Transcript Chapter 7 Powerpoint

CHAPTER 7
CELL STRUCTURE & FUNCTION
PGS. 168 - 199
CELL STRUCTURE &
FUNCTION
ANTON VAN LEEUWNENHOEK
One of the first
person’s to use
a microscope.
 Looked at pond
water and saw
small organisms.

ROBERT HOOKE
 Looked
at plant
tissues in 1665.
 He specifically
looked at cork.
 Looked like tiny
chambers he
called “cells”
THE CELL THEORY
All living things are composed of
cells.
 2. Cells are the basic unit of
structure & function in living things.
 3. New cells are produced by existing
cells.

1.
Cells are the basic unit of life.
 Cells
come in
all different
shapes & sizes.
 All living things
are made up of
cells!
Microscopy Today: Compound Light
Microscope

Light passed through specimen

Focused by glass lenses

Image formed on human retina

Max magnification about 1000X

Resolves objects separated by 0.2 mm, 500X
better than human eye
6
Compound Light Microscope
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
85 µm
amoeba, light micrograph
eye
ocular lens
light rays
objective lens
specimen
condenser lens
light source
a. Compound light microscope
© Robert Brons/Biological Photo Service
7
Microscopy Today: Transmission
Electron Microscope

Abbreviated T.E.M.

Electrons passed through specimen

Focused by magnetic lenses

Image formed on fluorescent screen

Similar to TV screen

Image is then photographed

Max magnification 1000,000sX

Resolves objects separated by 0.00002 mm,
100,000X better than human eye
8
Transmission Electron Microscope
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
200 nm
pseudopod segment, transmission electron
micrograph
electron source
electron beam
electromagnetic
condenser lens
specimen
electromagnetic
objective lens
electromagnetic
projector lens
observation screen
or
photographic plate
b. Transmission electron microscope
© M. Schliwa/Visuals Unlimited
9
Microscopy Today: Scanning
Electron Microscope

Abbreviated S.E.M.

Specimen sprayed with thin coat of metal

Electron beam scanned across surface of specimen

Metal emits secondary electrons

Emitted electrons focused by magnetic lenses

Image formed on fluorescent screen

Similar to TV screen

Image is then photographed
10
Scanning Electron Microscope
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
500µm
amoeba, scanning electron micrograph
electron gun
electron beam
electromagnetic
condenser
lenses
scanning coil
final
condenser
lens
secondary
electrons
specimen
electron
detector
TV
viewing
screen
c. Scanning electron microscope
© Kessel/Shih/Peter Arnold, Inc.
11
Microscopy and Amoeba proteus
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
85 µm
amoeba, light micrograph
eye
ocular lens
light rays
electron source
electron beam
electromagnetic
condenser lens
specimen
electromagnetic
objective lens
objective lens
500µm
200 nm
pseudopod segment, transmission electron
micrograph
amoeba, scanning electron micrograph
electron gun
electron beam
electromagnetic
condenserl
enses
scanning coil
specimen
condenser lens
electromagnetic
projector lens
observation screen
or
photographic plate
light source
a. Compound light microscope
b. Transmission electron microscope
final
Condenser
lens
secondary
electrons
specimen
electron
detector
TV
Viewing
screen
c. Scanning electron microscope
a: © Robert Brons/Biological Photo Service; b: © M. Schliwa/Visuals Unlimited; c: © Kessel/Shih/Peter Arnold, Inc.
12
Cells are the basic unit of life.
 Cells
come in
all different
shapes & sizes.
 All living things
are made up of
cells!
Structures common to most cells
 1.
cell membrane
 2. DNA
 3. cytoplasm
Biologist divide cells
into one of two types:
1. PROKARYOTE: do not contain a membrane
bound nucleus
(all bacteria are prokaryotes)
2. EUKARYOTE: DO contain a membrane bound
nucleus, and most have other specialized
organelles.
Chapter 7, Section 2
The Plasma
Membrane
Main Idea: The plasma membrane helps to maintain a
cell’s homeostasis.
Essential Questions:
 How does a cell’s plasma membrane function?
 What are the roles of proteins, carbohydrates, and
cholesterol in the plasma membrane?
Function of the
Plasma Membrane

Separates cells from the watery environment
Maintain homeostasis – the process of maintaining
balance in an organism’s internal evnrionment

How does it do this?


Selective permeability – a property of the plasma membrane
that allows some substances to pass through while keeping
others out.
Cell Boundries
Cell membrane is selectively permeable &
provides protection & support
Small particles move more easily than large particles
Neutral molecules more easily than charged ions
Non polar more easily than polar
Substances that move across the cell membrane can vary from
cell to cell, or the same cell from moment to moment
Major component of the cell membrane is a lipid bilayer
Proteins & carbohydrates are also found in the cell
membrane
Cell membrane
Cell Wall



Found in plants, algae, fungi,
and nearly all prokaryotes.
MAIN FUNCTION: provide
support & protection for the
cell
Animal cells DO NOT have cell
walls!
Maintaining Homeostasis

All cells must regulate what materials enter &
leave; sometimes no energy is required to do
this, other times energy is required

Passive transport – no
energy is required to
move substances from
an area of high
concentration to an
area of low concentration

Types of Passive Transport
Diffusion – the movement of a solute from an area of high conc.
To an area of low conc. Equilibrium is reached when an equal
number of molecules move in both directions

Types of Passive Transport
Osmosis – the diffusion of water across a membrane from a
region of high water concentration to a region of low water
concentration
http://highered.mcgrawhill.com/sites/0072495855/student_view0/chapter2/animation__how_diffusion
_works.html

Types of Passive Transport
Facilitated diffusion – process by which transport proteins carry
certain molecules across a membrane from high concentration to
low concentration

Types of Osmotic Solutions
Isotonic solution
– solution has the
same solute
concentration as
that of the living
cell, there is no net
movement of H2O

Types of Osmotic Solutions
Hypertonic
solution– solution
has a higher solute
concentration than
the inside of the
cell; H2O moves out
of the cell; animal
cell will shrink
(crenate); vacuole
collapses in plant
cells

Types of Osmotic Solutions
Hypotonic
solution – solution
has a lower solute
concentration than
the inside of the
cell; H2O moves into
the cell; animal cell
will burst (lyse);
plant cell will not
(why?)
Types of Osmotic Solutions
http://highered.mcgrawhill.com/sites/0072495855/student_view0/chapter21/animation__hemolysis_and
_crenation.html (animation of isotonic, hypertonic, hypotonic solutions)
Types of Osmotic Solutions
Active Transport

Energy is required to move substances from
an area of low concentration to an area of
high concentration; allows cells to have
internal environments that are different
chemically from the external environment
Types of Active Transport

Molecular transport - proteins in the cell
membrane work as “pumps” to move
substances against the concentration
gradient
Types of Active Transport

Endocytosis - process by which a cell
takes material into the cell by infolding of
the cell membrane



Phagocytosis – large particles taken in
Pinocytosis – H2O or small particles are taken
in
Exocytosis – process by which cell
releases large amounts of material; vacuole
membrane fuses with the cell membrane
Types of Active Transport

http://bcs.whfreeman.com/thelifewir
e8e/content/cat_040/0504003.html