Chapter 10 (test 3) Flashcards
nuclear division, reducing the chromosome number from the diploid (2n) to the haploid (n) number.
Meiosis
the total number of chromosomes, which exists in two sets.
diploid (2n) number
half of the diploid number of chromosomes.
haploid (n) number
What happens in sexual reproduction?
gamete formation and then fusion of gametes to form a zygote.
reproductive cell
gamete
fusion of gametes form a
zygote
A zygote always has the (blank) number of chromosomes.
full, or diploid (2n)
If gametes contained the same number of chromosomes as body cells, (blank) would soon fill cells.
doubling
In diploid body cells, chromosomes occur as (blank).
pairs
Each set of chromosomes is a (blank); each member is a (blank) or (blank)
(blank) look alike, have the same length and centromere position, and have a similar banding
pattern when stained.
homologous pair; homologous chromosome or
homologue.
Homologue
A (blank) on one homologue contains a gene for the same trait that occurs at this (blank) on the other
homologue, although the genes may code for different variations of that trait; alternate forms of a
gene are called (blank).
location; locus; alleles.
Chromosomes (blank) immediately prior to nuclear division.
duplicate
Duplication produces two identical parts called (blank); they are held together at the (blank)
sister chromatids; centromere
One member of each homologous pair is inherited from the (blank) parent, the other member from the
(blank) parent.
male, female
One member of each homologous pair will be placed in each (blank) or (blank)
sperm or egg
Meiosis involves (blank) nuclear divisions and produces (blank) haploid daughter cells.
two; four
Each daughter cell has (blank) the number of chromosomes found in the diploid parent nucleus.
half
Meiosis I is the (blank) nuclear division.
first
Prior to meiosis I, (blank) occurs, each chromosome thus has (blank) sister chromatids.
DNA replication; two
During meiosis I, homologous chromosomes pair forming a (blank); this process is called (blank).
synaptonemal complex; synapsis
During synapsis, the two sets of paired chromosomes lay alongside each other as a (blank) (sometimes called a tetrad).
bivalent
In meiosis II, the (blank) divide and (blank) (derived as sister chromatids) separate.
centromeres; daughter chromosomes
No replication of DNA is needed between meiosis I and II because chromosomes are already (blank)
doubled
In Meiosis II, Chromosomes in the four daughter cells have (blank) chromatid(s)
one
In Meiosis II, Counting the number of centromeres verifies that parent cells were (blank); each daughter cell is (blank)
diploid; haploid.
In the animal life cycle, daughter cells become (blank) that fuse during (blank).
gametes; fertilization
Fertilization restores the (blank) number in cells.
diploid
In the plant life cycle, daughter cells become haploid (blank) that (blank) to become a haploid
generation.
spores; germinate
Due to (blank), offspring have a different combination of genes than their parents.
genetic recombination
Without recombination, asexual organisms must rely on (blank) to generate variation among offspring;
this is sufficient because they have great numbers of offspring.
mutations
Meiosis brings about genetic recombination in two ways:
crossing-over and independent assortment
an exchange of genetic material between non-sister chromatids of a bivalent; this introduces variation.
crossing-over
{Genetic Recombination} At synapsis, homologous chromosomes are held in position by a (blank) (the synaptonemal complex).
nucleoprotein lattice
{Genetic Recombination} The lattice holds the (blank) together so that the (blank) of the duplicated chromosomes of each homologue pair is aligned, then (blank) may occur.
bivalent; DNA; crossing-over
{Genetic Recombination} As the lattice of the synaptonemal complex breaks down, homologues are temporarily held together by (blank), regions where the non-sister chromatids are attached due to DNA strand exchange and crossing-over.
chiasmata
{Genetic Recombination} The homologues (blank) and are distributed to (blank) Due to this (blank) daughter chromosomes derived from sister chromatids are no longer identical.
separate; daughter cells; genetic recombination
During (blank), the homologous chromosomes separate independently or in a random
manner.
independent assortment
Independent assortment in a cell with only three pairs of chromosomes is 2^3 or eight combinations of
(blank and blank) chromosomes.
maternal and paternal
In humans who have (blank) pairs of chromosomes, the combinations possible from independent assortment
alone are 2 23 or 8,388,608.
