Structures in human cells

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Cells
 Carry out all chemical activities needed to sustain life
 Cells are the building blocks of all living things
 Cells are not all the same, but they share general
structures
 All cells have three main regions
 Nucleus
 Cytoplasm
 Plasma membrane
Figure 3.1a

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The Nucleus
 Control center of the cell
 Contains genetic material (DNA)
 Three regions
 Nuclear envelope (membrane)
 Nucleolus
 Chromatin (DNA and proteins)

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The Nucleus
Figure 3.1b

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The Nucleus
 Nuclear envelope (membrane)
 Barrier of the nucleus
 Consists of a double membrane
 Contains nuclear pores that allow for
exchange of material with the rest of the cell.
(DNA never goes out)

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The Nucleus
 Nucleoli (1 or more)
 Sites of ribosome assembly
 Ribosomes migrate into the cytoplasm
through nuclear pores

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The Nucleus
 Chromatin
 Condenses to form chromosomes when the
cell divides

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The Nucleus
Figure 3.1b

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Plasma Membrane (Cell membrane)
 Controls what moves in and out the cell
 Phospholipid bilayer
 Hydrophilic heads
 Hydrophobic tails
 Also contains proteins and cholesterol

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Plasma Membrane
Figure 3.2

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Cytoplasm
 Cytoplasm is the gel-like fluid outside the nucleus
and inside the plasma membrane

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Cytoplasm
 Contains
 Cytosol
 Fluid that suspends other elements
 Organelles
 “Little organs” that perform functions for
the cell
Ej 1, 2 and 3 page 7

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Cytoplasmic Organelles
Figure 3.4

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Cytoplasmic Organelles
 Mitochondria
 “Powerhouses” of the cell
 Carry out reactions where oxygen is used to
break down food (Cell respiration)
 Provides ATP for cellular energy

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Cytoplasmic Organelles
 Ribosomes
 Made of protein and RNA
 Sites of protein synthesis
 Found at two locations
 Free in the cytoplasm
 As part of the rough endoplasmic
reticulum (RER)

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Cytoplasmic Organelles
 Endoplasmic reticulum (ER)
 Fluid-filled tubules
 Two types of ER
 Rough endoplasmic reticulum
 With ribosomes
 Synthesizes and modifies proteins
 Smooth endoplasmic reticulum
 Functions in lipid metabolism

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Rough Endoplasmic Reticulum
Figure 3.5
Ribosome
Protein
Protein inside
transport vesicle
Transport
vesicle buds off
mRNA
Rough ER
As the protein is synthesized
on the ribosome, it migrates
into the rough ER cistern.
In the cistern, the protein folds
into its functional shape. Short
sugar chains may be attached
to the protein (forming a
glycoprotein).
The protein is packaged in a
tiny membranous sac called a
transport vesicle.
The transport vesicle buds from
the rough ER and travels to the
Golgi apparatus for further
processing or goes directly to
the plasma membrane where its
contents are secreted.

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Rough Endoplasmic Reticulum
Figure 3.5, step 1
Ribosome
Protein
mRNA
Rough ER
As the protein is synthesized
on the ribosome, it migrates
into the rough ER cistern.

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Rough Endoplasmic Reticulum
Figure 3.5, step 2
Ribosome
Protein
mRNA
Rough ER
As the protein is synthesized
on the ribosome, it migrates
into the rough ER cistern.
In the cistern, the protein folds
into its functional shape. Short
sugar chains may be attached
to the protein (forming a
glycoprotein).

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Rough Endoplasmic Reticulum
Figure 3.5, step 3
Ribosome
Protein
Transport
vesicle buds off
mRNA
Rough ER
As the protein is synthesized
on the ribosome, it migrates
into the rough ER cistern.
In the cistern, the protein folds
into its functional shape. Short
sugar chains may be attached
to the protein (forming a
glycoprotein).
The protein is packaged in a
tiny membranous sac called a
transport vesicle.

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Rough Endoplasmic Reticulum
Figure 3.5, step 4
Ribosome
Protein
Protein inside
transport vesicle
Transport
vesicle buds off
mRNA
Rough ER
As the protein is synthesized
on the ribosome, it migrates
into the rough ER cistern.
In the cistern, the protein folds
into its functional shape. Short
sugar chains may be attached
to the protein (forming a
glycoprotein).
The protein is packaged in a
tiny membranous sac called a
transport vesicle.
The transport vesicle buds from
the rough ER and travels to the
Golgi apparatus for further
processing or goes directly to
the plasma membrane where its
contents are secreted.

