ANATOMY & PHYSIOLOGY
CHAPTER 3: The Cellular Level of Organization
STRUCTURE OF A CELL MEMBRANE PROTEINS
Two types of membrane proteins
1. Integral (also called
transmembrane) proteins
2. Peripheral proteins
THE CELL CAN BE SUBDIVIDED INTO 3
PARTS:
1. Plasma (cell) membrane FUNCTIONS OF MEMBRANE PROTEINS
2. Cytoplasm -Membrane proteins can serve a variety of
• Cytosol functions
• Organelles -The different proteins help determine
3. Nucleus many of the functions of the cell
• Chromosomes membrane
• Genes
PLASMA MEMBRANE
-is a flexible yet sturdy barrier that
surrounds and contains the cytoplasm of
the cell
ANATOMY & PHYSIOLOGY
CHAPTER 3: The Cellular Level of Organization
MEMBRANE FLUIDITY - Macromolecules are only able to
◼ Membranes are fluid structures pass through the plasma membrane
because most of the membrane by vesicular transport
lipids and many of the membrane GRADIENTS ACROSS THE PLASMA
proteins move easily in the bilayer MEMBRANE
❑ Membrane lipids and proteins ◼ A concentration gradient is the
are mobile in their own half of difference in the concentration of a
the bilayer chemical between one side of the
◼ Cholesterol serves to stabilize the plasma membrane and the other
membrane and reduce membrane ◼ An electrical gradient is the
fluidity difference in concentration of ions
between one side of the plasma
membrane and the other
◼ Together, these gradients make up
an electrochemical gradient
Transport Across the Plasma Membrane
Transport processes that move substances
across the cell membrane are:
❑ Passive processes
◼ Simple diffusion
◼ Facilitated diffusion
◼ Osmosis
❑ Active processes
◼ Primary and Secondary
transport
MEMBRANE PERMEABILITY ◼ Vesicular transport
Plasma membranes are selectively
permeable PASSIVE TRANSPORT: SIMPLE DIFFUSION
- The lipid bilayer is always permeable Diffusion is influenced by:
to small, nonpolar, uncharged 1. Steepness of the concentration
molecules gradient
- Transmembrane proteins that act as 2. Temperature
channels or transporters increase the 3. Mass of diffusion substance
permeability of the membrane
ANATOMY & PHYSIOLOGY
CHAPTER 3: The Cellular Level of Organization
4. Surface area Passive Transport: Channel Mediated
5. Diffusion distance Facilitated Diffusion
Passive Transport: Carrier Mediated
Facilitated Diffusion
Passive Transport: Facilitated Diffusion
-Transmembrane proteins help solutes that
are too polar or too highly charged move
through the lipid bilayer
The processes involved are:
❑ Channel mediated facilitated
diffusion
❑ Carrier mediated facilitated
diffusion
Diffusion: A Comparison
Passive Transport: Osmosis
- The net movement of a solvent
through a selectively permeable
membrane from an area of high
concentration to an area of low
concentration
ANATOMY & PHYSIOLOGY
CHAPTER 3: The Cellular Level of Organization
PASSIVE TRANSPORT: SECONDARY
- Energy stored (in a hydrogen or
sodium concentration gradient) is
used to drive other substances
against their own concentration
gradients
TONICITY
-of a solution relates to how the solution
influences the shape of body cells
Active Transport in Vesicles: Receptor-
mediated Endocytosis
ACTIVE TRANSPORT: PRIMARY
- Energy derived from ATP changes
the shape of a transporter protein
which pumps a substance across a
plasma membrane against its
concentration gradient
ANATOMY & PHYSIOLOGY
CHAPTER 3: The Cellular Level of Organization
Active Transport in Vesicles: Phagocytosis Active Transport in Vesicles: Exocytosis &
Transcytosis
◼ Exocytosis – membrane-enclosed
secretory vesicles fuse with the
plasma membrane and release their
contents into the extracellular fluid
◼ Transcytosis – a combination of
endocytosis and exocytosis used to
move substances from one side of a
cell, across it, and out the other side
A COMPARISON OF TRANSPORT TYPES
Active Transport in Vesicles: Bulk Phase
Endocytosis (Pinocytosis)
ANATOMY & PHYSIOLOGY
CHAPTER 3: The Cellular Level of Organization
STRUCTURES OF CELL
CYTOSKELETON
CYTOPLASM
The cytoplasm has 2 components:
Cytosol - also known as the intracellular
fluid portion of the cytoplasm
Organelles - the specialized structures that
have specific shapes and perform specific
functions
CELL PARTS & THEIR FUNCTIONS
CENTROMES/CENTRIOLES
ANATOMY & PHYSIOLOGY
CHAPTER 3: The Cellular Level of Organization
CILIA & FLAGELLA ENDOPLASMIC RETICULUM
GOLGI COMPLEX
RIBOSOMES
ANATOMY & PHYSIOLOGY
CHAPTER 3: The Cellular Level of Organization
Lysosome PROTEASOMES
are barrel-shaped structures that destroy
unneeded,
damaged, or
faulty
proteins by
cutting long
proteins into
smaller
peptides
MITOCHONDRIA
Peroxisomes
-are structures that are similar in shape to
lysosomes, but are smaller and contain
enzymes
NUCLEUS
that use
oxygen to
oxidize
(break
down)
organic
substances.
