Transcript Chapter 1: Organization of the Human Body

Chapter 3
Cells and Their Functions
Copyright © 2015 Wolters Kluwer Health | Lippincott Williams & Wilkins
Key Terms
active transport
filtration
mitosis
cancer
gene
mutation
carcinogen
hemolysis
nucleus
chromosome
hypertonic
organelle
cytology
hypotonic
osmosis
cytoplasm
interphase
phagocytosis
diffusion
isotonic
plasma membrane
DNA
micrometer
ribosome
endocytosis
microscope
RNA
exocytosis
mitochondria
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The Cell
Cytology
• The study of cells
The Cell
• The basic unit of life
• Shows life characteristics
– Organization
– Homeostasis
– Metabolism
– Growth
– Responsiveness
– Reproduction
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Microscopes
Microscope
• An instrument that magnifies structures not visible to
the naked eye
• Types of microscopes:
– Compound light microscope
– Transmission electron microscope
– Scanning electron microscope
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Microscopes (cont.)
Figure 3-1 Cilia photographed under three different
microscopes.
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Microscopes (cont.)
Pop Quiz
3.1
Which microscope is most commonly used in
laboratories?
A) Scanning electron microscope
B) Transmission electron microscope
C) Compound light microscope
D) Simple light microscope
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Microscopes (cont.)
Pop Quiz Answer
3.1
Which microscope is most commonly used in
laboratories?
A) Scanning electron microscope
B) Transmission electron microscope
C) Compound light microscope
D) Simple light microscope
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Cell Structure (cont.)
General Cell Organization
• Plasma membrane
• Nucleus
• Cytoplasm
– Cytosol
– Organelles
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Cell Structure (cont.)
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
–
Proteins
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Cell Structure (cont.)
Table 3-1 Proteins in the Plasma Membrane and Their
Functions
Type of Protein
Function
Channels
Pores in the 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
Help stabilize the plasma membrane and
attach cells together
Cell identity markers
Proteins unique to a person’s cells;
important in the immune system and in
transplantation of tissue from one person to
another
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Cell Structure (cont.)
Figure 3-3 The plasma membrane.
Why is the plasma membrane described as a bilayer?
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Cell Structure (cont.)
Plasma Membrane (cont.)
• Membrane potential
– The difference in electric charge on either side of the
plasma membrane
– Caused by separation of positive and negative ions
and proteins on either side of the membrane
– Ion concentrations are determined by
• Channels
• Pumps
• Membrane potential allows the plasma membrane to act
as a battery. It uses electrical energy to power
membrane functions.
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Cell Structure (cont.)
Nucleus
• Largest organelle of cell
• Surrounded by a nuclear membrane
• Contains
– Chromosomes
• Units of heredity; govern all cellular activity
– Nucleolus
• Assembles ribosomes
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Cell Structure (cont.)
Cytoplasm
• Material between the nuclear membrane and plasma
membrane
– Cytosol
• Fluid portion of cytoplasm
– Organelles
• Specialized cell structures that perform different
cell functions
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Cell Structure (cont.)
Table 3-2 Cell Parts
Name
PLASMA MEMBRANE
Description
Function
Outer layer of the cell; composed mainly of lipids and Encloses the cell contents; regulates what
proteins
enters and leaves the cell; participates in
many activities, such as growth,
reproduction, and interactions between cells
Microvilli
NUCLEUS
Short extensions of the plasma membrane
Absorb materials into the cell
Large, membrane-bound, dark-staining organelle near Contains the chromosomes, the hereditary
the center of the cell
structures that direct all cellular activities
Nucleolus
CYTOPLASM
Small body in the nucleus
Makes ribosomes
Colloid that fills the cell from the nuclear membrane to Site of many cellular activities; consists of
the plasma membrane
cytosol and organelles
Cytosol
The fluid portion of the cytoplasm; contains water,
enzymes, nutrients, and other substances
Endoplasmic reticulum Network of membranes within the cytoplasm. Rough
(ER)
ER has ribosomes attached to it; smooth ER does
not
Ribosomes
Small bodies free in the cytoplasm or attached to the
ER; composed of RNA and protein
Golgi apparatus
Layers of membranes
Mitochondria
Lysosomes
Peroxisomes
Proteasomes
Vesicles
Large organelles with internal folded membranes
Small sacs of digestive enzymes
Membrane-enclosed organelles containing enzymes
Barrel-shaped organelles
Small membrane-bound sacs in the cytoplasm
Centrioles
Rod-shaped bodies (usually two) near the nucleus
SURFACE PROJECTIONS
Cilia
Flagellum
Structures that extend from the cell
Short, hairlike projections from the cell
Long, whiplike extension from the cell
Surrounds the organelles; site of many
chemical reactions and nutrient storage
Rough ER modifies, folds, and sorts proteins;
smooth ER participates in lipid synthesis
Manufacture proteins
Further modifies proteins; sorts and prepares
proteins for transport to other parts of the
cell or out of the cell
Convert energy from nutrients into ATP
Digest substances within the cell
Break down harmful substances
Destroy improperly synthesized proteins
Store materials and move materials into or
out of the cell in bulk
Help separate the chromosomes during cell
division
Move the cell or the fluids around the cell
Move the fluids around the cell
Moves the cell
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Cell Structure (cont.)
