Meiosis Flashcards
A chromosome consists of ___ coiled around ______.
DNA; histones (proteins)
What is the chromatin network?
The thread-like network which DNA forms when the cell is not dividing.
What is a somatic cell?
A body cell. i.e. snot a sex cell (gamete)
What is a homologous chromosome pair?
A pair of chromosomes, one maternal and one paternal, which are similar to each other in size and shape and the type of genetic information they carry.
How many sets of chromosomes do gametes have? And does this make them diploid or haploid?
One set; haploid
Is the zygote haploid or diploid?
Diploid
Does the zygote divide by mitosis or meiosis?
Mitosis
What is a karyotype?
The complete set of chromosomes, arranged by size, shape and number in homologous pairs, within a somatic cell.
What are autosomes?
Ordinary chromosomes that have nothing to do with determining sex.
What are gonosomes?
The pair of sex chromosomes.
How many pairs of autosomes does a human karyotype have?
22 pairs.
Which pair of chromosomes are the gonosomes?
Pair number 23
What is the cell cycle?
The period during which a cell grows, replicates genetic material and divides.
What are the two parts of the cell cycle?
Interphase and Dividing phase.
What are the two types of cell division?
Mitosis and meiosis.
Which type of cells undergo mitosis?
Somatic cells.
What are the phases of mitosis?
Prophase
Metaphase
Anaphase
Telophase
Where does meiosis occur?
In the primary reproductive organs
What occurs during prophase 1?
Nuclear membrane starts to disappear
Centrosome splits into centrioles which separate and form spindle fibres
Bivalent is formed as chromosomes form
Crossing over
What is the chiasma (/chiasmata)?
The point at which the inner chromatids of a homologous pair touch
What occurs during metaphase 1?
Chromosomes align at equator with homologous chromosomes on opposite sides
Chromosomes become attached to spindle fibres
What occurs during anaphase 1?
One whole chromosome from each pair is pulled to opposite poles by the spindle fibres
What occurs during telophase 1?
A new nuclear membrane forms around the groups of chromosomes at the poles
Nuclear membrane returns
Cytokinesis splits mother cell
What occurs during prophase 2?
Nuclear membrane and nucleolus start to disappear
Centrosome splits into centrioles which separate and form spindle fibres
What occurs during metaphase 2?
Single chromosomes align with the centromere on the equator
Each chromosome attaches to a spindle fibre
What occurs during anaphase 2?
Centromere splits and the two chromatids are pulled to opposite poles
What occurs during telophase 2?
New nuclear membrane forms around the unreplicated chromosomes at each pole
Cytokinesis
Define meiosis
The cell division that produces reproductive cells in sexually reproducing organisms
