Organelles in Animal and
Plant Cells
Basics of Cell Structure
 Not all cells are alike! They vary in…
 A) size
 B) shape
 C) internal organization
SIZE: range from .2m – 0.2um (most are 10-50um)
-not all are microscopic (most are) ex: giraffe’s nerve cells
extend 6.5 ft. down it’s leg!!
Cells are limited in size by the ratio
between their outer surface area
and their volume
Eukaryotic Cells
 Large
 Genetic material is ENCLOSED IN A NUCLEUS
 Contain a variety of organelles – membrane-enclosed
structures that perform specific functions within the
cell
Cell Walls
 Stiff coatings on outer surfaces of bacteria,
plants, fungi, and some protists are cell
walls

Support and protect fragile cells; usually
porous
 Cell walls are composed of polysaccharides
like cellulose or chitin
 Cell walls in plants may have multiple layers

Primary cell walls in plants are
outermost

Secondary cell walls are innermost

Cell walls of adjacent cells joined by
middle lamellae
Plasma Membrane
 Double layer of
phospholipids
 Isolates cell contents from
external environment
 Regulates flow of materials
into and out of the cell
 Interaction with other cells
and extracellular
environment (outside of
cell)
Cytoplasm
All material and structures that
lie inside the plasma membrane,
but outside nucleus
 Cytosol: fluid potion; water,
salts and organic molecules; site
of biochemical reactions
Cytoskeleton
 Protein fibers, give shape an organization to the cell
 Microfilaments, intermediate filaments, and
microtubules
 3 functions:
1.
Shape (intermediate filaments)
2.
Cell/Organelle Movement (microfilaments and
microtubules)
3.
Cell Division (microfilaments and microtubules)
Cell Movement
 Cilia (“eyelash”) - move cell through fluid/fluid past
cell
 Flagella (“whip”) - move cell through fluid
Structure:
• Ring of nine, one
pair in the center
• Outer pairs of arms
interact to cause
movement
• Arise from basal
body (just below
plasma membrane)
• Use ATP to move
Centrioles and centrosome
• Produce the microtubules of
cilia and flagella, and those
that form the spindle during
animal cell division
Nucleus
 Membrane bound hold chromosomes
 3 components
 Nuclear membrane
 Chromatin
 Nucleolus
The Nucleus
 The nuclear envelope separates chromosomes from
cytoplasm
 Envelope is a double membrane with nuclear pores for transport
 Outer membrane is studded with ribosomes
The Nucleus
 The nucleus contains DNA in various configurations
 Compacted chromosomes (during cell division)
 Diffuse chromatin (as DNA directs reactions through an RNA
intermediate by coding for proteins)
The Nucleus
 Darker area within the nucleus called the nucleolus




Functions as the site of ribosome synthesis
Ribosomes synthesize proteins
Free Floating Ribosome: make proteins for the cell
Ribosomes attached to ER: make proteins to be exported from
the cell
Endoplasmic Reticulum
 Endoplasmic Reticulum: (ER) acts as
a highway for molecules to move
around the cell.
 Smooth ER: does NOT contain
ribosomes; Contains enzymes that
detoxify drugs (in liver cells) or
synthesizes lipids
 Rough ER: does contain ribosomes;
Produces proteins and phospholipids
destined for other membranes or for
secretion (export)
Golgi Apparatus (Body)
 A set of stacked flattened sacs
 product is assembled (moves from ER
to golgi, where it is put together and
adjusted)
 product is packaged (in new sacs)
 product is mailed out (sent out of cell)
Lysosome
 Membrane enclosed vesicles
 Contain digestive enzymes
 Digest food particles by fuding with food
vacuoles and digest food into basic
nutrients
Vacuole
 Fluid-filled sacs with a single membrane
 Functions of vacuoles
 Contractile vacuoles in freshwater organisms
used to collect and pump water out
 Plant central vacuoles used in several ways
 Maintain water balance
 Store hazardous wastes, nutrients, or
pigments
 Provide turgor pressure on cytoplasm to
keep cells rigid
Mitochondria
 Extract energy
from food
molecules and
store in high
energy bonds of
ATP
• Energy extraction
process involves
anaerobic and
aerobic reactions
Plastids
a) chloroplasts : site for
photosynthesis
b) chromoplasts: stores red and
yellow pigment
c) leucoplasts: non pigmented
Chloroplasts
 A type of plastid
 Functions of plastids
 Storage for photosynthetic products like
starch
 Storage of pigment molecules giving color to
ripe fruit
Cell Wall
 Cell Wall: rigid covering made of cellulose, protects
cell, goes OUTSIDE cell membrane, porous enough for
certain substances
Prokaryotes
 Small
 Surrounded by stiff cell wall
 Surface features – capsules and slime layers
 Single circular chromosome in central region called
nucleoid; DO NOT CONTAIN A NUCLEUS
 Ribosomes