Openstax Biology Chapter 10

Cell Division

enables multicellular eukaryotes to develop from a single cell and, once fully grown, to renew, repair, or replace cells as needed.

cell cycle

an ordered series of events involving cell growth and cell division that produces two new daughter cells.

DNA, two

Most cell division results in the distribution of identical genetic material "____" to ____ daughter cells.

chromosomes

DNA Molecules in a cell are packaged into ________.

eukaryotic, characteristic

Every _______ species has a ________ number of chromosomes in each cell nucleus

Somatic

have two sets of chromosomes.

one set from the mother and one set from the father.

not reproductive cells- sperm and egg)

Gametes

have one set of chromosomes.

reproductive cells; sperm and eggs)

Preparation for Cell Division

DNA is replicated and the chromosomes condense

Sister chromatids

Each duplicated chromosome has two _______ ________, joined identical copies of the original chromosome.

Centromere

where the chromatids are mostly closely attached.

nuclei

During cell division, the two sister chromatids of each duplicated chromosome separate and move into two ______.

Chromosomes

Once separate, the chromatids are called _______.

mitotic spindle

structure made of microtubules and associated proteins and it controls chromosome movement during mitosis.

microtubule organizing center

In animal cells, assembly of spindle microtubules begins here (also known as the centrosome)

centrosome

replicates during interphase, forming two centrosomes that migrate to opposite ends of the cell during prophase and and metaphase.

aster

radial array of short microtubules extends from each centrosome.

mitotic spindle

includes the centrosomes, the spindle microtubules, and asters.

cell cycle

consists of:

Mitotic (phase), including mitosis and cytokinesis.

Interphase, including cell growth and copying of chromosomes in preparation for cell division.

Interphase

about 90% of cell cycle can be divided into sub phases.

G1 phase ("first gap")-growth.

S phase ("synthesis")- growth and DNA duplication.

G2 phase ("second gap")-growth.

Cell Division

consists of:

Mitosis

Cytokinesis

Mitosis

Mitosis

(karyokinesis), the division of the genetic material in the nucleus.

cytokinesis

the division of the cytoplasm (this is not part of mitosis)

Mitosis

prophase

prometaphase

metaphase

anaphase

telophase

Prophase

-the chromosome condense.

-spindle figures emerge from the centrosomes and centime begins to move to opposite sides of cell.

-nuclear envelope breaks down.

Prometaphase

-Kinetochores appear at the centromeres

-The spindle fibers connect to the kinetochores (at centromere) of the chromosomes.

-centromeres move towards opposite poles.

Metaphase

-Chromosomes are moved to the metaphase plate

-Centrosome finishes moving to opposite sides of cell.

Anaphase

-sister chromatids are separated, they are now each a chromosome

-spindle fibers pull chromosome toward opposite poles of the cell.

Telophase

-chromosome reach each side of the cell

-nuclear envelop redevelops.

Cytokinesis

-begins during anaphase.

-in animal cells, by a process known as cleavage, forming a cleavage, a furrow.

-in plant cells, a cell plate forms.

Cell Cycle Control System

The sequential events of the cell cycle are directed by a distinct ________

Checkpoints

where the cell cycle stops until a go-ahead signal is received.

G1 checkpoints

-checks the conditions that favorable for cell division

-checks for genomic damage, cell size, etc...

-if the cell does not receive the go-ahead signal, it will exit the cycle, witching into a non-dividing state called the G0 phase.

G2 checkpoints

replication complete

M checkpoints

at end of metaphase to check that all sister chromatids are attached to spindle microtubules.

density-dependent inhibition

crowded cells stop dividing.

anchorage dependence

cells must be attached to a strubstratom in order to divide.

cancer cells

exhibit neither density-dependent inhibition nor anchorage dependence.

cancer cells

-do not respond to signals that normally regulate the cells cycle

-form tumors, masses of abnormal cells within otherwise normal tissue.

benign

if abnormal cells remain only at original site

malignant

invade surrounding tissues and can metastasize, exporting cancer cells to other parts of the body where they may form additional tumors.