Download Ch. 7 Cell Structure and Function

Chapter 7 CELLS
Chapter 7- Cell Structure
and Function
I. The Cell Theory
A. Development of Cell Theory (history)
1. 1500’s- first lenses used by merchants to
determine quality of cloth (look at precision of
the weave)
2. 1600’s- microscope and telescope
constructed
a. Anton van Leeuuwenhoekmade simple compound
microscope- observed living
things in pond water for the first
time
b. Robert Hooke- looked at thin slice of cork.
Noticed it was made of tiny chambers- called
them “cells” First to ID cells.
Hooke’s work stimulated others to
search for cells in other living
things. It became apparent that
cells were basic units of all
living things
c. 1838- Matthias Schleiden- German
botanist concluded all plants made of cells
d. 1839– Theodor SchwannConcluded that all animals made
up of cells
c. 1855- Rudolf VirchowRussian physician said “Where
a cell exists, there must have
been a preexisting cell……..”
What theory did this help to support?
The Theory of Biogenisis
B. The Cell Theory-summary of before
mentioned scientists and other biologists is one of
fundamental concepts of biology
1. All living things are composed of
cells
2. Cells are the basic units of
structure and function in all living
things.
3. New cells are produced from
existing cells
II. Basic Cell Structures
A. Cells come in many
shapes and sizes
a. Smallest- 0.2
micrometers (bacteria)
b. Largest- birds egg and giant amoeba (1000
micrometers)
B. Structures common in most Cells
1. Cell membrane-thin, flexible barrier around
the cell.
a. Many also have cell wall- strong layer
around the cell membrane (found in plants,
algae, fungi, and bacteria)
b. Support and protect cells,
while allowing them to interact
with surroundings.
2. Nucleus-large structure containing cell’s
genetic material- controls cell’s activities
(“brain”)
3. Cytoplasm- “soup-like liquid” inside the cell
membrane but not including nucleus.
C. Prokaryotes and Eukaryotes- Scientists
divide cells Into two groups depending on
whether they have a nucleus or not.
1. Prokaryotes-no nucleus - ex. bacteria
a. Smaller and simpler than
cells of eukaryotes
b. Do have cytoplasm and cell
membrane
c. Still carry out all activities
associated with life
2. Eukaryotes-do contain nucleus and
membrane bound organelles (includes
plants, animals, fungi)
a. Contain cytoplasm and cell
membrane
b. Also contain dozens of other
specialized structures called
organelles (means tiny
organs)
III. Cell Structure (a closer look)
A. Cell Membrane
1. Regulates what enters and exits the cell
2. Provides protection and support
3. Made of double-layered sheet called- lipid
bilayer with scattered proteins
Lipid molecules
4. Membrane is a “mosaic” of many different
kinds of molecules (protein channels and
pumps, carbohydrate “identification cards”)
B. Cell Wall- found in plants, algae, fungi, nearly
all prokaryotes. NOT animal cells
1. Lies outside the cell membrane- provides
support and protection for the cell
2. Made from fibers of carbohydrate (like
cellulose) and proteins
C. Nucleus- (first identified by Robert Brown in
1831
1. Controls most of cells processes and
contains hereditary information (DNA)
(controls activities with instructions for
making proteins)
2. Found in eukaryotic cells
3. Chromatin and Chromosomes-DNA
material visible inside the nucleus
a. Chromatin- short condensed strands
of DNA wrapped around histone proteins
b. Chromosomes- chromatin condenses
when cell gets ready to divide. Contains
genetic material passed from one generation
to the next
c. Nucleolus- small dense region in nucleus
where ribosomes are made
d. Nuclear envelope- double membrane layer
surrounding the nucleus containing tiny
nuclear pores (allows materials to move into
and out of nucleus. Eg. RNA)
D. Cytoskeleton1. Network of protein
filaments that help the cell to
maintain its shape and
involved in many forms of cell
movement
2. Made up of microtubules
and microfilaments
a. Microtubules- serve as “tracks” along
which organelles are moved. Important in
cell division- help to separate chromosomes.
