Download Concept 6.4: The cell builds a diversity of products

Concept 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”
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
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
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
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
Concept 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
C. The phospholipids form a two-layer 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
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
Concept 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
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
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
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”
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
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
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
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
Concept 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
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
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
Concept 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”
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
Concept 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
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
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