chapter 12 ap bio

cell theory

all living things made of cells, smallest unit of life are cells, cells come from pre-existing cells

cell divison

the reproduction of cells

In unicellular organisms, division of one cell reproduces what?

the entire organism

Multicellular organisms depend on cell division for:

development from a fertilized cell, growth, repair

what do most cell divisions result from?

daughter cells with identical genetic information

meiosis

a special type of division that can produce sperm and egg cells

genome

all dna in a cell. it can consist of a single dna molecule (prokaryotic cells, common in) or a number of dna moleculs (common in eukaryotic cells)

chromatin

genetic materal during interphase consists of a complex of dna and protein (histones). looks like spaghetti

what do eukaryotic chromosomes consist of?

chromatin that condenses during cell division

somatic cells (body cells)

have two sets of chromosomes and are considered diploid

gametes (reproductive cells)

have half as many chromosomes as somatic cells and are considered haploid

mitosis

the division of the genetic material in the nucleus

cytokinesis

the division of the cytoplasm

how are gametes produced

by a variation of cell division called meiosis

what does DNA do in preparation for cell division?

DNA replicates and the chromosomes condense

sister chromatids

each duplicated chromosome has two sister chromatids (joined copies of the original chromosome), which separate during cell division

centromere

the narrow “waist” of the duplicated chromosome, where the two chromatids are most closely attached

what happens to the sister chromatids during cell division?

the two sister chromatids of each duplicated chromosome separate and move into two nuclei

what happens when the two sister chromatids of each duplicated chromosome separate?

the chromatids are called chromosomes

what are inside nucleosomes?

histones

the cell cycle consists of:

interphase (cell growth and copying of chromosomes in preparation for cell division)

mitotic (M) phase (mitosis and cytokinesis)

how much time is the cell in interphase?

about 90%. but some cells can be in interphase for its entire life

what are the three subphases of interphase?

g1 phase - growth

s phase - synthesis. growth and chromosomes are duplicated

g2 phase - growth

how much of the time of the cell is spent in the m phase?

10%

what occurs during m-phase

cell division

what does the m phase include?

mitosis, cytokinesis

phases of mitsosis

prophase, metaphase, anaphase, telophase (PMAT)

what type of genetic material is present in interphase?

chromatin

is the spindle present in interphase?

no because spindles are used to move chromosomes during cell division

do animals or plants have centrioles?

animals

centrosomes vs centrioles

centrosomes - regions in plant and animal cells that make spindle

centrioles - found in the centrosome of animal cells and help make the spindle

what phase of mitosis is this?

prophase

what phase of mitosis is this?

metaphase

what phase of mitosis is this?

anaphase

what phase [of mitosis] is this

telophase and cytokinesis (cytokinesis isnt apart of mitosis but)

what type of genetic material is present in mitosis

chromosomes because the genetic material must be condensed in order to divide

is the spindle present during mitosis?

yes because it is used to move the proper chromosoems to the daughter cells

what is happening during mitosis?

the division of the nucleus

how does cytokinesis occur in animal cells?

cleavage, forming a cleavage furrow

what forms during cytokinesis in plant cells?

a cell plate

how do prokaryotes reproduce?

a cell division called binary fission

what happens in binary fission?

the chromosomes replicate (beginning at the origin of replication), and the two daughter chromosomes actively move apart. the plasma membrane then pinches inward, dividing the cell into two

the frequency of cell division varies with the type of what?

the type of cell

cell cycle control system

the events of the cycle. it is regulated by both internal and external conditions. it has checkpoints where the cell cycle stops until a go-ahead signal is received

what seems to be the most important checkpoint for many cells?

G1 checkpoint

G0 phase

if the cell doesn’t receive the go-ahead signal, it will exit the cycle, switching into a nondividing state called the G0 phase

what are some factors that the cell checks to make sure it is ready for mitosis (G2 checkpoint)

cell size and the chromosomes duplicated

maturation promoting factor (MPF)

a protein kinase that regulates the transition of cells from the G2 phase to the M phase of the cell cycle

m checkpoint

occurs during metaphase. ensures all chromosomes aligned at the miotic plate are under bipolar tension. tension is sensed and initiates anaphase entry and sister chromatid separation

what checkpoint is the restriction point?

g1 checkpoint because it is a point at which the cell irreversibly commits to the cell division process

what are the two types of regulatory proteins involved in cell cycle control?

cyclins and cyclin-dependent kinases (Cdks)

why does Cdks activity fluctuate during the cell cycle

because it is controlled by cyclins, so named because their concentrations will vary with the cell cycle

what molecule varies in concentration during the cell cycle?

cyclin

what is an example of an internal signal at the checkpoints?

the kinetochores not attached to the spindle microtubules send a molecular signal that delays anaphase

growth factors

proteins released by certain cells that stimulate other cells to divide. an example of external signals

density-dependent inhibiton?

another external signal. crowded cells stop dividing once they touch

anchorage dependence

most animal cells exhibit this, which means they must be attached to a substratum in order to divide

do cancer cells exhibit density-dependent inhibition or anchorage dependnce?

NO TO BOTH

how do cancer cells ignore density-dependent inihibition?

cancer cells continue to divide and pile up, ignoring density-dependent(or contact) inhibition

how do cancer cells ignore anchorage dependence?

they lose their anchorage dependence and can travel to new locations

how come cancer cells may not need growth factors to grow and divide?

they can make their own growth factor, they can convey a growth factor’s signal without the presence of the growth factor, and they may have an abnormal cell cycle control system

transformation

a normal cell converted to a cancerous cell

cancer cells that are not eliminated by the immune system form what?

tumors

benign tumor

abnormal cells reman only at the original site

malignant tumor

they invade surrounding tissues and metastasize

why don’t cancer cells respond normally to the body’s control mechanisms?

two different gene pathways are disrupted or damaged by mutations. mutation or loss in these genes can cause cancer

protooncogenes (accelerator) (one gene pathway in the body’s control mechanisms)

make proteins that stimulate cell division, inhibit cell differentiation, and halt cell death

tumor suppressor genes (brake) (another gene pathway of the body’s control mechanisms)

make proteins that dampening or repressive the cell cycle or/and promote apoptosis