23
When gametes fuse at fertilization, chromosomes donated by parents (blank)
combine
The chromosomally different zygotes from same parents have (blank) or 70,368,744,000,000 combinations possible without crossing-over. If crossing-over occurs once, then (blank) or 4,951,760,200,000,000,000,000,000,000 genetically different zygotes are possible for one couple.
(2^23 )^2; (4^23 )^2
A successful parent in a particular environment can reproduce (blank) and produce (blank) adapted to
that environment.
asexually; offspring
If the environment changes, differences among (blank) provide the (blank) of sexually reproducing
parents with much improved chances of survival.
offspring, offspring
Both meiosis I and meiosis II have four phases:
prophase, metaphase, anaphase, and telophase.
In Prophase I, (blank) is about to occur: (blank) disappears; (blank) fragments; (blank) migrate away from each other; and (blank) assemble.
nuclear division; nucleolus; nuclear envelope; centrosomes; spindle fibers
In Prophase I, Homologous chromosomes undergo (blank) to form (blank); (blank) may occur at this time in which case sister chromatids are no longer identical.
synapsis; bivalents; crossing-over
In Prophase !, (blank) condenses and (blank) become microscopically visible.
Chromatin; chromosomes
In Metaphase I, (blank) held together by (blank) have moved toward the (blank) plate at the equator of the
(blank).
Bivalents; chiasmata; metaphase; spindle
In metaphase I, there is a fully formed (blank) and alignment of the (blank) at the (blank) plate.
spindle; bivalents; metaphase
In metaphase I, (blank), protein complexes just outside the centromeres attach to spindle fibers called kinetochore spindle fibers.
Kinetochores; kinetochore spindle fibers.
In metaphase I, (blank) independently align themselves at the metaphase plate of the (blank).
Bivalents; spindle
In metaphase I, (blank) and (blank) homologues of each (blank) may be oriented toward either (blank).
Maternal and paternal; bivalents; pole
In Anaphase I, The (blank) of each bivalent separate and move toward opposite (poles).
homologues; separate; poles
In Anaphase I, Each chromosome still has two (blank)
chromatids
In Telophase I, In (blank), this stage occurs at the end of meiosis I.
animals
In Telophase, When it occurs, the (blank) reforms and (blank) reappear.
nuclear envelope; nucleoli
In Telophase I, This phase may or may not be accompanied by (blank)
cytokinesis
(blank) between meiosis I and II is similar to the (blank) between mitotic divisions; however, no
(blank) occurs (the chromosomes are already duplicated).
Interkinesis; interphase; DNA replication
During metaphase II, the (blank) number of chromosomes align at the (blank) plate.
haploid; metaphase
During anaphase II, the (blank) separate at the (blank); the two (blank) move toward the poles.
sister chromatids; centromeres; daughter chromosomes
In meiosis II, Due to (blank), each (blank) can contain chromosomes with different types of (blank)
crossing-over; gamete; genes
At the end of telophase II and cytokinesis, there are (blank) haploid cells.
four
In meiosis II, In animals, the (blank) mature and develop into (blank)
haploid cells; gametes
In meiosis II, In plants, the (blank) become (blank) and divide to produce a haploid generation; these haploid
cells fuse to become a (blank) that develops into a diploid generation.
daughter cells ;spores; zygote
The type of life cycle of alternating haploid and diploid generations is called
alternation of generations.
Meiosis requires two (blank); mitosis requires only one (blank).
nuclear divisions; nuclear division
The daughter cells produced by meiosis are (blank); the daughter cells produced by mitosis are (blank)
haploid; diploid
The daughter cells produced by meiosis are not (blank); the daughter cells produced by mitosis are (blank) to each other and to the (blank).
genetically identical; genetically identical; parent cell
In humans, meiosis occurs only in (blank) to produce (blank).
reproductive organ; gametes
Mitosis occurs in all (blank) for growth and repair.
tissues
During prophase I of meiosis, (blank) pair and undergo crossing-over; this does not occur during (blank).
homologous chromosomes; mitosis
During metaphase I of meiosis, (blank) align at the metaphase plate; in mitosis (blank, blank) align.
