6.1 All organisms are made of cells

I. The Cell Theory
A. In 1655 Robert Hooke observed
“ compartments
” in a thin slice of cork which he named cells
B. In 1700 Anton van Leeuwenhoek had developed light microscopes to observe tiny living organisms which he named
“ animalcules
”

First microscopes
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The Cell Theory
C. Cell theory is the generalization that all living things are composed of cells, and that cells are the basic unit of structure and function in living things

II. Microscopes as Windows to
Cells
A. Light microscopes can magnify objects up to about 1,000 X
B. Electron microscopes can magnify objects up to about 1,000,000 X
C. A photograph of the view taken through a microscope is called a micrograph

Microscopes
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Microscopes
SEM- scanning electron microscope
TEM- transmission
Both must use preserved specimens.

Microscopes
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III. An Overview of Animal and
Plant Cells
A. Each part of a cell with a specific job to do is called an organelle
B. The plasma membrane defines the boundary of the cell and regulates traffic in and out of the cell

Overview of animal and plant
C. The nucleus stores the genetic material of the cell
D. The region of the cell between the nucleus and the plasma membrane is called the cytoplasm

Animal Cell

Animal Cell

Plant cell

Plant cell

IV. Two Major Classes of Cells
A. A prokaryotic cell lacks a nucleus and most other organelles
B. A eukaryotic cell has a membrane bound nucleus and organelles

Animal v. Plants
Animal Plant
Plasma membrane Membrane and cell wall
Mitochondria Mitochondria and chloroplast
Cytoplasm, nucleus Both
Most organelles Most organelles

Eukaryotic v. Prokaryotic
Eukaryotic
Nucleus
Prokaryotic
No nucleus
Plants and animals Bacteria
Cytoplasm Cytoplasm
Organelles Lacks organelles

6.2 Membranes organize a cell
’ s activities

I. Membrane Structure
A. Membranes regulate the transport of substances across it
B. Membranes are composed mostly of proteins and phospholipids

Membrane structure
C. The phospholipids form a twolayer sandwich called a
“ phospholipid bilayer
” which surrounds the organelle or cell
D. The membranes are fluid-like rather than sheets of molecules locked rigidly into place

Plasma membrane

Plasma membrane

II. The Many Functions of
Membrane Proteins
A. Many types of proteins are embedded in the membranes phospholipid bilayer
B. Some proteins carry out some of the cells important chemical reactions, others helps cell communicate and recognize each other, other proteins move substances like sugar and water across the membrane

Functions of Membrane Proteins
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6.3 Membranes regulate the traffic of molecules

I. Diffusion
A. Diffusion is the net movement of the particles of a substance from where they are more concentrated to where they are less concentrated
B. Equilibrium is reached when the movement of particles in one direction is equal to the number of particles moving in the other

Diffusion
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II. Passive Transport
A. A selectively permeable membrane allows some substances to cross the membrane more easily than others and blocks the passage of some substances altogether

Passive transport
B. Diffusion across a membrane is called passive transport because no energy is expended by the cell, only the random motion of molecules is required to move them across
C. Facilitated diffusion is when transport proteins provide a pathway for certain molecules to pass

Passive transport
Carbon dioxide, oxygen- nonpolar
Water, glucose - polar molecules

III. Osmosis
A. The passive transport of water across a selectively permeable membrane is called osmosis
B. A solution with a higher concentration of solute is called
hypertonic hyper =
“ above
”
C. A solution with a lower concentration of solute is called hypotonic hypo =
“ below
”

III. Osmosis
D. A solution that has an equal concentration of solute is called
isotonic iso =
“ equal
”
When an animal cell is placed in a hypotonic solution it swells
- When an animal cell is placed in a hypertonic solution it shrinks

Osmosis
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IV. Active Transport
A. When a cell expends energy to move molecules or ions across a membrane it is called active transport
B. A specific transport protein pumps a solute across a membrane, usually in the opposite direction it travels in diffusion

