QOD 10/17/11
• What is the basic unit of all life?
Cell Structure and Function
Timeline:History of Cells
• Robert Hooke -1665• First person to use the
term cell• From the Latin “cella”
meaning “small chamber”• Father of microscopy
Timeline:History of Cells
• Anton van Leeuwenhoek-1675
• A Dutch cloth merchant who became interested in studying cells.
• Was the first to see and describe bacteria, sperm cells and protista
Timeline:History of Cells
• Rene Dutrochet-1824• 1st scientist to
hypothesize that cells are the basic unit of life.
Timeline:History of Cells
• Robert Brown- 1833• Names the nucleus
and proposes that it has an important role in the control of cellular processes
• Matthias Schleiden (1838) – all plants are composed of cells.
• Theodor Schwann (1839) – all animals are composed of cells.
Timeline:History of Cells
Timeline:History of Cells
• Rudolf Virchow (1856) • “Where a cell exists,
there a cell must previously have existed”
How do we see cells?
• There are 3 kinds of microscopes:
1. Light Microscope• Magnifies up to 1000x
2. Scanning Electron Microscope (SEM)• Magnifies up to 100000x
3. Transmission Electron Microscope (TEM)• Magnifies up to 200000x
Scanning Electron Microscope
• Can look at surface of the specimen
• Specimen is coated in gold and an electron beam is sent into it, electrons bounce off onto a piece of film, which forms a 3-D picture of the specimen
Transmission Electron Microscope
• Can only look at thin sections of the specimen in 2-D
• A beam of electrons is sent through the thin slice of specimen, the image is enlarged and put on film
Electron micrographs of rabbit trachea
A) transmission electron micrograph - TEM
B) scanning electron micrograph - SEM
Copyright © 2005 Pearson Education, Inc., publishing as Benjamin Cummings
A Paramecium
QOD 10/18/11
• Who is the father of microscopy?
Robert Hooke
• NOTE: I will be collecting QODs on Friday, you should have 25 by then…
• QUIZ 10/25 over cell organelles and functions
3 Parts of the Cell Theory
1. All living things are composed of cells.
2. Cells are the basic unit of structure and function in living things.
3. All cells come from preexisting cells.
Number of Cells• Unicellular – composed of one cell
• Multicellular- composed of many cells that may organize
•Colonial – unicellular organisms that group together
There are 2 main types of cells:
Prokaryotic Cells
• Lack a true nucleus and membrane bound organelles
• Much smaller than eukaryotic cells
• Bacteria is an example
Basic Bacterial Cell(fill in blanks on notes)
Eukaryotic Cells• Have a true
nucleus and membrane bound organelles
• Include plants, animals, fungi and protista
Plasma Membrane
Cell Membrane• Present in all
cells• Regulates the
passage into and out of the cell
• Provides protection and shape
Plasma Membrane Structure• Composed of a double layer of phospholipids• It is semi-permeable (some things get in, some don’t) • Lipid bilayer is made up of hydrophilic and
hydrophobic regions
Cytoplasm• Also found in all
cells• Cytoplasm: the
liquid part of the cell• This is where
chemical reactions occur
• Mainly made of water
Nucleus• contains the DNA of
the cell–DNA is also called
chromosomes and chromatin
• surrounded by a membrane called the nuclear envelope
• Controls the cell’s activities
10/19/11
•What is the leader of the cell?–Nucleus!!
Nucleolus
• Where the DNA is concentrated within the nucleus
• This is where ribosomes are produced
Ribosomes• Make proteins • May be free in
the cytoplasm OR bound to the rough ER
Endoplasmic Reticulum• Comes from the
Greek Endo = “within” Latin reticulum = “network.”
• A membrane network within the cytoplasm
• This is the assembly line of the cell
Rough ER• Produces lipids and proteins• Called rough because of ribosomes• Things made here leave by Vesicles (little
sacs) that pinch off and move in the cytoplasm
Smooth ER
• No ribosomes• Builds lipids
Golgi Apparatus• Processes unfinished proteins• Packages finished proteins• Distributes finished proteins (in
vesicles)• Like the mailman of the cell
Vesicles
• Small, spherically shaped sacs that are surrounded by a single membrane and that are classified by their contents
Lysosomes• Vesicles that
contain digestive enzymes
• Used to digest cell invaders, old organelles, or food
• Also help to “kill” cells when needed, by releasing their enzymes
• Only in Animal Cells
• The cell’s powerhouse
• Involved in cellular respiration
• Helps to convert “food” into cellular energy = ATP
Mitochondria
Cytoskeleton
• A network of thin tubes and filaments made of proteins that crisscross in the cytosol.
