Transcript introduction to cell biology

INTRODUCTION TO CELL
BIOLOGY
E. D. Salmon - Biology 205
1. Organization:
• 2 part course, 2 instructors
• 4 exams, 4 count, all exams scaled,
• recitations run by TA’s, material covered in
lecture exams
• problem questions for recitations, similar
questions on exams
2. Book
• : Essential Cell Biology, Alberts et al., 2nd
edition (2004)
3. Scope of Course:
• Theme: Molecular Organization ---->
Structure ----> Function
• Significant molecules in cells, their general
structure and function
• Major cell structural features
• How structure determines function
• Biochemistry-only identification of major
molecules and forces which drive
reactions and determine structure
4. Cell Unity and Diversity:
A. Cell Theory: Cells are units of
life; they all have:
• Delimiting plasma membrane to separate inside
from outside
• Metabolism to generate complex molecules from
foodstuffs and energetic molecules from light
(photosynthesis) or from respiration
• Capacity for reproduction
• genes --> transcription --> translation -->
structure and regulation
• (DNA) --> mRNA --> proteins --> subunits and
enzymes
All cells share the same "central dogma":
(how they create essential components for life from their genetic code)
DNA
TRANSCRIPTION
mRNA
TRANSLATION
Protein
All cells share the same information code
0 and 1
A, G, C, and T
GENOME = entire collection of genes for an organism
Genome size varies based on the complexity of the organism:
Mycoplasma:
477 genes
E.coli:
4289 genes
Budding Yeast: ~6300 genes
Fruit Fly:
~14,000 genes
Chimpanzee: ~30,000 genes
Human:
~30,000 genes
B. Unity:
• Common biochemistry-small molecules,
macromolecules and linkers (see
Biochemistry Handout)
• Common supramolecular structures and
physiology - e.g., lipid bilayers, ribosomes
C. Diversity:
• 2 major classes of cells based on
complexity of intracellular organization:
• 1) Procaryotes (no nuclear envelope) Single cell
• 2) Eucaryotes (nuclear envelope) Protista, Fungi, Plants, Animals; single cell
and multicellular; cell differentiation,
specialization and intercellular
communication
5. Viruses (are NOT cells):
• 20-300nm size
• DNA (RNA) + protein capsule
• not cells but highly
specialized parasites; specific
for host cell
• gene 1 kbase, several
proteins for coat, infection
and control of host
metabolism
• diversity of form-rods,
icosahedron, phage
6. Procaryotes: Mycoplasma,
bacteria and blue-green algae
A. Mycoplasma are simplest cells
• 1) 100nm in size
• 2) DNA-750 kb; 500-1000 different
proteins
• 3) Produce disease in animals and plants
- e.g., pleuropneumonia
B. Bacteria: Simple structure but
complex biochemistry
• 1) 1-10 m typically
• 2) 3000kb, DNA 1mm long; several
thousand different proteins
• 3) Cell cycle = 20 min in nutrient media
• 4) Metabolism diverse: aerobic,
anaerobic, nitrogen fixation, sulfur, severe
environment, photosynthetic, spores
• 5) General bacterial structure:
6) Special Features:
• Respiration produces ATP and proton gradient
across PM
• PM provides selective transport
• Bacteria containing bacteriochlorphyll do
photosynthesis in membrane sacs enfolded from
the PM
• Motility produced by rotary engine in plasma
membrane rotating stiff helical bacterial flagella
(flagellin)
• DNA not complexed with proteins
6) Special Features (cont):
• Ribosomes similar but distinct from
eukaryotic ribosomes
• DNA structure and ribosomes similar to
those in mitochondria and chloroplasts
• Cell division by fission, Mesosome
structure involved
C. Blue-green algae
(cyanobacteria)
• 1) photosynthetic; contain unique
pigments, the phycobilins-phycocyanin
(blue) and phycoerythin (red) plus
chlorophyll a
• 2) Fix CO2 and N2 into organic molecules
• 3) Evolution of electron source: H2S -->
H2O: O2
7. Eucaryotes
•
Complex structure, complex biochemistry
many functions and biochemical
processes compartmentalized within
membrane bound organelles; uni and
multicellular organisms, specialization
and differentiation.
A. Function of major structures and
organelles (Animals and Plants):
• Plasma membrane: selective transport,
receptors, connectors
• Nucleus- DNA complexed with histones; double
membrane with pores
• SER: lipid synthesis; calcium regulation
• Ribosomes in cytosol- synthesis of proteins
• RER: site protein synthesis for secretion
• Golgi: glycosylation, packaging for secretion
• Lysosomes: digestion
Function of major structures and
organelles (Animals and Plants):
• Coated vesicles: endo and exocytosis
• Mitochondria: aerobic respiration; own DNA and
ribosomes like a bacteria; double membrane
• Intercellular junctions: gap, tight, desmosomes
or plasmadesmada
• Extracellular matrix: ex. glycocalyx (animals) or
cellulose (plants)
• Cytoskeleton (actin-myosin, microtubules,
intermediate filaments): cell motility, organelle
transport, cell morphogenesis and cell division
B. Plants (vs animal) cell
structure:
• Rigid cell wall
• Cells do not move, but exhibit vigorous
cytoplasmic streaming
• Chloroplasts and other plastids:
photosynthesis; own DNA and ribosomes;
double membrane
C. Cell specialization and
differentiation:
• Protozoa, Yeast
• Multicellular organisms