CELL DIVISION Flashcards
What are the two main reasons new cells are
needed in a human?
Growth and repair of body cells.
Production of specialised sex cells.
how many chromosomes do humans have?
Humans have 46 chromosomes, or 23 pairs.
Why do you think chromosomes are described in pairs?
Half of the chromosomes are inherited from the mother (nucleus of egg cell) and half from the father (nucleus of sperm cell).
Diploid nucleus (2n) ?
is a nucleus containing two complete sets of
chromosomes, one from each parent
Where would you find a haploid nucleus?
Gametes (sex cells) – sperm and egg
Where would you find a diploid nucleus?
All body cells
Which cell would be neither diploid or haploid?
Red blood cell
Haploid nucleus (n) ?
is a nucleus containing a single set of unpaired
chromosomes
What is the diploid and haploid number for humans?
Diploid = 46
Haploid = 23
what is mitosis?
Mitosis is a type of cell division
which occurs during growth,
repair, cloning and asexual
reproduction.
A type of cell division which makes new cells
that are genetically identical to the original
cell
mitosis explained?
Mitosis begins with a single parent cell with 46 chromosomes (2n - diploid). First the cell makes a copy of each chromosome and then it divides to produce two identical daughter cells, each with a full set of chromosomes (2n – diploid).
3 roles of mitosis?
Tissue Growth
Tissue Repair
Asexual reproduction
MITOSIS KEY POINTS
Involves one cell division
2 new daughter cells are produced
Each daughter cell is genetically identical to
each other and to the parent cell
Chromosome number stays the same
Occurs in all body cells
Used for growth and repair (& asexual
reproduction in some organisms)
what is meiosis?
Gametes (sex cells) have half the usual number of
chromosomes, so that when fertilisation occurs the new
offspring will have a diploid nucleus.
Gametes are produced by meiosis.
Random fertilisation produces genetic variation in offspring
meiosis explanied?
Meiosis begins with a single parent cell with 46 chromosomes (2n - diploid). First the cell makes a copy of each chromosome and then it divides to produce four non-identical daughter cells, each with half the number of chromosomes (n – haploid).
This results in the formation of
genetically different haploid
gametes producing variation.