BIO 102 CHAPTER 9 - OLE MISS
Which of the following statements is/are true about meiosis?
-The daughter cells of meiosis have half as many chromosomes as the parent cell. -Meiosis produces gametes. -Meiosis produces four haploid cells. -Meiosis produces nonidentical cells.
How do human body and sex cells differ in the number of molecules of DNA?
-humans have 23 pairs of chromosomes: 1-22 are autosomes, body traits; 23 is the sex chromosome
How many chromosomes do cells resulting from meiosis II have?
15 chromosmes
If a cell has 16 pairs of chromosomes, how many unique configurations of chromatids can be produced in gametes as a result of random orientation during meiosis?
2 to the 16th power = 256
How many molecules of DNA does a sex cell have?
23
How many chromosomes do daughter cells of meiosis I have?
23 chromsomes
How many pairs of homologous chromosomes does a human body cell have?
23 pairs
Human diploid cells have
23 pairs of chromosomes
A diploid cell is indicated by what abbreviation?
2n
How many cells result from the process of meiosis?
4 gamete cells
How does that number compare to the original cell?
46
How many molecules of DNA does a diploid cell have?
46
How many chromosomes does a cell have as it begins meiosis?
46 chromosomes
If a cell has 3 pairs of homologous chromosomes, how many unique configurations of chromatids can occur in gametes as a result of random orientation of chromosomes in metaphase I?
8
Between meiosis and random fertilization, the combination of genes that any individual has is one of how many possible combinations?
8 million
How many molecules of DNA do the new cells have?
92
If an animal has 6 chromosome pairs in its cells, then 64 combinations of chromatids are possible for a gamete. If both male and female gametes have 64 possible chromosome combinations, how many genetically unique zygotes could be produced due to random fertilization? (Assume crossing over does not occur.)
About 4,000
What type of reproduction produces offspring that are identical to the parent (except for mutations)?
Asexual
How are diploid cells, homologous chromosomes, and alleles related?
Diploid cells have homologous pairs of chromosomes, which carry the same genes as one another but not necessarily the same alleles.
An extra copy of chromosome 21 causes
Down syndrome
What is trisomy 21?
Down syndrome
Meiosis produces cells for which of the following processes?
Fertilization
What process occurs when gametes from two parents fuse?
Fertilization
______ is the merging of a sperm and an egg to create a diploid zygote.
Fertilization
______ are haploid sex cells which combine to form new offspring.
Gametes
How are "gamete," "chromosomes," and "zygote" related?
Gametes unite, forming zygotes with two sets of chromosomes.
Which phase of meiosis is most similar to mitosis?
Meiosis II
What occurs when chromosomes do not separate during meiotic divisions?
Nondisjunction
What produces gametes with a missing or extra chromosome and may result in embryonic, fetal, or infant death or a trisomic individual?
Nondisjunction
What results in a random mixture of paternal and maternal genetic material in each daughter cell during meiosis?
Random orientation of chromosome pairs during metaphase I
What type of reproduction produces offspring that are genetically different from each other and from the parents?
Sexual reproduction
The most common cause of Down syndrome is
Trisomy 21
What's the relationship between homologous chromosomes and sister chromatids?
Two copies of one chromosome, linked together in the centromere are called sister chromatids.
What are homologous chromosomes?
Two genetically similar chromosomes, one from each parent
Random fertilization is a mechanism outside of meiosis from which genetic variation is created; what about it is random?
When a male gamete and a female gamete finally meet, each is the result of an immense number of genetic possibilities created during independent assortment and crossing over.
Nondisjunction of the ______ chromosome during meiosis can produce offspring that are XXX or XXY.
X
which of the following are true about the X and Y chromosomes in humans?
