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I.
Cell Notes
Cells and Cell Theory
a. Cell- the smallest unit that can perform all life
processes.
i. All are surrounded by a membrane
ii. Have DNA
iii. Have cytoplasm
b. Robert Hooke (1665)
i. First person to describe cells under a
microscope
ii. Described “little boxes” when he looked at
cork.
iii. Also looked at living plants and saw that
some cells were filled with “juice”
iv. What do you think the “juice” was?
c. Anton van Leeuwenhoek (1673)
i. Made his own microscopes
ii. Looked at various living things, like pond
scum, blood cells, bacteria and yeast
d. Cell Theory
i. Consists of 3 main statements about ALL living
things.
1. All organisms are made of one or more
cells.
2. The cell is the basic unit of living things.
3. All cells come from existing cells.
e. Cell size
i. Most cells are too small to be seen with the
naked eye
ii. Some cells, like the yolk of a chicken egg or
the nerve cells of a giant squid, can be very
large.
II.
III.
Parts of a cell
a. All cells have the following parts
i. Cell Membrane- a protective layer that covers
the cells surface and acts as a barrier
ii. Cytoplasm- the fluid contained inside the cell
iii. Organelles- structures that perform certain
functions within the cell
1. Examples- nucleus, ribosomes,
chloroplasts
iv. Genetic Material
1. in the form of DNA (deoxyribonucleic
acid)
2. Carries information to make new cells
and new organisms.
3. In some cells, the DNA is found in the
nucleus (an organelle)
Two kinds of cells
a. Prokaryotes
i. Single celled
ii. No nucleus
iii. No organelles
iv. 2 groups of animals are prokaryotes- bacteria
and Archaea (group of animals that live in
extreme environments like volcanic vents or
in swamps)
b. Eukaryotes
i. Cells have a nucleus
ii. Cells have organelles
iii. Many, but not all, eukaryotes are
multicellular.
iv. Examples; Animals, plants, protists, fungi,
algae, etc.
v. Yeast are single celled eukaryotes
IV.
Parts of a Eukaryotic Cell
a. Cell Wall- In a plant cell, this rigid structure surrounds the
cell membrane and provides support to the cell.
b. Cell Membrane- A phospholipid layer that covers a cells
surface, acts as a barrier between the inside of a cell and
the cell’s environment
c. Cytoskeleton- web of proteins inside the cytoplasm,
which acts as both a muscle and a skeleton
d. Nucleus- in a eukaryotic cell, a membrane bound organelle
that contains the cell’s DNA and has a role in the processes
such as growth, metabolism and reproduction
e. Ribosomes- Organelles that make proteins
i. Proteins are made of amino acids
ii. Amino Acids- any of about 20 different organic
molecules that are used to make proteins
f. Endoplasmic Reticulum- System of folded membranes
in which proteins, lipids and other materials are made.
Part of the internal delivery system of the cell.
i. Rough Endoplasmic Reticulum- Part of the ER
covered in ribosomes, delivers proteins that the
ribosomes make.
g.
h.
i.
j.
k.
l.
V.
ii. Smooth Endoplasmic Reticulum- Part of the ER not
covered in ribosomes, makes lipids and breaks down
toxic materials
Mitochondria- Main power source of the cell, organelle
where sugar is broken down to make energy
i. Energy is stored in ATP
ii. Adenosine Triphosphate (ATP) - storage place for
energy released by the mitochondria- can be used to
do work.
Chloroplasts- Organelles in plants and algae in which
photosynthesis takes place.
i. Chloroplasts are necessary for photosynthesis.
ii. Photosynthesis = sunlight + carbon dioxide + water
= sugar + oxygen
iii. Chloroplasts are green due to a green pigment they
contain called chlorophyll.
iv. Chlorophyll traps the energy of sunlight.
Golgi Complex- Organelle that packages and distributes
proteins
Vesicle- a small sac that surrounds material to be moved
into or out of a cell.
Lysosome- Organelles that contain digestive enzymes that
destroy worn out or damaged organelles, get rid of waste
materials and protect the cell.
Vacuoles- Organelle that stores water and other materials
Organization of living things
a. Cells work together to form tissues
i. Example; Cardiac muscle tissue
ii. Four types
1. nerve tissue, muscle tissue, connective tissue
and protective tissue
b. Tissues work together to form organs
i. Example; lungs, stomach, etc.
c. Organs work together to form organ systems
i. Example; digestive system, endocrine system