1. CELL STRUCTURES

2. CELL STRUCTURES
Cell theory:
1) All living things are
made of one or more
cells
2) The cell is the basic
organizational unit of
life
3) All cells come from
pre-existing cells

3. CELL STRUCTURES
Organelles – internal structures performing specialized
functions (not in bacteria)
All organelles have a membrane except for ribosomes and centrioles.

4. CELL STRUCTURES
Nucleus: protects and controls access to DNA, makes
ribosomes
Nuclear envelope/
membrane – double
membrane; selectively
permeable; continuous with
ER
Nucleolus – where subunits
of ribosomes are made from
proteins and RNA
Nuclear pores – protein
channels that allow certain
substances in and out of the
nucleus

5. CELL STRUCTURES
Nucleus: protects and controls access to DNA, makes
ribosome subunits
Chromatin – combination of
DNA and protein in nucleus
Chromosomes – single piece
of condensed (coiled) DNA
with protein and RNA
Note: Some of the
chromosomes look
condensed in this
diagram, while others don’t.

6. CELL STRUCTURES
Endoplasmic reticulum (ER): routes and modifies new
proteins, & metabolizes lipids and carbohydrates
Rough ER (RER)– studded
with ribosomes for protein
synthesis
- Predominately found in
liver cells where protein
synthesis occurs actively
Smooth ER (SER)– no
ribosomes; performs lipid
metabolism, carbohydrate
metabolism, and
detoxification

7. CELL STRUCTURES
Golgi apparatus/body: packages proteins and lipids before
they are sent to their destination; creates lysosomes
Cis face – where vesicles
enter the Golgi body
Trans face – where vesicles
exit the Golgi body
Cisternae – the central
stacks of the Golgi body

8. CELL STRUCTURES
1. Nuclear membrane
2. Nuclear pore
3. Rough endoplasmic reticulum
4. Smooth endoplasmic reticulum
5. Ribosome attached to RER
6. Macromolecules
7. Transport vesicles
8. Golgi apparatus
9.Cis face of Golgi apparatus
10. Trans face of Golgi apparatus
11. Cisternae of the Golgi Apparatus
Summary:

9. CELL STRUCTURES
Vesicles: Membrane-bound containers inside a cell (4 kinds)
1) Transport/secretory vesicles –
transports substances within a
cell, or releases them from the
cell
2) Peroxisomes – contain enzymes
to break down lipids and amino
acids; inactivates toxins
3) Lysosomes – contains digestive
enzymes; digest excess or worn-
out organelles, food particles, and
engulf viruses and bacteria
4) Vacuole – contain waste products
(“garbage cans”), water, enzymes
and/or other small
molecules, export unwanted

10. CELL STRUCTURES
Secretory/Transport Vesicle – Can release important
molecules in the body (i.e. proteins, hormones, etc.)

11. CELL STRUCTURES
Mitochondrion: Generates ATP and other molecules
-The inner membranes
contain enzymes & channel
proteins for respiration
-Have their own RNA

12. CELL STRUCTURES
Ribosome: translates messenger RNA (mRNA) to
polypeptide chains used to form proteins
Made of two subunits which
sandwich mRNA in between

13. CELL STRUCTURES
Cytoskeleton: Dynamic system of filaments and
microtubules
Functions:
-Provides cell structure
-Helps with cell division
-Enables cell and organelles
to move around

14. CELL STRUCTURES
Cytoskeleton: Made of 3 different structures

15. CELL STRUCTURES
Centriole: Organizes the spindle fibres during mitosis and
cytokinesis
Most centrioles are made of
9 sets of microtubule
triplets.

16. CELL STRUCTURES
Cilia & Flagella: Used for locomotion; rotates around in a
whip-like fashion. Made of microtubules.
Cilia – smaller, more
numerous, and can move
fluids around stationary cells
Flagella – larger, less
abundant

17. CELL STRUCTURES
Cytoplasm: Includes the cytosol, organelles, and chemicals
(i.e. sugar and water); all contained by the cell membrane
Cytosol: the fluid between
the cell membrane and
nucleus

18. CELL STRUCTURES
Outside cell
Inside cell
Hence the cell membrane is called the phospholipid bilayer.
Cell membrane: A bilayer of phospholipids which contains
the contents of the cell

19. CELL STRUCTURES
This bilayer is not static; it is dynamic. There is fluidity in
the membrane.

20. CELL STRUCTURES
Extracellular matrix (ECM): Supports and anchors cells;
mixture of fibrous proteins and polysaccharides secreted by
the cell.
-Provides structural support
for tissues
-Separates tissues
-Functions in cell signalling
-Bone is mostly ECM (fibrous
collagen, hardened by
mineral deposits)
-Insects’ exoskeletons are
also ECM

21. PLANT CELLS

22. PLANT CELLS
Plant cells have additional organelles and features that are
not found in animal cells.

23. PLANT CELLS
Cell wall: Tough, flexible, and rigid layer around
plant, bacteria, fungi, and algae cells. Surrounds cell
membrane. -Prevents overexpansion
when water enters cell
-Protects cells against
mechanical stress
-Made primarily of cellulose

24. PLANT CELLS
Cell wall: Made of 3 layers
-Pectin layer (also called
middle lamella) glues
adjacent plant cells together
-Primary cell wall is thin and
flexible, and forms when cell
is growing; like a cellulose
“coating”
-Secondary cell wall is thick
and more rigid, but not
found in all cell walls

25. PLANT CELLS
Plastids: Organelle found in plants and algae; site of
manufacture and storage of important chemicals (3 kinds)
Chloroplasts – Make sugars
using light energy, CO2, and
H2O; contain the pigment
chlorophyll for photosynthesis
Chromoplasts –synthesis and
storage of pigments other than
chlorophyll
Amyloplasts – non-pigmented;
synthesis and storage of starch
granules (abundant in stems &
seeds)