Biology 12
Early Earth Condition
-Temperature 75-95 C
-Global ocean
-No ozone layer
-Reductive gases in the atmosphere (CO2 and water vapour, methane and ammonia)
-Extreme weather conditions
How did cells form?
-Simple carbon based compounds formed
-Eventually became the building blocks for proteins, lipids and nucleaic acids
8 Process of life
-Metabolism
-Response to stimuli
-Homeostasis (consistent internal conditions despite changes in environment)
-Movement
-Reproduction
-Excretion
-Nutrition
-Growth
Spontaneous orgin of cells (5 steps)
-Simple organic molecules formed (amino acids and hydrocarbon chains)
-Chemical reactions accelerated in catalyst
-Large organic molecules (RNA and phospholipids) assembled from smaller molecules
-Some of these molueces (RNA) are able to self replicate
-Formation of memebrane bound compartment, allowing internal chemistry of cell to become different from outside environment
Miller Urey Experiment
-1952, simulated earths pre biotic atmosphere to attempt to replicate the formation of organic molecules
-Contained: water, gases (methane, ammonia and hydrogen), electrical spark to simulate electrical storms
RNA First hypothesis steps (7)
-RNA formed from inorganic source
-RNA able to replicate using ribozomes
-Able to catalyst protien synthesis
-Membrane compartmentalization occured
-RNA produced protein and DNA in the cell
-DNA took over as main genetic material (more stable)
-Proteins took over catalytic role (more capable of variety)
LUCA
Last Universal Common Ancestor
Endosymbiosis
Theory that eukaryotic cells evolved by engulfng and incorporating prokaryotic cells, which then became organelles
Horizontal Gene Transfer
Genetic exchange of materials between induviduals without reproduction
Stromatolites
Fossils formed by mirco-organisms
LUCA - Info
-2.5-3.5 billion years ago
-lived in the deep ocean in alkaline hydrothermal vents, used as energy source
-anaerobic
-autotrophic
Robert Hooke
Discovered cells
Cytokinesis
The physical division of the parent cell into two daughter cells
Contractile Ring
Network of Actin and myosin proteins form a ring that pinches the cell membrane forming a cleavage furrow, which eventually splits.
Cell Plate
Formed from the fusion of vesicles containing cell wall materials, grows outward until it hits an existing cell wall, which it fuses with, splitting into two separate cells.
Vesicles
Small membrane bound sacs that transport and store a variety of molecules
Each daughter cell must receive at least one?
Each daughter cell must receive at least one mitochondrion, as it can only be made by inheriting it from a parent cell
Peroxisomes
Small membrane bound organelle regulates and breaks down toxic substances within the cell
Oogenesis
The production of mature ovum
Polar Body
Small cell formed during oogenesis containing a discarded set of chromosomes and minimal cytoplasm
Budding
A form of asexual reproduction in which a new organism develops as an outgrowth or bud from the parent organism, eventually detaching become and independent organism
Anucleated
a eukaryotic cell having no nucleus, like red blood cells
Diploid
Cells that contain two copies of each autosome and two sex chromosomes, always have an even number of chromosomes
Haploid
Cells that contain a single set of chromosomes
Crossing over
The exchange of equivalent segments of DNA between non-sister chromatids
Independent assortment
The separation of homologous chromosomes and sister chromatids being independent of their pairs during meiosis due to random orientation
Reductive division
Involves halving the chromosome number before the nucleus is divided in two
Prophase
chromatin becomes chromosomes
Metaphase
Sister chromatids line up
Anaphase
Stuff separates, sister chromatids are pulled apart to opposite poles of the cell
Telophase
chromosomes condense, nuclear membranes begin to reform
Chromatin
The complex of DNA and proteins that make up chromosomes in their relaxed form in eukaryotic cells.
Histones
Proteins around which eukaryotic DNA is wrapped, forming structures called nucleosomes. This organization helps to regulate gene expression and protect the structural integrity of DNA.
Microtubules
Long, thin, cylindrical fibrous proteins that form the spindle apparatus during cell division
Nondisjunction
Genetic error that can concur during meiosis, happens during anaphase 1 or 2, leads to gametes with one extra or one less chromosome
Chiasma
point where two non sister chromosomes cross over
Morula
Solid ball of cells formed by division of the zygote
Blastocyst
A cluster of dividing cells, formed by the fertilized cells during the embryonic development
Totipotent
eight cells of the morula, can give rise to new organism
Pluripotent
in the blastocyst, can become all body cells, but cannot become new organism
Multipotent
umbilical cord cells, can differentiate into a few closely related types of cells
Unipotent
Can only differentiate into what they are already supposed to be
Stem cell niche
The microenvironment within the organism in which the stem cells exist and receive their instructions.
A micrometre is?
-0.001 mm
-0.0001 cm
-0.000001 m