Studied by 37 people
Eukaryotes
Belonging to multicellular organisms
Protista, Fungi, Plants, Animals
Believed to have evolved from prokaryotic cells
Golgi body
Stores, modifies and packages proteins
Free Ribosomes (E)
Synthesis of proteins for use IN the cell
80S
rER (rough Endoplasmic Reticulum)
Synthesis of proteins for use OUTSIDE of the cell
Lysosomes
Contain digestive enzymes, and can fuse with vesicles containing damaged organelles
Nucleus
Surrounded by a double membrane with pores, contains the cell’s DNA
Mitochondria
The site of Aerobic respiration- the production of ATP energy
Plasma membrane (E)
Controls the movement of materials into and out of the cell
Allows cell to maintain concentrations of substances that are very different from those in the surrounding environment
Semi-permeability replies on the lipid bilayer
Cytoplasm (E)
Fluid within the plasma membrane where organelles occur
Mainly composed of water with many substances dissolved or suspended in it
Enzymes catalyze different chem reactions
Prokaryotes
Belong to single celled organisms
Ex. Bacteria
Cell Wall (peptidoglycan)
A rigid non-cellulose structure that surrounds cells of bacteria or plant cells
Plasma membrane (P)
A phospholipid bilayer that surrounds the cell
Cytoplasm (P)
The gel-like fluid inside the cell membrane where the reactions of metabolism occur
Pili
Hair-like protein structure that allows bacteria to attach to things
Flagella
Long, thin, whip-like structures, made from the protein ‘flagellin’ that enables movement
Ribosomes (P)
Organelles made of protein and RNA that direct protein synthesis
70S
Nucleoid
A dense region of DNA in a prokaryotic cell
Conditions of early earth
Pre-biotic period (no life)
Lack of O2 = lack of ozone
(due to O reacting with other elements)
Higher concentration of methane
(Due to intense volcanic activity & meteorite strikes)
Higher concentration of CO2
(Probably due to emission from volcanoes)
Higher temps
High levels of ultraviolet light penetration
The pre-biotic formation of Carbon Compounds
Formed spontaneously by chemical processes that do not occur today
Why conditions on Earth today make spontaneous formation of organic carbon compounds less likely than they were
higher O2 levels (0% to 20%) causing the ozone layer to form
Drop in CO2
Reduction in greenhouse effect
Evidence that cells are living
Cells use ATP energy to maintain highly ordered state
Cells can divide or reproduce on their own to make new cells
Cells can evolve
Cells are separate from their environment but can still communicate with other cells
Cells can receive and respond to stimuli
Why are viruses are considered non-living
Non-cellular and lack organelles to carry out metabolism and protein synthesis independently
Can only replicate in living cells using their components
3 common features of cells
A stable, semi-permeable membrane
Genetic material able to be passed on
Metabolic processes that allow ATP energy generation (enables growth, reproduction and self-maintenance)
Origin of carbon compounds
Molecules were mainly made up of C H O, some N P S
Living things make these by action of enzymes in their cells
Synthesis of simple organic molecules needed to occur for non-living materials to = life
Miller-Urey Experiment
Passed steam through a mixture of H2 and CH4 and NH3
Used electrical discharge to simulate lightning
Amino acids, fatty acids and sugars were produced
Spontaneous formation of vesicles
By coalescence (merging) of fatty acids into spherical bilayers
Importance of phospholipids in the formation of cells & their components
If phospholipids were part of the carbon compounds on pre-biotic earth, they would have self-assembled into bilayers and vesicles would likely have formed
Why was RNA was presumed as the first genetic material in living organisms and not DNA
Can form as an enzyme
Can act as a catalyst
Can replicate
Earliest life forms may have used it to store genetic material (RNA world hypothesis)
LUCA
All life forms share a common ancestor
Likely that other forms of life evolved at the same time, but became extinct
What is evidence for LUCA
