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Chapter 7Cell Structure and Function (Aligned with 7.1 Intro Sheet and 7.2 Cell Structure Chart)
IMPORTANT: My hope is that you will use this on your computer as a way to ensure that your chart is filled in completely. If you MUST print it out, please make sure you print SIX SLIDES PER PAGE!! Save a tree!!
7-1 Life is Cellular
A. Cells – basic units of structure and function in living things
** Cell discovery only occurred after the microscope was invented
B. Early scientists that led to the cell theory
❙ Anton van Leeuwenhoek (1600s) – given credit for developing the 1st mini microscope, looked at pond water and made detailed drawings
❙ Robert Hooke – coined the term “cell” when he looked at slices of cork and dead plant cells
❙ Robert Brown (1833) – observed a dark structure near the center of the cell (we now know this is the nucleus)
❙ Matthias Schleiden (1838) – stated all plants are made of cells
❙ Theodore Schwann (1839) – stated all animals are made from cells
❙ Rudolph Virchow (1855) - stated all cells come from the division of preexisting cells
❙ Lorenz Oken – stated all new cells are the result of division of preexisting cells…VIRCHOW STOLE HIS THUNDER
Schleiden
Schwann
Virchow
C. Cell Theory
❙ All living things are composed of cells.
❙ Cells are the basic units of structure and function in living things.
❙ All cells come from preexisting cells.
D. Exploring the Cell: Microscopes* Lenses used to magnify image by focusing beams of light OR
electrons
• Magnification = image size * Resolution = clarity of detail
The light microscope (LM):
• Enables us to shape and structure of a cell
• Magnify cells up to 1,000X
The electron microscope (EM):• Allows greater magnification and reveals cellular details• Magnify cells up to 2 mill X• Limits: no living specimens
SEM
2,000 ×
TEM
2,800 ×
Figure 4.1C Figure 4.1D
Scanning EM: (SEM) surface
structures
Transmission EM: (TEM)
inside details
LM
1,000
×
Figure 4.1B
E. What is in a Cell?ALL ALL cells:
* contain cytoplasm, cell membrane, and DNA
* are either a prokaryotic or a eukaryotic
Prokaryote Eukaryote
•The smallest cells in nature•DNA not contained in a nucleus, free in the cytoplasm•Ribosomes are the ONLY cell organelle•Who are they? Bacteria
•Much larger and more complex•DNA is wrapped with a nuclear membrane (nuclear envelope)•MANY more cell organelles•Who are they? Protists, Fungi, Plants, Animals
7-2 Cell StructuresA. Cellular Control Center
• Nucleus, nucleolus, chromatin/chromosomes, nuclear membrane/pore
B. Organelles that Store, Clean Up and Support
• Vacuoles, vesicles, lysosomes, cytoskeleton (microtubules, microfilaments), centrioles
C. Organelles that Build Proteins
• Ribosomes, endoplasmic reticulum (smooth and rough), golgiapparatus
D. Organelles that Capture and Release Energy
• Chloroplasts, mitochondria
E. Cellular Boundaries
• Cell wall, cell membrane
F. Fluid Portion Outside of Nucleus (Sort of a boundary!)
• Cytoplasm
CELLULAR CONTROL CENTER: NUCLEUS
❚ Function:❙ Information center of the
cell❙ Contains DNA (chromatin
vs. chromosomes)❙ Directs cell activities
❚ 2 categories of organisms
❙ Prokaryotes – organisms whose cells lack nuclei (i.e. bacteria)
❙ Eukaryotes – organism whose cells contain nuclei
Structure:❙ NUCLEOLUS – a small, darkened region in the nucleus
that is made up of RNA and proteins, this is where ribosomes are made
❙ CHROMOSOMES – large structures formed from DNA that contain the genetic info❘ CHROMATIN – uncondensed DNA found in non-dividing
cells
❙ NUCLEAR ENVELOPE – double membrane around the nucleus that contains pores, allows molecules to move in and out of the nucleus, and protects the nucleus❘ NUCLEAR PORES – allows passage of materials into or
out of nucleus (RNA, ribosomes)
Nucleus
Nucleus
ORGANELLES THAT STORE, CLEAN UP, SUPPORT: VACUOLE
❚ Structure:❙ Large, central structure in plants
❙ Many, small, circular structures in animal cells
❙ Filled with liquid
❚ Function:❙ Storage of water, salts, proteins, carbohydrates, waste products
❙ Pressure system for plants, prevents wilting
❙ Special case: contractile vacuole - prevents excess water intake, leading to cell-bursting
❚ Store and move materials between cell organelles and
to/from cell surface
ORGANELLES THAT STORE, CLEANUP, SUPPORT: VESICLE
ORGANELLES THAT STORE, CLEAN
UP, SUPPORT: LYSOSOME
❚ Structure:❙ Small, circular structures
❙ Found only in animal cells
❙ Contain digestive enzymes
❚ Function:❙ Digestion of:
❘ Worn out organelles
❘ Debris
❘ Large ingested particles
❙ Lysosomes are responsible for your hands not being webbed!!
