Biology chp 9 Meiosis and the Genetic Basis of Cellular Reproduction
Turner Syndrome
*caused by a lack of an X chromosome *female *underdeveloped ovaries, oviducts, and uterus *characteristics include short stature, broad chest, and webbed neck
Klinefelter Syndrome
*caused by an extra X chromosome *male *underdeveloped testes and prostate gland *characteristics include large hands and feet and long arms and legs
Meiosis II
*results in four genetically diverse haploid nuclei *a haploid number of dyads align at the spindle equator during metaphase
Meiosis I
*results in two genetically diverse haploid nuclei *crossing-over occurs during synapsis *homologous chromosomes pair up during prophase *tetrads align at the spindle equator during metaphase
Mitosis
*results in two genetically identical diploid nuclei *a diploid number of dyads align at the spindle equator during metaphase
What is the end result after telophase I?
2 haploid cells
A person with Down Syndrome typically has an extra copy of chromosome _____.
21
A human skin cell has 46 chromosomes. A haploid sperm cell from the same human would have how many chromosomes?
23 chromosomes
One parent cell beginning meiosis has divided into ______ haploid daughter cells following telophase II and cytokinesis.
4
How many autosomes are in a normal diploid human cell.
44
Which of the following occur during anaphase I?
Homologues move to poles
In terms of the actual division process, mitosis is most similar to meiosis:
II
How do cells in metaphase I of meiosis differ from cells in metaphase of mitosis?
In metaphase of mitosis the chromosomes align single file along the metaphase plate while in metaphase I homologous pairs align.
Which of the following does NOT describe a reason that meiosis is important?
Meiosis increases the chromosome numbers over time.
Which of the following describes human sex chromosomes?
The X and Y chromosomes differ in the genes they carry and in their size.
Which statement applies to Meiosis and not Mitosis?
The end result is the production of 4 genetically unique cells.
How do homologous chromosome compare?
They both carry the same genes but may have different alleles for the genes.
Which of these is an important difference between the formation of gametes in males and females?
Timing, or the age at which the process takes place
Which of the following are the most likely outcome if meiosis did NOT cut the chromosome number in half in daughter cells in humans?
When the sperm and egg fused during fertilization, the resulting zygote would have 92 chromosomes and the sperm and egg would each have 46 chromosomes.
A person with Turner syndrome is indicated by which of the following?
XO
Female sex chromosomes are written as ____.
XX
A person with Klinefelter syndrome is indicated by which of the following?
XXY
A gene on the ______ chromosome produces a hormone that plays a critical role in the development of male genitalia.
Y
A Barr body is
an inactivated X chromosome
Homologous chromosomes are moved to opposite poles of the cell during what meiotic phase?
anaphase I
During which stage of meiosis will sister chromatids separate and go to opposite poles?
anaphase II
The chromosomes found in our cells that are not sex chromosomes are termed _____.
autosomes
In normal females, the second X chromosome forms an inactive mass called a ______ ________.
barr body
The exchange of genetic material between homologous chromosomes in meiosis I is called ______ _______.
crossing over
Which two events are not shared by mitosis and meiosis?
crossing over and separation of homologues
During meiosis I the process of ______ produces cells that are not genetically identical.
crossing-over
Which process begins in telophase II?
cytokinesis
A typical skin cell has 23 pairs of chromosomes or 46 total chromosomes. This type of cell would be considered a _____ cell.
diploid
When a person is born with Down syndrome, it is typically due to the _______ containing an extra chromosome.
egg
True or false: Sister chromatids separate during anaphase I.
false
Individuals with an inactive SRY gene on the Y chromosome have their sex classified as ______.
female
A person with Turner syndrome is a _____ with one ______ chromosome.
female/missing X
Which of the following occurs at the completion of both mitosis AND meiosis I?
formation of 2 cells
A key difference between meiosis II and mitosis is that the cells in meiosis II will have the _________ number of chromosomes.
haploid
Chromosomes that have the same size, shape and gene order, but not necessarily the same alleles are called _______ chromosomes.
homologous
What processes happen in meiosis that do not occur in mitosis?
homologous chromosomes line up, crossing over, and homologous chromosomes are separated
The sex of someone with Klinefelter syndrome would be _____.
male
During the process of cell division called _______, haploid gametes are formed.
meiosis
Individual members of the same species are genetically very different because of a process called _________, which creates gametes.
meiosis
Nondisjunction occurs during _____.
meiosis
The type of nuclear division that leads to the formation of haploid gametes in both males and females is _______.
meiosis
When does synapsis occur?
meiosis I
As a wound heals, the process of ______ is occurring to replace lost and damaged cells.
mitosis
The human life cycle includes which two types of nuclear division?
mitosis and meiosis
The improper separation of chromosomes during meiosis I or meiosis II is called _______.
nondisjunction
Meiosis is a type of nuclear division that produces haploid daughter cells in organisms that reproduce through _________ reproduction.
sexual
During meiosis I, homologous chromosomes undergo crossing over while they are side-by-side in an event called ______.
synapsis
Individuals with an inactive SYR gene do not produce the _______ __________ factor and are classified as females.
testis determining
In humans, an "XY" female may occur if there is a problem with:
the SRY gene
In sexually reproducing organisms, all the reproductive events that occur from one generation to the next are referred to as:
the life cycle
Down syndrome is a type of _____.
trisomy