bivalents; individual chromosomes
During anaphase I in meiosis, (blank, blank) (with centromeres intact) separate and move to opposite poles; in mitosis at this stage, (blank, blank) separate and move to opposite poles.
homologous chromosomes; sister chromatids
Events of meiosis II are similar to those of mitosis. However, in meiosis II, the nuclei contain the (blank) number of chromosomes.
haploid
refers to all reproductive events between one generation and the next.
life cycle
In animals, the adult is always (blank) [Instructors note: some (blank), etc., have haploid male adults].
diploid; bees
In plants, there are two adult stages: one is diploid (blank) and one is haploid (blank)
called the sporophyte; called the gametophyte
in plants, the sporophyte is (blank)
diploid
in plants, the gametophyte is (blank)
haploid
Mosses are (blank) most of their cycle; the majority of higher plants are (blank) most of their cycle.
haploid; diploid
In fungi and some algae, only the zygote is (blank), and it undergoes (blank)
diploid; meiosis
Animals are (blank), and meiosis occurs during the production of (blank)
diploid; gametes
the production of gametes
gametogenesis
In males, meiosis is part of (blank), and occurs in the (blank).
spermatogenesis; testes
production of sperm
spermatogenesis
In females, meiosis is part of (blank), and this occurs in the (blank)
oogenesis; ovaries
the production of eggs
oogenesis
After birth, mitotic cell division is involved in growth and tissue regeneration of (blank, blank)
somatic tissue
In the testes of males, primary (blank) with (blank) chromosomes undergo meiosis I to form two
secondary (blank), each with (blank) duplicated chromosomes.
spermatocytes; 46; spermatocytes; 23
Secondary spermatocytes divide (meiosis II) to produce (how many blank), also with (blank) daughter chromosomes. Spermatids then differentiate into (blank, blank)
four spermatids; 23; sperm (spermatozoa).
Meiotic cell division in males always results in (blank) cells that become (blank).
four; sperm
In the ovaries of human females, primary (blank) with (blank) chromosomes undergo meiosis I to form two cells, each with (blank) duplicated chromosomes.
oocytes; 46; 23
In oogenesis, one of the cells, a secondary (blank), receives almost all the (blank); the other cell, (blank, blank), disintegrates or divides again.
oocyte; cytoplasm; a polar body
The secondary oocyte begins (blank) and then stops at (blank)
meiosis II; metaphase II.
At ovulation, the secondary oocyte leaves the ovary and enters an (blank) where it may meet a sperm.
oviduct; sperm
If a (blank) enters the secondary oocyte, the oocyte is activated to continue (blank) to completion; the result is a mature (blank) and another (blank, blank), each with (blank) daughter chromosomes.
sperm; meiosis II; egg; polar body; 23
Meiosis produces (blank) egg and (blank) polar bodies;(blank) serve to discard unnecessary chromosomes and retain most of the cytoplasm in the egg. The (blank) serves as a source of nutrients for the developing (blank)
one; three; polar bodies; cytoplasm; embryo.
failure of chromosomes to separate
nondisjunction
changes in chromosome number or structure
chromosomal mutations
name what increases the amount of variation among offspring (4)
- Mutations
- Crossing-over
- Recombination of chromosomes during meiosis
- Gamete fusion during fertilization,
The correct number of chromosomes in a species is called
euploidy
changes in chromosome number resulting from nondisjunction during meiosis is called
aneuploidy.
(2n – 1) occurs when an individual has only one of a particular type of chromosome.
Monosomy
(2n + 1) occurs when an individual has three of a particular type of chromosome.
Trisomy
In nondisjunction both members of the homologous pair go into the same (blank)
gamete
occurs during meiosis I when both members of a homologous pair go into the same daughter cell
Primary nondisjunction
occurs during meiosis II when the sister chromatids fail to separate and both daughter chromosomes go into the same gamete.
Secondary nondisjunction
Monosomy and trisomy occur in plants and animals; in (blank) of animals, it is generally lethal.
autosomes
the most common autosomal trisomy in humans.
Trisomy 21
(blank) also called (blank) occurs when three copies of chromosome 21 are present.
