Cell

Some vocabulary

•  Euglena complex Eukaryotic cell - self sufficient, swim, photosynthesize

•  Prokaryote •  Eukaryote •  Protozoan (Paramecium) •  vs. Metazoan, complex, starts as 1 cell.

Cells can multiply and divide

•  Mitoses - daughter cells, become specialized •  control of gene expression •  (1) different genes turned on in different cells

(and at different times) •  (2) ALL CELLS HAVE SAME GENES -

CELLS ARE DIFFERENT BECAUSE OF WHICH GENES ARE TURNED ON

•  (3) but this can be fairly permanent, developmental change in gene regulation

Microscopy

light vs electron microscopy. •  Dyes (that absorb light) are used to highlight

substructures in cells. •  Consider, for instance, the word

"chromosome" which translates to "colored body."

•  Similarly, electron dense materials, heavy metals like osmium, uranium and lead create an electron density in the EM.

Orientation

•  membrane is a selective barrier to polar, charged, hydrophilic molecules and ions.

•  These need to be pumped at the expense of energy or come through specific channels (pore molecules) through the membrane

•  (more later in membrane coverage). •  Eukaryotic cells have specific little bodies that

are the small cell parallel of organs in the body, and hence they are called "organelles."

In summary •  rough endoplasmic reticulum where mRNA is

translated into protein, •  "rough" - ribosomes seen in EM. •  smooth ER - other reactions, steroid hormone •  Liver hepatocytes detoxify. •  Barbiturates induce an increase •  "microsomal fraction," smooth ER •  free ribosomes and polysomes •  proteins that go to different places. •  10 amino acids per second

Traffic

•  Golgi apparatus •  receives vesicles from ER (at cis face) •  secretory products that bleb off (from trans)

reactions after protein synthesis (post-translational modification of proteins)

•  different routings for different proteins in cell. •  inside the ER, Golgi complex, or vesicle is

outside the cell, •  much like inside the gut is outside the body.

Mitochondria & Chloroplasts •  Mitochondria- inner and outer membranes, •  inner one with shelves called cristae. •  ATP production •  mitochondria (and chloroplasts), evolved from

prokaryotes, engulfed into eukaryotic cells; •  They have some genes. •  Also mitochondria are intimately involved in

programmed cell death (apoptosis) •  pigments for photosynthesis, deployed in

multiple layers of membranes.

Lysosomes

•  phagocytosis (phag - eat as in hyperphagic, eating too much, or bacteriophage, a virus that infects bacteria)

•  Lysosomes merge and digest. •  This also applies to autophagy, where

cell eats itself in a process of turnover of its components.

Last slide at last

•  Microtubules - flagella and cilia - "9 + 2" •  Paramecia swimming cilia - beat reverses

when bump •  sperm flagella, •  cilia to clear mucus from trachea •  Microfilaments(will be covered in muscle

lectures) also many other functions, streaming and anchoring of cytoplasm