Transcript Chapter 1: Organization of the Human Body

Chapter 3:
Cells and Their
Functions
Copyright © 2013 Wolters Kluwer Health | Lippincott Williams & Wilkins
Cohen: Memmler’s The Human Body in Health and Disease
Overview
Copyright © 2013 Wolters Kluwer Health | Lippincott Williams & Wilkins
Cohen: Memmler’s The Human Body in Health and Disease
The Cell
Cytology
• The study of cells
The Cell
• The basic unit of life
• Shows life characteristics
– Organization
– Homeostasis
– Metabolism
– Growth
– Responsiveness
– Reproduction
Copyright © 2013 Wolters Kluwer Health | Lippincott Williams & Wilkins
Cohen: Memmler’s The Human Body in Health and Disease
Microscopes
Cytology
• The study of cells
Microscope
• An instrument that magnifies structures not visible with
the naked eye
• Types of microscopes:
– Compound light microscope
– Transmission electron microscope
– Scanning electron microscope
Copyright © 2013 Wolters Kluwer Health | Lippincott Williams & Wilkins
Cohen: Memmler’s The Human Body in Health and Disease
Figure 3-1 Cilia photographed under three different
microscopes.
Which microscope shows the most internal structure of the cilia? Which shows the
cilia in three dimensions?
Copyright © 2013 Wolters Kluwer Health | Lippincott Williams & Wilkins
Cohen: Memmler’s The Human Body in Health and Disease
Cell Structure
General Cell Organization
• Plasma membrane
– Selectively permeable
– Also called the cell membrane
• Nucleus
• Cytoplasm
– Cytosol
– Organelles
Copyright © 2013 Wolters Kluwer Health | Lippincott Williams & Wilkins
Cohen: Memmler’s The Human Body in Health and Disease
Figure 3-2 A generalized animal cell, sectional view.
What is attached to the ER to make it look rough? What is the liquid part of the
cytoplasm called?
Copyright © 2013 Wolters Kluwer Health | Lippincott Williams & Wilkins
Cohen: Memmler’s The Human Body in Health and Disease
Cell Structure
Plasma Membrane
• Encloses cell contents
• Regulates what enters and leaves cell
• Participates in many cell activities (e.g., growth,
reproduction, cell-to-cell interactions)
• Plasma membrane components
–
Phospholipid bilayer
–
Cholesterol
•
–
Main lipid in plasma membrane*
Proteins
Copyright © 2013 Wolters Kluwer Health | Lippincott Williams & Wilkins
Cohen: Memmler’s The Human Body in Health and Disease
Cell Structure
Table 3-1 Proteins in the plasma membrane and their
functions.
Type of Protein
Function
Channels
Pores in membrane that allow passage of
specific substances
*Transporters
Shuttle substances across membrane
Receptors
Allow for attachment of substances to
membrane; used for cell-to-cell signaling
Enzymes
Participate in chemical reactions at
membrane surface
*Linkers
Give structure to membrane and attach cells
to other cells
Cell identity markers
Proteins unique to a person’s cells;
important for immunity
Copyright © 2013 Wolters Kluwer Health | Lippincott Williams & Wilkins
Cohen: Memmler’s The Human Body in Health and Disease
Cell Structure
Nucleus
• Largest organelle of cell
• Surrounded by nuclear membrane
• Contains
– Chromosomes
• Units of heredity; govern all cellular activity
– Nucleolus
• Assembles ribosomes
Copyright © 2013 Wolters Kluwer Health | Lippincott Williams & Wilkins
Cohen: Memmler’s The Human Body in Health and Disease
Cell Structure
Cytoplasm
• Material between nuclear membrane and plasma
membrane
– Cytosol
• Fluid portion of cytoplasm
– Organelles
• Specialized cell structures that perform
different cell functions
Copyright © 2013 Wolters Kluwer Health | Lippincott Williams & Wilkins
Cohen: Memmler’s The Human Body in Health and Disease
Organelles*
• Mitochondria
– Power plants
• Golgi apparatus
– Sort and modify proteins
• Lysosomes
– Remove wast and foreign material
• Peroxisomes
– Contain enzymes that destroy harmful substances
produced in metabolism
• Vesicles
– Storage sacs/microbodies
Copyright © 2013 Wolters Kluwer Health | Lippincott Williams & Wilkins
Cohen: Memmler’s The Human Body in Health and Disease
Cell Structure
Table 3-2 Cell parts (cytoplasmic organelles).
