1. 1st gap phase: G1, growth and preparation for DNA synthesis

2. Synthesis: S phase, cell synthesizes a replica of the genome

3. 2nd Gap phase: G2, 2nd growth phase prepares the cell for mitosis. During this phase mitochondira and other organelles replicates, microtubules begin to assemble at a spindle

4. M Phase, Mitosis, replicated chromosomes are partitioned. 

5. C phase, Cytokinesis, the cytoplasm divides, creating two daughter cells. 

The length of the cell cycle varies.

Cells in animal embryos can complete their cell cycle in under 20 min. 

Mature cells (for example skin cells) divide in about 24 hours. 

Liver cells have cell cycles lasting more than a year. 

Most of variation in the length of the cell cycle between one organism or cell type and another occurs in the g1 phase. 

It is tightly coiled DNA.

The vehicle by which hereditary information is physically transmitted from one generation to the next; in a bacterium the chromosome consists of a single naked circle of DNA; in eukaryotes, each chromosome consists of a single linear DNA molecule and associated proteins.  

G1, S, and G2 constitute interphase. 

Interphase is the portion of the cell cycle between cell divisions. 

Chromosomes are not visible during interphase. 

DNA Replication occurs during interphase

Nuclear envelope disappears

Chromosomes are tightly coiled, condensed, and visible

Chromosomes appear as two sister chromatids held together at the centromere

Cytoskelton is disassembled: spindle begins to form

Golgi and ER are dispersed

Chromosomes line up alone "metaphase plate"

Spindles made of tublin microtubules attach to centromere such that the kinetochores of sister chromatids are attached to microtubules from opposite poles

Chromosomes attach to microtubules at the kinetochores 

Motor proteins (i.e. kinesin) walks along microtubule pulling chromosomes apart.  

Depolymerization (like pacman munching along) happens at centromeres 

Spindle poles move apart

- They are "genetic entities"

-They are bits of information in the form of DNA and/or RNA

Chromosomes are clustered at opposite poles and decondense

Nuclear envelopes reform around chromosomes

Golgi Complex and ER reform

In animal cells, cleavage furrow (belt of actin) forms to divide the cells.

In plant cells, cell plate forms to divide the cells. 

-Chromosomes begin to condense

-Spindle of microtubules begins to form

-The DNA has been replicated. 

-There are homologous chromosomes, they pair up and become closely associated during synapsis. 

-Crossing over occurs, forming chiasmata, which hold homologous chromosomes together. 

-Pairs of homologous chromosomes align along the metaphase plate. Microtubules from opposite poles attach to sister kinetochores of each homologue. 

-A kinetochore microtubule from one pole of the cell attaches to one homologue on a chromosomes, while a kinetochore microtubule form the other cell pole attaches to the other homologue pair. 

-Kinetochore microtubules shorten

-Homologue pairs are pulled apart.

-One duplicated homologue goes to one pole of the cell, and the other goes to the other pole. 

-Sister chromatids do not separate. (CONTRAST to MITOSIS)

-Separated homologues form a cluster at each pole of the cell, and the nuclear envelope reforms around each daughter cell nucleus. 

-Cytokinesis may occur. 

-Resulting 2 cells have 1/2 the number of chromosomes as the original cell. 

-There are two nonidentical sister chromatids that form the homologous chromosomes. 

-A completed spindle apparatus is in place in each cell. 

-Chromosomes consisting of sister chromatids joined at the centromere align along the metaphase plates in each cell. 

-Kinetochore microtubules from opposite poles attach to kinetochores of sister chromatids. 

-The nuclear membranes reform around four different clusters of chromosomes.

-After cytokinesis, four haploid cells result. 

-potential for loss or not gained at all, is out of synchrony with our cells

-sometimes doesnt replicate or wont even make it to into DNA

-Most viruses are on this end of the spectrum

-Virus in synchrony with cells, is either benign or beneficial 

-Virus has the potential to go towards either side of the spectrum

-replicates at the same time as the DNA

-Out of synchrony, does not wait for DNA to replicate

-has small number of genes, throws them together in a messy way

-builds protein coat, has an extra disguise coat around it 

-travels via sneezing coughing itching etc (could be caused by the virus in order for it to travel)

They are gametes with an improper number of chromosomes. 

In humans, this condition is the most common cause of spontaneous abortion. 

