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Cell Structure and Function
Chapter 4
Robert Hooke (1635
(1635-1703)
1703)
Discovered “cells”
cells by
studying the cork
layer of bark from
an oak tree.
Found cells when
studied tree stems
stems,
roots, and leaves.
Antony van Leeuwenhoek (16321723)
Learned how to make
excellent lenses &
placed them into
simple microscopes
microscopes.
He was the first person to
observe living cells.
Vorticella
spirogyra
Matthias Schleiden & Theodor
S h
Schwann
Schleiden (botanist) &
Schwann (zoologist)
developed the Cell
Theory.
Rudolf Virchow (1821
(1821-1902)
1902)
Noted that cells
come from
other cells
from
studying
human
diseases.
The Cell Theory
1 All organisms are made up of one or
1.
more cells.
2 Cells are the basic unit of structure
2.
and function of organisms.
3 New
3.
N
cells
ll come from
f
existing
i ti cells
ll by
b
cell reproduction.
Microscopes
Light: light waves
pass through a
small organism, or
thin slices of a
larger organism, &
th structures
the
t
t
are
magnified through
the lens system.
system
Phase contrast:
modifies differences
in light waves so
that transparent cell
structures appear as
li ht & dark
light
d k regions.
i
Electron: enables us
to see cell parts at
very high
magnifications by
using an electron
b
beam
instead
i t d off a
light beam to
illuminate the
object.
Transmission Electron
Microscope: (TEM)
Cell structures can be
enlarged as much
as 1,000,000x &
provides
photographs that
show remarkable
detail.
apoptosis
Cells
Basic unit of living organisms.
2 basic types:
prokaryotes: do not have a membrane
enclosing their DNA. Do not contain
membrane-bound
e b a e bou d organelles.
o ga e es
Prokaryotes
o a yotes a
are
ed
divided
ded into
to ttwo
o
domains:
Bacteria: includes organisms that are
similar to the first cellular life-forms.
Archae: includes organisms
g
that are
thought to be more closely related to
eukaryotic
y
cells found in all other
kingdoms of life.
eukaryotes: usually have at least one
membrane enclosed structure, the nucleus,
which contains DNA;; contain membranebound organelles.
unicellular: consists of a single
cell which carries out all the
many activities of that
organism.
multicellular: contain from dozens to billions of
cells Organisms have a number of different
cells.
types of cells; each type of cell has a certain
role to play.
Colonies: a collection of genetically identical
cells that live together
g
in a collected group.
g
p
Colonies are not truly multicellular since few of
their activities are coordinated.
Volvox
Levels of Organization
Cells
tissue (group of similar cells that
carry out a specific function)
organs
(group of tissues that perform a particular
job in an organism)
organ system
(group of organs that accomplish related
t k )
tasks)
organism
i
(th combining
(the
bi i off
organ systems)
Organelles
Structures that carry out specific
functions.
Plasma Membrane
•
•
•
•
Outer membrane that encloses the cell contents
Controls the passage of materials in & out of the cell
Made of 2 thin layers of lipid molecules.
Protein molecules floating on & within the lipid
layers help molecules move in & out of the cell.
4
1
3
2
5
1 - cell-surface marker: glycoprotein that identifies cell type.
2 - receptor protein: recognizes and binds to substances outside of cell.
3 – intergral protein: enzyme that assists chemical reactions inside cell
cell.
4 – transport protein: helps substances move across cell membrane.
5 – peripheral proteins: lie on only one side of membrane and not
embedded in it.
it
The cell membrane is a fluid mosaic model. The bilayer behaves like a
fluid more than a solid. The membrane’s lipids and proteins can move
laterally within the bilayer.
Cytoplasm
• Jellylike
y
material found within the cell.
• Contains the organelles.
• cytosol: includes molecules and small particles but
not membrane-bound organelles.
• Many of the chemical reactions of a cell take place in
the cytosol
cytosol.
Nucleus
• Control center of the cell
• Contains most of the cell’s genetic information in
DNA
• Contain one or more nucleoli, sites of synthesis &
assembly of rRNA & tRNA
• genes: control the basic functions of the cell
• chromosomes: contain DNA & proteins
Nuclear Envelope & Nucleolus
• Double membrane surrounding
g nucleus
• It is continuous at several pts. w/a complex network
of other membranes in the cytoplasm
• The nucleolus manufactures ribosomes. It is a knot
of chromatin.
The portion of the cell
nucleus which contains
all of the DNA of the
nucleus in an animal or
plant cell.
Endoplasmic Reticulum
• Provide passageways for the movement of materials
throughout the cell
• 2 ttypes:
RER – Rough Endoplasmic Reticulum
SER – Smooth Endoplasmic Reticulum
RER
• Produces phospholipids and proteins
• The ribosomes produce digestive enzymes
SER
• Builds lipids
p
like cholesterol.
• Produces estrogen and testosterone.
• Releases calcium in skeletal and heart muscle,
which stimulates contractions.
• Detoxify drugs and poisons in the liver and kidney
cells.
cells
Ribosomes
Responsible
p
for protein
p
synthesis.
y
Made of protein and RNA molecules and do not have a
membrane.
Mitochondria
• Powerhouse of the cell
• Transfer energy from organic molecules to
Ad
Adenosine
i T
Triphosphate
i h
h t (ATP) which
hi h powers mostt
of the cell’s chemical reactions.
• Consists of an outer membrane & a folded inner
membrane
cristae
Vacuole
Store & transport
p
nutrients & waste products
p
Golgi Complex
• Helps
p package
p
g cell products
p
for export
p
from the cell
Vesicles
• Small,, spherical
p
shaped
p sac that are surrounded by
y
a single membrane.
• Classified by their contents.
• Often migrate to and merge with the plasma
membrane.
• Release their contents to the outside of the cell.
cell
• “shuttle service”
• Include lysosomes
y
and p
peroxisomes
Lysosomes
Contain digestive
g
enzymes
y
which help
p break down
large molecules & worn-out cell parts
Peroxisomes
• Similar to lysosomes but contain different enzymes
and not produced by Golgi Apparatus.
• Abundant in liver and kidney cells.
cells
• Break down fatty acids, which is then used by
mitochondria.
• Produce hydrogen peroxide when breaking down
alcohol and killing bacteria.
Centrioles
Present in p
pairs and play
p y an important
p
role in mitosis.
Cytoskeleton (Microtubules & Microfilaments)
Tiny tubes composed of proteins.
Form the cell’s skeleton
Enable the cell to maintain its distinct shape & internal
organization.
Microfilaments contribute to cell movement
movement.
Cell Wall
Provides strength and protection
Formed by living plant cells of cellulose fibers.
Central Vacuole
• Reservoir that stores large amounts of water.
• Also stores enzymes, metabolic waste, and
other materials.
Plastids
• Organelles surrounded by a double
membrane and contain their own DNA.
2 types:
yp
CHLOROPLASTS
CHROMOPLASTS
Chloroplasts
Contain the pigment chlorophyll, essential for
capturing the light energy of the sun
sun.
Contain complicated membranes where
photosynthesis takes place called
thylakoids.
Chromoplasts
• Contain colorful pigments that may or may
not take part in photosynthesis.
Carotene: orange
g pigment
pg
found in carrot root
cells.
petal cells contain red,, purple,
p p , yellow.
y
Flower p
or white pigments.