Post on 12-Mar-2020
Cell (Outline)
- Components of a functional cell- Major Events in the History of Earth: abiotic and biotic phases;
anaerobic and aerobic atmosphere- Prokaryotic cells impact on the biosphere- Origin of Eukaryotic cells- Emergent properties of eukaryotic cells: animal and plant cells- Role of cellular membranes: external and internal- Cytoskeleton: structure and functions- Flow of genetic information: DNA to protein- The endo-membrane system- Other organelles: Fatty acid metabolism and Energy Processing- Cell surface and extracellular matrix
Components of a functional cell
• Boundary-membrane• Cytoplasm: Cytosol (soluble components)
& particulates• DNA-information• Ribosomes-protein synthesis
Major Events in the History of EarthCenozoic
Humans
Land plants
Animals
Multicellulareukaryotes
Single-celledeukaryotes
Origin of solarsystem andEarth
1
2
4
3
Proterozoiceon
Archaeaneon
Atmospheric oxygen
Prokaryotes
Anaerobic
Aerobic
Copyright © 2002 Pearson Education, Inc., publishing as Benjamin Cummings
Prokaryotic Cell Structure
Eukaryotic Cell Structure
Differ in - size - complexity- internal membrane, creating
organelles
(Sub-cellular compartments where different cell functions of eukaryotic cells are carried out)
Comparing Prokaryotic and Eukaryotic Cells
Evolution of Eukaryotic cells
“The Endo-symbiotic Theory”
Cenozoic
Humans
Land plants
Animals
Multicellulareukaryotes
Single-celledeukaryotes
Origin of solarsystem andEarth
1
2
4
3
Proterozoiceon
Archaeaneon
Atmospheric oxygen
Prokaryotes
The Endo-symbiotic Theory:
Origin of Eukaryotes
Engulfing ofphotosyntheticprokaryote
Chloroplast
Mitochondrion
Somecells
Host cell
Mitochondrion
Host cellEngulfing of aerobicprokaryote
Ancestral eukaryotic cells two or more prokaryotic cells in a state of endo-symbiosis:• animal cell- 2 different prokaryotes• plant cell- 3 different prokaryotes
Overview of Eukaryotic Cell structureshttps://www.youtube.com/watch?v=URUJD5NEXC8 (7:21 minutes)
Organelles of the Cell (updated)https://www.youtube.com/watch?v=RKmaq7jPnYM (~ 30 minutes)
The Inner Life of the Cellhttps://www.youtube.com/watch?v=B_zD3NxSsD8 (~ 8 minutes)
Emergent Properties of Eukaryotic cells
Functions– Structural support, movement, and
communication– Manufacturing of molecules– Breakdown of molecules– Energy processing
Eukaryotic cells structures and organelles specialize for functions
Copyright © 2002 Pearson Education, Inc., publishing as Benjamin Cummings
Role of Cell membranes in Compartmentalization of cellular
functions
https://www.khanacademy.org/science/biology
A. Plasma membrane- Boundary of the cell- Surrounds the cytoplasm- Selective barrier- Allows passage of oxygen, nutrients, and wastes.B. Internal membranes of eukaryotes‒ Partitioning the cell into compartments‒ Local environments that facilitate specific metabolic biochemical
functions
The cytoskeleton is a network of protein fibersthat functions in cell structural support and motility
Cytoskeleton
Microfilament
Actin subunit
7 nm
Intermediate filament
Fibrous subunits
10 nm
Microtubule
Tubulin subunit
25 nm
Nucleus
Nucleus
Components of the cytoskeleton pull past each other
Vesicles or organelles carried to various destinations along “monorails’ of microtubules
Role of Microtubules
The Flow of Genetic Information:The “Central Dogma” of Molecular Biology
The sequence of bases in DNA determines the sequence of amino acids in proteins
- DNA codes for the production of messenger RNA. - Messenger RNA codes for the production of protein. - Proteins do not code for the production of protein, RNA or DNA
Cell organelles and structures involved with the flow of genetic information
• Nucleus– Home of most genetic material (DNA)– Double membrane with pores, nuclear
envelope – Site of transcription of RNA – Nucleolus is the place where ribosomes are
made• Ribosomes