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
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Cell Structure (cont.)
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.
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Cell Structure (cont.)
Figure 3-4 Cellular diversity.
Which of the cells shown would best cover a large surface
area?
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Cell Structure (cont.)
Pop Quiz
3.2
What is the main substance of the plasma
membrane?
A) Cholesterol
B) Phospholipid
C) Protein
D) Steroid
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Cell Structure (cont.)
Pop Quiz Answer
3.2
What is the main substance of the plasma
membrane?
A) Cholesterol
B) Phospholipid
C) Protein
D) Steroid
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Cell Structure (cont.)
Pop Quiz
3.3
Which organelle generates ATP?
A) Centriole
B) Golgi apparatus
C) Mitochondrion
D) Ribosome
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Cell Structure (cont.)
Pop Quiz Answer
3.3
Which organelle generates ATP?
A) Centriole
B) Golgi apparatus
C) Mitochondrion
D) Ribosome
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Movement of Substances across the
Plasma Membrane (cont.)
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
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Movement of Substances across the
Plasma Membrane (cont.)
Figure 3-5 Diffusion of a solid in a liquid.
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Movement of Substances across the
Plasma Membrane (cont.)
Figure 3-6 Diffusion using transporters.
How would a change in the number of transporters affect a
solute’s movement by facilitated diffusion?
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Movement of Substances across the
Plasma Membrane (cont.)
Figure 3-7 A simple demonstration of osmosis.
What would happen in this system if the solute could pass
through the membrane?
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Movement of Substances across the
Plasma Membrane (cont.)
Figure 3-8 Osmotic pressure.
What would happen to osmotic pressure if the
concentration of solute were increased on side B of this
system?
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Movement of Substances across the
Plasma Membrane (cont.)
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
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Movement of Substances across the
Plasma Membrane (cont.)
Table 3-3 Solutions and Their Effects on Cells
Solution
Description
Examples
Effect on Cells
Isotonic
Has the same
concentration of
dissolved substances
as the fluid in the cell
0.9% salt
(normal
saline);
5% glucose
None
Hypotonic
Has a lower
concentration of
dissolved substances
than fluid in the cell
Less than
0.9% salt or
5% glucose
Cell takes in
water and may
burst (lysis)
Hypertonic
Has a higher
concentration of
dissolved substances
than fluid in the cell
Higher than
0.9% salt or
5% glucose
Cell loses water
and shrinks
(crenation)
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Movement of Substances across the
Plasma Membrane (cont.)
Figure 3-9 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?
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Movement of Substances across the
Plasma Membrane (cont.)
Table 3-4 Membrane Transport
Process
Definition
Example
Do not require cellular energy (passive)
Diffusion
Random movement of particles down the
Movement of gases through the membrane,
concentration gradient (from higher concentration to ions through an ion channel, or nutrients
lower concentration)
via transporters
Osmosis
Diffusion of water through a semipermeable
Movement of water across the plasma
membrane
membrane through aquaporins
Filtration
Movement of materials through a membrane down a Movement of materials out of the blood
pressure gradient
under the force of blood pressure
Require cellular energy
Active transport (pumps) Movement of materials through the plasma membrane Transport of ions (e.g., Na+, K+, and Ca2+) in
against the concentration gradient using transporters neurons
Bulk transport
Endocytosis
Exocytosis
Movement of large amounts of material through the
plasma membrane using vesicles; also called
vesicular transport
Transport of bulk amounts of materials into the cell
using vesicles
Transport of bulk materials out of the cell using
vesicles
Phagocytosis—intake of large particles, as
when white blood cells take in waste
materials; also pinocytosis (intake of fluid),
and receptor-mediated endocytosis,
requiring binding sites in the plasma
membrane
Release of neurotransmitters from neurons
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Movement of Substances across the
Plasma Membrane (cont.)
Figure 3-10 Phagocytosis.
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Movement of Substances across the
Plasma Membrane (cont.)
