Download Concept 6.4 - Plain Local Schools

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 mov’t
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