Post on 20-Jan-2016
THE CELL
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
Microscopes
Sizes The body is made of 100 trillion cell (1014) Extremely small…The human eye can
see .01 cm, a human cell is 5x smaller 5 to 50 micrometers…µm 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
Cells Basic units of life
Robert Hook (1665) Englishman Looked at cork
Made of dead plant cells 1st person to observe
cells Coined the term “cells”
What he saw under the microscope looked like the tiny, empty chambers called cells, that the monks lived in
Compound microscope
Anton van Leeuwenhoek (1660’S)
(LAY vun Hook) Holland Single lens
microscope Pond water “animalcules” 1st person to observe
LIVING cells
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 3 parts and key people
1. All living things are made of cells (Hooke, van Leeuwenhoek, Schwann and
Schleiden)
2. Cells are the basic units of structure and function in all living things (Hooke, van Leeuwenhoek, Schwann and
Schleiden)
3. New cells are produced from pre-existing cells (Virchow)
Lots of different shapes and sizes of cells
2 categories for cells… Prokaryotes (pro-care-ee-ohts)
No nucleus Cell’s genetic material is not
contained in the nucleus…found in NUCLEOID:
Region in cytoplasm where DNA is found
Less complicated that eukaryotes
Some have internal membranes
Do NOT have membrane bound organelles
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
2 things in every cell… Surrounded by a barrier…
Plasma/cell membrane At some point in their life they contain….
DNA
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!!!)
Cell Membrane What does it do for cell?
Controls what goes in and out Regulates molecules moving from one liquid side of the
cell to the other liquid side of the cell
Protects Supports
Cell Membrane Lipid bilayer
What are lipids? What does bi- mean? What’s a layer?
A cell membrane is made of two
layers of lipid molecules
Cell membrane Phospholipids bilayer
Made of a negatively charged phosphate “head” PO4
3-
Attracts water because the phosphate is
charged (-)
Water is a polar , slightly positive ends and
slightly negative ends
Attached to the phosphate group are 2 fatty acid chains Hydrophobic= don’t like water So the inside of the cell
membrane doesn’t let water in but the outside allows cells to be dissolved in aqueous environments
Plasma/Cell Membrane Phospholipid bilayer
Hydrophilic Hydophobic
Fluid Mosaic Model Why?
Controls exchange of materials between cell and its environment
Other things in the membrane…
Proteins embedded in lipid bilayer
Carbohydrates attached to proteins
So many different molecules in membrane, we call it a “mosaic” of different molecules
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
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 Condensed structures that contain genetic
information (DNA) 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 Consists of 2 parts:
Large subunit Small subunit
Found: In Cytoplasm On Rough ER In nucleus
Function: hold mRNA in place while tRNA brings
over specific amino acids; makes a polypeptide chain
Site of protein synthesis
Endoplasmic reticulum (ER)
Internal membrane system 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
Endomembrane System & Protein Synthesis
1. DNA in nucleus gives message to mRNA
2. mRNA leave thru nuclear pore into cytoplasm
3. Ribsome “catches” mRNA
4. tRNA come over and start adding amino acids together making polypeptide chain
5. Polypeptide chain either functions immediately or goes onto next step
6. Ribosome deposits polypeptide chain into lumen of the RER
7. Polypeptide chain is modified (2* and 3* structure)
8. Functioning protein either stays and works in RER or…
9. Vesicle buds off RER and transports it to Golgi Apparatus
10. Protein is further modified in GA and leaves in a vesicle (either secretory or peroxisome or membrane)
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…why? Is this good? Many human diseases result from
malfunction of lysosome Tay-Sachs disease DNA does not make the enzyme
hexoaminidase A that breaks down lipids in nerve cells
Build up of lipids in nerve cells causes those cells to stop working
Noticeable 3-6 months after birth, child lives to be about 4-5 years old
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
Two ways cells get energy…
From food molecules From the sun
Mitochondria Convert chemical energy stored in
food into compounds that are more convenient for the cell to use
Has 2 membranes Inner membrane
Lots of FOLDS (cristae)= INCREASE surface area= more ATP being produced
Outer membrane
In Animal AND Plant cells Nearly all come from the ovum
You get your mitochondria from your mom!
Chloroplasts Plant and some Bacteria cells
only ( NOT in animal cells) 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 chlorophyll
Chloroplast (found in cells in leaves)
Concentrated in the cells of the mesophyll (inner layer of tissue) in leaf
Stomata Tiny pores on surface of leaf Allows carbon dioxide and
oxygen in and out of the leaf Veins
Carry water and nutrients from roots to leaves
Deliver organic molecules produced in leaves to other parts of the plant
Chloroplast Cellular organelle where
photosynthesis takes place Double membrane Outer membrane Stroma (fluid filled space) Inner membrane Thylakoids
Thylakoid membrane contains CHLOROPHYLL
Granum Intermembrane space
Contain chemical compound called Chlorophyll This molecule gives chloroplast
its green color
Structure of Chloroplast Structures organize the many
reactions that take place in photosynthesis
Stomata Small pores in the underside of leaves
that release water and oxygen and take in carbon dioxide
Guard cells Control the opening and closing of
stomata depending on environment Stroma
Thick fluid enclosed by the inner membrane
Thylakoids Disc-like sacs suspended in the
stroma Has membrane that surrounds inner
thylakoid space Grana (sing. Granum)
Stacks of thylakoids
Organelle DNA Chloroplasts and
mitochondria contain their own genetic info In form of small, circular
DNA molecules mDNA
Lynn Margulis American biologist Chloroplasts and
mitochondria are descendants 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(Intermediate filaments is a 3rd type)
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 Cilia: hundreds of extension of the cell membrane that move like
the oars of a boat Flagella: one or two long extensions off the cell that move in a
whip like fashion Enable cells to swim rapidly through liquid
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 bacteria Cell Theory Electron microscope Prokaryote Eukaryote Organelles Cytoplasm Nuclear envelope Chromatin Nucleus nucleolus Ribosome Smooth ER Rough ER Chromosome Vacuole Osmosis Endocytosis exocytosis Proteins DNA RNA
Microscope Micrograph Magnifier Lens Contractile vacuole Central Vacuole Centrioles Centrosomes Nuclear pores Nuclear-plasm Stomata ATP synthase Chlorophyll Cell membrane Cell Wall Cellulose Phospholipids Thylakoid Cristae Matrix Inner membrane Outer memebrane
Golgi apparatus Micrometer Millimeter Picameter Lysosome Vacuole Mitochondria Chloroplast Cytoskeleton Centriole Mictrotubule Microfilament Theodor Schwann Matthias Schleiden Rudolph Virchow Lynn Margulis Endosymbiotic Theory Cilia Flagella Photosynthesis Pseudopodia Aquaporin Transmembrane protein Facilitated diffusion