– Site of protein synthesis
Nucleus Ribosomes
The Endomembrane SystemSub-cellular components
Nuclear envelopeEndoplasmic reticulum Golgi apparatus VesiclesLysosomes Vacuoles Plasma membrane
Function- Sites of certain metabolic functions in the cell (Synthesis, modification, & breakdown of macromolecules)- Regulation of protein traffic within the cell http://vcell.ndsu.edu/animations/proteintrafficking/movie-flash.htm
Two connected regions of ER that differ in structure and function.– Smooth ER
(No ribosomes)– Rough ER
(bound ribosomes) are attached to the outside
Smooth ERContains enzymes for – synthesis of lipids, phospholipid, steroids– Metabolism of carbohydrates– Detoxification of poison– Storage of Ca+2 for in muscle cells (necessary
for contraction)
Rough ER (membrane factory)- Produces proteins and membranes for
transport by vesicles, destined for secretion
- Membrane-embedded and secretory proteins
- Site of protein glycosylation (glycoproteins)
The Golgi Apparatus• Finishing, sorting, and shipping cell products• Transport vesicles from the ER travel to the Golgi
apparatus for modification of their contents• Extensive in cells specialized for secretion.
Lysosomes• Garbage collector for recycling and breakdown
within the cells. Membrane-bounded sacs of hydrolytic enzymes that digests macromolecules: proteins, fats, polysaccharides, and nucleic acids.
http://highered.mcgraw-hill.com/sites/0072437316/student_view0/chapter5/animations.html#
Vacuoles
• Larger versions of vesicles• Many functions in cell maintenance
– Food vacuoles– Central vacuoles- mature plant cells storage
of some pigments.
Other Membranous Organelles not part of the endomembrane system
• Peroxisomes– generate and degrade H2O2 in performing various
metabolic functions– Fatty Acid metabolism
• Mitochondria and chloroplasts- sites of energy transformation from one form to another and of recycling of matter- Mitochondria (respiration) are present in animal &
plant cells- Chloroplasts (photosynthesis) only in plant cells
Peroxisomes
• A single membrane• Abundant in liver and
kidney- breakdown of fatty acids for transport to mitochondria for fuel - detoxify alcohol and other harmful compounds.- Conversion of fatty acids in seeds to sugars.
Mitochondria and Chloroplasts
• Contain their own ribosomes and cytosol• Have double membranes.• Contain small quantities of DNA that direct the
synthesis of the polypeptides produced by these internal ribosomes.
• Grow and reproduce as semi-autonomous organelles
• Not part of the endomembrane system• Mobile and move around the cell along tracks in
the cytoskeleton
• Matrix-contains DNA and ribosomes
• Cristae-contains enzymes for ATP generation during cellular respiration
MitochondriaVideo (4)
Chloroplasts• Present in plants and eukaryotic algae are the • Sites of photosynthesis-production of sugar from
CO2 and water(high levels of the green pigment chlorophyll)
Review of Functional Compartments of Eukaryotic cells
• Structural support, movement, and communication: cytoskeleton, plasma membrane, and cell wall
• Manufacturing: nucleus, ribosomes, endoplasmic reticulum, and Golgi apparatus
• Breakdown of molecules: lysosomes, vacuoles, and peroxisomes
• Energy processing: chloroplasts & mitochondria
• Cell wall in plant cells
• The extracellular matrix (ECM) in animal cells
• Extracellular components and connections between cells help coordinate cellular activities
Cell Surfaces
Polysaccharidemolecule
Carbo-hydrates
Proteoglycanmolecule
Coreprotein
A proteoglycan complex
Functions of the ECM include– Support– Adhesion– Movement– Regulation
EXTRACELLULAR FLUID
Microfilaments
Collagen fiberConnectingglycoprotein
Integrin
Plasmamembrane
Glycoproteincomplex with longpolysaccharide
CYTOPLASM
Intercellular junctions
• Plants-Plasmodesmata
• Animals-Tight junctionsDesmosomesGap junctions