UNIT 2: THE CELL
Chapter 7 (Cell Structure and Function)
CHAPTER 7.1:
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LIFE IS CELLULAR
Key questions
What is the cell theory
 How do microscopes work
 How are prokaryotic and eukaryotic cells different
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Vocab
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Cell
Cell theory
Cell membrane
Nucleus
Eukaryote
prokaryote
DISCOVERY OF THE CELL
Originally “seeing is believing”
Early microscopes
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1665, Robert Hooke: made a compound microscope to
see a slice of cork
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Several small compartments = “Cells”
Anton van Leeuwenhoek: used a lense to look at pond
water and material within his mouth
 1838: Matthias Schleiden discovered allplants are
made of cells
 Theodore Schwann discovered all animals are made
up of cells
 1855: Rudolf Virchow concluded that new cells can
be created by the division of cells
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THE CELL THEORY
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The cell theory states:
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All living things are made up of cells
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Cells are the basic units of structure and function in
living things
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New cells are produced from existing cells
EXPLORING THE CELL
How do microscopes work?
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use lenses to magnify the image with light or electrons
Light microscopes:
Uses reflected light:
 Only good for 1000x magnification
 Can see items as small as 1 millionth or a meter
 Must have stains or dyes because of transparency of item
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Electron microscopes:
1 billionth of a meter
 Transmission EM
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Beams of electrons pass through the thin samples only
2-D
Scanning EM
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Scans the surface of the sample
Giving a 3-D of specimen surface
PROKARYOTES AND EUKARYOTES
Cells come in varying shapes and sizes
 Typical size being 5-50 micrometers
 Smallest being .2 micrometers and the largest
being 1 millimeter in diameter (chaos choas; the
giant amoeba)
 All cells have a cell membrane (plasma
membrane)
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CHAOS CHAOS
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Two categories:
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Organized nucleus  Eukaryote
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No organized nucleus  Prokaryote
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Nucleus: a large membrane-enclosed structure that
contains genetic material like DNA and controls
many of the cells activities
EUKARYOTE
PROKARYOTE
7.1 ASSESSMENT REVIEW
1.
Cell
1.
2.
3.
2.
Microscope
1.
2.
3.
What is a cell?
What 3 statements make up the cell theory
How did the invention of the microscope help the
development of the cell theory
How do microscopes work?
What does it mean if a micrograph is “false-colored”
Features of a cell
1.
2.
What features do all cells have
What are the differences between prokaryotes and
eukaryotes?
7.2 CELL STRUCTURE
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Key questions:
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What is the role of the Nucleus
What are the functions of the Vacuoles, lysosome, and the cytoskeleton
What organelles help make and transport proteins
What are the functions of chloroplasts and mitochondria?
What is the function of the cell membrane?
Vocab:
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Cytoplasm
Organelle
Vacuole
Lysosome
Cytoskeleton
Centriole
Ribosome
Endoplasmic reticulum
Golgi aparatus
Chloroplast
Mitochondrion
Cell wall
Lipid bilayer
Selectively permeable
CELL ORGANIZATION
http://www.youtube.com/watch?v=D3fOXt4MrOM
http://www.youtube.com/watch?v=LMVQ-INMSVw
Simple breakdown into 2 groups:
1.
Nucleus
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2.
Contains nearly all cell’s DNA and the coded
instructions for making proteins and other important
molecules
Cytoplasm
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The fluid portion of the cell outside the nucleus
**Both Eukaryote and prokaryote cells have cytoplasm**
ANIMAL CELL
PLANT CELL
NUCLEUS
“The control center”
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Nuclear envelope
Dotted with holes
 Allows for particles (messages) to flow
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Chromosomes
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Carry genetic information
Chromatin
 Nucleolus:
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Assembly of RNA
ORGANELLES
Specialized structures that act like organs within the
cell aid with storage, clean up, and support
Vacuoles (storage)
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storage of materials like water, salts, proteins, and
carbohydrates
In plant cells, one large one filled with liquid to help with
rigidity with things like flowers and leaves
Vesicles:
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Store and move material between organelles and to and
from the surface of the cell
Lysosome: (cleaning crew) get rid of the “Junk”
Small organelles filled with enzymes
Break down lipids, carbohydrates, and proteins into
smaller molecules that can be used throughout the cell
 Breaking down useless organelles
 Link to disease when not functioning
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ORGANELLES…CONTINUED
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Cytoskeleton: (the building)
Shape and internal organization of the cell
 Aids in movement of cell
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2 principle protein filaments
 Microfilaments: actin
 Microtubules: hollow structures of protein
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GREEN = MICROTUBULES
RED
= ACTIN
MAKING PROTEIN
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1.
Proteins are responsible for so many essential functions for life…therefore it needs to be
produced in high amounts
Ribosomes:
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2.
small particles of RNA and protein found throughout the cell
Assemble protein
http://www.youtube.com/watch?v=D3fOXt4MrOM
Endoplasmic Reticulum:
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3.
