Mitosis Flashcards
What is mitosis?
Cell division of somatic cells
Why is mitosis necessary?
For growth
To replace dead cells
What is a histone?
The protein around which DNA folds
How many chromosomes does a human cell have?
46
23 pairs
What do chromosomes look like when replicated?
Like an x
What does an unreplicated chromosome look like?
Like a vague S
What is the first phase of the cell cycle?
Interphase
What happens during interphase?
Three phases occur
What are the phases within interphase?
G1
S
G2
What happens during the G1 phase?
The cell grows
The cellular content replicates
What happens during the S phase?
Synthesis
DNA replication
What happens during the G2 phase?
The cell checks that replication happened correctly
How many phases of karyokinesis are there?
Four
What are the four phases of mitosis?
Prophase
Metaphase
Anaphase
Telophase
What is a chromatid?
The one half of the ‘x’ of a replicated chromosome
What connects the two chromatids of a chromosome?
The centromere
How do you remember the four phases of mitosis?
PMAT
What happens during prophase?
The nuclear membrane, nucleus and nucleolus disintegrate
Chromosomes condense
In an animal cell, the centrioli move to opposite poles
They form spindle fibres
What happens during metaphase?
The chromosomes line up down the equatorial line (in the middle of the cell)
Spindle fibres attach to the centromeres
What happens during anaphase?
The spindle fibres of the centrioles shorten and pull the chromosomes apart
Chromatids separate and move to opposite poles
Cytokinesis begins
What happens during telophase?
The nuclear and plasma membrane form in the different daughter cells
Nucleolus forms
Spindle fibres disappear
What happens during cytokinesis?
The cells separate
Animal: cytoplasm invaginate
Plant: transverse wall /cell plate forms
What is the main purpose of mitosis?
A mother cell divides to form two daughter cells
Do the daughter cells differ, either from the mother cell or from each other?
No, they are all identical and have the same genetic material
What are chromosomes?
Thread-like structures found in the cell nucleus in all cells
What do chromosomes do?
Transfer hereditary characteristics from generation to generation
How do chromosomes appear when not dividing?
As a mass of threads in the nucleus called the chromatin network
What happens to the chromatin network when the cells divide?
The chromatin network condenses
The threads become thicker and shorter
They become single stranded chromosomes
What is the structure of a chromosome like?
The nucleic acid DNA that is wrapped helically around histones