Lysosome
ORGANELLES THAT STORE, CLEAN UP, SUPPORT: CYTOSKELETON
❚ Structure:❙ Hollow tubes of proteins
❙ Examples: cilia, flagella, centrioles
❚ Function:❙ Framework
❙ Provide cell with support, structure and shape
❙ Movement (cilia, flagella)❘ Microfilaments - allow movement of cytoplasm within the cell (cytoplasmic streaming)
❘ Microtubules - Maintain cell shape, make up cilia, flagella and centrioles
ORGANELLES THAT STORE, CLEAN UP, SUPPORT: CENTRIOLES
❚ Organize cell division
ORGANELLES THAT STORE, CLEAN UP, SUPPORT:PLASTID
❚ Structure:❙ Differ based on type of plastid (chloroplast is one example)
❙ Found only in plants
❚ Function:❙ Store food/starch ❙ Store pigments (give color to fruits & veggies)
ORGANELLES THAT BUILD PROTEINS: RIBOSOMES
❚ Structure:❙ Small (25 nm) ball-like
structures
❙ Found free-floating in cytoplasm or attached to rough endoplasmic reticulum
❙ Composed of RNA and protein
❚ Function:❙ Synthesis of proteins (where
proteins are made)
❚ Structure:❙ Network of flattened sacs❙ Can be rough (w/ ribosomes) or smooth (w/o)
❚ Function:❙ Transport materials within or out of cell
❙ Synthesis of macromolecules
❘ Rough - proteins, lipids, carbs
❘ Smooth - lipids
ORGANELLES THAT BUILD PROTEINS: ENDOPLASMIC RETICULUM
ORGANELLES THAT BUILD PROTEINS: GOLGI APPARATUS
❚ Structure:❙ Flattened stacks of membranes
❙ Vesicles attached to top and bottom
❚ Function:❙ Collection, modification, packaging of proteins and other substances
❘ Vesicles attach, deposit materials
❘ GA modifies materials based on needs
❘ Vesicles attach to membrane and distribute modified substances
ORGANELLES THAT CAPTURE/RELEASE ENERGY:
CHLOROPLAST
❚ Structure:❙ Double membrane
❙ Elaborate structure inside
❚ Function:❙ Another power station
❙ Found in plant cells only
❙ Conversion of light energy (sun) into chemical energy (glucose)
ORGANELLES THAT CAPTURE/RELEASE ENERGY:
MITOCHONDRIA❚ Structure:
❙ Double membrane❘ Cristae - inner folds, increase surface area
❘ Outer membrane for protection of cell
❚ Function:❙ “Powerhouse” of the cell
❙ Able to self-replicate (↑ # in cells with high energy need)
❙ Converts sugars into energy for cells
CELLULAR BOUNDRIES: CELL WALL
❚ Only in plants, algae, and some bacteria❚ Lies outside the cell membrane❚ Function
❙ Helps to protect and support the cell ❙ Very porous (water, oxygen, carbon dioxide, etc. can pass
through easily)❙ Gives rectangular shape to plant cells
❚ Layers❙ 1st layer – contains pectin (gluey substance that helps
hold the cells together)❙ 2nd layer – primary cell wall (made of cellulose)❙ 3rd layer (in woody stems) – secondary cell wall
(composed of cellulose and lignin to make cellulose more rigid)
CELLULAR BOUNDRIES:CELL MEMBRANE – outer boundary
❙ Structure:❘ Phospholipid bilayer
• hydrophilic heads, hydrophobic tails
❘ Contains lipids (bilayer), proteins (channels), and carbohydrate chains (identification cards)
❙ Function:❘ Regulates what enters and leaves the cell❘ Semi-permeable membrane❘ Protection and support
Cell/Plasma Membrane
CELLULAR BOUNDRIES:CYTOPLASM
❚ Material between the cell membrane and the nucleus
❚ Contains the organelles of the cell
QUESTIONS:❚ Describe the steps involved in the synthesis, packaging, and exporting of a
protein from a cell. ❙ Proteins assembled on ribosomes (if targeted for export to cm or to
specialized locations w/in cell, complete their assembly on RER���� protein in vesicle ���� Golgi apparatus (further modifies, proteins before sorting and packaging them in membrane bound vesicles ���� vesicle ���� final destination
❚ What are the two major parts of the cell? ❙ Cytoplasm with organelles, and nucleus
❚ How do contractive vacuoles help maintain water balance? ❙ Pump out excess water
❚ What is the difference between rough and smooth ER? ❙ Rough has ribosomes, smooth does not
❚ Why is the cell membrane sometimes referred to as a fluid mosaic? What part of the cell membrane acts like a fluid? And what makes it like a mosaic? ❙ It is made of many parts (like a mosaic) that can float around in the
fluid phospholipid bilayer❚ How do the properties of lipids help explain the structure of the cell
membrane? ❙ Hydrophilic lipid heads are attracted to water, hydrophobic fatty acid
tails turn away from water. A bilayer forms when heads turn outward towards water inside and outside a cell
❚ Why do you think it’s important that cell membranes are selectively permeable? ❙ Allows needed substances to enter and wastes to leave, while keeping
molecules that are not needed out
Plant vs. Animal Cell
Animal Cell
Plan
t Cell