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Cell Organelle Review
Cell Theory
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The cell is the fundamental unit of structure
and function in living things
All living things are composed of cells
Cells come from preexisting cells.
Why is the cell theory a theory and not a
scientific fact?
Prokaryotes
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Very simple cells
Contain only a membrane
(sometimes a cell wall),
cytoplasm and a strand of
DNA
No nucleus – prokaryote
means “before nucleus”
Prokaryotes are bacteria
Eukaryotes
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All other cells
Cell membrane – outer
boundary of cell
Cytoplasm – jelly-like
fluid interior of cell
Nucleus – the “control
center” of the cell,
contains DNA
Organelles – little organs
that carry out cell
functions
Organelle - Nucleus
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Control center of cell
Contains
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Nucleolus – areas of condensed chromatin that produce
ribosomes
Chromatin
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a protein (when it thickens and coils around DNA we call it
chromosomes)
When it condenses and is surrounded by a membrane it forms a
nucleolus
Where ribosomes are made
DNA – deoxyribonucleic acid
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Has instructions for making protein
Has chemical code for directing cell activity
Has information that’s passed on to the next generation
Organelles - Mitochondria
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Energy center or
powerhouse of the cell
– center of cellular
respiration
Releases energy for
cell’s activities
Turns food into
useable energy (ATP)
Controls a few other
important functions
Organelles - Ribosomes
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Protein factories of the
cell
Contain RNA
(ribonucleic acid)
Very small but very
significant
Organelles – Golgi Apparatus
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Takes proteins from ER
and puts them in an
envelope – this package
will either:
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Be stored by the cell for
future use
Be excreted from the cell
Become an organelle to
function in the cell
Organelles - Lysosome
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Contains digestive enzymes
Digests proteins, cell
debris, and waste materials
breakdown of worn out
cells by bursting in injured
or damaged cells releasing
enzymes due to the
cessation of active
processes in the cell
Not ‘suicide’ digesting
nutrients of healthy living
cells, the dead cells are not
actively digesting
themselves
Organelles - Endoplasmic Reticulum
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Transports
Parallel double membrane
system
“Intracellular highway” –
assists in giving a way for
materials to pass through
cytoplasm
Provides a place for enzymes
and some organelles to attach,
especially ribosomes
2 types
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Smooth ER – little or not
ribosomes attached
Rough ER – lots of
ribosomes attached
Endomembrane System
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rough endoplasmic reticulum (rough ER) is an ER with
ribosomes attached which assists in synthesize proteins and
transporting them
smooth endoplasmic reticulum (smooth ER) is an ER
without attached ribosomes; synthesize lipids and steroids,
metabolize carbohydrates and steroids (but not lipids), and
regulates attachment of receptors on cell membrane proteins
endomembrane system is composed of the nuclear
envelope, ER, Golgi apparatus, lysosomes, vacuoles,
vesicles and cell membrane that form a single functional and
developmental unit, either being connected together directly,
or exchanging material through plasma membrane that
transport, modify, and synthesize materials
Vacuoles vs. Vesicles
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Functions: store water or
other substances, like food or
lipids or proteins
Technically, the animal cell
has vesicles and the plant cell
has vacuoles. Really they are
both the same sort of
organelle
With Protists the organelle is
called a vacuole
Parts that are not found in animal cells
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Plastids – either organic chemical (protein)
factories or storage areas
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Examples:
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Chloroplast – have enzymes that form
carbohydrates
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Chlorophyll – green pigment that gives flowers and fruits
its color
Xanthophylls – example carotene
Chromoplast (potatoes, tomatoes, apples) – leucoplast –
food storage areas with enzymes that turn glucose into
starch
Selectively Permeable Membranes
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Allow some materials to pass through
while preventing the passage of other
material
Homeostasis
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Maintaining a living systems life processes
by responding to the external environment
with internal changes
Homeostasis in made possible in cells by
selectively permeable membranes
Selectively Permeable Membranes
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Plasma membrane
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Surrounds the cytoplasm of a cell
Separates the animal cell from its
environment and is inside the cell wall in
plant cells
Nuclear envelope
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Made up of membrane with pores
Separates the nucleus from the cytoplasm
Selectively Permeable Membranes
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Cell wall
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Surrounds the plant cell, bacteria cells, fungi cells, and some
protist cells
Protects, supports, separates cell from its environment
Parts of plant cell walls
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Middle lamella
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Primary Walls
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beginning layer between cell walls of plant cells
Contains pectin- a jelly like substance
Next to middle lamella
Contains cellulose and pectin
The harder the stem the thicker the primary wall
What would the inside layer touching the cytoplasm be?
Cell size
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The cell is small because the cell has to be
able to transport material through the cell
membrane
If the cell is too big, then the material can’t
travel through the cell. How does this
relate to diffusion and osmosis?
Therefore, small size is important!!