Characteristics:
Anaerobic (survived without oxygen)
Carbon fixing (convertesd CO2 into glucose)
Hydrogen dependent
Nitrogen fixing (converted N2 into NH3)
Thermophilic (survived high temps)
Outline the cell theory
Cells are the smallest unit of life
All organisms are made of cells
All cells come pre-existing cells
Outline cells as the base of all living things
The cell is the basic structural, functional, and biological unit of all living organisms
Can be multicellular or unicellular
Calculating the magnification, size or actual size of an image
Magnification = size of image / actual size of specimen
1mm = 1000um
Light microscopes
Simple (1 lens), compound (2 lenses: ocular lens and objective lenses)
Can magnify up to ~1500x
4× 10× 40x
Max resolution: 0.2um (200nm)
Reveals only the structure of the cell
Electron microscopes
Scanning, transmission
Can magnify up to ~1,000,000x (1mill)
Uses beams of electrons to cause shorter wavelengths (more energy = more resolution)
Resolution: 0.001um (1nm)
Reveals the ultra structure of cells
Developments in microscopy
17th century, lenses were used
1665, the cell was named
1670: first living cell was seen
1931: Germans invented light microscopes
3 structures common to cells in all living organisms
Cell membrane
Cytoplasm
DNA
Atypical Cell
Organisms that do not follow the typical structure and patterns in a eukaryotic cell
Describe the origin of eukaryotic cells by endosymbiosis
Began as prokaryotic cells, but were swallowed up by other prokaryotes until they became eukaryotes (gained mitochondria and or chloroplasts)
3 features that distinguish Eukaryotic cells from Prokaryotic cells
Nucleus
Ribosomes (different sizes)
Mitochondria
Advantages to Multicellularity
Multicellular organisms:
Tend to have a longer lifespan
Are generally larger than unicellular
Are more complex
Processes required for the survival of organisms
Homeostasis (constant internal environment)
Metabolism (sun of biochem rxns)
Nutrition
Excretion
Growth
Response to stimuli
Reproduction
What kind of environment did LUCA live in?
High concentration of H2 CO2 and Fe
Conditions found in and around hydrothermal vents
Most suited to life were the alkaline hydrothermal vents (white smokers)
Slime Capsule (Glycocalyx)
Thick polysaccharide layer used for protection against desiccation (drying out) and phagocytosis
Phagocytosis
When a cell eats / consumes another cell
Naked DNA (P)
Usually only 1 DNA strand that is circular or forms a loop
Not associated with histone proteins
Plasmid (P)
Independent circular DNA molecule that may be transferred between bacteria (horizontal gene transfer)
DORA
DNA:
P- DNA is naked, it is circular, usually has no introns
E- DNA is bound to protein, linear, usually has introns
Organelles:
Not membrane bound vs membrane bound, 70S vs 80S, no nucleus vs nucleus
Reproduction:
P- Binary fission, single chromosome
E- Mitosis and meiosis, chromosomes paired
Average Size:
P- (~1-5um) E- (~10-100um)
4 types of Atypical cells
Red blood cells
Do not have a nucleus
Phloem Sieve Tube Elements
No nucleus and lack many other organelles
Have sieve tubes, each of which is connected to a companion cell which helps the element survive
Skeletal Muscle
Cells fuse together to make a multinucleated cell
Aseptate Fungal Hyphae
Fungi have thread-like structures called hyphae that are separated into cells by septa
These have NO septa = multinucleated
Endosymbiotic Theory
Mitochondria and Chloroplasts were once prokaryotic but were engulfed by larger prokaryotes via phagocytosis
Animal Cells = Mitochondria
Plant Cells = Mitochondria and Chloroplasts
Cell Differentiation
Stem cells can become anything (turn into specialized cells)
Only express genes that code for the required proteins
Housekeeper Genes
genes that are always needed in a cell
Regulate processes required (ex. metabolism, growth, DNA replication, transcription)
Protocell
It is a compartment enclosed in a phospholipid membrane.
It is likely that self-replicating molecules were encapsulated by this membrane
Note 
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