Use LEFT and RIGHT arrow keys to navigate between flashcards;
Use UP and DOWN arrow keys to flip the card;
H to show hint;
A reads text to speech;
55 Cards in this Set
- Front
- Back
Why does replication of DNA have to occur before the start of mitosis and meiosis?
|
DNA must be replicated in order to have the correct number of chromosomes present in daughter cells and gametes.
|
|
What are gametes?
|
Sex cells including sperm and eggs.
|
|
What is isogamy?
|
The production of sex cells that are approximately the same size.
|
|
What is heterogamy?
|
The production of gametes that are of markedly different sizes. Eg. The human egg cell is almost 20 times larger than a sperm cell.
|
|
What is cytokinesis?
|
The splitting of the cytoplasm
|
|
What are the four stages of the cell cycle?
|
1. Interphase G1,
2. Interphase S, 3. Interphase G2, 4. M phase - Mitosis & cytokinesis |
|
What happens in the G1 phase of the cell cycle?
|
G1 stands for the "1st gap". During this stage the cells grows and senses whether all conditions are "go" for division.
|
|
What happens in the S phase of the cell cycle?
|
Replication of DNA
|
|
What happens in the G2 phase of the cell cycle?
|
G2 stands for the "2nd gap". The cell continues to grow in size and checks that the chromosomes have been fully copied and that the stage is set for the actual division of the cell into two daughter cells.
|
|
What happens in the "M" phase of the cell cycle?
|
"M" refers to mitosis/cytokinesis. During this phase prophase, metaphase, anaphase, and telophase occur.
|
|
Name the four divisional stages of mitosis.
|
prophase, anaphase, metaphase, and telophase
|
|
What is the stage between cell division called?
|
interphase
|
|
What happens during prophase of mitosis?
|
1. Replicated chromosomes condense<br />2. Spindle fibers (microtubules) form and grow. <br /><br />The nuclear envelope begins to break down allowing cytoplasm and nucleoplasm to mix.
|
|
What happens in metaphase of mitosis?
|
Replicated chromosomes line up along the "equator" of the cell. Microtubules (spindle fibers) are attached to each chromosome at the centromere.
|
|
What happens during anaphase of mitosis?
|
The centromeres "split" and the spindle fibers shorten pulling each sister chromatid to opposites poles (sides) of the cell.
|
|
What happens during telophase of mitosis?
|
The nuclear envelope reforms around daughter nuclei. Chromosomes uncondense. Cytokinesis divides the cytoplasm and the daughter cells are produced. The original cell no longer exists - it has become two daughter cells.
|
|
What is diploid?
|
a full compliment of chromosomes
|
|
What is haploid?
|
half the diploid number of chromosomes
|
|
What is the cell plate?
|
In plant cells, which have non-living rigid cell wall composed of cellulose, pieces of new cellulose begins forming in the center of the parent cell, working 3-dimensionally to the outside dividing the plant cell in two down the center. This is the cell plate. NOTE: Since animal cells do not have a cell wall, cell plates do not form.
|
|
What is the pinching in two of the parent cell called during telophase?
|
cytokinesis
|
|
What is it called when mitosis goes wild and cells become immortal?
|
cancer
|
|
If we could figure out how to regulate this substance in normal cells which prevents chromosomal degradation we could practically be immortal.
|
telomerase
|
|
What is telomerase?
|
the enzyme (see the "ase" ending) that prevents chromosomal degradation
|
|
In reference to cancer, what is the "multiple hit" model?
|
This describes the fact that multiple mutations are required for cancer to occur. These can be inherited aberrations, or caused by the environment. If you get enough of these "hits" in a lifetime you can develop a cancer.
|
|
What is the purpose of mitosis?
|
to provide identical copies of the parent cell with no variation
|
|
What is the purpose of meiosis?
|
to provide sex cells (eggs and sperm) that are haploid
|
|
What are human body cells called?
|
somatic cells
|
|
How many chromosomes do human somatic cells have?
|
46
|
|
What is the genetic makeup of the oogonium in the human?
|
2N
|
|
What is the genetic makeup of the human primary oocyte?
|
2N
|
|
What is the genetic makeup of the secondary oocyte?
|
haploid - N
|
|
What is the genetic makeup of the ovum?
|
haploid - N
|
|
What are the polar bodies formed during oogenesis?
|
Polar bodies are the result on an uneven cytokinetic division of the cytoplasm occurring during oogenesis in telophase 1 & 2. This means that two polar bodies are formed by the end of oogenesis. In humans these tend to disintegrate leaving only a single ovum at the end of oogenesis.
|
|
How many eggs are produced at the completion of oogenesis?
|
one
|
|
How many sperm cells are produced at the end of spermatogenesis?
|
four
|
|
What is the genetic makeup of the spermatogonium?
|
2N
|
|
What is the makeup of the primary spermatocyte?
|
2N
|
|
What is the makeup of the secondary spermatocyte?
|
N - haploid
|
|
What is the genetic makeup of the spermatid?
|
N - haploid
|
|
What is a homologous pair?
|
chromosomes which have the same genes and similar sequences
|
|
How many cytokinetic divisions occur in mitosis?
|
one
|
|
How many cytokinetic divisions occur in meiosis?
|
two
|
|
What is the purpose of meiosis?
|
to produce haploid gametes and allow for variation to occur
|
|
Which of the phases of meiosis is the one in which genetic variation occurs?
|
prophase 1
|
|
What is the process called when homologous chromosomes come together in Prophase 1?
|
synapsis
|
|
What happens during synapsis?
|
During synapsis homologous chromosomes come to line along side of one another forming a tetrad.
|
|
What is crossing over?
|
Crossing over may occur during prophase 1 of meiosis when homologous pairs of chromosomes overlap and exchange pieces of genetic information at corresponding loci (locations on the chromosome). This is what permits variation and is the engine which drives evolution.
|
|
What is the purpose of sex?
|
to shuffle the genetic deck in prophase 1 to get new combinations that are adaptive
|
|
What is an adaptive trait?
|
One that increases an organism's chance of surviving to the age of reproduction and passing that trait to the next generation. Adaptive traits tend to accumulate in gene pools.
|
|
What is a maladaptive trait?
|
a trait that decreases the chances of survival to the age of reproduction<br />Maladaptive traits do not accumulate in the gene pool for this very reason.
|
|
How does metaphase of mitosis and metaphase of Meiosis 1 differ?
|
In mitosis individual duplicated chromosomes line up on the equator and pulled apart during anaphase to produce daughter cells with the same number of chromosomes as the parent cell. In Meiosis 1 metaphase, tetrads line up at the equator and homologues are pulled apart reducing chromosome number in half making haploid gametes.
|
|
How many autosomes and sex chromosomes are found in a human karyotype?
|
In humans there are 22 pairs of autosomes and one pair of sex chromosomes.
|
|
Which sex chromosome is markedly smaller than its counterpart?
|
the male "Y" chromosome
|
|
When an egg and a sperm unite what is the product called?
|
a zygote
|
|
What is the process called when the male and female gametes unite to form a zygote?
|
fertilization
|