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THE CELL
Chapter 7
Microscopy Micrographs
Photograph of the view through a microscope Light Microscopes Electron Microscopes
Scanning EM To look at the surface of cells/specimen 3-D images
Transmission EM To look at internal structures of cells/specimen
Robert Hook (1665)
Englishman cork “cells” Compound
microscope
Anton van Leeuwenhoek (1660’S)
(LAY vun Hook)
Holland Single lens
microscope Pond water “animalcules”
Cell Theory
3 parts and key people
Cells
Basic units of life
Matthias Schleiden (1838)
German botanist Plant cells
Theodor Schwann (1839)
German biologist Animal cells
Rudolf Virchow (1855)
German physician New cells could only
come from the division of existing cells
Cell Theory
All living things are compose of cells Cells are the basic units of structure and
function in living things New Cells are produced from existing
cells
Lots of different shapes and sizes of cells
Sizes
5 to 50 micrometers How big is a micrometer? 1m=100cm=1,000,000 micrometers 1 micrometer=.000001m Basically you can’t see it Remember: KHDmDCM..micro..nano..pico
Chaos chaos Largest protozoan You can see without
microscope 1000 micrometers How many meters is this?
.001 m How many centimeters is
this? 0.1 cm
2 things in every cell…
Surrounded by a barrier, cell membrane At some point in their life they contain….
DNA
What is a Nucleus? Plural: nuclei Large, membrane enclosed
structure that contains the cell’s genetic material in the form of DNA
What is a membrane? A thin layer of material that
serves as a covering or lining
2 categories for cells…
Prokaryotes (pro-care-ee-ohts) No nucleus Cell’s genetic material is not contained in the
nucleus Less complicated that eukaryotes Some have internal membranes Bacteria and prokaryotes
All bacteria are prokaryotes Carry out every activity associated with living
things…which are…
Eukaryotes (you-care-ee-othts) Contain nucleus in which the genetic
material is separated from the rest of the cell Contains dozens of structures and internal
membranes High Variety Single celled or multi-cellular Plants, animals, fungi, and protists
Eukaryotic cell structure
The Cell factory Organelles
Highly specialized structures within the cell Little organs
2 major divisions of the eukaryotic cell Nucleus
The “brain” DNA
Cytoplasm Portion outside the nucleus but inside the cell membrane
2 types of Eukaryotic cells Plant cells
Animal cells What are the differences? (write them down!!!)
Nucleus
Brain of the cell Office of the factory Contains nearly all the cell’s DNA and
with it the coded instructions for making PROTEINS and other important molecules
Nuclear envelope Surrounds nucleus Made of 2 membranes Dotted with thousands of nuclear pores
How do we get messages, instructions and blueprints out of the office?
Allow material to move in and out of nucleus by using “little runners” such as proteins, RNA and other molecules
Inside the nucleus we see…
Contain a granular material called… CHROMATIN
Chromatin= DNA + protein Usually spread out in nucleus During cell division, chromatin clumps
together or condenses…we call this…. CHROMOSOMES
Chromosomes
Threadlike structures that contain genetic information that is passed on from one generation to the next
Nucleolus
Small dense region inside the nucleus Function: assembly of ribosomes begin…
Ribosomes Most important function of cell is…
Making proteins Proteins regulate a zillion different things Like…
Proteins are assembled ON Ribosomes Ribosomes are small particles of protein &
RNA (what’s RNA?) They follow instructions from the nucleus to
make proteins…follow the orders from the “head haunchos” in the main office
Scattered throughout the cell They are like little factories If a cell’s main function is making proteins, how
many ribosomes are you going to have?
Endoplasmic reticulum (ER)
Internal membrane system The site where the lipid components of
the cell membrane are assembled, along with proteins and other materials exported from the cell
2 types Smooth ER Rough ER
Rough ER Involved in protein making (synthesis) So what are we going to see on it?
ribosomes Once a protein is made, it leaves the
ribosome and goes into the Rough ER The rough ER then modifies the protein All proteins that are exported by the cell
are made on the RER Membrane proteins are made on the
RER too
Smooth ER NO ribosomes on it Looks smooth Contains collections of ENZYMES that have
specialized tasks What do enzymes do?