ANATOMY & PHYSIOLOGY
CHAPTER 3: The Cellular Level of Organization
◼ The nucleus contains the hereditary PROTEIN SYNTHESIS: TRANSCRIPTION
units of the cell, called genes Transcription occurs in the nucleus and is
◼ Genes are arranged along the process by which genetic information
chromosomes. encoded in DNA is copied onto a strand of
RNA to direct protein synthesis
Protein Synthesis During Transcription
PROTEIN SYNTHESIS
Gene
Expression
ANATOMY & PHYSIOLOGY
CHAPTER 3: The Cellular Level of Organization
PROTEIN SYNTHESIS: TRANSLATION CELL DIVISION
Translation occurs in the nucleus and is the is a process by which cells reproduce
process of reading the mRNA nucleotide themselves
sequence to determine the amino acid ❑ Cell cycle
sequence of the newly formed protein
INTERPHASE
◼ G1 phase
◼ S
REPLICATION OF DNA ◼ G2 phase
MITOSIS
Mitosis occurs when the nucleus of a cell
divides Mitosis results in the distribution of
2 sets of chromosomes into 2 separate
nuclei
Mitosis is divided into 4 steps:
1. Prophase
2. Metaphase
3. Anaphase
4. Telophase
ANATOMY & PHYSIOLOGY
CHAPTER 3: The Cellular Level of Organization
MITOSIS: PROPHASE
-During prophase chromatin
condenses into chromosomes and
the nuclear membrane disappears
and centrosomes move to opposite
poles
MITOSIS: TELOPHASE
-During telophase the mitotic spindle
dissolves, chromosomes regain their
chromatin appearance, and a new nuclear
membrane forms
MITOSIS: METAPHASE
-During metaphase centromeres of
chromosomes line up at the metaphase
plate
CYTOKINESIS
During cytokinesis a cleavage furrow forms
MITOSIS: ANAPHASE and eventually the cytoplasm of the parent
During anaphase centromeres of cell fully splits
chromosomes split and sister chromatids ❑ When this is complete,
move toward opposite poles of the cell interphase begins
ANATOMY & PHYSIOLOGY
CHAPTER 3: The Cellular Level of Organization
Events of the Somatic Cell Cycle
Control of Cell Destiny
3 possible destinies:
1. Remain alive and functioning
without dividing
2. Grow and divide
3. Die
REPRODUCTIVE CELL DIVISION:
MEIOSIS I
ANATOMY & PHYSIOLOGY
CHAPTER 3: The Cellular Level of Organization
REPRODUCTIVE CELL DIVISION: MEIOSIS II CELLULAR DIVERSITY
AGING & CELLS
COMPARISON BETWEEN As we age:
MITOSIS (LEFT) AND MEIOSIS (RIGHT) -Our cells gradually deteriorate in
their ability function normally and in their
ability to respond to environmental
stresses
The numbers of our body cells
decreases
We lose the integrity of the
extracellular components of our tissues
DISORDERS
- Cancer
❑ Melanoma
❑ Sarcoma
❑ Osteogenic sarcoma
❑ Leukemia
❑ Lymphoma
- Growth and spread
- Causes
- Treatment
