surrounds nucleus
 Chromatin: consists of DNA tightly
coiled around protein
 1. Chromatin forms chromosomes
when the cell divides
 A. Chromosomes contain genetic
information

RIBOSOMES
Small particles of RNA that make protein
 They can be found:
 A. Alone in cytoplasm- makes proteins for
use within the cell
 B. Attached to the rough ER- makes proteins
for export out of the cell

ENDOPLASMIC RETICULUM
 Site
where lipid
components of the cell
membrane are assembled,
along with proteins and
other materials that are
exported from the cell

Two kinds:
 Smooth ER
 Rough ER
ENDOPLASMIC RETICULUM
Rough ER
 The portion of the
ER involved in the
synthesis of
proteins
 Ribosomes are
found on the
surface

Smooth ER
 Ribosomes are not
found on the surface
 Outer portion of the ER
 Contains enzymes that
help synthesize lipids
and helps in detoxifying
drugs

GOLGI APPARATUS
 Stacked
flattened sacks
 Site where cell products are modified,
sorted, and packaged for storage or
export
 Involved in the production of lysosomes
LYSOSOMES
Produced by the Golgi apparatus.
 Small organelles filled with enzymes
 Functions:

Breakdown of organelles that have outlived their
usefulness
 They breakdown (recycle) lipids, carbohydrates,
and proteins into small molecules that the rest
of the cell uses

VACUOLES
The vacuole acts as a container, storing water,
salts, proteins, and carbohydrates
 Unicellular animals can use vacuoles for
movement
 Larger in plant cells than animal cells

MITOCHONDRIA
 Convert
chemical energy stored in food
into compounds that are easier for the
cells to use



Powerhouse of the cell
Contains fold
Structures that need a lot of energy will have
more mitochondria


Example: muscle cells
Structure- cristae, outer and inner membranes
CYTOSKELETON
Network of protein filaments that help cells to
maintain their shape and for movement
 Types:

A. microfilaments- produce a tough, flexible
framework that supports cells and helps cells
move
 B. microtubules- maintain cell shape and are
involved in cell division
 1. form spindle fibers
 2. form centrioles- help organize cell division, only
in animal cells

CENTRIOLES
 Found
ONLY in ANIMAL cells
 Cylindrical structures found near the
nucleus
 Made of hollow, tubular structures
arranged in bundles
 Important in cell division
CHLOROPLASTS
 Capture
energy from sunlight and convert
it into chemical energy
 Contain green pigment called chlorophyll
 Found ONLY in PLANTS
CELL MEMBRANE
 Found
in ALL cells
 Provides protection and support for the cell
 Controls what enters and leaves the cell

“Fluid mosaic model”- of cell membrane structure
refers to the many different kinds of molecules in
cell membranes- lipids (double layer membrane),
protein molecules, and carbohydrate molecules.
CELL WALL
 Provides
support and
protection
 Found in plant cells
 Plant cell walls are
made of cellulosetough carbohydrate
fiber
PLANT VS. ANIMAL
PLANT
CELL
HAVE:
Cell Wall
LARGE vacuoles
Chloroplasts
DO NOT HAVE:
Centrioles
CELLS
ANIMAL
CELL
Cell membrane
Mitochondria
Golgi apparatus
Nucleus
Cytoskeleton
Ribosomes
Endoplasmic
reticulum
Lysosomes
HAVE:
Centrioles
DO NOT HAVE:
Cell Wall
LARGE vacuoles
Chloroplasts
MOVEMENT ACROSS THE CELL
MEMBRANE
TYPES OF CELL MEMBRANE:
 Permeable:
When all substances cross the membrane
 Impermeable: Substances that can’t pass across the
membrane
 Semi-permeable: “selectively permeable”- some
substances can pass across the membrane and some
cannot
A. DIFFUSION
 The
movement of molecules to an area of high
concentration to an area of low concentration
 1. no energy is required to diffuse across the
membrane
 2. equilibrium- when the concentration of the
solute is the same throughout
a system
B. OSMOSIS
 The
diffusion of water through a selectively
permeable membrane (pg 186)
1. isotonic- when the concentration of 2 solutes is the same
inside and outside the cell
 2. hypertonic- “above strength”- the solution with the
greater concentration of solutes
 Animal cells shrink
 3. hypotonic- “below strength”- the solution with the lesser
concentration of solutes
 Animal cells swell and burst

C. FACILITATED DIFFUSION
 Movement
of specific glucose molecules across cell
membranes through protein channels that act as
carriers to make it easier for certain molecules to cross
(pg 187)
 1. ex- glucose passes through RBC cell membrane
with help of protein channel (only glucose can pass
through)
D. ACTIVE TRANSPORT
 Transport
of materials from an area of low
concentration to an area of high concentration which
requires energy

1. endocytosis- the process of taking material into the cell by
means of infoldings or pockets of the cell membrane
 2 Types
 A. phagocytosis- “cell eating” – extensions of cytoplasm
surround a particle and package it within a food vacuole
which the cell engulfs
 1. ex- amoeba
 B. pinocytosis- process by which a cell takes in a liquid
from the surrounding environment
ACTIVE TRANSPORT CONT.

2. exocytosis- process by which a cell releases large
amounts of material
III. DIVERSITY OF CELLULAR LIFE
 A.
Unicellular Organism- single-celled organism
1. They do everything that you expect a living thing to do:
 Grow
 Reproduce
 Respond to stimuli
 Transform energy
 2. more unicellular organisms on Earth than multicellular
organisms
 3. Ex- yeast, Volvox (alga cells)

EXAMPLES OF UNICELLULAR ORGANSISMS
B. MULTICELLULAR ORGANISMS
 Made
of many cells
 1. cell specialization- cells throughout an organism
can develop in different ways to perform different
tasks
 A. ExRBC- transports oxygen
 Pancreatic cells- produce protein
 Muscle cell- body movement- cytoskeleton
 Stomata- guard cells control the opening and closing of
stomates to exchange CO2, O2, water vapor, and other
gases

C. LEVELS OF ORGANIZATION
 Cells
Tissues
Organs
Systems
 1. tissues- group of similar cells that perform
a particular function

 2.
4 main types of tissue:
 A. muscle
C. epithelial
 B. nervous
D. connective
organs- many groups of tissues working
together
 3. systems- group of organs that work
together to perform a specific function