BIO PRINCIPLES UNIT 2
I. Core Concepts
a. Cell is a major unifying, evolutionary theme
i. Cell theory = all organisms are made of cells and come from cells
b. Cells are small so cell membrane can control the constituents of life found within
i. Cell size increases = membrane gets smaller compared to cell volume
ii. Transport across membrane is essential to maintaining life, as materials
must go both ways while homeostasis is regulated
c. All functions necessary for life are in the cell, including special membrane-bound
structures called organelles found in eukaryotes
i. Prokaryotes can perform same functions in a less complex cellular format
ii. Nucleus houses DNA, another major unifying, evolutionary theme
1. “All” organisms carry their genetic information in the form of
DNA (prokaryotes do not have nuclear membranes but still possess
DNA)
iii. Mitochondria produces the majority of ATP for the cell in eukaryotes
1. Mitochondria possess DNA/RNA, which suggests they were
bacteria that developed an endosymbiotic relationship with other
cells
iv. Chloroplasts produce food molecules using sunlight (photosynthesis)
1. They also have DNA/RNA suggesting an independent organismal
existence at one time
d. Natural laws (thermodynamics) dictate that cells of organisms require energy to
maintain their structure and function and thus living condition
e. Through chemical reactions energy can be attained and stored
i. Exergonic reactions release energy while endergonic reactions require a
sufficient amount of energy to create complex products (e.g.,
macromolecules)
ii. Cellular metabolism, which involves releasing energy from food
molecules (catabolism) and using this energy to build cells, tissues, etc.
(anabolism)
iii. Enzymes are necessary for these reactions to occur at efficient and safe
levels
f. Biochemistry involves the chemical reactions involved in transferring energy to
produce ATP from food (cellular respiration) and the production of food
(photosynthesis or chemosynthesis)
i. Significant unifying, evolutionary theme is all organisms use and produce
ATP in the same basic way
ii. Food and oxygen produced during photosynthesis is key to the survival of
much of life on Earth
II. Cells: Their Structure & Function
A. Cytology the study of cells
a. Robert Hooke – “how can cork float”
i. Took sections, looked under microscope and found that they had
tiny chambers (aka cells)
,B. Microscopes
a. Light microscope
i. Part of electromagnetic spectrum via sun, delivering energy that
can be recorded as wavelengths (convert into color – ROY G BIV:
red, orange, yellow, green, blue, indigo, violet)
ii. However, there is no use for light microscope because there are
also shorter wavelengths (ultraviolet)
b. Electron microscope
i. Uses electrons
ii. Bombards organism with electrons, shape will determine where
electron is scanning electron microscopy (SEM)
iii. Other way is to put thin slices under microscope, which will allow
more electrons to pass through transmission electron
microscopy (TEM)
iv. Cannot take pictures of electrons because they are too small and
too fast
C. Cell Theory & Organelles
a. All organisms are composed of cells and come from pre-existing cells
b. Cells are made up of smaller components called organelles
D. Cell Size
a. Why are most cells small? compactness; to maximize surface area to
volume ratio for regulating the internal cell environment
b. Surface area/volume ratio
i. More surface area = take in more nutrients and carry out wastes
ii. More surface area allows for cell transport to be maximized
c. The smaller the cell, the larger the surface area
i. Except for eggs
ii. To hold more nutrients, the host cell of the mother is the host cell
for the new organism so its larger
E. Prokaryotic Cells pro–: before, –karyotic: nucleus; before nucleus
a. 3 domains – Bacteria, Eukarya, Archaea
b. Nucleoid (nucleus-like, but not nucleus) with DNA in continuous loop
c. Simple cellular organization with no nucleus or other membrane-bound
organelles
d. Flagella rotate
e. Ribosomes present all cells must have them; used to create protein
f. Plasma membrane produces ATP crista membrane, inner membrane of
mitochondria (was once bacteria); produces ATP, which explains why
plasma membrane produces ATP
i. Cell membrane composed of a fluidlike phospholipid bilayer,
proteins, cholesterol and glycoproteins
g. Cell wall outside of the cell membrane in some organisms
F. Cell Structure – Eukaryotes
a. Complex cellular organization
i. Cytoplasm – material outside nucleus
1. Site for metabolic activity
, 2. Cytosol: solutions with dissolved substances such as
glucose, CO2, O2, etc.
3. Organelles: Membrane-bound subunits of cells with
specialized functions
ii. Membrane-bound organelles, located inside cell membrane
1. Nucleus – contains DNA in the form of chromosomes,
controls cellular activities via genes
2. Nucleolus – located within the nucleus, site for ribosome
synthesis
3. Rough Endoplasmic Reticulum – has ribosomes, which are
necessary for protein synthesis
4. Smooth Endoplasmic Reaction – without ribosomes;
involved primarily in lipid synthesis
5. Golgi Apparatus – packaging center for molecules;
carbohydrate synthesis
6. Lysosomes – intracellular digestive enzymes; contains
hydrolytic enzymes for intracellular digestion
7. Peroxisomes – H2O2 metabolism; involved in hydrogen
peroxide synthesis and degradation
8. Chloroplast – site of photosynthesis; chlorophyll pigments
9. Chromoplast – contains non-green pigments
10. Leukoplast – stores starch
11. Mitochondrion – ATP synthesis; aerobic
12. Vacuole – general storage & space-filling structure
G. Cytoskeleton supportive and metabolic structure composed of microtubules,
microfilaments and intermediate filaments; internal framework, consisting of
many proteins, for materials to meet each other (highways)
a. Microtubules largest in size; tubular molecule (tubin); can form cilia,
flagella and centrioles
b. Microfilaments smallest in size; Actin (example) is a major protein in
muscle contraction
c. Intermediate filaments between microfilaments and microtubules in
size
H. Plasma Membrane “Fluid Mosaic Model”
a. Cytoplasm cyto- = cell, plasm = fluid; materials inside the cell
membrane, but outside the nucleus
b. Mosaic = thrown in haphazardly
c. Phospholipids makes up for most of the membrane
d. Glycoproteins carbohydrates as antigen; self-identification (name tag);
not-self are destroyed
e. Proteins membrane transport
f. Cholesterol helps maintain proper cell fluidity
I. Cell Wall
a. Outside of plasma membrane in some organisms (plants, fungi, bacteria),
but aren’t polyphyletic