X is much bigger than Y carry different genes
a zygote is
a diploid cell
What is a zygote?
a fertilized egg cell
A gene has different versions, or , which are carried on homologous chromosomes and encode different versions of the gene's protein product.
alleles
What are different versions of a gene?
alleles
which of the following can result from nondisjunction in humans?
an extra copy of a chromosome failed development due to missing genetic material trisomy
When do sister chromatids separate?
anaphase
When in meiosis do homologous chromosomes separate?
anaphase I
The X and Y chromosomes in humans.....
are not homologous
When ______ reproduction occurs in a one-celled organism, the organism replicates its DNA and splits into two genetically identical cells.
asexual
While ______ reproduction is less costly, ______ reproduction is commonly utilized because it generates genetic diversity.
asexual; sexual
A pair of what chromosomes are the same size and contain the same genes in both males and females?
autosomes
The 22 pairs of human chromosomes that are the same in both males and females are called
autosomes
The 22 pairs of human chromosomes that are the same in both males and females are called...
autosomes
What is the functional difference between autosomes and sex chromosomes?
autosomes control the inheritance of all an organism's characteristics except the sex-linked ones, which are controlled by the sex chromosomes.
Explain what it meant by the haploid cells that result from meiosis are only four of 8 million different possibilities.
because it has half the number of chromosomes as the original parent cell
In plant life cycles, what stages can be multicellular?
both diploid and haploid stages
In eukaryotes, a molecule of genetic material and its associated proteins form a(n) , of which humans have 46 in each cell.
chromosome
what is true about meiosis?
creates four haploid cells from one diploid cell includes two cell divisions produces gametes with half the number of chromosomes as compared to somatic cells
Short segments of DNA are exchanged between homologous chromosomes during prophase I in a process called _______over.
cross
what are mechanisms that generate genetic variability in sexual organisms?
crossing over random orientation of chromosomes random fertilization
A(n) ______ cell contains two sets of chromosomes, one set of chromosomes inherited from each parent.
diploid
Located in the ovaries and testes of animals, specialized cells called germ cells are ______ and undergo meiosis to produce ______.
diploid; gametes
what describes meiosis?
divides eukaryotic chromosomes of one cell into daughter cells that contain half as many chromosomes as the parent cell cell division needed to produce gametes, or sex cells
Only germ cells have sex chromosomes.
false
When can the error occur in meiosis?
for frequently in the first division than the second
what are possible results of nondisjunction in sex chromosomes?
gamete contains an extra X XXX zygote gamete is missing a sex chromosome gamete contains an extra Y
In the human life cycle, the only haploid cells are the....
gametes
The special haploid cells required for sexual reproduction are called
gametes.
Crossing over, random orientation of chromosomes, and random fertilization are mechanisms involved in meiosis and sexual reproduction that generate __________diversity.
genetic
The chromosomes of offspring are not identical to those of their parents or siblings because ______ is shuffled during meiosis.
genetic information
What are the specialized diploid cells called that divide by this process into haploid gametes?
germ cells
In animals, specialized diploid cells that undergo meiosis are called
germ cells.
A(n) ______ cell contains only one copy of each chromosome.
haploid
The abbreviation n or 1n represents a _______cell.
haploid
Are cells after meoisis, diploid or haploid cells?
haploid cells
Two chromosomes with the same size, centromere location, and gene sequence are called a(n)_______ pair.
homologous
Chromosomes that look alike and carry the same genes are...
homologous chromosomes
Crossing over is the process in which ______.
homologous chromosomes physically exchange pieces.
Two matching chromosomes having the same basic structure and same sequence of genes are called a ______.
homologous pair
Where are germ cells found in the body?
in the ovaries and the testicals
What phase of the cell cycle immediately precedes meiosis?
interphase
which of the following are true about cells undergoing meiosis?
interphase precedes meiosis I cytokinesis occurs after the distribution of genetic material
In humans, what is the biological sex of an individual with XY sex chromosomes?
male
Homologous chromosomes are slightly different from each other because they
may carry different alleles for the same genes.
