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Human Biology
Instructor Terry Wiseth
CELL CELL STRUCTURE & STRUCTURE &
FUNCTIONFUNCTION
2
CELL MEMBRANECell membrane made up
of:
1) Phospholipids1) Phospholipids
2) Sterols2) Sterols
3) Proteins3) Proteins
4) Glycoproteins4) Glycoproteins
PHOSPHOLIPIDScell membrane - semi-permeable lipid
bilayertwo layers of Phospholipids
4
STEROLS
common sterols of cell membranesCholesterol (animal cells)
prevent packing of lipid cells in the cell membrane
5
PROTEINS
Proteins are embedded into the cell membraneThese proteins serve a variety of cell
membrane functions
6
GLYCOPROTEINSproteins are embedded in the bilayer
glycoproteins - sugar-protein combinations
sugars extend out to the extracellular fluid
CELL MEMBRANE
8
FLUID MOSAIC MODEL
membrane bilayer shows fluid behaviormolecules of the bilayer are in constant
motion
9
FLUID MOSAIC MODEL
membrane is composite of molecules allowing a “mosaic description”
cell survival depends on fluidity characteristics of the cell membrane
10
FLUID MOSAIC MODEL
extracellular fluid temperature decreases cause a stiffening of the cell membranedisrupts membrane protein function
11
CELL THEORYSmallest entity that retains the
characteristics of life1) Complex organization2) Metabolic activity3) Reproduction
12
CELL SIZE
Most cannot be seen without the aid of a microscopeLarger cells
”Yolk” of bird eggsFish eggs “caviar”
13
CELL SIZEHuman eyes able to see about 100
microns
14
LIGHT MICROSCOPE
The light microscope has a limit of resolution of about 200 nm (0.2 microns)
15
TEMThe Transmission Electron Microscope
(TEM) has a limit of resolution of about 2 nm
16
SEMThe Scanning Electron Microscope (SEM) also has a limit of 2 nm
Bronchiole cilia
WBC engulf bacteria
Sperm & Egg
17
GENERALIZATIONS OF CELL THEORY
Cells vary in size, shape and activitiesAll cells have:
1) Plasma membrane2) DNA region3) Cytoplasm4) Organelles
18
PLASMA MEMBRANEOuter membrane
maintains the integrity of the cell
Membrane does not however isolate the cell
19
PLASMA MEMBRANECell membrane
“Lipid bilayer”Boundary that bars free passage of water
soluble substances in and out of the cell
20
NUCLEUSDNA is localized in the cell nucleus
21
CYTOPLASMEverything enclosed by the plasma
membrane except the DNA semi-fluid
22
CYTOPLASMIC STREAMING
Cytoplasm is not stagnant but rather is constantly moving (streaming)
23
ORGANELLESOrganelles--internal sacs which have a
specific metabolic functionEssential in keeping chemical reactions in
the cytoplasm separate from each other
24
CELL MACHINERY
25
CELL MACHINERY
26
NUCLEUSNucleus sequesters DNA
1) Separates DNA from chemical reactions in cytoplasm
2) Nuclear membranes control access between nuclear material and cytoplasm
27
NUCLEUSNuclear envelope has pores to allow
passage of messenger units of nucleic acid
28
NUCLEUS
29
NUCLEOLUS1) AssemblyAssembly of RNA and
ribosomes2) StorageStorage of RNA and
ribosomes
30
DNAInstructions for building proteins (enzymes)
are contained in DNAInstructions of heredity are distributed in
several DNA molecules of various lengthsHumans = 46 DNA molecules
31
DNADNA is threadlikeprior to cell division the DNA molecules
duplicate
32
CHROMOSOMESDNA folds and twists into condensed
structures called chromosomes
33
CYTOMEMBRANE SYSTEM
Series of organelles through which lipids and proteins, produced on cytoplasmic ribosomes, pass through in becoming packaged for export
34
CYTOMEMBRANE SYSTEM
1) Endoplasmic reticulum (ER)
2) Golgi bodies3) Vesicles4) Lysosomes
35
ENDOPLASMIC RETICULUM
1) Rough endoplasmic reticulumRibbon like structure with ribosomes
attachedArranged as flat, stacked sacs
36
ENDOPLASMIC RETICULUM
37
RIBOSOMESRibosomes are small spherical shaped
structuresServe as the “working table” for
assembling proteins
38
RIBOSOMES
39
ENDOPLASMIC RETICULUM
2) Smooth endoplasmic reticulumLacks ribosomes
40
SMOOTH ENDOPLASMIC RETICULUM
Appears like a system of pipes1) Lipid synthesis
Ex: endocrine glands produce steroid hormones
2) Inactivate harmfulby-products ofmetabolism and drugsEx: liver cells
41
GOLGI BODIES
Resemble stacks of pancakes
42
GOLGI BODIES
Flattened sacs in which lipids and protein molecules are modified
43
GOLGI BODIESModifications allow for sorting and
packaging for transport
44
GOLGI MODIFICATIONS
45
GOLGI MODIFICATIONS
46
VESICLESSacs which transport or store enzymes,
lipids and proteins1) Peroxisomes2) Lysosomes (microbodies)
47
VESICLES1) Peroxisomes
Contain enzymes to break down fatty acids and amino acids
48
VESICLES2) LysosomesVesicles of intracellular digestionContain enzymes which can break down
any polysaccharide, protein, nucleic acid and some lipids
49
LYSOSOMESImportant in proper function of white
blood cells (immunity)
50
LYSOSOMES
51
CYTOMEMBRANE SYSTEM
Raw materials (amino acids and lipids) are dissolved in the cytoplasm
52
CYTOMEMBRANE SYSTEM
Under the instructions of the DNA molecule polypeptide chains of proteins are assembled from the dissolved raw materials
53
CYTOMEMBRANE SYSTEM
54
MITOCHONDRIAContains a series of inner membranes
folded repeatedly (cristaecristae)Increases the total surface area available
for reactions
55
MITOCHONDRIAUse oxygen to assist in liberating energy
stored in sugars (aerobic respiration)
56
MITOCHONDRIAEnergy is used to form ATP molecules
which is used for protein synthesis and transport
ATP-molecule is able to store and transport energy for short periods of time
57
MITOCHONDRIAMost numerous in high energy demanding
cellsEx: muscles, liver
58
MITOCHONDRIA
59
CYTOSKELETONInterconnected system of bundled fibers,
threads and lattices
60
CYTOSKELETONExtend from the cell membranes, organelles
and nucleus
61
CYTOSKELETON
Supply internal organization, shape, ability to move, reinforce the cell membrane and hold proteins in place
62
CELL SURFACE SPECIALIZATIONS
Gap Junctionschannels of exchange in animal cells
ex: liver, heart
63
CELL SURFACE SPECIALIZATIONS
Junction Proteinshold cells together in forming tissues
ENDEND
CellCell