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Cells
I.
Characteristics of Life
What makes something alive?
-has an orderly structure
-reproduces
-grows and develops
-adjusts to changes in the environment
Examples of living and non-living things:
Living-Plant, animals, bacteria, protests, fungi
Nonliving-viruses, rocks, water, sun, air, soil, wind, fire
Organization of living things:
CellTissueOrganOrgan SystemOrganism
-A cell is the smallest unit that makes up an organism.
II.
History of Cells and Microscopes
-In the 1600’s compound light microscopes were invented. These
microscopes use a series of lenses to magnify objects.
-Magnify means to make objects look bigger.
-After the invention of the microscope, scientists began to look at cells
under the microscope.
-Robert Hooke used a compound light microscope to look at dead cells
from an oak tree. He named what he saw “cells” because they reminded
him of the cells the monks lived in.
-In the 1930’s electron light microscopes were invented which allowed
scientists to look at even smaller objects, such as organelles.
-Organelles are membrane-bound structures found inside cells.
III.
Cell Theory
-In the 1830’s something called the “Cell Theory” became a popular way
of describing life in terms of cells.
-The cell theory is made up of three main ideas:
1. All organisms are composed of 1 or more cells. An organism may be
Made up of one cell, such as bacteria, or may be multicellular, that is
have many cells, such as plants and animals.
2. The cell is the basic unit of structure and organization or organisms.
Although organisms such as humans, dogs and trees can become very
large and complex, the cell remains the simplest, most basic part of an
organism.
3. All cells come from preexisting cells. This means that a cell comes
from a parent cell (one parent cell divides to become two daughter
cells).
IV.
Types of Cells
-There are two types of cells.
V.
VI.
Prokaryotic cells do not have a nucleus or any other membrane-bound
organelles. Ex: Bacteria
Eukaryotic cells do have a nucleus. Ex: Plant and animal cells.
Cell Parts and Processes
-Cytoplasm-clear jelly-like fluid in the cell. Cytoplasmic streaming is when
the cytoplasm moves and carries products around the cell.
-Plasma Membrane-phospholipid bilayer,selective permeability, homeostasis
-selective permeability-only certain things are allowed in and out of the
Cell-the pm is in charge of this.
-homeostasis-like a thermostat in the house-maintaining a balance inside
The cell.
-Cell Wall-only in plants, bacteria and fungi, not in animal cells!
-Nucleus -control center, where the DNA is found (Chromatin-DNA strands)
-Nucleolus-found inside the nucleus, where ribosomes are made.
-ER-where protein and lipids are assembled and transported
-Ribosomes are made in the nucleolus and then leave the nucleus through
nucleur pores into the cytoplasm where the attach to the ER and make protein.
-RER-ribosomes attach to ER and make protein-site of protein synthesis
-SER-where lipids are synthesized
-Golgi apparatus-sorts proteins into packages and packs them into membranebound structures, called vesicles which are sent to different places in the cell.
-Vacuoles-temporary storage space such as water. Usually found in plants.
-Lysosomes-contain digestive enzymes-digest waste products.
-Chloroplasts-only found in plants, capture light energy and convert it into
chemical energy. Contain chlorophyll which is the pigment which traps the
light energy and also gives plants their green color.
-Mitochondria-powerhouse of the cell-double-membrane bound structure
which breaks down sugar to produce energy in the form of ATP
-Cytoskeleton-support structure like a skeleton-made up of microtubules and
microfilaments.
-Centrioles-help with cell division-found only in animal cells.
-Cilia and flagella-help with cell movement, only found on certain cells.
Difference between Animal and Plant Cells
-Animal cells have centrioles.
-Plant cells have cell walls, vacuoles and chloroplasts.
-Everything else they have in common.