mitosis Flashcards
what structure do we find in the nucleus?
what molecule are these made from?
chromosomes which are made of the molecule DNA
describe how chromosomes are contained in a body cell
Body cells contain 2 of each chromosome. they are paired.
how many pairs of chromosomes do human body cells contain?
23 pairs of chromosomes
46 chromosomes in total
the chromosomes of a gamete are…
certain cells called gametes have chromosomes which are not paired
(e.g human gametes have 23 single chromosomes)
what do Chromosomes carry?
a large number of genes which determine many of our features
most human chromosomes contain hundreds of genes
what is the cell cycle
where cells must be able to divide.
what happens in the first stage of the cycle?
the DNA replicates to form 2 copies of each chromosome
what happens during cell division
the cell grows and copies it’s internal structures such as mitochondria and ribosomes.
what happens in the second stage of the cell cycle?
mitosis takes place
when mitosis takes place, what happens to a cell dividing?
one set of chromosomes is pulled to each end of the cell. the nucleus also divides.
what happens in the final stage of the cell cycle?
the cytoplasm and the cell membrane divide to form two identical cells.
what is cell division by mitosis?
where we start with 1 cell which had 2 present chromosomes and at the end we got 2 identical cells, again, each with 2 chromosomes
what does mitosis do?
it copies 1 cell into 2
what are the functions of mitosis?
- mitosis is essential for growth and development of multicellular (multicellular means a more than one cell) organisms (eg plants and animals).
- when an organism repairs itself (eg when a broken bone heals).
- for asexual reproduction
what type of cells divide in mitosis?
eukaryotes
why might mitosis occur in a body of a multicellular organism?
to repair and replace old worn-out cells with new ones
what might a eukaryotic cell need to do during mitosis?
copy it’s own DNA when dividing
what is produced when a cell divides by mitosis ?
2 genetically identical diploid daughter cells
describe the relative mass of the DNA during mitosis
relative mass of DNA in nucleus increases as chromosomes are being copied
relative mass of DNA in nucleus rapidly decreases as cell is divided
describe fully the steps of mitosis in order and names of each step
Interphase- the cell grows, performs routine life processes, and prepares to divide
Prophase - chromosomes are visible, nuclear membrane breaks down, spindle divers begin to form
Metaphase - sister chromatids line up at the centre of the cell
Anaphase - sister chromatids are pulled apart and move to opposite poles of the cell
Telophase - spindle fibres break down, nuclear membrane forms and chromosomes begin to uncoil and form chromatin
Cytokinesis - cytoplasm splits in 2 and cell divides
what happens to the chromosomes at the telophase
they uncoil and form chromatin
