Cellular Division Flashcards
DNA of prokaryotes is?
one circular chromosome attached to inside of cell membrane
eukaryotic cells store genetic info in chromosomes
10-50 chromosomes in cells.
humans have 23 pairs (46 chromosomes)
Each chromosome is comprised of?
A single DNA molecule
chromosomes can’t be seen when cells aren’t dividing and are called?
chromatin
DNA is tightly coiled around proteins called?
HISTONES
duplicated chromosomes are called chromatids and are held together by?
centromere
first 22 pairs are called?
autosomes
last pair is?
Alosome - sex chromosome (XX female, XY male)
asexual reproduction types?
mitosis and binary fission
sexual reproduction involves?
egg and sperm to form zygote (not identical to parent)
meiosis is eg
cell cycle consists of?
interphase, mitosis, cytokinesis
interphase consists of?
G1 - primary growth
S - synthesis (DNA replicated)
G2 - secondary growth phase
what happens in G1 stage?
cells mature by making more cytoplasm and organelles
what happens in S stage?
DNA is replicated
what happens in G2 stage?
all cell structres needed for division are made (centrioles).
organelles and proteins are synthesised
what is mitosis?
division of nucleus (happens only in eukaryotes)
aka karyokinesis
doesnt occur in brain cells
4 mitotic stages?
prophase, metaphase, anaphase, telophase
what happens in early prophase?
chromatin in nucleus condenses to form visible chromosomes
mitotic spindle forms from fibers in cytoskeleton or centrioles
what happens in late prophase?
nuclear membrane and nucleolus are broken down.
spindle fibres called KINETOCHORES attach to centromere.
spindle finishes forming
spindles form from what?
microtubules in plants.
centrioles in animals.
what happens in metaphase?
chromosomes which are attached to kinetochore fibres move to centre of the cell.
chromosomes are at the EQUATOR.
what happens in anaphase?
sister chromatids are pulled appart to opposite poles of the cell by kinetochore fibres
what happens in telophase?
spindle disassembles.
nuclear envelope forms around each set of sister chromatids.
nucleolus reappears.
CYTOKINESIS occurs.
chromosomes reappear as chromatin,
what is cytokinesis?
division of cytoplasm.
cell plate in plant cells.
cleavage furrow in animal cells.
properties of daughter cells of mitosis?
same number of chromosomes as parent cell.
identical to each other but smaller than parent.
Diploid number??
What are special proteins that increase chances that a normal cell develops into a tumor cell?
ONCOGENES
meiosis: how many chromosomes does daughter cell have?
half of original cell (parent cell is diploid, splits into 3 monoploid cells)
meiosis in testes?
SPERMATOGENESIS
meiosis in ovaries?
OOGENESIS
2 haploid games come together to form what?
a diploid zygote
same genes, same alleles = ?
sister chromatids
same genes, different alleles = ?
homologs (they separate in meoisis I)
meoisis must reduce chromosome number by half because?
fertilization restores 2n number
in meoisis I, homologs separate
in meoisis II, sister chromatids separate
meoisis: early prophase?
homologs pair up, crossing over happens
meoisis: late prophase?
chromosomes condense and spindle forms
2 homologous chromosomes join to form a?
TETRAD (called synapsis)
meoisis: metaphase I?
homologoues pairs of chromosomes align along equator
meoisis: anaphase I?
homologs separate and move to opposite poles.
sister chromatids remain attached at their centromeres
meoisis: telophase I?
nuclear envelopes reassemble.
spindle disappears.
cytokinesis.
