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The Cell
AP Biology
Chapter 6
AP Bio Big Ideas
• Big Idea 4: Biological Systems interact,
and these systems and their
interactions possess complex properties
– Essential Knowledge 4.A. 2- the structure
and function of subcellular components,
and their interactions, provide essential
cellular processes.
Why is life cellular?
• Because every living thing is
made up of cells.
The Immortal cells of Henrietta
Lacks- HeLa Cells.
Van Leeuwenhoek
• Anton van
Leeuwenhoek
one of the first
people to see
living things in
a drop of pond
water.
Robert Hooke
• Observed
tiny
chambers in
plants.
Called them
“cells”.
The Cell Theory
• All living things are made
of cells.
• Cells are the basic units
of structure and function
in living things.
• New cells come from
existing cells.
Basic Cell Structures
• All cells have a cell
membrane and cytoplasm.
Plant and some bacteria
have cell walls.
• Matthias
Schleiden and
Theodor Schwann
concluded that all
plant and animals
were made of
cells.
Limits to cell size
• A high ratio of surface area to volume is
important for cells
– Exchange of material with surroundings is
easier with a large surface area and
smaller volume.
– Elephants don’t have larger cells they have
more cells.
The cell
membrane is a
fluid “mosiac”
bilayer .
The cell membrane is semipermeable, it regulates
what enters and leaves the
cell.
Prokaryote vs. Eukaryote
• Scientist divide cells into two
categories
–Prokaryotes and Eukaryotes.
–The domains Bacteria and
Archaea are prokayotes.
–The domain Eukarya are
eukaryotes.
Prokaryote cells
• Smaller and
simpler than
eukaryotic cells
• Do not contain a
nucleus
• Have no
organelles
• All bacteria are
prokaryotes.
Eukaryote Cells
• Larger than
prokaryotic cells.
• Contain a
nucleus
• Have organelles
that carry out
special functions.
Prokaryote
•Cell membrane
•Cytoplasm
Eukaryote
•Cell membrane
•Cytoplasm
•Have no nuclei
•Have nuclei
•Have no organelles
•Have organelles
•All bacteria are
prokaryotes
•Can be single- celled or
multicellular organisms
•Includes plants,
animals, fungi, &
protists
The Eukaryotic Cell
• Extensive and elaborate internal
membranes
– Divide cell into compartments
– Participate in cellular metabolism
– Allow incompatible processes to occur
simultaneously.
Nucleus
• Controls most cell
processes
• Contains
hereditary
information (DNA)
• Directs protein
synthesis by
synthesizing RNA.
• Chromatin–the granular material
in the nucleus –
–made of DNA and
protein
• Chromatin is
separated into units
called chromosomes.
Nucleolus
• Small dark area
in an undividing
nucleus
• rRNARibosomes are
synthesized
into large and
small subunits.
• Some species
may have 2 or
more nucleoli.
Nuclear Envelope
• Surrounds the
nucleus
• Double-membrane
dotted with nuclear
pores
• RNA and other
molecules are sent
out of the nucleus
Ribosomes
• Small particles of
RNA
• Make proteins
following coded
instructions (mRNA)
from the nucleus.
• Free ribosomes in
the cytosol • Bound ribosomes
attached to the ER.
Endomembrane System
• Some of the different membranes in the
cell are part of endomembrane system.
• Related through direct contact or
vesicles
• Includes – nuclear envelope,
endoplasmic reticulum, Golgi apparatus,
lysosomes, some vacuoles and the
plasma membrane
Endoplasmic Reticulum
continuous with nuclear envelope
2 types
• Rough ER
– Ribosomes
attached
– Modifies proteins
into native
conformation
– Attaches
carbohydrates to
proteins –
glycoproteins
– Secretory proteins
are wrapped in
transport vesicles
• Smooth ER
– Lacks ribosomes
– Synthesizes lipids
– Metabolism of
carbohydrates
– Detoxification of
drugs and poisons.
– Stores Ca ions (i.e.
muscle cell
contractions)
Golgi Apparatus
• Protein
modification
• Proteins are
stored and
shipped to other
destinations
• Manufactures
some
macromolecules
Lysosomes
• Filled with
hydrolytic
enzymes
• Break down
lipids,
carbohydrates,
and proteins
from foods for
cell use.
Vacuoles
• Stores water,
salts, proteins, or
carbohydrates
• Provide pressure
for plants cells
• Include contractile
vacuoles and
central vacuole.
Mitochondria &
Chloroplasts
• Enclosed by membranes, but not part of
endomembrane system
• Two membranes
• Semi autonomous organelles – grow
and reproduce in the cell
• Contain their own DNA – synthesize
proteins made on their ribosomes.
Mitochondria
• Site of cellular
respiration –
production of ATP by
extracting energy
from sugars, fats,
and other fuels with
the help of O2
•
Folded inner membrane
provides large surface
area for proteins that
function in respiration.
Chloroplasts
• Specialized
member of
plastids family
• Site of
photosynthesis
• Plants and some
other type of
organisms are able
to use light energy
from the sun to
produce food.
Photosynthesis
• Uses the energy of
sunlight to change water
and carbon dioxide (CO2)
into oxygen (O2) and
high energy sugar.
• Inside the chloroplast are thylakoid
membranes. A granum is a stack of
thylakoids. The light dependent
reactions happen in the thylakoid.
Peroxisomes
• Metabolic compartment that contain
enzymes that transfer H from various
substrates to O to produce H2O2
• Some use O to break down fatty acids
into smaller molecules for transport to
mitochondria.
• Do not bud from endomembrane
system but increase by splitting in two.
Microfilaments
• Network of protein
filaments
• Maintain the cell
shape-Cytoskeleton
• Centrioles in animal
cells
• Use for many forms
of cell movement
Cell Wall
• Extracellular structure
• Found in plants &
algae.
• Provides support and
protection
• Made of cellulose, a
tough carbohydrate
fiber.
• Perforated by channels
called plasmodesmata,
between cells.