Name
Description
Function
Endoplasmic
reticulum
(ER)
Membranous network; only
rough ER has ribosomes;
smooth ER does not
Rough ER sorts and
modifies proteins; smooth
ER synthesizes lipids
*Ribosomes
Small bodies in cytoplasm or
attached to rough ER
Manufacture proteins
Mitochondri
a
Large bodies with internal
folded membranes
Manufacture ATP
Golgi
apparatus
Layers of membranous sacs
Prepares proteins for
export
*Lysosomes, Small sacs of enzymes
Peroxisomes
Digest intracellular
substances
Vesicles
Small storage sacs
Store materials; move
materials into or out of cell
Centrioles
Rod-shaped near nucleus
Separate chromosomes
during cell division
Copyright © 2013 Wolters Kluwer Health | Lippincott Williams & Wilkins
Cohen: Memmler’s The Human Body in Health and Disease
Cell Structure
Surface Projections
• Structures that extend from the cell
– Cilia
• Short, hairlike projections
• Move fluids around cells
– Flagellum
• Long, whiplike extension from the cell
• Moves cell
Copyright © 2013 Wolters Kluwer Health | Lippincott Williams & Wilkins
Cohen: Memmler’s The Human Body in Health and Disease
Cell Structure
Cellular Diversity
•Cell shape is related to cell function.
– A neuron’s long fibers transmit electric energy from
place to place in the nervous system.
– Small round red blood cells slide through tiny blood
vessels.
•Cell organelle number is related to cell function.
– Lipid-producing cells have lots of smooth ER.
– Metabolically active cells have lots of mitochondria to
manufacture ATP.
Copyright © 2013 Wolters Kluwer Health | Lippincott Williams & Wilkins
Cohen: Memmler’s The Human Body in Health and Disease
Figure 3-5 Cellular diversity.
Which of the cells shown would best cover a large surface area?
Copyright © 2013 Wolters Kluwer Health | Lippincott Williams & Wilkins
Cohen: Memmler’s The Human Body in Health and Disease
Movement of Substances Across the
Plasma Membrane
Selective Permeability
• Plasma membrane regulates what enters and leaves
• Travel across membrane is based on several factors
– Molecular size
– Solubility
– Electrical charge
• Types of travel
– Movement that does not require cellular energy
– Movement that requires cellular energy
Copyright © 2013 Wolters Kluwer Health | Lippincott Williams & Wilkins
Cohen: Memmler’s The Human Body in Health and Disease
Movement of Substances Across the
Plasma Membrane
Movement That Does Not Require Cellular Energy
Process
Definition
Example
Diffusion
Solute travels across plasma
membrane down its
concentration gradient
Movement of lipidsoluble materials across
plasma membrane
Facilitated
diffusion
Solute diffuses with help of a
transporter
Movement of glucose
into cell
Osmosis
Solvent travels across plasma
membrane down its
concentration gradient
Movement of water
across plasma
membrane
Filtration
Mechanical force pushes solute
and solvent across plasma
membrane
Movement of solutes and
water out of blood under
force of blood pressure
Copyright © 2013 Wolters Kluwer Health | Lippincott Williams & Wilkins
Cohen: Memmler’s The Human Body in Health and Disease
Figure 3-6 Diffusion of a solid in a liquid.
Copyright © 2013 Wolters Kluwer Health | Lippincott Williams & Wilkins
Cohen: Memmler’s The Human Body in Health and Disease
Movement of Substances Across the
Plasma Membrane
How Osmosis Affects Cells
• Another way to think about osmosis is in terms of solute
concentration.
High Solute
Low Solute
Osmosis
High Water
Low Water
Water Follows the Salt
Copyright © 2013 Wolters Kluwer Health | Lippincott Williams & Wilkins
Cohen: Memmler’s The Human Body in Health and Disease
Movement of Substances Across the
Plasma Membrane
Solutions and Their Effects on Cells
Solution
Description
Examples
Effect on Cells
Isotonic
Has same solute
concentration as cell
0.9% salt;
5% glucose
None
Hypotonic
Has lower solute
concentration than cell
<0.9% salt;
<5% glucose
Cell takes in
water and may
burst (lysis)
Hypertonic
Has higher solute
concentration than cell
>0.9% salt;
>5% glucose
Cell loses water
and shrinks
(crenation)
Copyright © 2013 Wolters Kluwer Health | Lippincott Williams & Wilkins
Cohen: Memmler’s The Human Body in Health and Disease
Figure 3-10 The effect of osmosis on cells.
What would happen to red blood cells in the body if blood lost through injury
were replaced with pure water?
Copyright © 2013 Wolters Kluwer Health | Lippincott Williams & Wilkins
Cohen: Memmler’s The Human Body in Health and Disease
Figure 3-11 Filtration.
Copyright © 2013 Wolters Kluwer Health | Lippincott Williams & Wilkins
Cohen: Memmler’s The Human Body in Health and Disease
Movement of Substances Across the
Plasma Membrane
Movement That Requires Cellular Energy
Process
Definition
Example
Active
transport
Solute moves through plasma
membrane against its
concentration gradient with
help of transporters
Ion movement in
nervous system and
muscular system
Endocytosis
Large amounts of solute and
solvent are transported into
cell using vesicles
Phagocytosis of waste
materials by white blood
cells
Exocytosis
Large amounts of solute and
solvent are transported out of
the using vesicles
Release of
neurotransmitters from
neurons
Copyright © 2013 Wolters Kluwer Health | Lippincott Williams & Wilkins
Cohen: Memmler’s The Human Body in Health and Disease
Protein Synthesis
Overview
• Proteins give a cell its structure and function.
