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Chapter 7
Cell Structure
and
Function
7.1 Life is Cellular
•Discovery of the Cell/ Cell Theory
formulation: scientists and their contributions
•Leeuwenhoek: invented single-lens microscope
•Hooke: looked at slice of cork, named the cell
•Schleiden: concluded all plants are made of cells
•Schwann: concluded all animals are made of cells
•Virchow: concluded that cells come from
preexisting cells
The Cell Theory
1. All living things are made up of cells.
2. Cells are basic units of structure and function in
living things.
3. New cells are produced from existing cells.
-one cell splitting
into two new cells
•Prokaryote
Cells
-Small, simple
-No nucleus
Have:
-Cytoplasm
-Cell Membrane
-Ribosomes
•All Bacteria- Archaebacteria, Eubacteria
•Eukaryote
-Larger, more complex
–Have
-Nucleus
-Cytoplasm
-Cell Membrane
-Ribosomes
-organelles-specialized
structures
•Plants, Animals, Fungi, Protists
Eukaryotic Cells
• Contains Organelles
- “tiny organs”
inside the cell
- are Specialized:
have a specific
function (job to do)
7.2 Cell Structure and Function
Structure
Function
Location
1. Cytoplasm
-site of chemical activity
and supports cell
structure
-inside cell membrane
of prokaryotic &
eukaryotic cells
2. Cell Membrane
-allows certain materials
in and out of the cell
-outside cytoplasm of
prokaryotic &
eukaryotic cells
3. Cell Wall
-support/protection
-outside cell membrane
of Prokaryotic cells and
some Eukaryotic cells
Structure
4. Nucleus
5. Chromatin
Function
Location
-controls cell processes/holds DNA -anywhere in
Eukaryotic cells
-DNA bound to protein;
-inside nucleus in
in non-dividing cells
eukaryotic cell
6. Chromosomes
-tightly coiled chromatin
-inside nucleus in
/containing genetic info.; in
eukaryotic cell
dividing cell
-inside nucleus in
7. Nucleolus
eukaryotic cell
-makes ribosomes
8. Nuclear envelope -protects nucleus
-surrounds nucleus
9. Nuclear pores -allow things to enter/exit nucleus -in nuclear envelope
Structure
10. Ribosomes
Function
-make protein used inside cell
11. Endoplasmic Reticulum
-makes lipids, detoxes
a. Smooth ER
(ex. liver cells)
b. Rough ER -makes proteins and
modifies proteins exported
or become part of cell
membrane
Location
-free or attached to
ER Prokaryotic =
free and Eukaryotic
cells = both types
-within cytoplasm
of Eukaryotic cells
-within cytoplasm
of Eukaryotic cells
12. Golgi Apparatus
- attaches carbs/lipids to
proteins made by RER and
sends off (modify, sort,
secrete)
-within cytoplasm
of Eukaryotic cells
Structure
13. Lysosomes
Function
-break down lipids, carbs
and proteins for cell to
use (clean up crew)
Location
-cytoplasm of animal
cells (are eukaryotic
cells); but not plant
cells
14. Vacuoles
- store materials/transport -cytoplasm of plant
(water, salts, proteins,
cells; much smaller in
carbs)
animal cells
15. Mitochondria
-site of ATP synthesis,
-cytoplasm of
cellular respiration
Eukaryotic cells
(powerhouse of the cell)
Structure
Function
Location
16. Chloroplast
-site of photosynthesis -within cytoplasm of
convert sunlight into plant and some protist
food
cells (eukaryotic cells)
17. Cytoskeleton
-maintain cell shape
-within cytoplasm of
prok. and euk.
a. Microtubules -cell shape/tracking
•forms
-movement
cilia: short hair-like projections
flagella: long whip-like projections -movement
centrioles: help organize cell division -near
nucleusanimal cell
b. Microfilaments -movement/support
7.3 Cell Boundaries
Cell (Plasma) Membrane
Function: 1. Regulates what enters/leaves cell
2. Protection/support
-Made up of:
1. Lipid bilayer
2. Proteins
a. transport proteins: allow molecules to pass through
b. identifier (marker) proteins: with carbohydrates attached
c. structural proteins: cell flexibility and support
d. receptor proteins: receive signals from outside of cell to relay to
inside
3. Carbohydrates
Movement of Substances:
• Passive Transport
movement of molecules where the cell uses no ATP energy
•Types:
1. Diffusion:
•molecules move from
high conc. to low conc.
2. Osmosis:
•diffusion of water through selectively permeable membrane
3. Facilitated Diffusion:
•movement of large particles across the plasma membrane
with help of transport proteins
Solution Types:
Osmotic Pressure
• Isotonic Solution:
–equal amounts of dissolved particles inside and outside
the cell; no net movement of water; cells stays same size
•Hypotonic Solution:
Extracellular
–Fewer dissolved particles
outside the cell than inside, so
more water; net movement of
water into the cell by osmosis;
cell swells
•Hypertonic Solution:
–More dissolved particles outside the cell than
inside, so less water; net movement of water out
of the cell by osmosis; cell shrinks
Movement of Substances:
• Active Transport:
- Material moves from low conc. to high conc.