Also form cillia and flagella which allow cells
to move
b. Microfilaments- long, thin
fibers function in movement
and support the cell
E. Organelles in the Cytoplasm- (act like
specialized “organs” in the cell)
1. Ribosomes- makes proteins (hormones
and enzymes) on Rough Endoplasmic
Reticulum.“Protein Synthesis”
2. Endoplasmic Reticulum- cell’s internal
transport system. “Assembly line”
a. Components of the cell membrane
assembled, some proteins modified and
stored like enzymes and hormones.
b. Rough ER- (has ribosomes attached)
and Smooth ER (no ribosomes)
3. Golgi Apparatus- “post office” of the cell.
“mails out” the proteins made at ER.
a. Carbohydrates and lipids (the packaging)
enclose the proteins or hormones.
b. Then sent to final destination
4. Lysosomes- “clean-up” crew of the cell
a. Break down lipids, carbohydrates,
proteins from food particles with enzymes
(little “digestive sacs”)
b. Break down ‘old’ cell parts, removing
debris
5. Vacuoles- storage “sacs”- store water, salts,
proteins, carbohydrates
a. Large in plant cells (single large
vacuole)
b. In animals, smaller vacuoles
called vesicles. They transport
substances within the cell
6. Chloroplasts- found in plants and some
other organisms (none found in animals and
fungi)
a. Produce energy-rich food (glucose) from
sunlight by photosynthesis
b. Green pigment- chlorophyll found in
photosynthetic membranes
7. Mitochondria- found in nearly all eukaryotic
cells “powerhouse”
a. Use energy from food to power growth,
development and movement
b. Cells that require more energy- have
more mitochondria
D. Organelle DNA- DNA found in mitochondria
and chloroplasts. Essential for normal function of
both organelles.
1. Mitochondria and chloroplasts thought to be
descendants of ancient prokaryotes. (theory of
Lynn Margulis)
2. Thought to have formed relationship with
early eukaryotic cells that benefited both cells
3. Mitochondrial DNA comes from mother
IV. Movement Through the Membrane
A. Cell Membrane- regulates what enters and
exits the cell and provides support and
protection
1. Lipid BilayerDouble layered sheet
(not soluble in water)
a. Contains protein molecules that form
chemical “pumps” and channels to
move material across membrane
b. Carbohydrate
molecules act like “ID
cards” allowing cells
to identify each other
and to allow certain
molecules in or out of
the cell
B. Diffusion- Movement of materials from
areas of high concentration to areas of low
concentration
1. All living cells have a liquid interior
(cytoplasm) and are surrounded by liquid
2. Diffusion causes many
substances to move across
cell membrane but does not
require the cell to use energy
(called passive transport)
3. Equilibrium- when
concentration of molecules
are equal on both sides of
membrane
C. Osmosis- Diffusion of water molecules
through selectively permeable membrane
1. Most membranes are selectively
permeable (some materials can pass
across membrane and others cannot) like
“coffee filter”
2. Effects of osmosis- water rushes to dilute
a. Isotonic- “same strength”
b. Hypotonic- “below strength”water-in;
greater solute concentration in cell.
c. Hypertonic- “above strength”water-out;
greater solute concentration out of cell.
hypotonic
solution
hypertonic
solution
Isotonic
solution
Hypertonic-water rushes out of the
cell to dilute the salt thus
losing water in the cell
making it “thirsty”.
3. Osmotic Pressure- osmosis exerts pressure
on hypertonic side of a cell membrane


a. Cells filled with salt, sugars, protiens and
other molecules always hypertonic to fresh
water.
b. Osmotic pressure produces movement of
water into a cell that is surrounded by fresh
water
3. Osmotic Pressure- osmosis exerts pressure
on hypertonic side of selectively permeable
membrane
a. Cells filled with salts, sugars, proteins and
other molecules- always hypertonic to fresh
water
b. Osmotic pressure produces movement of
water into cell that is surrounded by fresh
water.
c. Fortunately cells don’t come into contact
with fresh water. Usually bathed in isotonic
solutions (e.g. blood) or protected by cell
wall (e.g. bacteria) or mechanism to pump
out excess water (contractile vacuole)
D. Facilitated Diffusion- membrane proteins
help (faciliate) the movement of certain molecules
across the cell membrane by diffusion (from high
conc. To low conc.) that can’t diffuse through lipid
bilayer directly.)
