Chapter 8 Flashcards
asexual reproduction
- offspring from a single parent
2. offspring and parent are genetically identical
sexual reproduction
- offspring from two parents
2. offspring is a unique combination of genes from two parents
binary fission
- chromosome duplicates and moves to opposite poles
- cell elongates
- cytoplasm divides
chromatin
loosely packed DNA and proteins
chromosomes
condensed, chromatin present immediately before cell division
sister chromatids
both sides of a chromosome each containing the SAME genetic information
centromere
area where sister chromatids are attached
cell cycle
series of events extending from the time a cell is formed until it divides into two
phases of cell cycle
interphase, mitosis, cytokinesis
interphase
G0: non-dividing phase (heart and brain)
G1: cell grows in size, function
S: DNA synthesis (replication) occurs
G2: Cell continues to grow and prepare for division
mitosis (M)
nuclear division
cytokinesis
cytoplasm division
events of mitosis
prophase prometaphase metaphase anaphase telophase
prophase
spindle is forming, centrioles migrate to opposite ends of the cell
prometaphase
chromosomes form, nucleolus and nuclear membrane disperse
metaphase
spindle fully formed, chromosomes aligned single file with centromeres at metaphase plate
anaphase
chromosomes separate at centromere, move towards opposite poles, cell elongates
telophase
cell elongation continues, nucleolus and nuclear envelope reform, chromatin forms
events of cytokinesis
Animal cells - ring of microfilaments contracts into cleavage furrow
Plant cells - vesicles fuse into a membranous cell plate which develops into a cell wall
anchorage dependence
being in contact with a solid surface
density-dependent inhibition
cells stop dividing when they touch each other
growth factors
proteins secreted by cells stimulating other cells to divide
required for division, division stops when no more growth factor
cell cycle control system
cyclical operating set of molecules that triggers and coordinates key events in the cell cycle
if a growth factor is not released at three major checkpoints, the cell cycle will stop
cyclins
a group of proteins regulating cell cycle by binding to Cdks
cyclin-dependent kinases (Cdk)
always present in cell, activated when bound to cyclins
when does cancer occur?
occurs when cells do not respond normally to the cell cycle control system
what makes cancer dangerous?
uncontrollable division
can invade other body tissues
why doesn’t every abnormal cell turn into a tumor or cancer?
immune system does destroy malformed cells however, some evade destruction
benign tumors
abnormal cells remain at original site, take up space, easily removed
malignant tumors
abnormal cells spread to other tissues and parts of the body, displace tissues, interrupt organ function, signal blood vessels to grow into it
metastasis
spread of cancer via circulatory
major categories of cancer
carcinomas
sarcomas
leukemias/lymphomas
carcinomas
originate in coverings of the body (skin)
sarcomas
originate in tissues that support the body (bone)
leukemias/lymphomas
originate in blood-forming tissue
abilities of stem cells
can divide and renew themselves for long periods of time
remain undifferentiated in form
develop into a variety of specialized cell types
