Cell growth Bio

Rudolf Virchow

was one of the first to study cell reproduction

all cells come from

other cells

why do we need new cells

growth(getting bigger), repair(heal wounds and replace old cells), reproduction( making new organisms)

cell cycle

regular pattern of growth, DNA duplication, and cell division that occurs in eukaryotic cells

2 main stages of cell cycle

interphase, mitotis

interphas

the longest phase of the cell cycle, where the cell grows, DNa is replicated or copied and organelle are copied/additional growth occurs

interphase is divided into

G1, S, G2

G1 (gap 1)

gap= growth, carries out normal functions

S (Synthesis)

copy DNA (2 complete set by end of S phase)

G2

carries out normal functions, orgnalles replicate

mitosis purpose

to create two genetically identical daughter cells with the same number of chromosomes as parent cells

mitosis reason

replacing cell with 2 new cells, both with the same function

mitosis broken up into

4 phases

chromosome

tightly condensed structure made of DNA and proteins; typically represented in its duplicated form in a x shape

histones

protein DNA coils around

nucleosome

a segment of DNA wrapped around 8 histones

coils/supercoils

increasingly more complex tightly packed DNA

chromatin

loosely packed mass of DNA and proteins; typically form of DNA when cells are in interphase, DNA condense into chormosomes during cell division

chromatid

half of a duplicated chromosome

sister chromatids

two halves of a duplicated chromosome; created in s phase

centromere

location where sister chromatids are joined

telomere

end caps of chromosome; do not contain coding DNA; function to protect coding region of chromosome

interphase is ______ stage of cell cycle

longests, NOT PART OF mitosis

interphase prepares

the cell to divide; DNA is uncoiled into chromatin; DNA duplicates

prophase

chromatid condenses into chromosomes; centrioles begin to migrate toward opposite ends; nuclear membrane and nucleolus disappear

centrioles

control the development and attachment of spindle fibers

spindle fibers

thin hollow tubes that are part of the cytoskeleton used to move chromosomes

metaphase

chromosomes line up along the middle of the cell; spindle fibers attach to the centromere

anaphase

sister chromatids (duplicated chromosomes) seperate into chromatids; chromatids move toward opposite ends of the cell

telophase

spindle fibers disappear; nuclear membrane forms in each daughter cell; chromosomes uncoil into chromatin; division of the nucleus is now complete; overlaps with cytokinesis

cytokinesis

divison of the cytoplasm

animal cells

cleavage furrow forms to pinch cell membrane inward

plant cells

cell plate forms through the center of the cell outward

rate at which cell divides is linked to

body's need for those cells

skins cell are replaced the

most frequently and therefore divide most frequently

some cells leave the cell cycle and

do not divide

G0 phase of cell cycle

no growth phase ex. brain and nervous tissue

cell cycle checkpoints occur

three times during cell cycle

checkpoint function

ensure stages happen correctly and cell is not damaged

if cell is defective it will undergo

apoptosis

apoptosis

programed cell death

without checkpoints

cells would grow uncontrolled

1st checkpoint

end of gap 1; checks DNA for damage before copying

2nd checkpoint

end of Gap2; checks to make sure parts of the cytoskeleton are in place before division

3rd checkpoint

middle of mitosis; checks the two copies of DNA have been attached to cytoskleton, that will pull them apart

the cell cycle can be

turned on and off

stimuli inside and outside of the cell

regulate the cell cycle

growth factors

broad group of proteins that stimulate cell divison; wound healing and embryo development

cancer

uncontrolled cell division due to a break down in the regulation of the cell cycle

normal cells

density dependent (crowded cells stop dividing), anchorage- dependent (cells must be attached to a surface to divide), normal angiogenesis (blood vessel growth)

cancer cells

density independent (growing cells in multiple layers forming a tumor); anchorage independent (detach from tumor and grow in new locations); advanced angiogenesis (aggressive blood vessel growth)

bengin tumor

does not invade nearby tissue or spread to other body parts

malignant tumor

harmful tumor that can metastasize

metastasize

when tumor cells invade bloodstream, break away and travel to other parts of the body

carcinogens

cancer causing agents, resulting in mutations in DNA

oncogenes

genes responsible for normal cell growth; become mutated and are permenently turned on

tumor supressor gene

prevent uncontrolled cell growth by repairing damaged DNA; become mutated and get turned off

cyclins

proteins that control the timing of the cell cycle; rise and fall at regular intervals; coenzymes that promote spindle movement

asexual reproduction

the production of genetically identical offspring from a offspring parent

sexual reproduction parents

2

sexual reproduction offspring

genetically unique

sexual reproduction ex

eukaryotes

sexual reproduction advantage

diversity adaptation

sexual reproduction disadvantage

slow/energy, find mate

asexual reproduction parent

1

asexual reproduction offspring

genetically identical

asexual reproduction ex

prokaryotes, some eukaryotes

asexual reproduction advantage

no mate, fast, well adapted to enviroment *if no change

asexual reproduction disadvantage

no variation, no adaptation

all specialized cells of the body can be grouped into two main categories

somatic cells, gametes

somatic cells

body cells; ex. heart, brain, liver cells; not passed on to offspring; created through mitosis

gametes

sex cells; eggs in females; sperm in males; are passed onto offspring; are created through meiosis

humans have

46 chromosomes in all somatic cells; 23 from mom and 23 from dad

all somatic cells are

diploid

diploid

cells that have a full set of chromosomes (abbreviated:2n)

all gametes are

haploid

haploid

cells that have half the diploid number of chromosomes (abbreviated:n)

sexual reproduction

union of sperm and egg to produce diploid cell through fertilization

fertilization

the union of sperim and egg; creates a diploid cell from two haploid cells

somatic cells contains

23 pairs of homologous chromosomes

homologous chromosomes

a pair of the same chromosomes, one paternal and one maternal; are the same size; contain the same gene

autosomes

chromosomes pairs 1-22; contain genes that typically do not determine the sex of organism; carry majoirty of organism's gene

sex chromosomes

chromosomes pair 23; contains the genes that determine sex

female

homologous sex chromosomes

male

non- homologous sex chromosomes

Females

XX; haploid egg cells always carry an x chromosome

Males

XY; haploid sperm cells carry an x or y chromosome; males inherit y chormosome directly from father

karyotype

a display of an individual's chromosomes; chromosomes are paired and sorted according to size

karyotype uses

determine sex of fetus, detect chromosomal disorders

nondisjunction

when homologous chromosomes or sister chromatids fail to seperate

nondisjunction can occur

in meiosis 1 or meiosis 2

nondisjunction results in

aneuploidy

anueploidy

a cell with abnormal number of chromosomes

autosomal nondisjunction

trisomy 21(down syndrome), trisomy 18 ( Edward's syndrome)

meiosis

a process where sperm and egg cells are created by cutting the number of chromosomes in half

mitosis produces genetically

identical cells

mitosis results in

diploid cells

mitosis produces

somatic cells

mitotsis takes place

throughout an organisms lifetime

meiosis produces genetically

unique cells