Cell Structure and Function
Cell Structure and Function
1. The Cell Theory A. All organisms composed of one or
more cellsB. Cell is smallest living organizational
unitC. Cells arise only from division of other
cells
1. The Cell Theory A. All organisms composed of one or
more cellsB. Cell is smallest living organizational
unitC. Cells arise only from division of other
cells
Attributes of cells Attributes of cells
A. Plasma membrane
B. DNA
C. Cytoplasm
D. Obtain energy and nutrients from their environment
A. Plasma membrane
B. DNA
C. Cytoplasm
D. Obtain energy and nutrients from their environment
Cell Size 1–100µ Cell Size A. Limitations of molecular diffusion
1. Faster passage through small cell 2. More efficient communication B. Limitations of surface-to-volume ratio
1. With increase in size, greater increase in volume than surface area
a. Interaction with outside occurs only at surface b. Insufficient exchange of materials at plasma
membrane for survival
1–100µ Cell Size A. Limitations of molecular diffusion
1. Faster passage through small cell 2. More efficient communication B. Limitations of surface-to-volume ratio
1. With increase in size, greater increase in volume than surface area
a. Interaction with outside occurs only at surface b. Insufficient exchange of materials at plasma
membrane for survival
adult human
tallest trees
chicken egg
frog embryo
most eukaryotic cells
mitochondrionmost bacteria
virus
proteins
atoms
diameter of DNAdouble helix
Prokaryotic—no nucleus, circular DNA, ribosomes, peptiglycon-prokayotic cell wall
a. Carbohydrate matrix cross linked with peptide units
Eukaryotic—larger, nucleus, linear chromosomes, membraned organelles,
Compartmentalization Include true bacteria
On earth 3.8 million years Found nearly everywhere
Spores in each breath; intestines
Naturally in soil, air, hot springs
Prokaryotic—no nucleus, circular DNA, ribosomes, peptiglycon-prokayotic cell wall
a. Carbohydrate matrix cross linked with peptide units
Eukaryotic—larger, nucleus, linear chromosomes, membraned organelles,
Compartmentalization Include true bacteria
On earth 3.8 million years Found nearly everywhere
Spores in each breath; intestines
Naturally in soil, air, hot springs
Cell typesCell
types
ribosomes
cell wall
plasma membrane
food granule
prokaryoticflagellum
cytoplasm
nucleoid (DNA)
Eukaryotic CellsEukaryotic Cells Have numerous internal structures
Various types & forms Plants, animals, fungi, protists
Multicellular organisms Nucleus is control center of the cell
1. Membrane bound (nuclear envelope)
2. Contains nucleoli; synthesizes ribosomal RNA
3. DNA in chromosomes (DNA and proteins)
Have numerous internal structures
Various types & forms Plants, animals, fungi, protists
Multicellular organisms Nucleus is control center of the cell
1. Membrane bound (nuclear envelope)
2. Contains nucleoli; synthesizes ribosomal RNA
3. DNA in chromosomes (DNA and proteins)
1. Plant cells a. Square-
geometric shaped
b. Cell wall-
cellulose c. Chloroplast d. No centrioles e. Large
vacuoles
1. Plant cells a. Square-
geometric shaped
b. Cell wall-
cellulose c. Chloroplast d. No centrioles e. Large
vacuoles
chloroplast
central vacuole
rough endoplasmicreticulum
ribosomes
microtubules(part of cytoskeleton)
cell wall
mitochondrion
Golgi complex
plasmamembrane
intermediatefilaments
smooth endoplasmicreticulum
free ribosome
vesicle
nuclear porechromatin
nucleolus
nuclear envelope
nucleus
Animal Cellsa. Irregular
shapedb. Just Cell
membranec. Small vacuolesd. Centrioles
Animal Cellsa. Irregular
shapedb. Just Cell
membranec. Small vacuolesd. Centrioles
flagellum
cytoplasmrough endoplasmicreticulum
ribosome
microtubules
lysosome
mitochondrion
Golgi complex
plasmamembrane
intermediatefilaments
vesicle
smooth endoplasmicreticulum
free ribosomevesicle
nuclear porechromatin (DNA)
nucleolusnuclear envelope
nucleus
nuclear pores
chromatin
nucleolus
nuclear envelope
nuclear pores
nucleus
chromosome
chromatin
0.05 micrometers
Eukaryotic cell structure
Eukaryotic cell structure
• Organelles • Endoplasmic
reticulum consists of folded membranes attached to the nucleus
• Rough ER is site of protein synthesis and protein secretion. Proteins made here are processed and shipped out of the cell
• Organelles • Endoplasmic
reticulum consists of folded membranes attached to the nucleus
• Rough ER is site of protein synthesis and protein secretion. Proteins made here are processed and shipped out of the cell
Eukaryotic Cell Structure
Eukaryotic Cell Structure
• Ribosomes assemble amino acid into polypeptide chains
• a. Associated with the ER
• b. Composed of RNA and proteins
• Proteins for inside the cell
• Ribosomes assemble amino acid into polypeptide chains
• a. Associated with the ER
• b. Composed of RNA and proteins
• Proteins for inside the cell
0.5 micrometers
ribosomes
rough endoplasmic reticulum
0.5 micrometerssmooth endoplasmic reticulum
vesicles
Eukaryotic Cell StructureEukaryotic Cell Structure• Golgi apparatus
are membranous sacs associated with ER
• Processing and transport of proteins, lipids exported from the cell
• Synthesis and transport of polysaccharides
• Lysosomes are Golgi-derived vesicles containing digestive enzymes
• Golgi apparatus are membranous sacs associated with ER
