cell division Flashcards
what is cell division?
one parent cell divides to make two daughter cells with the same genetic material/DNA
before cell division what must happen?
parent must copy all of its DNA
FACT: each daughter cell gets 1 copy of genetic information
why do cells divide?
for reproduction
what is asexual reproduction?
organisms divide and make exact copies of themselves
what is the problem with asexual reproduction?
no genetic diversity
what kind of organisms reproduce asexually?
organisms, bacteria, protists
what is sexual reproduction?
fusion of 2 sex cells AND has genetic diversity
what kind of organisms reproduce sexually?
plants, animals
what is the problem with sexual reproduction?
lots of resources and finding a partner
DNA is usually in the form of chromatin, what is chromatin?
long string like fibers
once cells get ready to divide, what happens to DNA?
it coils up into compact structures
what are those compact structures that DNA coils up into called?
chromosomes
FACT: chromosomes are single DNA molecules coiled up
chromosomes have two identical copies called what?
sister chromatids
FACT: sister chromatids are exact copies of eachother
the sister chromatids are held together at the center of what?
the centromere
what do sex chromosomes do?
determine the sex of a chromosome
FACT: XX- female XY-male
what are autosomes?
nonsex chromosomes
1 organism has how many copies of each autosome?
2- one from each parent
the two copies of each autosome are called what?
homologous chromosomes
FACT: homologous chromosomes are the same size and shape and carry genes for the same traits
how many chromosomes do humans have?
46 in body cells, 2 sex cells
what are diploid cells?
two sets of chromosomes -> 2n; called somatic cells (body cells)
what are haploid cells?
one set of chromosomes -> 1n, called germ or gamete cells (sex cells)
FACT: each diploid cell has 46 chromosomes, each haploid cell has 23 chromosomes
what are prokaryotes?
division of binary fission- each daughter cell has an exact copy of the parent
what are the two divisions of eukaryotes?
mitosis- division of diploid/ somatic/body cells
- daughter cells genetically identical to parent
meiosis- division of haploid/gamete/sex cells
-daughter cells genetically different to parent
what is the G1 phase, S phase and G2 phase?
G1 phase- cell growth, after cell division daughter cell is much smaller than parent
S phase- synthesis phase, DNA copies itself
G2 phase- cell growth pt. 2, prep for cell division
what comes after these 3 phases?
Cell division -> PMAT (mitosis) AND cytokinesis
what is cytokinesis?
division of cytoplasm
what is the G0 phase?
dormant phase- no division takes place
what is prophase?
spindle fibers begin to form, DNA condenses into chromosomes (sister chromatids together), nuclear envelope disappears
what is metaphase?
chromosomes line up in the middle of the cell, spindle fibers grow and bind into centromeres
what is anaphase?
centromere breaks and each chromatid is pulled by spindle fibers to each side of the cell
what is telophase?
spindle fibers disassemble, DNA returns to chromatin form
what are animal cells?
cell membrane pinches inward between the cells creating a cleavage furrow, 2 new cells
what are plant cells?
vesicles fuse at the midline creating a membrane bound cell wall called a cell phase
what are plant cells?
vesicles fuse at the midline creating a membrane bound cell wall called a cell phase
what protein tells the cells to divide?
cyclins
what are tetrads?
arrangement of 4 chromosomes
what is apoptosis?
process of programmed cell death
what are stem cells?
undifferentiated cells that become different cell types
what is cancer?
uncontrolled cell division, form a mass of cells called a tumor
what is a benign and malignant tumor?
benign- does not spread, malignant- invade and destroy
what causes cancer?
genetic factors, tobacco, poor diet- lack of physical activity, sun and UV exposure, radiation exposure, carcinogens,
how is cancer treated?
radiation, chemo, Immuno, hormone, targeted, stem cell therapy
what happens after PMAT II (meiosis II)?
4 daughter cells all genetically different at the end of division
what happens in Meiosis I Prophase I?
DNA coils up to chromosomes, spindle fibers begin to form, nuclear membrane disappears
what happens in Prophase I?
homologous chromosomes pair up called synapse, each pair of homologous chromosomes are called tetrad, crossing over occurs- homologous recombination
what are tetrads?
each pair of homologous chromosomes
what is a synapse?
homologous chromosomes pair up
what is metaphase I?
tetrads line up along midline, spindle fibers attach to each homologous pairs
what is anaphase I?
each homologous pair of chromosomes moves to opposite poles,
in anaphase I, what is the random separation of homologous chromosomes called?
independent assortment
what happens in telophase I?
same as mitosis, DNA returns to chromatin form, nuclear membranes reform
what happens after Meiosis II?
no copying of DNA, similar to the stages of mitosis, end up with four gamete cells at the end of division, all genetically different from each other