Tasks include: Synthesis of membrane lipids Detoxification of drugs Liver cells
Big in detox therefore….what do u think liver cells have a lot of?
Golgi Apparatus Discovered by Italian scientist Camillo Golgi Once proteins are done being “modified” in the
RER, they move onto the Golgi apparatus Looks like a stack of pancakes Function: modify, sort, and package proteins
and other materials from the ER for STORAGE or SECRETION outside the cell Proteins are “shipped” to final destination
They are the CUSTOMIZATION SHOP Finishing touches on proteins before they leave
factory
Lysosomes (Lie-so-soh-mz) The factory’s clean-up crew It’s an Organelle filled with
enzymes Function: Digestion (break
down) of lipids, carbohydrates, and proteins into smaller molecules that can be used by the cell
Also digest organelles that have outlived their usefulness
What do you think happens if lysosomes malfunction?
A bunch of “junk” build up in the cell Is this good? Many human diseases result from
malfunction of lysosome Tay-Sachs disease
Vacuoles The factory’s storage place Only in certain cells Sac-like organelles Function: stores material such as water,
salts, proteins, and carbohydrates Plant cells have a single, large central
vacuole Pressure of central vacuole allows plants to
support heavy structures
Single-celled organisms and some animals also have vacuoles…
Paramecium Contractile vacuole Contracts rhythmically to pump excess water
out…this maintains what? homeostasis
What is the one thing all living things need to eat, breath, reproduce, move and much more?
ENERGY!!!!
Two ways cells get energy…
From food molecules From the sun
Mithochondria
Convert chemical energy stored in food into compounds that are more convienent for the cell to use
Has 2 membranes Inner membrane Outer membrane
Nearly all come from the ovum You get your mitochondria from your mom!
Chloroplasts
Capture energy from the sunlight and convert it into chemical energy…what is this process called? PHOTOSYNTHESIS
Like solar power for plants 2 membranes Inside: large stacks of other membranes
that contain chlorphyll
Organelle DNA
Chloroplasts and mitochondria contain their own genetic info In form of small DNA
molecules
Lynn Margulis
American biologist Chloroplasts and
mitochondria are descendents of prokaryotes
She said… Ancient Prokaryotes from wayyyyy back in the
day had a symbiotic relationship with the ancient eukaryotes What is symbiotic? (review ecology!!!)
The prokaryotes lived inside the eukaryotes There were prokaryotes that used oxygen to
make energy (ATP) Mitochondria
There were prokaryotes that used photosynthesis to get energy Chloroplasts
Endosymbiotic Theory
Idea that mitochondria and chloroplasts evolved from prokaryotes
Cytoskeleton
Supporting structure and transportation system Network of protein filaments that helps
the cell to maintain its shape and to help the cell move
2 main type of filaments Microtubules Microfilaments
Microfilaments
Threadlike structures Made of protein called ACTIN Extensive networks Tough, flexible framework Help cells move Assembly and disassembly helps cells
move (like amoebas)
Microtubules
Hollow structures Made of proteins called TUBULINS Maintain cell’s shape Important in cell division
Make mitotic spindle (separates chromosomes)
Help build projections from cell surface…
Cilia and Flagella
Plural: cilium and flagellum Enable cells to swim rapidly through liquid Like oars of a boat
Centrioles
Only animal cells Made of protein
TUBULIN What else is made of
tubulin?
Near nucleus Help organize cell
division
Antwon van Leeuwenhook
Robert Hook Cell Theory Electron microscope Prokaryote Eukaryote Organelles Cytoplasm Nuclear envelope Chromatin Nucleus Ribosome Smooth ER Rough ER Chromosome Vacuole Osmosis Endocytosis exocytosis Proteins DNA Contractile vacuole Central Vacuole
Golgi apparatus Lysosome Vacuole Mitochondrian Chloroplast Cytoskeleton Centriole Mictrotubule Microfilament Theodor Schwann Matthias Schleiden Rudolph Virchow Lynn Margulis Endosymbiotic Theory Cilia Flagella Photosynthesis Aquaporin Transmembrane
protein Facilitated diffusion