• DNA directs protein synthesis.
– Nucleotides make up DNA
– DNA organized into genes
– Genes organized into chromosomes
• RNA participates in protein synthesis but is not part of
chromosomes.
Copyright © 2013 Wolters Kluwer Health | Lippincott Williams & Wilkins
Cohen: Memmler’s The Human Body in Health and Disease
Figure 3-15 Structure of DNA.
Two of the DNA nucleotides (A and
G) are larger in size than the other
two (T and C). How do the
nucleotides pair up with regard to
size?
Copyright © 2013 Wolters Kluwer Health | Lippincott Williams & Wilkins
Cohen: Memmler’s The Human Body in Health and Disease
Protein Synthesis
Role of RNA
Types
Function
mRNA
- Is built on a strand of DNA in the nucleus and
transcribes the nucleotide code
- Moves to cytoplasm and attaches to a ribosome
rRNA
- With protein makes up the ribosomes, the sites of
protein synthesis in the cytoplasm
- Involved in the process of translating the genetic
message into a protein
tRNA
- Works with mRNA and rRNA to translate the genetic
code into protein
- Each molecule of tRNA carries an amino acid that can
be used to build a protein at the ribosome.
Copyright © 2013 Wolters Kluwer Health | Lippincott Williams & Wilkins
Cohen: Memmler’s The Human Body in Health and Disease
Protein Synthesis
Two-Step Process of Protein Synthesis
• Transcription
– First step; occurs in nucleus
– DNA code is transcribed into mRNA by nucleotide base
pairing
• Translation
– Second step; occurs in cytoplasm
– mRNA leaves nucleus and travels to ribosomes
– Ribosomes and tRNA translate mRNA into protein’s
amino acid sequence
Copyright © 2013 Wolters Kluwer Health | Lippincott Williams & Wilkins
Cohen: Memmler’s The Human Body in Health and Disease
Cell Division
Types of Cell Division
• Meiosis
– Produces gametes (n)
– Cuts chromosome number in half to prepare for union
of egg and sperm during fertilization
• Mitosis
– Produces somatic cells (2n)
– Parent stem cell gives rise to two identical daughter
cells
Copyright © 2013 Wolters Kluwer Health | Lippincott Williams & Wilkins
Cohen: Memmler’s The Human Body in Health and Disease
Cell Division
Preparation for Mitosis
• DNA replicates during interphase
• Identical strands held together at centromere until they
separate during mitosis
DNA replication
during interphase
Mitosis
Copyright © 2013 Wolters Kluwer Health | Lippincott Williams & Wilkins
Cohen: Memmler’s The Human Body in Health and Disease
Cell Division
Stages of Mitosis
Description
Prophase
- DNA strands coil into chromosomes
- Nucleolus and nuclear membrane disappear
- Centrioles move to opposite poles and form spindle
Metaphase
- Chromosomes line up across center of cell
- Chromosomes attach to spindle
Anaphase
- Centromeres split
- Identical chromosomes move toward opposite
centrioles
Telophase
- Chromosomes continue to move toward centrioles
- Nuclear membrane forms around each group of
chromosomes
- Plasma membrane pinches off in middle of cell to form
two new identical daughter cells
Copyright © 2013 Wolters Kluwer Health | Lippincott Williams & Wilkins
Cohen: Memmler’s The Human Body in Health and Disease
Figure 3-18 The stages of mitosis.
If the original cell shown has 46 chromosomes, how many chromosomes will
each new daughter cell have?
Copyright © 2013 Wolters Kluwer Health | Lippincott Williams & Wilkins
Cohen: Memmler’s The Human Body in Health and Disease
Cell Aging
• As cells multiply, changes occur that may lead to their
damage or death.
– Free radical injury
– Enzyme injury
– Gene mutation
– Slowing cell activity
– Apoptosis
Copyright © 2013 Wolters Kluwer Health | Lippincott Williams & Wilkins
Cohen: Memmler’s The Human Body in Health and Disease
Word Anatomy
Word Part Meaning
Example
cyt/o
cell
Cytology is the study of cells.
endo-
in, within
The endoplasmic reticulum within the
cytoplasm.
hypo-
deficient, below,
beneath
A hypotonic solution’s concentration is lower
than cytoplasm’s.
hyper-
above, over,
excessive
A hypertonic solution’s concentration is
higher than cytoplasm’s.
exo-
outside, out of,
away
In exocytosis, the cell moves material out
from vesicles.
pro-
before, in front
Prophase is the first stage of mitosis.
meta-
change
During metaphase chromosomes change
position and line up across the equator.
ana-
upward, back,
again
During anaphase, chromosomes move to
opposite sides of the cell.
tel/o
end
Telophase is the last stage of mitosis.
Copyright © 2013 Wolters Kluwer Health | Lippincott Williams & Wilkins