Transcript Chapter 7 Cells

Chapter 7
Cells
1.1.1 and 1.1.2
Cell Theory
 All living things are made up of cells
 Cells are the basic unit of life
 New cells are made from existing cells
Historical Background
 Improvements to microscope allowed the
development of the cell theory since they
could now see the cells
 Prominent scientists were:
– Leeuwenhoek
– Hooke
– Brown
– Schleiden
– Virchow
Ways to see the cells
 Compounds light microscope: living or dead,
thin, stained for easy viewing, 1000 times
magnification
 Electron microscope: dead, prepared ,1
million times magnification
 Dissecting microscope
 Ultracentrifuge: separates parts
CELLS ALIVE ANIMATION
 http://www.cellsalive.com/cells/cell_model.ht
m
Organelles (little organs):
Names and Functions
 Plasma Membrane or Cell Membrane:
surrounds the entire cell and regulates the
movement of materials or signals into and
out of the cell.
 Cytoplasm: fluid environment between the
nucleus and plasma membrane in which
other organelles are suspended. This is
where biochemical processes occur.
Organelles:
Names and Functions
 Nucleus: surrounded by nuclear membrane,
contains DNA and directs cellular activities
through expressing different genes.
 Nucleolus: in the nucleus, no membrane
network synthesis of ribosomes. Where
formation of ribosomes begins.
Organelles:
Names and Functions
 Endoplasmic Reticulum: interconnecting
channels responsible for storage, synthesis,
and transport of substances throughout the
cell. Where lipid components of the
membrane are put together. Also, where
proteins and other materials are exported.
– Two kinds
 Smooth ER: has no ribosomes
 Rough ER: has ribosomes
Organelles:
Names and Functions
 Ribosomes: site of protein synthesis, may
be associated with the ER or located free in
the cytoplasm
 Mitochondria: site of aerobic (with O) cellular
respiration. This process makes ATP. ATP
is aka adenosine triphosphate. This is
cellular energy.
Organelles:
Names and Functions
 Golgi complex or Golgi apparatus: site of
packaging and modification of proteins to be
secreted.
 Lysosome: contains digestive enzymes that
break down proteins or nucleic acids only at
low pH.
– How lysosomes work: http://highered.mcgrawhill.com/sites/0072495855/student_view0/chapt
er2/animation__lysosomes.html
Organelles:
Names and Functions
 Vacuole: membrane bound space
containing water or other materials.
– Food vacuoles are for digestion
– Contractile vacuoles maintain water balance
Organelles:
Names and Functions
 Centriole: cylindrical structure which
functions during cell division, these are
common in animal cells but not in plants
(Honors) Organelles:
Names and Functions
 Chromatin: granular material in the nucleus
 Nuclear Pores: control flow in and out of
nucleus to the cytoplasm
 Cilia: tiny hairs used for movement
(Honors) Organelles:
Names and Functions
 Cytoskeleton: how eukaryotic cells maintain
their shape and gain support.
– Microtubules: hollow structures make up of
proteins known as tubulins. Help maintain
shape, big part of cell division, because they
form the spindle fibers
 Centrioles are located near the nucleus and help to
organize cell division.
-Microfilments: threadlike structures make up
of protein called actin and help cells move.
(Honors) Organelles:
Names and Functions
 Peroxisomes: breaks down uric acid, amino
acids and fatty acids. Works like a lysosome
with a different set of materials. The break
down of fatty acids gives energy to the cell
Organelles:
Names and Functions
 Found only in plants:
– Chloroplasts: green pigment containing
structure, the actual site of photosynthesis in
plants.
– Cell Wall: contains cellulose; surrounds and
supports plant cells
– Plasmodesmata: are narrow channels that act
as intercellular cytoplasmic bridges to facilitate
communication and transport of materials
between plant cells
Prokaryote vs Eukaryote
 Prokaryote
– Usually smaller
– No membrane bound organelles
– DNA is not in a nucleus
– Generally less complicated
– Example: bacteria
Prokaryote vs Eukaryote
 Eukaryote
– Usually larger
– More complex
– Membrane bound organelles
– Contain nucleus where DNA is stored,
separately
– Wide variety
– Some are unicellular
– Example: plants, animals, fungi, protists
Cell boundaries
 Cell Membrane:
– Main function: controls movement in and out of
the cell
 Phosopholipid bilayer
 Called Fluid Mosaic Model
– Just because it has so much stuff in it, it cannot be
concretely identified
Cell Membrane
 Contains:
– Lipids
– Protein molecules that are embedded in the
lipid bilayer
– Carbohydrate molecules are attached to many
of these proteins
 some of the proteins form channels and pumps that
help to move material across the cell membrane.
Many of the carbohydrates act like chemical
identification cards, allowing individual cells to
identify one another.
Cell boundaries
 Cell Wall
– Main function: provide support and protect the
plant cell
 made from fibers of carbohydrate and protein.
– Made within the cell
– Released from cell membrane
– It is cellulose a carbohydrate fiber
Active Art on Diffusion
 http://www.pearsonsuccessnet.com/snpapp/
iText/BrowseITEXTServlet?eventType=ope
nIEXT&ISBNUrl=%2FiText%2Fproducts%2
F0-13-203512-X%2Findex.html&ISBN=013-203512-X&ITEXTOID=0-13-203512X&DisplayTitle=Biology+2008&TitleInFrame
=Y&isbnUrlIsJavascript=false
Diffusion
 Does not require energy
 Happens when random particles move from
an area of higher concentration to an area of
lower concentration through the cell
membrane.
 General diffusion animation:
– http://highered.mcgrawhill.com/sites/0072495855/student_view0/chapt
er2/animation__how_diffusion_works.html
Osmosis
 Diffusion of water across a selectively
permeable membrane
Osmotic Pressure
 Isotonic: equal
 Hypotonic: too little (ions)
 Hypertonic: too much (ions)
Facilitated Diffusion
 Diffusion of specific cell needs.
 Completed by a carrier protein to take
particles in or out
 Requires no energy
 Animation
– http://highered.mcgrawhill.com/sites/0072495855/student_view0/chapt
er2/animation__how_facilitated_diffusion_works
.html
Cell Boundaries
 Active versus Passive transport
 Active: requires energy
 Passive: does not require energy
Active Transport
 Moves molecules with pumps across the
concentration gradient
– Exocytosis: EXITS the cell
– Endocytosis: ENTERS the cell
Endocytosis
 the process of taking material into the cell by
means of infoldings, or pockets, of the cell
membrane.
 The infolding makes a vacuole
 Large molecules, clumps of food, and even
whole cells can be taken up in this way.
Endocytosis
 Two types
– phagocytosis
 Amoebas do it
 Take piece of food, form around it, make a vacuole
– pinocytosis (py-nuh-sy-TOH-sis)
 Take water, form around it, make a vacuole
Exocytosis
 How cells release large amounts of material
from the cell
 Vacuole fuses with membrane
 Forces contents out
– Example: contractile vacuoles remove water
this way
Cellular Diversity
 Unicellular vs Multicellular
Unicellular
 Single cells can be an entire organism
 The meet the criteria for life
 Bacteria are living unicellular organisms
Multicellular
 Cells throughout an organism can develop
in different ways to perform different tasks
 This is called cells specialization
 Red blood cells in animals
 Stomata or guard cells in plants to regulate
the influx of water