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Cytoplasmic Organelles
 Golgi apparatus
 Modifies and packages proteins
 Produces different types of packages:
 Cell membrane components
 Secretory vesicles
 Lysosomes

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Figure 3.6
Extracellular fluid
Plasma membrane
Golgi vesicle containing
membrane components
fuses with the plasma
membrane
Golgi vesicle containing
digestive enzymes
becomes a lysosome
Proteins in cisterna
Lysosome fuses with
ingested substances
Membrane
Transport
vesicle
Pathway 3
Pathway 2
Secretory vesicles
Pathway 1
Golgi
apparatus
Golgi vesicle containing
proteins to be secreted
becomes a secretory
vesicle
Cisterna
Rough ER
Proteins
Secretion by
exocytosis

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Figure 3.6, step 1
Extracellular fluid
Plasma membrane
Proteins in cisterna
Membrane
Golgi
apparatus
Cisterna
Rough ER

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Figure 3.6, step 2
Extracellular fluid
Plasma membrane
Proteins in cisterna
Membrane
Transport
vesicle
Golgi
apparatus
Cisterna
Rough ER
Pathway 1

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Figure 3.6, step 3
Extracellular fluid
Plasma membrane
Proteins in cisterna
Membrane
Transport
vesicle
Golgi
apparatus
Cisterna
Rough ER
Pathway 1

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Figure 3.6, step 4
Extracellular fluid
Plasma membrane
Proteins in cisterna
Membrane
Transport
vesicle
Secretory vesicle
Pathway 1
Golgi
apparatus
Golgi vesicle containing
proteins to be secreted
becomes a secretory
vesicle
Cisterna
Rough ER

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Figure 3.6, step 5
Extracellular fluid
Plasma membrane
Proteins in cisterna
Membrane
Transport
vesicle
Secretory vesicles
Pathway 1
Golgi
apparatus
Golgi vesicle containing
proteins to be secreted
becomes a secretory
vesicle
Cisterna
Rough ER
Proteins
Secretion by
exocytosis

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Figure 3.6, step 6
Extracellular fluid
Plasma membrane
Proteins in cisterna
Membrane
Transport
vesicle
Pathway 2Golgi
apparatus
Cisterna
Rough ER

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Figure 3.6, step 7
Extracellular fluid
Plasma membrane
Proteins in cisterna
Membrane
Transport
vesicle
Pathway 2Golgi
apparatus
Cisterna
Rough ER

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Figure 3.6, step 8
Extracellular fluid
Plasma membrane
Golgi vesicle containing
membrane components
fuses with the plasma
membrane
Proteins in cisterna
Membrane
Transport
vesicle
Pathway 2Golgi
apparatus
Cisterna
Rough ER

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Figure 3.6, step 9
Extracellular fluid
Plasma membrane
Proteins in cisterna
Membrane
Transport
vesicle
Pathway 3
Golgi
apparatus
Cisterna
Rough ER

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Figure 3.6, step 10
Extracellular fluid
Plasma membrane
Golgi vesicle containing
digestive enzymes
becomes a lysosome
Proteins in cisterna
Membrane
Transport
vesicle
Pathway 3
Golgi
apparatus
Cisterna
Rough ER

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Figure 3.6, step 11
Extracellular fluid
Plasma membrane
Golgi vesicle containing
digestive enzymes
becomes a lysosome
Proteins in cisterna
Lysosome fuses with
ingested substances
Membrane
Transport
vesicle
Pathway 3
Golgi
apparatus
Cisterna
Rough ER

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Figure 3.6, step 12
Extracellular fluid
Plasma membrane
Golgi vesicle containing
membrane components
fuses with the plasma
membrane
Golgi vesicle containing
digestive enzymes
becomes a lysosome
Proteins in cisterna
Lysosome fuses with
ingested substances
Membrane
Transport
vesicle
Pathway 3
Pathway 2
Secretory vesicles
Pathway 1
Golgi
apparatus
Golgi vesicle containing
proteins to be secreted
becomes a secretory
vesicle
Cisterna
Rough ER
Proteins
Secretion by
exocytosis

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Cytoplasmic Organelles
 Lysosomes
 Contain enzymes that digest materials within
the cell

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Cytoplasmic Organelles
 Cytoskeleton
 Network of protein structures that maintains
cell shape and transports substances from
one place to another in the cytoplasm.
Figure 3.7a

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Cytoplasmic Organelles
 Centrioles (centrosome)
 Rod-shaped bodies made of microtubules
 Direct the formation of mitotic spindle during
cell division

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Cellular Projections
 Not found in all cells
 Used for movement
 Cilia move materials across the cell surface
(located in the respiratory system to move
mucus)
 Flagella propel the cell (sperm cell)

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Cell Diversity
Figure 3.8a
Differentiation is the process by which an
unspecialized cell (such as a fertilized egg cell),
divides many times to produce specialized cells
that work together and make up the body.

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Cell Diversity
Figure 3.8a

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Cell Diversity
Figure 3.8b

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Cell Diversity
Figure 3.8c

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Cell Diversity
Figure 3.8d

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Cell Diversity
Figure 3.8e

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Cell Diversity
Figure 3.8f

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Cell Diversity
Figure 3.8g