DNA cell test

Phases of Mitosis

prophase, metaphase, anaphase, telophase

Centrioles

Cell organelle that aids in cell division in animal cells only

Prophase

Chromatin condenses into chromosomes and Nucleolus disappears.

Metaphase

chromosomes line up along metaphase plate

Anaphase

Chromosomes break at centrosomes and sister chromatids move to opposite ends of the cell

Telophase and Cytokinesis

Nuclear membrane reforms and nucleoli reappear and chromosomes unwind into chromatin.

What cells do not preform mitosis

Sex Cells

Which cell splits from the inside

Plant cell

telophase under microscope

Which cell forms a cleavage and splits from the outside

Animal cell

anaphase under microscope

metaphase under microscope

prophase under microscope

Base parring

(A-T C-G) This guarantees that a copied strand of DNA always end up being the same as the original.

DNA structure

* 2 deoxyribose (sugar) backbone strands
* Bases held together by \n hydrogen bonds
* DNA shape is a double helix

How is DNA fit in a Chromosome

DNA wraps around a Histone to from a Nucleosome

Nucleosomes come together to form Chromatine

Chromatine then from loops

The Chromatine loops condense to form a Chromosome

Helicase

* “Unzips” or unwinds the DNA double helix.
* Binds at the location called the replication fork
* Exposes the leading strand to the next enzyme
* Separates bases from each other

DNA Polymerase

* Synthesizes free nucleotides onto the template DNA
* Matches the right nucleotide with the exposed bases
* Creates the complementary strand

DNA Ligase

* An enzyme that puts things together
* Glues together Okazaki fragments after matching

Primase

* Enzyme that makes a primer


* The primer is the starting point for polymerase on the lagging strand

Leading strand

* replicated (copied) in 3’-5’ direction
* copied straight off, no fragments made.

Lagging strand

* replicated in 5’-3’ direction
* replicated in small pieces, known as Okazaki fragments, starting at a primer
* The polymerase has to jump back and make a small section
* Ligase glues the Okazaki fragments together

Prophase I

* The DNA is already replicated forming two pairs of chromosomes
* The homologous sister chromatids pair up 2 and 2
* Chromosomes form tetrad
* Sometimes parts of the chromosomes are exchanged between the maternal and paternal chromosomes: crossing over or recombination
* In meiosis

tetrad

two homologous chromosomes that have each already replicated into a pair of sister chromatids

Metaphase I

The chromosomes are moved to the metaphase plate (the middle) they line up randomly

* In meiosis

Anaphase I

* The paired homologous chromosomes start to separate from each other
* The whole sister chromatid is being moved to either pole
* Pulled apart by the mitotic spindle
* In meiosis

Telophase I

* Cell starts cytokinesis, dividing the cells completely
* The cells are now haploid
* In meiosis

Haploid

having a single set of __unpaired__ __chromosomes__.

Diploid

containing two complete sets of __chromosomes__, one from each parent

Prophase II

* Very short phase
* Centrioles start migrating
* Nucleolus dissolves
* Mitotic spindle forms
* In meiosis

Metaphase II

* Sister chromatids line up at metaphase plate
* In a line this time
* Spindle fibers attach to the centromere (middle of chromatid)
* In meiosis

Anaphase II

* Sister chromatids are being pulled to opposite sides of the cell
* Sister chromatids break down the middle
* Chromatids become separate chromosomes
* In meiosis

Telophase II

* The chromosomes have completely moved to their cells
* Membrane forms around each set of chromosomes
* The cells bud off to become individual haploid cells
* In meiosis

cytokinesis

bringing about the separation into two daughter cells