1. Many different protein
channels for ions, sugars,
salts.
2. Does not require addition
of energy (passive transport)
E. Active Transport- movement of molecules
and ions against a concentration difference (from
low to high)
1. Requires input of energy
2. Small molecules “pumped” across
membrane (e.g. Na+ and K+ ions)
3. Large amounts of
material transported
through movements
of the cell
membrane
a. Endocytosis- movement into cell by
means of “infolding”
1). Pinocytosis- “cell drinking”
2). Phagocytosis- “cell eating”
b. Exocytosis- removal of large amounts of
material from a cell. Membrane of vacuole
surrounding the material fuses with the cell
membrane
V. The Diversity of Life
A. Unicellular Organisms- single celled
organisms
1. Perform all life functions (grow, respond to
environment, reproduce, etc.)
2. Unicellular organisms dominate life on Earth
B. Multicellular Organisms
1. Cell specialization- cells in multicellular
organisms are specialized to perform particular
functions within the organism
2. Cells are interdependent and do not live on
their own
C. Levels of Organization- levels of organization
that make it easier to classify and describe the
cells within an organism
1. Cells- smallest unit of living thing (e.g.
Nerve, muscle, bone, etc.)
2. Tissues- First level
of organization in
multicellular organism.
group of similar cells
that perform particular
function
3. Organs- groups of tissues working together.
(eg. Muscle, stomach, etc.)
4. Organ System- group of organs that work
together (11 major organ systems in human
body. E.g. Muscular, skeletal, circulatory, etc.)
5. Organism- living thing
Video
Quiz
The cell theory applies to
a.
bacteria.
b.
plants and animals.
c.
multicellular organisms.
d.
all of the above
The cell theory applies to
a.
bacteria.
b.
plants and animals.
c.
multicellular organisms.
d.
all of the above
Who was the first person to identify
and see cells?
a.
Anton van Leeuwenhoek
b.
Robert Hooke
c.
Matthias Schleiden
d.
Rudolf Virchow
Who was the first person to identify and see
cells?
a.
Anton van Leeuwenhoek
b.
Robert Hooke
c.
Matthias Schleiden
d.
Rudolf Virchow
Which cell structure contains the
cell's genetic material and controls
the cell's activities?
a.
organelle
b.
nucleus
c.
cell envelope
d.
cytoplasm
Which cell structure contains the cell's
genetic material and controls the cell's
activities?
a.
organelle
b.
nucleus
c.
cell envelope
d.
cytoplasm
Prokaryotes lack
a.
cytoplasm.
b.
a cell membrane.
c.
a nucleus.
d.
genetic material.
Prokaryotes lack
a.
cytoplasm.
b.
a cell membrane.
c.
a nucleus.
d.
genetic material.
Eukaryotes usually contain
a.
a nucleus.
b.
specialized organelles.
c.
genetic material.
d.
all of the above.
Eukaryotes usually contain
a.
a nucleus.
b.
specialized organelles.
c.
genetic material.
d.
all of the above.
The main function of the cell wall is to
a.
support and protect the cell.
b.
store DNA.
c.
direct the activities of the cell.
d.
help the cell move.
The main function of the cell wall is to
a. support and protect the cell
b. store DNA.
c. direct the activities of the cell.
d. help the cell move.
Which of the following is a function
of the cytoskeleton?
a.
helps a cell keep its shape
b.
contains DNA
c.
surrounds the cell
d.
helps make proteins
Which of the following is a function of the
cytoskeleton?
a.
helps a cell keep its shape
b.
contains DNA
c.
surrounds the cell
d.
helps make proteins
Which organelle breaks down food
into particles the cell can use?
a.
Golgi apparatus
b.
lysosome
c.
endoplasmic reticulum
d.
mitochondrion
Which organelle breaks down food into
particles the cell can use?
a.