Figure 3-11 Exocytosis.
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Movement of Substances across the
Plasma Membrane (cont.)
Pop Quiz
3.4
Which process uses transporters but not ATP?
A) Active transport
B) Endocytosis
C) Facilitated diffusion
D) Simple diffusion
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Movement of Substances across the
Plasma Membrane (cont.)
Pop Quiz Answer
3.4
Which process uses transporters but not ATP?
A) Active transport
B) Endocytosis
C) Facilitated diffusion
D) Simple diffusion
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Movement of Substances across the
Plasma Membrane (cont.)
Pop Quiz
3.5
Which method transports bulk amounts of material
into the cell using vesicles?
A) Active transport
B) Endocytosis
C) Exocytosis
D) Osmosis
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Movement of Substances across the
Plasma Membrane (cont.)
Pop Quiz Answer
3.5
Which method transports bulk amounts of material
into the cell using vesicles?
A) Active transport
B) Endocytosis
C) Exocytosis
D) Osmosis
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Movement of Substances across the
Plasma Membrane (cont.)
Pop Quiz
3.6
Cells crenate when they are placed in solutions that
are
A) Catatonic
B) Hypertonic
C) Hypotonic
D) Isotonic
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Movement of Substances across the
Plasma Membrane (cont.)
Pop Quiz Answer
3.6
Cells crenate when they are placed in solutions that
are
A) Catatonic
B) Hypertonic
C) Hypotonic
D) Isotonic
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Protein Synthesis (cont.)
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.
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Protein Synthesis (cont.)
Figure 3-12 Chromosomes and DNA.
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Protein Synthesis (cont.)
Table 3-5 Comparison of DNA and RNA
DNA
Location
RNA
Almost entirely in the nucleus Almost entirely in the cytoplasm
Composition Nucleotides contain adenine
(A), guanine (G), cytosine
(C), or thymine (T)
Sugar: deoxyribose
Structure
Function
Nucleotides contain adenine (A),
guanine (G), cytosine (C), or
uracil (U)
Sugar: ribose
Double-stranded helix formed Single strand
by nucleotide pairing A–T; G–
C
Makes up the chromosomes, Manufacture proteins according
hereditary units that control to the codes carried in the DNA;
all cellular activities; divided three main types: messenger
into genes that carry the
RNA (mRNA), ribosomal RNA
nucleotide codes for the
(rRNA), and transfer RNA
manufacture of proteins
(tRNA)
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Protein Synthesis (cont.)
Table 3-6 The Genetic Code
Amino Acid
Transcribed DNA
mRNA
tRNA
Triplet
Glycine
CCC
GGG
CCC
Proline
GGG
CCC
GGG
Valine
CAC
GUG
CAC
Phenylalanine
AAA
UUU
AAA
The nucleotide triplet code in DNA and RNA is shown
for four amino acids.
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Protein Synthesis (cont.)
Table 3-7 Role of RNA
Types
Function
Messenger
RNA (mRNA)
Is built on a strand of DNA in the nucleus and
transcribes the nucleotide code
Moves to cytoplasm and attaches to a ribosome
Ribosomal
RNA (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
Transfer RNA
(tRNA)
Works with other forms of RNA 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.
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Protein Synthesis (cont.)
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
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Protein Synthesis (cont.)
Figure 3-13 Transcription.
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Protein Synthesis (cont.)
Figure 3-14 Translation.
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Protein Synthesis (cont.)
Pop Quiz
3.7
Which DNA nucleotide pairs with adenine?
A) Cytosine
B) Guanine
C) Thymine
D) Uracil
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Protein Synthesis (cont.)
Pop Quiz Answer
3.7
Which DNA nucleotide pairs with adenine?
A) Cytosine
B) Guanine
C) Thymine
D) Uracil
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Protein Synthesis (cont.)
Pop Quiz
3.8
Which RNA is transcribed from DNA?
A) Amino acid
B) Messenger RNA
C) Ribosomal RNA
D) Transfer RNA
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Protein Synthesis (cont.)
Pop Quiz Answer
3.8
Which RNA is transcribed from DNA?
A) Amino acid
B) Messenger RNA
C) Ribosomal RNA
D) Transfer RNA
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Protein Synthesis (cont.)
Pop Quiz
3.9
What is synthesized during translation?
A) Amino acid
B) Protein
C) Starch
D) Triglyceride
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Protein Synthesis (cont.)
Pop Quiz Answer
3.9
What is synthesized during translation?
A) Amino acid
B) Protein
C) Starch
D) Triglyceride
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Cell Division (cont.)
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
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Cell Division (cont.)
