Bio - Class 9/25

cell size

ranges from barely visible with a light microscope to cells over 100x that size

microscopy

how we study cells

magnification

ratio of an objects image size to real size

contrast

visible difference in parts 

resolution

measure of clarity

TEM

transmission electron microscope, focuses a beam of electrons through specimen to see internal structure

SEM

scanning electron microscope, focuses a beam on surface of specimen providing 3D images

cell fractionation

grind and fine, form of reductionism, blending

why is cell size important

size of cells limited by logistics, surface area to volume ratio, bigger the cell larger the transport problem, bigger the # smaller the ratio

surface area/volume

important for nutrient exchange in and out of cell

strategies to overcome SA/V exchange

be small, be thin, increase internal area, and branched/folded structure

basic features of all cells

plasma membrane, cytosol, chromosomes, ribosomes

prokaryotes

unicellular, no nucleus, DNA in unbound region called nucleoid region, no membrane bound organelles

eukaryotes

unicellular and multicellular, DNA thats bound by membranous nuclear envelope, organelles with membrane, cytoplasm in part between plasma membrane and nucleus; younger

nucleus

holds genetic material (DNA)

nuclear envelope

double membrane around nucleus that contains pores

nuclear pores

exchange of material in and out of nucleus like macromolecules

nuclear lamina

net array of protein fibers that maintain shape of nucleus

nucleolus

part of chromatin that makes subunits of ribosomes (rRNA)

ribosome

made in the nucleolus region of nucleus, two types, free (in cytoplasm) and bound (in membrane)

endomembrane system

multifunctional system, includes nuclear envelope, endoplasmic reticulum, Golgi apparatus, lysosomes, vacuoles, plasma membrane

ES functions

synthesis/transport proteins, metabolism and lipid movement

rough er

has bound ribosomes to make proteins

smooth er

makes lipids and detox cell, no ribosomes

transport vesicles

membranous spheres to carry ER products to other parts of cell