Download Notes: Chapter 7

Notes: Chapter 7
Cell Structure & Function
Section 7-1: Life is Cellular
I. Discovery of the cell
A. A. Early microscopes: In the 1600s scientists began using
microscopes to observe living things
1. 1665 – Robert Hooke looked at cork, a plant material,
and saw empty chambers which he called “cells”
2. 1674 – Anton van Leeuwenhoek observed pond
water and saw many living cells
3. 1838 – Schleiden concluded that all plants are made
of cells
4. 1839 – Schwann concluded that all animals are made
of cells
5. 1855 – Virchow concluded that all cells come from
other living cells
B. B. The Cell Theory states: (from Schleiden, Schwann, &
Virchow)
1. All cells are composed of living cells
2. Cells are the basic unit of structure & function
3. New cells are produced from existing cells
II. Categories of Cells
A. Prokaryotes – cells that don’t have a nucleus
1. Small in size
2. Contains genetic material, but not in a nucleus
3. Example: bacteria
B. Eukaryotes – cells that have a nucleus
1. Larger & more complex than prokaryotes
2. Genetic material contained inside a nucleus
3. Example: plants, animals, fungi, & protists
Section 7-2: Eukaryotic Cell Structure
I. Eukaryotic cells contain organelles
A. Organelles – tiny parts within a cell that have a specific
function; “tiny organs”
B. Organelles & their functions:
1. Cytoplasm – fluid portion outside of the nucleus
2. Nucleus – holds the genetic material
3. Chromosomes – genetic material; threadlike
structures made of DNA
4. DNA – the instructions for making important proteins
and other important molecules
5. Nuclear Envelope – surrounds the nucleus; contains
tiny openings called nuclear pores
6. Ribosomes – make proteins
7. Endoplasmic Reticulum – transport system
i. Rough ER – has ribosomes on its surface
ii. Smooth ER – no ribosomes
8. Golgi Apparatus – modifies, sorts & packages
molecules from the ER
9. Lysosomes – contains enzymes that break down
unnecessary molecules within the cell; removes the
“junk”
10. Vacuoles – storage area
11. Mitochondria – changes food molecules into energy
12.Cytoskeleton – helps the cell maintain its shape; also
allows for transportation inside the cell
13. *Chloroplasts – changes energy from the sun into
energy for use by the cell; Found only in plants, algae,
and cyanobacteria
14.*Cell Wall – provides protection & support; Found
only in plants, algae, fungi, & many prokaryotes
Section 7-3: Cell Boundaries
I. Cell Membrane
A. Functions of the Cell Membrane:
1. Allows molecules into & out of the cell
2. Provides protection & support
B. Structure of the Cell Membrane
1. Made of a lipid bilayer (2 layers of lipids)
2. Contains proteins in the lipid bilayer
i. Channel proteins – allows molecules in & out of the
cell
ii. Marker proteins - “name tag” for a cell
iii. Receptor proteins II. How Do Things Move Into & Out of the Cell?
A. Passive Transport – no energy required
1. Diffusion – molecules move from an area of high
concentration to an area of lower concentration
2. Osmosis – the diffusion of WATER from a lower solute
concentration to a higher solute concentration across a
SELECTIVELY PERMEABLE MEMBRANE
i. Isotonic – solute concentration inside & outside a cell
are equal, or in equilibrium
ii. Hypertonic – solute concentration is higher outside
the cell; cell shrinks
iii. Hypotonic – solute concentrations is higher inside
the cell; cell swells causing osmotic pressure against cell
membrane or wall. If a cell does not have a cell wall, it
may burst if the osmotic pressure is too high.
3. Facilitated Diffusion – large molecules such as
glucose, move through protein channels
B. Active Transport – energy (ATP) is required
1. “Pumps” – move certain molecules against a
concentration gradient
2. Endocytosis – cell takes material into cell by folding in
its membrane
i. Phagocytosis – cell takes in material; eating
ii. Pinocytosis – cell takes in liquid; drinking
3. Exocytosis – cell releases material from the vacuole to
the outside of the cell
Section 7-4: Diversity of Life
I. Living organisms can be unicellular or multicellular
A. Multicellular Organisms
1. Made of different types of cells
2. Cell Specialization – when cells develop into different
types of cells that have different functions
i. Example: muscle cells, blood cells, skin cells, bone cells,
guard cells (in plants)
B. Levels of Organization in a multicellular organism:
1. Cells
2. Tissues – a group of similar cells that have a specific
function
3. Organs – groups of tissues working together
4. Organ Systems – groups of organs working together