- Requires energy from the cell in the form of ATP
–Types:
•Endocytosis: taking material into cell by “folding”
- Phagocytosis: extensions of cytoplasm surrounds and
engulf large molecule
- Pinocytosis: surrounds liquid particles
•Exocytosis:
–Cell forces out material
–Secretion – release useful products (ex. hormones)
–Excretion – release of waste (ex. sweat)
7.4 Diversity of Cellular Life
• Unicellular: one cell
–Prokaryotes = all bacteria
–Eukaryotes = yeast, some protists
•Multicellular: many cells that are interdependent
–Eukaryotes = humans, animals, plants, most fungi,
some protists
•Cell Specialization:
–cell have a specific job/function to do
• Levels of Organization:
• Cell  Tissue  Organs  Organ System  Organism
•
Specialized group of similar
group of tissues
cells perform same working together
function
group of organs
working together
7-1
The cell theory states that new cells are
produced from
a. nonliving material.
b. existing cells.
c. cytoplasm.
d. animals.
7-1
The person who first used the term cell was
a. Matthias Schleiden.
b. Lynn Margulis.
c. Anton van Leeuwenhoek.
d. Robert Hooke.
7-1
Electron microscopes are capable of revealing more details than
light microscopes because
a. electron microscopes can be used with live organisms.
b. light microscopes cannot be used to examine thin tissues.
c. the wavelengths of electrons are longer than those of light.
d. the wavelengths of electrons are shorter than those of light.
7-1
Which organism listed is a prokaryote?
a. protist
b. bacterium
c. fungus
d. plant
7-1
One way prokaryotes differ from eukaryotes is
that they
a. contain DNA, which carries biological
information.
b. have a surrounding barrier called a cell
membrane.
c. do not have a membrane separating DNA
from the rest of the cell.
d. are usually larger and more complex.
7-2
In the nucleus of a cell, the DNA is usually
visible as
a. a dense region called the nucleolus.
b. the nuclear envelope.
c. granular material called chromatin.
d. condensed bodies called chloroplasts.
7-2
Two functions of vacuoles are storing
materials and helping to
a. break down organelles.
b. assemble proteins.
c. maintain homeostasis.
d. make new organelles.
7-2
Chloroplasts are found in the cells of
a. plants only.
b. plants and some other organisms.
c. all eukaryotes.
d. most prokaryotes.
7-2
Which of the following is NOT a
function of the Golgi apparatus?
a. synthesize proteins.
b. modify proteins.
c. sort proteins.
d. package proteins.
7-2
Which of the following is a function of the
cytoskeleton?
a. manufactures new cell organelles
b. assists in movement of some cells from
one place to another
c. releases energy in cells
d. modifies, sorts, and packages proteins
7-3
Unlike a cell wall, a cell membrane
a. is composed of a lipid bilayer.
b. provides rigid support for the surrounding cell.
c. allows most small molecules and ions to pass
through easily.
d. is found only in plants, fungi, algae, and many
prokaryotes.
7-3
The concentration of a solution is defined as the
a. volume of solute in a given mass of solution
b. mass of solute in a given volume of solution.
c. mass of solution in a given volume of solute.
d. volume of solution in a given mass of solute.
7-3
If a substance is more highly concentrated outside the
cell than inside the cell and the substance can move
through the cell membrane, the substance will
a. move by diffusion from inside the cell to outside.
b. remain in high concentration outside the cell.
c. move by diffusion from outside to inside the cell.
d. cause water to enter the cell by osmosis.
7-3
The movement of materials in a cell against a
concentration difference is called
a. facilitated diffusion.
b. active transport.
c. osmosis.
d. diffusion
7-3
The process by which molecules diffuse
across a membrane through protein channels
is called
a. active transport
b. endocytosis.
c. facilitated diffusion
d. osmosis
7-4
Cell specialization is characteristic of
a. bacteria.
b. all unicellular organisms.
c. yeasts.
d. multicellular organisms.
7-4
Which of the following cells is specialized for
contraction?
a. muscle cell
b. red blood cell
c. pancreatic cell
d. nerve cell
7-4
The stomach is an example of a(an)
a. tissue.
b. organ.
c. organ system.
d. organism.
7-4
Which of the following shows the levels of
organization in an organism from the
simplest to the most complex?
a. organ system, organ, cell, tissue
b. tissue, cell, organ, organ system
c. cell, tissue, organ, organ system
d. cell, organ, tissue, organ system
7-4
Which of the following would probably
contain the greatest variety of specialized
cells?
a. an organ system
b. a tissue
c. an organ
d. a multicellular organism