Basic Cell Structure
ADAPTED FROM
GEORGIA
AGRICULTURAL EDUCATION
CURRICULUM
Cells
Basic building blocks of life
Understanding of cell
morphology is critical to the
study of biotechnology
Cell
Smallest living unit of an
organism
Grow, reproduce, use energy,
adapt, respond to their
environment
Cell
Many cannot be seen with the
naked eye
A cell may be an entire
organism or it may be one of
billions of cells that make up the
organism
Cells
Divided and classified in many
ways
One common classification
method is the presence or
absence of a cell nucleus
Nucleus
Relatively large structure
within a cell
Directs cell activities
Some simple single-celled
organisms lack a nucleus
Nucleus
Prokaryotes – have no
nucleus
Eukaryotes – have a nucleus
Prokaryotes
Single celled organism
Kingdom Monera
Lacks a cell nucleus
Internal structure is less
organized than other cells
Prokaryotes
Genetic info needed is within
the cell
Two most common – blue
green bacteria and true
bacteria
Blue green bacteria
Have ability to produce their
own food like plants
Most bacteria get their food
from other sources
Prokaryotes
Less complex than
eukaryotes
Still have many of the basic
internal characteristics
Common prokaryote structures
Cytoplasm
Chromosomal material
Cell membrane and wall
Ribosomes
Some have flagellum for
mobility
Eukaryotes
Organism made up of cells that
have a nucleus
May be single celled – Kingdom
Protista
May have billions of cells like
plant and animal kingdoms
Eukaryotes
Single celled eukaryotes
include paramecia, euglena,
and diatoms
Eukaryotes
Typically are highly
organized
Infinite number of shapes
and purposes
Eukaryotes
Human body has at least 85
different cell types
All eukaryotes have a number
of structures in common
Common structures
Organelles – smaller parts of
the cell with specific
functions
Cell membrane – acts as a
gatekeeper
Cell membrane
Controls what enters and leaves
the cell
Plants, algae, and bacteria
typically have a tough outer
structure known as a cell wall
Cell wall
Provides additional structure
and protects the cell from
pressure caused by movement of
water
Animal cells do not have walls
Cytoplasm
Organelles are surrounded by a
jelly-like substance
Primary component is water
Nucleus
Largest and most identifiable
part of the cell
Other organelles
Ribosomes
Mitochondria
Golgi bodies
Endoplasmic reticulum
Other organelles
Lysosomes
Vacuoles
Chloroplasts in plants
Nucleus
Brain of the cell
Site of much of the
manipulation done in
biotechnology
Nucleus
Controls activity of the cell
Round or oval structure
Typically found in the middle of
the cell
Appears darker than
surrounding material
Nucleus
Surrounded by a membrane that
controls passage of materials in
and out of the area
Nucleus
Contains DNA
DNA is located on chromosomes
Most organisms are diploid –
have tow chromosomes for each
trait
Diploid
Humans – 23 pair
Goldfish – 90 chromosomes, 45
pair
Cytoplasmic Organelles
 Organelles are required for proper
cell function
 Ribosome – make proteins for
cellular use and communication
 May be attached to endoplasmic
reticulum
Endoplasmic reticulum
Layered membraneous
Make and transport proteins
Vacuole
Large organelle, without specific
shape
Store waste or raw materials
used in synthesis of proteins
Golgi Bodies
Golgi apparatus
Similar to endo. Ret.
Look like a thick elastic band
that has been folded several
times
Golgi Bodies
Adds modifications to
unfinished proteins
Makes lysosomes
Lysosome
Small and round
Store enzymes that break down
food into chemical compounds
Destroy cell organelles and the
cell itself
Mitochondria
Energy factories
Rod-shaped
Change food into molecules that
can be used for energy
Mitochondria
Contain DNA
Can replicate themselves
Chloroplast
Found in plants and some other
organisms
Contain chlorophyll
Cellular processes
Respiration
Osmosis
Diffusion
Photosynthesis
Respiration
Cells break down carbohydrates
and other molecules to produce
energy
Oxidation of glucose is one of
most common forms
Respiration
Breaking down of sugar into
water, carbon dioxide, and
energy
Energy is used to do the work of
the cell
Osmosis & Diffusion
Transportation of raw materials,
wastes, and synthesized
materials out of the cell
Diffusion
Movement of molecules;
especially gases and liquids
from areas of high
concentration to areas of low
concentration
Osmosis
Specific type of diffusion
Movement of water through a
membrane from areas of high
concentration to areas of low
concentration
Equilibrium
Diffusion and osmosis happen
to enable a cell to reach
equilibrium
Cellular reproduction
Three ways:
Fission
Mitosis
Meiosis
Fission
 Prokaryotes
 Cell grows larger and makes a
second copy of its DNA
 At some point the cell membrane
divides the cell by the growth of a
transverse septum
Fission
 Two new cells are formed as the
division grows inward from either
side of the cell
 Two cells now called “daughter
cells”
 Sometimes known as “binary
fission”
Mitosis
Eukaryotes
Requires 6 stages
Interphase, prophase,
metaphase, anaphase,
telophase, cytokinesis
Mitosis
Creates cells that are identical to
the original cell.
Have the entire compliment of
chromosomes existing in pairs diploid
Meiosis
Division of sex cells
Stages of Meiosis I: Interphase
I, prophase I, metaphase I,
anaphase I, telophase I,
cytokinesis I
Meiosis
Meiosis II
Interphase II, prophase II,
metaphase II, anaphase II,
telophase II, cytokinesis II
Meiosis
Each cell receives one
chromosome from each pair
randomly
Resulting cells have half the
normal number of
Chromosomes – haploid