A diploid germ cell will produce cells with half the number of chromosomes, haploid cells, in
meiosis
A second way of meiosis that creates genetic diversity depends on how each pair of replicated homologous chromosomes come to the center of the cell before being pulled apart. What is this process called?
meiosis
By what process does the body create new sex cells?
meiosis
What is the cell division process that makes haploid gametes from diploid cells?
meiosis
Dividing cells that contain only one chromosome from each homologous pair aligned at the equator of the cell must be undergoing
meiosis II.
How do cells resulting from meiosis compare genetically to each other?
meiosis produces four haploid (n) gametes that are genetically unique from each other and the original parent (germ) cell.
Crossing over and random orientation of chromosomes lead to genetic variability in the process of ______, but the process of ______ does not generate genetic variability because it lacks these mechanisms.
meiosis; mitosis
By what cell reproduction process does the zygote grow into multiple cells?
mitosis
What process produces daughter cells for growth and repair, but not for sexual reproduction?
mitosis
A process called ______ is an error in meiosis in which chromosomes fail to separate and a gamete with too many or too few copies of a particular chromosome can be produced.
nondisjunction
Meiotic cell division replicates a cell's DNA ________ and then divides ________.
once; twice
For a particular gene, a chromosome typically carries ______ of each gene, and a homologous pair of chromosomes carries ______.
one allele; two alleles, one allele from each parent.
A chromatid that has undergone meiosis and has the same alleles as one of the parent chromatids is called a....
parental chromatid.
Name the process of meiosis I that results in the exchange of DNA between pairs of homologous chromosomes.
prophase 1
what are features of both mitosis and meiosis?
prophase, metaphase, anaphase, and telophase steps preceded by interphase spindle fibers made of microtubule proteins
In sexual reproduction, exactly what egg cell matures and what sperm cell fertilizes the egg is....
random and results in genetic variability.
What is the error in downs syndrome and what do we call it?
random error in cell division that results in the presence of an extra copy of chromosome 21
A chromatid that has undergone crossing over and has a different combination of alleles than either chromatid of the parents is called a...
recombinant chromatid
The X and Y chromosomes in humans are called
sex chromosomes
The ______ are the genetic components that determine whether a mammal develops as a male or female.
sex chromosomes
A species that reproduces by ______ has the greatest chance of surviving in a changing environment.
sexual reproduction
Which cells are diploid and which are haploid?
sexually reproducing organisms consist of mostly diploid cells which contain 46 chromosomes
A chromosome is a(n) ______.
single molecule of DNA and its associated proteins
In meiosis I, homologous chromosomes separate, whereas in meiosis II,
sister chromatids separate.
Other than the germ cells, all diploid cells in the body are called_________ cells, which are able to undergo mitosis but do not undergo meiosis.
somatic
Neurons and muscle cells of animals are examples of ______.
somatic cells
which of the following that take place during interphase preceding meiosis?
synthesis of proteins and enzymes needed for cell division replication of DNA production of two identical sister chromatids attached at the centromere
in the male human body, germ cells are found in the
testes
What's the difference between cells after meiosis I and after meiosis II?
the number of cells is doubled but the number of chromosomes is not.
Both somatic cells and germ cells are diploid, although only germ cells can undergo meiosis. T/F
true
Meiosis produces four nonidentical cells, each containing neither homologous chromosomes nor sister chromatids. T/F
true
The gene shuffling that occurs during meiosis allows two parents to produce genetically diverse offspring. T/F
true
How many rounds of cell division occur in meiosis?
two
Diploid means having...
two homologous sets of chromosomes.
What are the two sex chromosomes?
x + y chromosomes
Which sex chromosomes do females carry?
xx
Which sex chromosomes do males carry?
xy
The diploid cell created from the fusion of gametes is called a(n)
zygote
The first diploid cell of a new organism, called a(n)_______ , has a set of chromosomes from each parent.
zygote