Unit 2 - Ch 4 - Cells Flashcards
(49 cards)
Maximum Cell Size is determined by two factors:
- Surface Area to Volume Ratio
2. Nuclear Distance
Explain surface area to volume ratio
as cells grow, SA(V) ratio decreases
a. Volume - determines the nutrients needed and wastes produced
b. Surface Area - exchange surface for nutrients and wastes
c. Exceptions:
1. Large Surface Area - nerve cells
2. Low Metabolic Activity -egg cells (fertilization causes rapid division)
Components of cell theory:
A. All organisms are made of cells - Schleiden, plants *
- Schwann, animals*
- multicellular and unicellular
- viruses and prions not cellular
B. Cell is basic unit of life
- basis for cell culture, cloning, stem cells
C. All cells come from previously existing cells - Virchow *
- spontaneous generation does not occur
Who were the first to discover all organisms are made of cells?
Schleiden, plants
Schwann, animals
Who discovered all cells come from previously existing cells?
Virchow
describe the Plasma (Cell) Membrane and its components
semi-permeable barrier around cells
- Fluid Mosaic Model - current understanding
a. Phospholipid Bilayer - 2 F.A. tails (hydrophobic) surrounded by 2 phosphate groups (hydrophilic) makes up the bulk of the cell membrane
b. Membrane Proteins - embedded in the bilayer - some serve as carrier molecules
c. Glycocalyx - composed of glycolipids and glycoproteins - only extends from cell surface - cell recognition sites
Phospholipid Bilayer
2 F.A. tails (hydrophobic) surrounded by 2 phosphate groups (hydrophilic) makes up the bulk of the cell membrane
Membrane Proteins
embedded in the bilayer - some serve as carrier molecules
Glycocalyx
composed of glycolipids and glycoproteins - only extends from cell surface - cell recognition sites
describe the Cell Wall and its components
outer layer surrounding the cell membrane in some organisms
- composed of cellulose in plants
- composed of chitin in fungi
- composed of peptidoglycan in bacteria
- Primary Cell Wall - formed first; can expand
- Secondary Cell Wall - forms later; fills the cell
- Middle Lamella - adheres adjacent plant cells
Describe the Nucleus and its components
responsible for genetic regulation of the cell - usually one per cell ( multinucleate and anucleate )
- Nuclear Envelope
- Nucleoplasm
- Nucleolus
- Chromatin
Nuclear Envelope
or nuclear membrane - double membrane structure that isolates the nuclear material - contains nuclear pores
Nucleoplasm
Semi-liquid nuclear material
- clear in micrographs
- source of monomers of DNA and RNA
Nucleolus
(vs. nucleoli which is plural)
- condensed portion within the nucleus - involved in rRNA synthesis
Chromatin
complex of DNA and protein - forms chromosomes during cell division - granular and dark in micrographs
Cytoplasm
liquid material surrounding the nucleus - source of monomers (monosaccharides, amino acids, glycerol and FA’s) - buffered (pH) - clear
Vacuoles/Vesicles
membrane bound containers
- contain various substances
- food vacuoles
Ribosomes
composed of rRNA
- site of protein synthesis (condensation reactions)
- appear granular (dark)
- free in cytoplasm or attached to E.R.
Endoplasmic Reticulum
series of membranous canals
- lumen: internal space the membranes enclose
- part of the endomembrane system
- contain enzymes
Smooth ER
no surface ribosomes
- lipid synthesis (condensation)
Rough ER
ribosomes on the surface
- site of protein synthesis
Golgi Complex
part of the endomembrane sysem - stack of flattened membranes and associated vesicles
- site of chemical modification and packaging of materials into vesicles *immature vs mature
Lysosomes
membranous sacs that isolate hydrolytic enzymes (in animals)
- fuse with food vacuoles to digest contents
- rupture at cell death (apotosis)
- fuse with cell structures no longer needed by the cell
Peroxisomes
membrane bound containers that contain enzymes that break down peroxides