• Processing and transport of proteins, lipids exported from the cell
• Synthesis and transport of polysaccharides
• Lysosomes are Golgi-derived vesicles containing digestive enzymes
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Golgi complex
vesiclesfrom ER
vesiclesleavingGolgi complex
Mitochondria provide energy for cellular functions (respiration)
a. Matrix/cristae b. Have their own DNA and ribosomes; self-
replicate C. Bounded by double membrane-numerous
a. Outer membrane is smoothb. Inner membrane is folded into contiguous
layers called cristae1. Cristae are stuffed with 100,000
enzymes2. Site of cellular respiration-Oxidation3. Divides into inner matrix and outer
compartment4. Associated with proteins of oxidative
metabolism
Mitochondria provide energy for cellular functions (respiration)
a. Matrix/cristae b. Have their own DNA and ribosomes; self-
replicate C. Bounded by double membrane-numerous
a. Outer membrane is smoothb. Inner membrane is folded into contiguous
layers called cristae1. Cristae are stuffed with 100,000
enzymes2. Site of cellular respiration-Oxidation3. Divides into inner matrix and outer
compartment4. Associated with proteins of oxidative
metabolism
Energy sources for cell activities
5 micrometers
Chloroplasts—function in photosynthesis 1) Green—contain
chlorophyll pigment 2) Stroma/grana
(thylakoid stacks) 3) Have their own DNA
and ribosomes; self-replicate
4) Up to 100 per cell 5) Become leucoplasts
when deprived of lighta. Specialized
amyloplasts store starch
b. Plastids are derived from proplastids
Chloroplasts—function in photosynthesis 1) Green—contain
chlorophyll pigment 2) Stroma/grana
(thylakoid stacks) 3) Have their own DNA
and ribosomes; self-replicate
4) Up to 100 per cell 5) Become leucoplasts
when deprived of lighta. Specialized
amyloplasts store starch
b. Plastids are derived from proplastids
Energy sources for cell activities
CytoskeletonCytoskeleton Cytoskeleton
Internal infrastructure a. Actin filaments-microfiliments
a. Muscle movement b. Pinches cell when it divides during cytokinesis
b. Microtubules 1. Hollow tubes of 13 protein protofilaments-made of tubulin 2. Function
a. Help move materials within the cell itself b. Skeletal System c. Aides in cell Division-spindle d. Cilia, Flagella, sperm tails
c. Intermediate filaments
Surface structures extensions of the plasma membrane aid in movement of simple organisms
Cytoskeleton Internal infrastructure a. Actin filaments-microfiliments
a. Muscle movement b. Pinches cell when it divides during cytokinesis
b. Microtubules 1. Hollow tubes of 13 protein protofilaments-made of tubulin 2. Function
a. Help move materials within the cell itself b. Skeletal System c. Aides in cell Division-spindle d. Cilia, Flagella, sperm tails
c. Intermediate filaments
Surface structures extensions of the plasma membrane aid in movement of simple organisms
tubulinsubunit
actinsubunits
subunit
Prokaryotes & Eukaryotes
Prokaryotes & Eukaryotes
Similarities & differences
Both surrounded by plasma membrane, but very different
Prokaryotes – Archaebacteria and Eubacteria
Eukaryotes – everything else
Similarities & differences
Both surrounded by plasma membrane, but very different
Prokaryotes – Archaebacteria and Eubacteria
Eukaryotes – everything else
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Evolution of Eukaryotic cell
Evolution of Eukaryotic cellEndosymbiotic Hypothesis
Similarities between bacteria, mitochondria and chloroplasts
Self-reproducing by binary fission
Size of organism and genome
Single circular naked DNA
Proportion of (G & C) to (A & T)
Same sized ribosome
Protein synthesis inhibited by antibiotics
Enzymes for synthesis of DNA, RNA and protein
Electron transport system
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Plant & Animal CellsPlant & Animal Cells
Similarities
Both constructed from eukaryotic cells____________________________________________________________
____________________Both contain similar organelles____________________________________________________________
______________________Both surrounded by cell membrane____________________________________________________________
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Similarities
Both constructed from eukaryotic cells____________________________________________________________
____________________Both contain similar organelles____________________________________________________________
______________________Both surrounded by cell membrane____________________________________________________________
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Plant & Animal CellsPlant & Animal CellsDifferences
Plants haveCell wall – provides strength & rigidity
Have chloroplasts, photosynthetic
Animals haveOther organelle not found in plants (lysosomes formed from Golgi)
Centrioles, important in cell division
Differences
Plants haveCell wall – provides strength & rigidity
Have chloroplasts, photosynthetic
Animals haveOther organelle not found in plants (lysosomes formed from Golgi)
Centrioles, important in cell division
Brief Look at VirusesBrief Look at Viruses
Viruses are acellular
Not considered to be living
Cause serious diseases in most organisms
Viruses are acellular
Not considered to be living
Cause serious diseases in most organisms