– Give the cell shape and structure
Cilia and Flagella• Hair-like structures that
extend from the surface of a cell and they assist in movement
• Cilia are short and present in large numbers
• Flagella are long and usually very few are present
• Both are made of microtubules
QOD 10/20/11
• The cell’s ATP is made in which organelle?
–MITOCHONDRIA
Centrioles• Made of
microtubules• Organize movement
of all microtubules during cell division
• Only in animal cells
Differences in Plant and Animal Cells
• Plants have cell walls, chloroplasts, plastids, and a central vacuole; animals have none of these
• Animals have lysosomes and centrioles, while plants do not
Central Vacuole• Storage area• Stores nutrients in
animal cells• Helps to give
support in plant cells- holds water
Cell Wall• The cell wall is a rigid
structure that is found in plants, fungi, and bacteria cells
• Made mainly of cellulose• Has pores for the
movement of water, ions, and nutrients
• It supports and maintains the shape of the cell and is extremely strong.
Plastids• Organelles that are
surrounded by a double membrane and contain their own DNA (like mitochondria)
• Examples:– Chloroplasts- contain
green pigments– Chromoplasts- contain
other color pigments– Amyloplasts- store starch
• Site of photosynthesis• Contains the green pigment chlorophyll
Chloroplasts
QOD 10/20/10
• What do plant cells have that animal cells do not?
QOD 11/1/11
• What is the function of the cell membrane?
QOD 11/2/11
• What is osmosis?
Cell Transport
Cellular Transport
• Concentration gradient- from high concentration to low concentration
• Passive Transport - no energy needed– Goes WITH the concentration gradient– Examples are diffusion, osmosis, and
facilitated diffusion• Active Transport - needs energy
– Goes AGAINST the concentration gradient– Examples are protein pumps, endocytosis,
and exocytosis
Diffusion• Diffusion- The
movement of molecules from an area of high concentration to an area of low concentration–Movement WITH
the concentration gradient (passive transport)
Diffusion
• Diffusion occurs until equilibrium is reached– Equilibrium is when the concentration of
molecules is the same throughout a space they occupy
Osmosis• Water is one of the small, polar
substances that can easily pass through the selectively permeable plasma membrane
• The diffusion of water across a membrane is called osmosis.
• Water moves from high to low concentration
(passive transport)
Isotonic Solution (Iso=Same) The concentration of water molecules and solutes
are the same inside and outside the cell.
Remember, solutes are dissolved in water, like salt or sugar
Water molecules will move across the membrane at the same rate in both directions.
NO NET MOVEMENT, cell remains the same
Solute concentration
sare equal on both sidesof the cell
Hypertonic Solution (Hyper=above)
• Hypertonic solution = high solute / lower water on outside
• Water will move OUT of the cell• Plant cells will lose Turgor Pressure (the pressure
water molecules exert on the cell wall)• Plasmolysis occurs which is where cell
membranes shrivel
water moves out of the cell
cell will shrink
Hypotonic Solution (Hypo=below) • Lower concentration of solute on outside of cell
when compared to the inside of cell• Water will move IN the cell• Cell will swell or possibly burst (called cytolysis)• Plant cells will gain Turgor Pressure
Water moves into the cell
Cell May Burst
Plasma Membrane
• Remember, the function of the plasma membrane is control the movement materials into and out of the cell
Plasma Membrane
• The plasma membrane is selectively permeable which means some things can get through and some cannot.• It is made of a phospholipid bilayer, but also
contains embedded proteins that help with transport into it
• Small molecules pass– Water, carbon dioxide, and oxygen
• Large molecules like glucose and ions do not pass
Facilitated Diffusion• Proteins help transport molecules WITH their
concentration gradient that cannot diffuse by themselves (from HIGH to LOW concentration- passive transport)
• Carrier proteins or Channel Proteins assist these molecules with facilitated diffusion
Facilitated Diffusion• Different carrier proteins will transport different
molecules (each protein is specific!)• Glucose is transported this way• Molecules can be moved in OR out of the cell
Active Transport
• This type of transport requires energy and usually moves against the concentration gradient
• Carrier proteins are usually involved, but may be called protein pumps
Endo and Exocytosis• Some
substances are too large to transport into the cell through carrier proteins– So, endocytosis
and exocytosis are used
Endo and Exocytosis• Endocytosis is the process by which cells take
substances IN • Exocytosis is the process by which cells let
substances OUT
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