Ch 7: Mitosis and Meiosis Flashcards
After interphase, a human cell has a total of __ chromosomes, each made up of two ______.
46, chromatids
During the stage called interphase, how many of the cell’s chromosomes replicate?
All
Each chromosome has a _______ at its center that joins the chromatids together
centromere
Is DNA replication the only process that takes place during interphase?
No, it is one of the many processes
Before a cell undergoes mitosis, what phase does it go through?
Interphase, in which chromosomes replicate
What are the 4 steps of mitosis?
Prophase
Metaphase
Anaphase
Telophase
What happens in prophase?
Centrioles separate and begin forming a spindle fiber apparatus called the mitotic spindle
What happens in metaphase?
Centrioles go to opposite poles, chromosomes line up at the equator, and spindle fibers attach to centromeres
What happens in anaphase?
spindle fibers shorten and pull chromatids to opposite poles
What happens in telophase?
A nuclear membrane forms in each new cell, chromosomes uncoil and condense
What happens in cytokinesis?
Cytoplasm divides
Where does mitosis occur in plant cells?
Meristems- certain growing regions
During which phase do the cell’s chromosomes become visible?
Prophase
The spindle apparatus forms during a stage called _________
Prophase
The division of the cell’s cytoplasm is known as ________ and occurs during _________.
Cytokinesis, telophase
Chromatids separate from each other and move to opposite poles of the cell during what stage?
Anaphase
During what stage do all of a cell’s chromosomes replicate?
Interphase
The centromeres divide during what stage?
Anaphase
During prophase, the ________ move away from one another toward opposite sides of the cell.
Centrioles
What is a gene?
A portion of a chromosome that produces one protein
What is gene expression?
When a gene creates a protein
What is a gamete?
A sex cell
What is a diploid cell?
A cell that has 2 complete sets of chromosomes
What is a haploid cell?
A cell that has only 1 set of chromosomes
What are the only human cells that are haploid?
Sperm and ovum
What is a zygote?
The cell that is formed when chromosomes from the sperm join with the chromosomes in the ovum
The zygote is ______, so it must undergo ______
diploid, meiosis
What is synapsis?
When homologous chromosomes pair up in meiosis
When does synapsis occur?
Prophase I
In prophase I, instead of 46 replicated chromosomes, there are ______.
23 pairs of replicated chromosomes
When does crossing over take place and what is it?
prophase I, segments on homologous chromosomes are exchanged
What happens in metaphase in both meiosis and mitosis?
Chromosomes line up on the equator of the cells
What is independent assortment of chromosomes?
The random way that chromosomes line up during metaphase, which affects the outcome of the genetic information in the gametes that form.
What are linked genes?
Genes that are on the same chromosome and are inherited together
What separates in mitosis and meiosis? What happens in both?
Mitosis- chromatids of each chromosome separate
Meiosis- homologous pairs separate
Move to opposite poles of the cell
What happens in telophase I?
The cells finish dividing their cytoplasm, and nuclear membranes reform. The 2 new cells have 23 REPLICATED CHROMOSOMES not 23 homologous pairs
Meiosis II is virtually identical to _______.
Mitosis, except in mitosis the cell starts with 46 replicated chromosomes and in meiosis, it has only 23 replicated chromosomes.
What is the difference between mitosis and the second round of meiosis?
In interphase II, the chromosomes do not replicate
If the diploid number of chromosomes is 10, then the haploid number is _
5
Metaphase I of meiosis differs from metaphase of mitosis in that a _____ of chromosomes lines up on each spindle fiber.
pair
The four cells resulting from meiosis are _____.
Haploid
What refers to a cell for which each chromosome does not have a homologous partner?
Haploid
Anaphase I of meiosis differs from anaphase of mitosis in that centromeres _____ divide
do not
Prophase I of meiosis _____ similar to prophase of mitosis
Is not
The cells produced at the end of telophase I are considered to be ______
haploid
How many mature sperm are produced from a single spermatogonium?
4
How many mature ova are produced from a single primary oocyte?
1
Spermatogenesis takes place on a _____ basis, whereas oogenesis takes place on a ______ basis.
daily, monthly
The cells that disintegrate during oogenesis are called ________.
polar bodies
A cell that undergoes meiosis will yield how many cells?
4
What is the diploid cell that starts spermatogenesis called and where does it live?
spermatogonium, seminiferous tubules
What are the 3 causes of variation among offspring?
- Independent assortment of chromosomes during metaphase I of meiosis
- Crossing over during synapsis in Prophase I of meiosis
- Random fertilization
