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Cell Review
The Diversity of Cells in the Human Body
Over 200 different types of cells in the human body, all of them specialized to perform a specific function.
All human cells are EUKARYOTIC, meaning they are large, complex cells with a nucleus and specialized organelles.
Every organelle performs a specific function.
Nucleus Place where chromosomes are stored. In humans, 46 chromosomes contains approx. 25000 genes. 1 gene codes for one protein only!
Manufacture of mRNA & tRNA necessary to build coded proteins.
Smooth & Rough Endoplasmic Reticulum (SER & RER)RER: Building and modification of proteins in ribosomes.SER: Synthesis of lipids and carbohydrates, other cell-specific functions (detoxification of toxins and alcohols in liver cells. In testes,
testosterone secretion).
mRNA
Synthesis ofmRNA in thenucleus.
DNA
NUCLEUS
CYTOPLASM
1
DNA contains the instructions to make proteins. 1 gene = 1 protein.
Instructions coding for the amino acid sequence of a protein are copied to a molecule of mRNA.
MAKING PROTEINS
mRNA
Synthesis ofmRNA in thenucleus
DNA
NUCLEUS
mRNA
CYTOPLASM
Movement ofmRNA into cytoplasmvia nuclear pore.
1
2
mRNA
Synthesis ofmRNA in thenucleus.
DNA
NUCLEUS
mRNA
CYTOPLASM
Movement ofmRNA into cytoplasmvia nuclear pore.
Ribosome
AminoacidsProtein
Synthesisof protein.
1
2
3
Smooth ERLipids & carbohydrates synthesized here.
Nucleus
Rough ER
Plasma membrane
Rough & Smooth ER
RibosomesProtein factories.
Cytoplasm
cis face(“receiving” side of Golgi apparatus)
trans face(“shipping” side of Golgi apparatus)
TEM of Golgi apparatus
0.1 µm
Golgi ApparatusFine-tuning, folding and final modifications to proteins. Sorting and packing of finished materials.
Nucleus
Rough ER
Plasma membrane
GolgiModifies proteins. Ships proteins away.
LysosomeClean-up crew; contains enzymes.
VesiclesTransport materials
Smooth ERLipids & carbohydrates synthesized here.
RibosomesProtein factories
Golgi
Nucleus 1 µm
Lysosome
Lysosome
Digestive enzymes
Plasma membrane
Food vacuole
Digestion
Digestion
LysosomesClean-up crew.
Breakdown (digestion) of ingested food material (specialized lysosomes only in animal cells).
Disposal of old, worn out organelles.
Vesicle containingtwo damaged organelles
Mitochondrion fragment
Peroxisome fragment
Peroxisome
Lysosome
DigestionMitochondrionVesicle
Destruction of old organelles
1 µm
Mitochondrium Cellular power plants. Production of ATP from glucose molecules using oxygen.
Cytoskeleton Maintains cell shape, supports and anchors organelles, and allows transport of materials.
Plasma Membrane A flexible barrier that controls what enters and leaves the cell. Contains ID proteins used by the immune system.
Lipid structure1 glycerol molecule, up to 3 fatty acids.
Made of phospholipids.1 fatty acid replaced by a phosphate group.
Hydrophilichead
WATER
Hydrophobictail
WATER
PHOSPHOLIPIDS
CYTOPLASMICSIDE
EXTRACELLULARSIDE
Channel & carrier proteins allow materials to move in and out of the cell.
NATURE ABHORS
GRADIENTS!
Gradient: a difference in concentration.Diffusion: the movement of particles from areas of low concentration to areas of high concentration until an equilibrium is reached.
Molecules of dye Membrane (cross section)
WATER
Net diffusion Net diffusion Equilibrium
(a) Diffusion of one solute
Net diffusion
Net diffusion
Net diffusion
Net diffusion
Equilibrium
Equilibrium
(b) Diffusion of two solutes
Passive transport
Simple Diffusion
Facilitated diffusion
Active transport(Na+/K+ pump)
ATP
Na+
K+
Some proteins are ID proteins, used by the immune system to identify friend from foe.