Asexual Reproduction and Mitosis

Asexual Reproduction

unicellular organisms reproduce via cell division making an identical copy

Clone

in asexual reproduction cells produce identical copies of itself

telophase

cytokinesis

The actual splitting of the cell using the microfilament contractile ring

nucleolus

1-10microns

holds about 6 meters of DNA and other proteins that hold DNA in a small structure

binary fission

Simple division in prokaryotes

of 1 circular DNA gets replicated and cells then grows and it splits into 2 identical cells

cell cycle

complicated process of eukaryotic cell division as cells have one or more linear fragile DNA

chromosome

DNA double helix plus associated proteins - the actual stucuture

Tightly packed, condensed DNA

One chromosome can be one or two chromatids depending on the phase

chromatid

A single copy of a DNA molecule after it has been replicated

sister chromatid

Two identical chromatids that are joined together at the centromere

They are the exact copies made during DNA replication

telomere

ends of chromatid

chromatin

Loose, uncoiled form of DNA wrapped around histones, during interphase (the normal working life of the cell, before division).

Allows the DNA to be read and used for making proteins (gene expression)

histones

proteins that DNA wraps around to condense even more

nucleosome

A nucleosome is DNA wrapped around a core of 8 histone proteins, 2 copies H2A, H2B, H3, and H4

linker histone (H1)

histone that is not part of the nucleosome that packages nucleosomes into 30nm fibers condensing the DNA

30nm fiber

Highly condensed DNA and histones build the chromosome

metaphase chromosome

A highly condensed, X-shaped chromosome

It’s made of two identical sister chromatids.

interphase

appearance of cell constant as it grows in size

1st stage of the 2 main stage has 3 stages within this stage (G1,S,G2)

G1

gap 1 cell is growing

varies the most in how much time the cell is in this stage

Synthesis

DNA is synthesized making an exact copy so the end resulting cells are the same

G2

gap 2 cell growing

Right before the cell enters mitosis

G0

non-divding cell

mitosis

dramatic changes as the cell divides, 6 stages in this phase

prophase

microtubules begin to breakdown - will later form into miotic spindles and split chromosomes apart

chromatid condenses

replicated chromosomes are physically paired with their sister chromatids (identical pair)

prometaphase

nuclear envelope breaks down into small vesicles

spindle microtubules attach to kinetochores

kinetochores

proteins assembled on the centromeres of condensed chromosomes

metaphase

kinetochore microtubules line up paired chromatids at the metaphase plate

anaphase

microtubules pull the chromatids apart

mitotic spindle

A structure made mostly of microtubules and proteins.

Organizes and separates the chromosomes during mitosis

It grows out from the centrosomes (the microtubule-organizing centers) at opposite poles of the cell.

metaphase plate

“invisible line” where chromatids line up to then be split up

contractile ring

microfilaments forms cleavage furrow spiltting the cell in two

inside of cell

cleavage furrow

The visible indentation or pinch on the outside of the cell surface

outside of cell

cell plate

in plant cells as they don’t form cleavage furrows, will use cell plate to form a new membrane making 2 cells

cyclin

regulatory protein that controls the progression of cells through the cell cycle

cell dependent kinase

protein kinase that plays a crucial role in regulating the progression of the cell cycle. CDKs are enzymes that phosphorylate, which can activate or deactivate these target proteins. This action is essential for controlling the timing and progression of the different phases

M-promoting factor

is a key regulator of the transition from the G2 phase to the M phase (mitosis) in the cell cycle. MPF is essential for initiating mitosis, a process in which the cell divides to produce two daughter cells

Cell cycle checkpoint

critical control points in the cell cycle where the cell assesses whether the conditions are suitable to proceed to the next phase

compare and contrast how prokaryotic and eukaryotic cells reproduce asexually

As prokaryotic cells have simple circular DNA, they just replicate the DNA as the cell grows and splits creating 2 identical cells this process is called binary fission

Eukaryotic cells, on the other hand, go through the cell cycle, which is a more complicated process of breaking the nuclear envolope creating sister chromatid which are identical copies of chromatid and spliting them apart during mitosis which has 6 stages within itself to split the chromosomes and create 2 cells

describe the levels of chromatin packaging that organize and protect eukaryotic genomes

chromatin is loose DNA strand which can open and close so RNA can read it when needing to make protiens, nucleosomes are DNA wrapped around 8 histones protiens creating a more packed DNA 30nm fiber are those histones getting packed further creating a 30nm packed fiber of DNA and proteins this makes up chromatid a strand of double helix DNA packed into 30nm fiber making a chromosome when with its paired chromosome

name the major stages of eukaryotic cell cycle and describe what happens during each stage

interphase - within G1, S, G2

Mitosis

prophase - chromosome begin condensing sister chromatid pairing from centromere, miotic spindle forms outside nucleus

prometaphase- nuclear envelope breaks down, spindles attachs to kinetochores

centrosome on opposite poles of cell

metaphase- chromatids line up on metaphase plate

anaphase- microtubules from spindle pull sister chromatid apaert

telephase - chromatids seperated to oppostie poles and nucleus and envolope reform chromosome begin to decondense making it where they will be able to be read by RNA again

cytokensis- contractile ring forms a visible cleavage furrow and spilts the cell in two

describe the physical changes that occur during each stage of mitosis

the cell is growing in order to make two cells and becomes longer as the poles are getting furhter apart and pulling the chromatids aparts then the contractile ring finally splits the cell in two

recognize and draw eukaryotic cells in each stage of cell division

draw it

compare and contrast cytokinesis in animal and plant cells

plant cells don’t show a cleavage furrow and instead make a cell plate of forming a new cell wall to split unlike in animal which only have a plasma membrane with is more fluid

explain how cyclins, cyclin-dependent kinases, and cell-cycle checkpoints regulate cell division

cell-cycle checkpoints are points to see if the cell can go onto the next phase or not if the cell is still developing or not, cyclins are protiens which bind to cycling depedent kinases which activacte the cell to comtinue to the next phase