Preparation for Mitosis
• DNA replicates during interphase
• Identical strands held together at centromere until they
separate during mitosis
DNA replication
during interphase
Mitosis
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Cell Division (cont.)
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
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Cell Division (cont.)
Figure 3-15 The stages of mitosis.
If the original cell shown has 46 chromosomes, how many
chromosomes will each new daughter cell have?
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Protein Synthesis (cont.)
Pop Quiz
3.10 During which phase of mitosis are chromosomes
first visible?
A) Anaphase
B) Metaphase
C) Prophase
D) Telophase
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Protein Synthesis (cont.)
Pop Quiz Answer
3.10 During which phase of mitosis are chromosomes
first visible?
A) Anaphase
B) Metaphase
C) Prophase
D) Telophase
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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
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Cells and Cancer (cont.)
Development of Cancer
• Genetic mutations may cause uncontrolled cell division.
• Cells may spread (metastasize), producing cancer.
• Cancer cells form tumors, crowding out normal cells.
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Cells and Cancer (cont.)
Cancer Risk Factors
• Heredity
• Chemicals
• Radiation
• Diet
• Viruses
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Cells and Cancer (cont.)
Pop Quiz
3.11 Which of the following is a cancer risk factor?
A) A diet rich in fruits and vegetables
B) A family history of cancer
C) Regular exercise
D) Regular use of sunscreen
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Cells and Cancer (cont.)
Pop Quiz Answer
3.11 Which of the following is a cancer risk factor?
A) A diet rich in fruits and vegetables
B) A family history of cancer
C) Regular exercise
D) Regular use of sunscreen
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Case Study
Learning Objective
12. Use the case study to discuss the
importance of the plasma
membrane to the functioning of
the body as a whole.
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Case Study (cont.)
• Cystic fibrosis is an inherited disease
• Ben’s parents each carried a defective gene in their DNA
and both had by chance passed copies of the gene onto
Ben
• As a result, Ben was unable to synthesize a channel
protein causing a defect in the movement of chloride
into the cell
• Abnormal chloride channel function causes many organs
to produce thick, sticky mucus resulting in effects on the
entire body), for example, the lung (difficulty
breathing), intestines (inadequate absorption of
nutrients), pancreas (inability to produce digestive
enzymes)
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Word Anatomy (cont.)
Word
Part
Meaning
Example
Microscopes
cyt/o
cell
Cytology is the study of cells.
micr/o
small
Microscopes are used to view structures too
small to see with the naked eye.
Cell Structure
bi-
two
The lipid bilayer is a double layer of lipid
molecules.
chrom/o
color
Chromosomes are small, threadlike bodies
that stain darkly with basic dyes.
end/o
in, within
The endoplasmic reticulum is a membranous
network within the cytoplasm.
lys/o
loosening,
dissolving,
separating
Lysosomes are small bodies (organelles)
with enzymes that dissolve materials (see
also hemolysis).
-some
body
Ribosomes are small bodies in the
cytoplasm that help make proteins.
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Word Anatomy (cont.)
Word Part
Meaning
Example
Movement across the Plasma Membrane
ex/o
outside, out of,
away
In exocytosis, the cell moves material out from
vesicles.
hem/o
blood
Hemolysis is the destruction of red blood cells.
hyper-
above, over,
excessive
A hypertonic solution’s concentration is higher
than that of the cytoplasm.
hypo-
deficient, below,
beneath
A hypotonic solution’s concentration is lower than
that of the cytoplasm.
iso-
same, equal
An isotonic solution has the same concentration as
that of the cytoplasm.
phag/o
to eat, ingest
In phagocytosis, the plasma membrane engulfs
large particles and moves them into the cell.
pin/o
to drink
In pinocytosis, the plasma membrane “drinks”
(engulfs) droplets of fluid.
semi-
partial, half
A semipermeable membrane lets some molecules
pass through but not others.
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Word Anatomy (cont.)
Word Part Meaning
Example
Cell Division
ana-
upward, back,
again
In the anaphase stage of mitosis,
chromosomes move to opposite sides of the
cell.
inter-
between
Interphase is the stage between one cell
division (mitosis) and the next.
meta-
change
Metaphase is the second stage of mitosis
when the chromosomes change position and
line up across the equator.
pro-
before, in front
of
Prophase is the first stage of mitosis.
tel/o
end
Telophase is the last stage of mitosis.
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Word Anatomy (cont.)
Word Part Meaning
Example
Cells and Cancer
carcin/o
cancer,
carcinoma
A carcinogen is a chemical that causes
cancer.
-gen
agent that
produces or
originates
See preceding example.
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