Golgi apparatus
b.
lysosome
c.
endoplasmic reticulum
d.
mitochondrion
Which organelle makes proteins
using coded instructions that
come from the nucleus?
a.
Golgi apparatus
b.
mitochondrion
c.
vacuole
d.
ribosome
Which organelle makes proteins using
coded instructions that come from the
nucleus?
a.
Golgi apparatus
b.
mitochondrion
c.
vacuole
d.
ribosome
Which organelle converts food into
compounds that the cell uses for
growth, development, and movement?
a.
chloroplast
b.
Golgi apparatus
c.
endoplasmic reticulum
d.
mitochondrion
Which organelle converts food into
compounds that the cell uses for growth,
development, and movement?
a.
chloroplast
b.
Golgi apparatus
c.
mitochondria
d.
Endoplasimic reticulum
The cell membrane contains channels
and pumps that help move materials
from one side to the other. What are
these channels and pumps made of?
a.
carbohydrates
b.
lipids
c.
bilipids
d.
proteins
The cell membrane contains channels and
pumps that help move materials from one
side to the other. What are these channels
and pumps made of?
a.
carbohydrates
b.
lipids
c.
bilipids
d.
proteins
Diffusion is the movement of
molecules from
a.
an area of low concentration to an area
of high concentration.
b.
an area of high concentration to an area
of low concentration.
c.
an area of equilibrium to an area of high
concentration.
d.
all of the above
Diffusion is the movement of molecules from
a.
an area of low concentration to an area
of high concentration.
b. an area of high concentration
to an area of low concentration.
c.
an area of equilibrium to an area of high
concentration.
d.
all of the above
Which means of particle transport
requires input of energy from the
cell?
a.
diffusion
b.
osmosis
c.
facilitated diffusion
d.
active transport
Which means of particle transport requires
input of energy from the cell?
a.
diffusion
b.
osmosis
c.
facilitated diffusion
d.
active transport
The diffusion of water across a
selectively permeable membrane is
called
a.
osmotic pressure.
b.
osmosis.
c.
facilitated diffusion.
d.
active transport.
The diffusion of water across a selectively
permeable membrane is called
a.
osmotic pressure.
b.
osmosis.
c.
facilitated diffusion.
d.
active transport.
An animal cell that is surrounded by
fresh water will burst because the
osmotic pressure causes
a.
water to move into the cell.
b.
water to move out of the cell.
c.
solutes to move into the cell.
d.
solutes to move out of the cell.
An animal cell that is surrounded by fresh water
will burst because the osmotic pressure causes
a.
water to move into the cell.
b.
water to move out of the cell.
c.
solutes to move into the cell.
d.
solutes to move out of the cell.
Which term refers to cells having
different jobs in an organism?
a.
multicellular
b.
cell specialization
c.
levels of organization
d.
unicellular
Which term refers to cells having different
jobs in an organism?
a.
multicellular
b.
cell specialization
c.
levels of organization
d.
unicellular
A group of cells that perform similar
functions is called a(an)
a.
organ.
b.
organ system.
c.
tissue.
d.
division of labor.
A group of cells that perform similar functions
is called a(an)
a.
organ.
b.
organ system.
c.
tissue.
d.
division of labor.
What is the name of structure (a.)?
Rough Endoplasmic reticulum
What is the name of structure (b.)?
ribosome
Is this cell an animal or plant cell?
Animal cell
What is the name of structure (c.)?
Cell membrane
What is the name of structure (k.)?
nucleolus
What is the name of structure (g.)?
Golgi bodies
What is the name of structure (e.)?
Smooth endoplasmic reticulum
What is the name of structure (d.)?
mitochondria
What is the name of structure (m.)?
vacuole
What is the name of structure (k.)?
Cell membrane
What is the name of structure (j.)?
Cell wall
What is the name of structure (l.)?
chloroplast
What is the name of structure (f.)?
nucleus
What cell process is taking place
below?
phagocytosis
What cell structures found in the
organism below is responsible for
removing excess water from the
inside of the cell?
Contractile vacuole
What cell process is taking place
below?
osmosis