-means respiratory entoric orphan virus

-orphan means that the virus is not connected to a disease

-they are found in placentas and some think they may even be beneficial

- It fuses onto the the cell and then the cell creates a bud to let it in

-It can enter because of the disguise coat that is around the virus

A virus that bands to another virus to replicate

Two helper viruses can join to be a successful virus

-Single or double stranded DNA

-Single or double stranded RNA

-Combination of DNA and RNA

 nondisjunction of autosomes- failure to survive development, down syndrome, edwards syndrome, 

nondisjunction of sex chromosomes- turners syndrome, klinefelter's syndrome, Triple XXX syndrome. 

Trisomy is when nonsdisjunction gives you an extra autosome. This results in death most commonly, howevers some autosomes can be present as three copies and still allow the individual to survive, at least for a time. 

one trisomy is down syndrome. 

X chromosome nondisjunction: 

XXX- develops into a female with one functional X chromosome and two barr bodies. She may be taller in stature but otherwise is normal.

XXY- develops into a male who has many female body characteristics, and, in some cases but not all, diminished mental capacity. (Klinefelters syndrome). 1/500 male births

OY- fails to develop 

0X- develops into a sterile female of short stature, with a webbed neck and sex organs that never fully mature during puberty. Mental abilities= low-normal range. (Turners Syndrome) 1/5000 female births

Y chromosome nondisjunction:

XYY- develop into fertile males of normal appearance. (Jacobs syndrome) 1/1000 newborn babies

-A regulatory protein, named "finger" protein because it is coiled up to look like fingers

-Example, in males that have XX's is responsible for the binding of the crucial chunk from the Y that crosses over to the X during prophase

-function is to bind DNA, RNA, proteins or small molecules.  

- Has 13 fingers

-an abnormal number of chromosomes

-occurs during cell division

-

Chromosome

-monosomy= 1 (deletion on one, example turners syndrome)

-disomy=2 (normal)

-trisomy = 3 (famous example is downs syndrome, also known as trisomy 21)

-tetrasomy=4

the number of complete set of chromosomes

-monoploid (number of unique chromosomes in a single complete set)

-diploid (normal number of sets)

-triploid (occurs in a lot of plants but not humans)

- The one complete set of chromosomes necessary to define an organism

-For humans the haploid number is 23

-The normal number of chromosomes in a cell (twice the amount of the haploid #)

-is 46 for humans 

One of a pair of chromosomes of the same kind located in a diploid (2n) cell; one copy of each pair of homologous comes from each gamete that formed the zygote. 

-A virus that originate in one organism and then pass to another and cause disease.

-Example HIV, said to have been from chimpanzees

-Influenza is fundamentally a bird virus

-segmented RNA viruses

-Combination of hemagglutinn (aids the virus in in gaining access to the cell interior) and neuraminidase (helps the daughter viruses break free of the host cell once virus replication has been replicated)

-Recombination of the virus makes it difficult to form natural immunity and vaccines

-Viruses may contribute to about 15% of all human cancer cases worldwide 

-Ex. link between chronic hep B infections and the development of liver cancer, link between cervical cancer and HPV

-Tiny naked molecules of circular RNA that are infectious disease agents in plants. 

-It is unknown as to why viroids cause disease 

-it is where the virus only attacks a specific set of cells

-Rabies for example, grows in neurons and hepatitis replicates liver cells

-A virus that contains an RNA that that is transcribed into DNA by reverse transcriptase

-HIV/AIDs is an example

-Highly variable viruses that only infect bacteria (bacterial cells)

-also known as phage

1. The lytic cycle, kills the host cell

2. The lysogenic cycle where the virus is incorporated into the host genome as a prophage

-Injection of DNA

-macromolecular synthesis

-assembly of a new phage

-release of progeny phage

-infectious particles that misfolded protiens that serve as templates for normal proteins to misfold

-they are responsible for transmissable spongioform encepalopathies

Usual relationship.

Nitrogen fixing bacteria and plant roots (mutualism)

bacteria in digestive tracts of animals, cows they digest cellulose. 

humans in large intestine they produce vitamins

Outer surgace of animals and plants, do not cause damage. (commmensalissm)

Bacterial infection is a form of parasitism in a sense. 

A gene from a human can be inserted into a bacterial cell, and the bacterium will produce a human protein. 

Bacterias are also now widely used as "biofactories" in the commerical production of variety of enzymes, vitamins, and antibiotics.