Active Transport
Sodium / potassium pump

V. Transport of Large Molecules
A. Large molecules have to be packed into vesicles , which are small membrane sacs that specialize in moving products into, out of and within a cell

Transport of large molecules
B. When a cell exports its protein products, a vesicle fuses with the plasma membrane and spills its contents outside the cell-a process called exocytosis
C. The reverse process, endocytosis , takes materials into the cell within vesicles that bud inward from the plasma membrane

Transport of large molecules
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6.4 The cell builds a diversity of products

I. Structure and Function of the
Nucleus
A. The nucleus in a cell contains DNA which controls all of the activities inside the cell
B. The nucleus is surrounded by the nuclear envelope which has hole in it which allow substances to pass in and out of the nucleus
C. Inside the nucleus is the nucleolus which contains parts necessary to make ribosomes

nucleus

II. Ribosomes
A. DNA codes for the production of proteins which are made in the ribosomes
B. The ribosomes are either bound to the surface of the endoplasmic reticulum or suspended in the cytoplasm

III. The Endoplasmic Reticulum
A. The endoplasmic reticulum is an extensive network of membranes which functions as the main manufacturing and transportation facility in the cell
1. Rough ER -The rough ER has ribosomes which insert proteins right into or through the ER membrane or packaged in vesicles and transported outside the cell

Endoplasmic Reticulum
2. Smooth ER -The smooth ER lacks ribosomes but enzymes in the smooth ER allow it to make lipid molecules

IV. The Golgi Apparatus
A. The golgi apparatus receives products from the ER and modifies, stores and routes proteins and other products to their final destination
B. This organelle is analogous to a processing a shipping center of the cell

V. Vacuoles
A. The cytoplasm has large, membrane bound sacs called vacuoles
B. Some vacuoles contain undigested nutrients, some pump out excess water that diffuses into a cell, others store chemicals that contribute to cell growth

VI. Lysosomes
A. Membrane bound sacs called lysosomes contain digestive enzymes that can break down such molecules like proteins, nucleic acids and polysaccharides
B. Lysosomes will digest food, destroy bacteria and digest damaged organelles

V. Membrane Pathways in a cell
A. The membranes inside a cell are transferable from one organelle to another
B. Products may leave a cell without ever crossing a membrane

Membrane pathway in a cell

6.5 Chloroplasts and mitochondria energize cells

I. Chloroplasts
A. Chloroplasts are the photosynthetic organelles found in some cells of plants and algae
B. Photosynthesis is a complex, multi-step process and the chloroplasts provides the necessary organization for the process to take place
C. Inside the chloroplasts are disks that act as the
“ power pack
”

chloroplasts
A. Chloroplasts are the photosynthetic organelles found in some cells of plants and algae
B. Photosynthesis is a complex, multi-step process and the chloroplasts provides the necessary organization for the process to take place
C. Inside the chloroplasts are disks that act as the
“ power pack
”

II. Mitochondria
A. Mitochondria are structures where cellular respiration occurs, a process that most organisms use to access energy
B. ATP is the main energy source for the cell and is the end result of cellular respiration
C. Mitochondria have many infoldings which allows for a larger surface area which results in more sites for respiration to take place

mitochondria
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6.6 An internal skeleton supports the cell and enables movement

I. The Cytoskeleton
A. Straight hollow tubes of proteins that give rigidity, shape and organization to a cell are called microtubules
B. Thin solid rods of protein that enable the cell to move or change shape are called microfilaments

microtubules & microfilaments

II. Flagella and Cilia
A. Flagella are long, thin whip-like structures with a core of microtubules that enables the cell to move
B. Cilia are generally shorter and more numerous than flagella and move back and forth and moves a cell

flagella and cilia
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III.The Cell as a Coordinated Unit
A. It is important to remember that a cell
’ s organelles do not work alone
B. The structure of a cell and its organelles determine its function and all the individual parts must work together

SA 2 ( 4 pts total)
Draw a single cell.
Label the nucleus.
Is this a plant or animal cell - how do you know?

Bonus (4 pts)
Draw one organism.
Label any visible structures.
What are the structures used for?