Eukaryotic Cells
Formation of lipid component of cell membrane
Protein packaging
2 types of ER
Rough ER: ribosomes
Smooth ER: no ribosomes
Golgi aparatus: packaging of proteins:
1.
Modifies, sorts, and packages proteins and other materials from the ER for storage or
release from the cell.
THE PROCESS FROM NUCLEUS TO CELL
MEMBRANE
ENERGY FACTORY
All things need energy…how do cells get theirs?
Chloroplasts:
these organelles capture the energy from
sunlight and convert it into food that contains
chemical energy in a process called
photosynthesis.
Cholorphyll
ENERGY CONTINUED…
Mitochondria:
this organelle converts chemical energy stored in
food into compounds that are more convenient for
the cell to use.
Two layer membrane (like the chloroplasts)
**2 interesting facts**
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Heredity linked to mother
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Carries own DNA…may have been
Independent micro-organism at one time?
BOUNDARIES OF CELL
Cell wall:
A strong protective/supportive layer around the
cell
support
 shape
 protect the cell
 NOT IN ANIMAL CELLS!!
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Cell membranes:
regulate what enters and leaves a cell and also
protects and supports the cell.
Lipid bilayer: gives cell membrane a flexible
structure that forms a strong barrier between the
cell and its surroundings
LIPID BILAYER
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The lipid has two parts
One hydrophobic
 One hydrophilic
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These layers create a water
Tight envelope around the cell!
*protein molecules aid in allowing
particle to pass through the
membrane making it selectively
permeable
FLUID MOSAIC
7.2 REVIEW
1.
2.
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4.
5.
What are the major parts of the cell?
What is the function of lysosomes?
What is the difference between smooth and
rough ER?
What is the function of mitochondria?
Why is the cell membrane sometimes reffered to
as a fluid mosaic?
7.3 CELL TRANSPORT
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Key Questions:
What is active transport
 What is passive transport
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Vocab:
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Diffusion
Facilitated diffusion
Aquaporin
Hypertonic
Hypotonic
Osmotic pressure
CELL TRANSPORT…PASSIVE TRANSPORT
Read “think about it” on pg. 208
What is Passive transport:
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the movement of materials across the cell membrane without
using cellular energy.
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Diffusion:
The process by which particles move from an area of
high concentration to a an area of lower concentration.
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Cellular cytoplasm is made of many different substances
dissolved in water.
In any solution particles move constantly
They collide and spread out randomly
**diffusion is the driving force behind the movement of many
substances across the cell membrane**
PASSIVE TRANSPORT
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Facilitated Diffusion:
The process in which particles that cannot directly diffuse
across the membrane pass through special protein channels
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These particles pass through protein channels
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Channels are specifically sensitive to certain particles
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It is the “speed pass”
OSMOSIS
Osmosis(example of facilitated diffusion):
 Diffusion of water through a selectively permeable
membrane
-Because of the lipid bilayer, water needs a way in…so
 Aquporins are specific protein channels to allow for
H2O to pass quickly through the cell membrane.
 In the presence of a hypertonic (++) and hypotonic(--)
solution, equilibrium is needed= a isotonic solution
 Hypertonic: “above strength”
 Hypotonic: “below strength”
 Isotonic: “same strength”
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Osmotic pressure:?
OSMOSIS IN ACTION
ACTIVE TRANSPORT
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The movement of materials against a
concentration difference which requires energy.
The active transport of small molecules or ions
across the cell membrane are often carried out by
Transport proteins – protein pumps
The active transport of large molecules and
larger materials are transported by process called
endocytosis / exocytosis.
MOLECULAR TRANSPORT
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Most cells transport:
Calcium
 Potassium
 Sodium ions
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Energy (ATP) is used to power the “pump”
BULK TRANSPORT
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Endocytosis:
Taking in of material
 Phagocytosis: extensions reach out to the particle
and package it within a vesicle
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Exocytosis:
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Vesicle bonds with membrane and releases material
outside the cell
WHICH IS WHICH?
CHAPTER 7.3 REVIEW
1. what happens in diffusion?
 2. describe osmosis
 Difference between diffusion and facilitated
diffusion
 How is active and passive transport different
 2 major types of active tranport
 endocytosis vs. exocytosis
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7.4 HOMEOSTASIS AND CELLS
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Key Questions:
How do individual cells maintain homeostasis
 How do cells of multicellular organisms work
together to maintain homeostasis?
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Vocab:
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Homeostasis
Tissue
Organ
Organ system
receptor
HOMEOSTASIS
Homeostasis: responding to the environment
through growth, transforming energy, and
reproduction
* both in unicellular and multi-cellular
organisms:
MULTICELLULAR HOMEOSTASIS
Cells of multicellular organisms become specialized for
particular task and communicate within one another
to maintain homeostasis
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Tissue: groups of cells to perform a function
Organ: groups of tissues working together to perform
a function
Organ system: a group of organs working together to
perform a function
Communication:
receptors: on or in a cell, a specific protein
protein to whose shape fits that of a specific molecular
messenger.
REVIEW 7.4
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What is homeostasis?
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Single cell organisms vs. multicellular
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Cellular specialization
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Receptors?