Honors Biology Unit 7 - Cell Cycle

cell cycle

interphase, G1 phase, S phase, G2 phase, M phase, mitosis, cytokinesis

anaphase

chromosomes are pulled apart and start to migrate to the edges of the cell

telophase

• nucleus begins to form

• chromosomes revert back to chromatin

metaphase

• centromeres attached to microtubules

• chromosomes are lined up

interphase

the cell is performing all of its normal functions

• where cell spends most of its time

prophase

• sister chromatids appear

• spindle fibers form

• chromosomes migrate to spindle fibers

• nucleus disassembles

M phase

mitosis (division of the nucleus) and cytokinesis (division of cytoplasm)

S phase

DNA synthesis and replication

G1 Phase

• normal growth

• cell is doing its job

G2 Phase

cell prepares for division

cell plate

• a structure that forms when the cytoplasm of a plant cell divides

cleavage furrow

a plasma membrane invagination at the cell division site

cytokinesis

• differs in animal and plant cells because plant cells need to form a new cell wall

G0 Phase

• a resting phase where cells are not actively dividing but are actually doing their cellular jobs

apoptosis

• programmed cell death

• a defective cell or a cell designed to be eliminated will undergo an orderly death

centrosomes

specialized microtubuals where the chromosomes line up during division

binary fission

replication of chromosome then divide in half

mitosis

a more complicated process that evenly divides the genetic material in the nucleus for two new cells

mitotic spindle

• constructed from microtubules and their associated proteins

• pull the daughter chromosomes toward the poles of the spindle and move the poles apart

metastasis

the development of secondary malignant growths at a distance from a primary site of cancer

oncogene

mutated stimulators that are always on

• floor it

cancer cells

cells that are no longer under control by the body system

• overriding stop-and-go lights

• more likely when both chromosomes are mutated

stimulator

tend to increase until critical level is reached, promote cell to next phase

inhibitor

• check for damage

• act to prevent cell from moving into next phase

stem cells

somatic cells that do mitosis

• help with replication

cell division

why do they divide?

1. reproduction of unicellular organisms

2. repair of multicellular organisms

3. to replace worn out cells'

4. growth of multicellular organisms

5. when the surface area to volume ratio is too low

• dependent on the cell’s surface area to volume ratio

malignant tumor

cancerous or harmful

proto-oncogene

normally functioning stimulators

• go light

carcinogens

a substance or organism capable of causing cancer

tumor-suppressor genes

normally function as inhibitors but when mutated will fail to pause the cell cycle

tumor

a swelling of a part of the body, generally without inflammation, caused by an abnormal growth of tissue, whether benign or malignant

• build-up

regeneration

to replace lost or injured tissue or to regrow

chromatin

genetic material and histones in long strands

• normal life of a cell

chromosomes

form of genetic material during and right before cell division

histones

proteins that wrap DNA in long strands

asexual reproduction

• a single parent produces genetically identical offspring

• new individuals form from the seperation of cells

• many offspring, short time

• not very well adapted when conditions change

sexual reproduction

• sexual reproduction involves the fusion of two seperate parent cells

• offspring inherit some genetic information from each parent

• fewer offspring

• growth takes more time

• genetic diversity

• may be less well adapted to current conditions

differentiation

when a cell stops dividing in order to specialize in structure and function