cell structure and function. attributes of cells a. plasma membrane b. dna c. cytoplasm d. obtain...
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Attributes of cells
A. Plasma membrane
B. DNA
C. Cytoplasm
D. Obtain energy and nutrients from their environment
1. 1–100µm
2. Why is there a limit to cell size?
a. Surface-to-volume ratio
b. Distance from surface to center
Cell Size
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
Eukaryotic—larger, nucleus, linear chromosomes, membranous organelles
Cell types
Prokaryotic Cells
Have no membrane-bound organelles
Include true bacteria On earth 3.8 million years Found nearly everywhere
Spores in each breath; intestines
Naturally in soil, air, hot springs
Eukaryotic Cells
Have numerous internal structures
Various types & formsPlants, animals, fungi, protists
Multicellular organisms
flagellum
cytoplasmrough endoplasmicreticulum
ribosome
microtubules
lysosome
mitochondrion
Golgi complex
plasmamembrane
intermediatefilaments
vesicle
smooth endoplasmicreticulum
free ribosomevesicle
nuclear porechromatin (DNA)
nucleolusnuclear envelope
nucleus
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
Eukaryotic cell structure
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)
Eukaryotic cell structure
Organelles
Endoplasmic reticulum consists of folded membranes attached to the nucleus
Rough ER is site of protein synthesis and protein secretion
0.5 micrometers
smooth endoplasmic reticulum
vesicles
ribosomes
rough endoplasmic reticulum
0.5 micrometers
Eukaryotic Cell Structure
Organelles (cont.)
Ribosomes assemble amino acid into polypeptide chains
• a. Associated with the ER
• b. Composed of RNA and proteins
Eukaryotic Cell StructureOrganelles (cont.)
Golgi apparatus are membranous sacs associated with ER
• a. Processing and transport of proteins, lipids
• b. Synthesis and transport of polysaccharides
Eukaryotic cell structure
Organelles (cont.)
Lysosomes are Golgi-derived vesicles containing digestive enzymes
Eukaryotic Cells: Organelles Energy sources for cell activities
Mitochondria provide energy for cellular functions (respiration)
• a. Membrane bound, numerous
• b. Matrix/cristae
• c. Have their own DNA and ribosomes; self-replicate
Eukaryotic Cells: Organelles Energy sources for cell activities
• 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
Eukaryotic Cells: Organelles
CytoskeletonInternal infrastructure
Surface structures
extensions of the plasma membrane aid in movement of simple organisms
Prokaryotes & Eukaryotes
Similarities & differences
Both surrounded by plasma membrane, but very different
Prokaryotes – Archaebacteria and Eubacteria
Eukaryotes – everything else
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
Plant & Animal Cells
Similarities
Both constructed from eukaryotic cells
Both contain similar organelles
Both surrounded by cell membrane
Plant & Animal Cells
Differences
Plants have• Cell wall – provides strength & rigidity• Have chloroplasts, photosynthetic
Animals have• Other organelle not found in plants
(lysosomes formed from Golgi)• Centrioles, important in cell division
Brief Look at Viruses
Viruses are acellular
Not considered to be living
Cause serious diseases in most organisms