cells Flashcards
(22 cards)
name the two cell types
gametes
somatic cells
define somatic cells
all body cells excluding gametes (sex cells)
- skin cell, white blood cell, muscle cell, liver cell etc
- diploid
define diploid
(2n)
contains homologous pairs of chromosomes
define gametes
sex cells (egg and sperm)
-haploid
define haploid
(n)
contains an unpaired set of chromosomes (1 of each homologous pair)
what is the cell cycles
the series of events that take place in a eukaryotic cell (primarily interphase, mitosis and cytokinesis)
interphase
consists of G1, S and G2
what happens in G1 of interphase
normal cell functions, growth and preparation to divide
what happens in S phase of interphase
DNA replication
- the number of chromosomes remains the same
- the mass of DNA doubles
what happens in G2 of interphase
normal cell functions, growth and preparation to divide
what are chromosomes made up of
DNA ( and proteins if in eukaryotic cell)
why can’t prokaryotic cells undergo mitosis
Because mitosis is a nuclear division
Then prokaryotes do not have a nucleus
Therefore prokaryotic cells cannot undergo nuclear division
purpose of mitosis
growth, repair and replacement of cells
function of spindle fibres
- attaches to the centromeres of chromosomes in metaphase during mitosis
- pulls sister chromatids apart to opposite poles of the cell in anaphase during mitosis
function of centrosomes
forms spindle fibres for nuclear division (mitosis) in animal cells
what are centrosomes
each centrosomes are made up of two centrioles at right angles to one another
define cytokinesis
division of the cytosol which results in the formation of two daughter cells that are genetically identical to each other and the original parent cell
- the plasma membeane pinches together in the middle in order to create two new cells
-produces two daughter cells that are genetically identical to each other and the parent cell
meiosis
a form of nuclear division that produces 4 genetically different haploid daughter cells
purpose of meiosis
to produce haploid gametes for sexual reproduction
where does mitosis and meiosis occur?
mitosis: somatic cells
meiosis: ovaries, testes
how many daughter cells are produced in mitosis and meiosis after cytokinesis
mitosis: 2 genetically identical
meiosis: 4 genetically different
are diploid or haploid daughter cells produced in mitosis and meiosis
mitosis: diploid (2n=46)
meiosis: haploid (n=23)