Trisomy 21 (also called Down syndrome)
Usually (blank) copies of chromosome 21 are contributed by the egg; in 23% of the cases, the (blank) had the extra chromosome 21.
two; sperm
Chances of a woman having a Down syndrome child increase with (blank)
age
A Down syndrome child has many characteristic signs and symptoms, including a tendency for (blank), (blank), (blank), (blank), and an increased chance of developing (BLANK) disease later in life.
leukemia, cataracts, faster aging, mental retardation; Alzheimer
A (blank), a visual display of the chromosomes arranged by (blank), (blank), and (blank) may be performed to identify babies with Down syndrome and other aneuploid conditions.
karyotype; shape, size, and banding pattern
Nondisjunction during oogenesis can result in too few or too many (blank) chromosomes; nondisjunction during
spermatogenesis can result in missing or too many (blank) chromosomes.
X; Y
Any additional X chromosomes become an inactive mass called a (blank)
Barr body
(blank) syndrome females have only one sex chromosome, an X; thus, they are XO, with O signifying
the absence of a second sex chromosome.
Turner
(blank) females are short, have a broad chest and widely spaced nipples, along with a low
posterior hairline and neck webbing.
Turner
(blank) of Turner females never become functional; therefore, females do not undergo puberty.
Ovaries
(blank) syndrome males have one Y chromosome and two or more X chromosomes (e.g., XXY).
Klinefelter syndrome
Characteristics of (blank) Affected individuals are sterile males; the testes and prostate are underdeveloped. Individuals have large hands and feet, long arms and legs, and lack facial hair.
Klinefelter syndrome
In Klinefelter syndrome, Presence of the (blank) chromosome drives male formation but more than two (blank) chromosomes may result in mental retardation. (blank) usually only seen in the nuclei of a female’s cells, is seen in this syndrome due to the two X chromosomes.
Y; X; A Barr body
(blank) females (or superfemale) have three or more X chromosomes and therefore extra (blank) in the nucleus.
Poly-X; Barr bodies
There is no increased femininity; most lack any physical abnormalities. (blank) individuals are not mentally retarded but may have delayed motor and language development; (blank) females are usually tall and severely mentally retarded. Some experience menstrual irregularities but many menstruate regularly and are fertile; Characteristics of (blank)
XXX; XXXX; Poly-X
(blank) syndrome (XYY) are males with two Y chromosomes instead of one. This results from (blank) during spermatogenesis.
Jacobs; nondisjunction
Males with (blank) syndrome are usually taller than average, suffer from persistent acne, and tend to have speech and reading problems.
Jacobs
Environmental factors including (blank), (blank), and (blank) can cause chromosomes to break; if the broken ends do not rejoin in the same pattern, this causes a change in chromosomal structure.
radiation, chemicals, and viruses
A (blank) occurs when an end of a chromosome breaks off or when two simultaneous breaks lead to the
loss of an internal segment.
deletion
A (blank) is the presence of a chromosomal segment more than once in the same chromosome.
duplication
A broken segment from one chromosome can simply attach to its (blank) or unequal (blank) may occur.
homologue; crossing-over
A duplication may also involve an (blank) where a segment that has become separated from the chromosome is reinserted at the same place but in reverse; the position and sequence of genes are altered.
inversion
A (blank) is the movement of a chromosomal segment from one chromosome and inserted into another non homologous chromosome
translocation
in Down syndrome, 5% of cases are due to a (blank) between chromosome 21 and 14, a situation that runs in the family of the father or mother.
translocation
(blank) occurs when chromosome 7 loses an end piece: children look like pixies, have poor academic skills but good verbal and musical skills; lack of elastin causes cardiovascular problems and skin aging.
Williams syndrome
(blank) (“cry of the cat”) is a deletion in which an individual has a small head, is mentally retarded, has facial abnormalities, and an abnormal glottis and larynx resulting in a cry resembling that of a cat.
Cri du chat syndrome
If a (blank) results in the normal amount of genetic material, the person will remain healthy; if a person inherits (blank) of the translocated chromosomes, that person may have only one or three (blank) rather than the normal two.
translocation; one; alleles
In (blank), chromosomes 2 and 20 exchange segments, causing a small deletion on chromosome 20 that may produce some abnormalities.
Alagille syndrome
