exam 3 (practice questions) Flashcards
what is a karyotype?
organized image of a cells chromosomes
what defines a genome?
complete set of an organism’s genes and other DNA sequences
asexual reproduction occurs in which process?
mitosis
in sexual reproduction, individuals transmit _______ of their nuclear genes to each of their offspring
half
at which stage of mitosis are chromosomes usually photographed in the preparation of a karyotype?
metaphase
chromosomes are most condensed and visible, making it easier to observe and photograph them
what are 3 characteristics that all sexual life cycles have in common?
meiosis, fertilization, and gametes
gametophytes and sporophytes
gametophyte: haploid, gamete producing phase of plants and some algae (specialized cells that allow organisms to reproduce)
sporophyte: diploid, spore-producing phase of plants and some algae
alternation of generations
alternation of generations is a life cycle pattern found in certain plants and algae where two distinct phases, the sporophyte and gametophyte, alternate in a regular sequence
a diploid plant (sporophyte) produces a spore by meiosis that gives rise to a multicellular, haploid pollen grain (gametophyte)
an organism with 46 chromosomes in its karyotype produces gametes with how many chromosomes?
23
what mainly occurs during meiotic anaphase and what is a possible result of if it goes wrong?
phase in meiosis where chromosomes are separated and segregate to opposite poles of the cell
- going wrong during this time can cause incorrect amount of chromosomes in a human zygote
in a human karyotype, chromosomes are arranged in 23 pairs. if we choose one of these pairs, such as pair 14, which of the following do the two chromosomes of the pair have in common?
length, centromere position, staining pattern, and traits coded for by their genes
what characteristic do homologous chromosomes exhibit?
they carry information for the same traits
if meiosis produces haploid cells, how is the diploid number restored for these types of organisms?
by fertilization
which statement is correct regarding the human X chromosomes?
they carry genes that determines an individual’s biological sex
if a cell has completed meiosis I and the first cytokinesis, and is just beginning meiosis II, what is an appropriate description of its genetic contents?
it has half the amount of DNA as the cell that began meiosis
what statement describes the chromosomal makeup of each daughter cell after telophase of meiosis I?
the cells are haploid, and the chromosomes are each composed of 2 chromatids
sister chromatids vs nonsister chromatids
chromatids are one of the 2 joined chromosomes
main difference: whether chromatids are copies of the same chromosome (sister chromatids) or come from different chromosomes with similar genetic information (non-sister chromatids)
- sister chromatid separated and distributed to daughter cells during mitosis and meiosis II
-non-sister chromatids can undergo genetic recombination during meiosis I through crossing over
how do cells at the completion of meiosis compare with cells that are in prophase of meiosis I?
the cells have 1/2 the number of chromosomes and 1/4 the amount of DNA
what event happens at the conclusion of meiosis I?
sister chromatids are separated
during which process do sister chromatids separate from each other?
during mitosis and meiosis II
which process occurs in meiosis but not in mitosis?
synapsis of chromosomes
synpasis: homologous chromosomes pair up during meiosis and exchange genetic material
what is chiasmata & what stage are they first seen?
physical crossover points where the homologous chromosomes cross over and exchange genetic material
first seen in prophase I
at what stage of meiosis does the following occur:
homologous chromosomes are aligned at the equator of the spindle
metaphase I
at what stage of meiosis does the following occur:
centromeres of sister chromatids disjoin and chromatids separate
anaphase II
what is the major difference between meiosis II and mitosis in a diploid animal?
meiosis II occurs in a haploid cell, while mitosis occurs in diploid cell
what is the major difference between meiosis I and mitosis in a diploid animal?
sister chromatids separate in mitosis, while homologous pairs of chromosomes separate in meiosis I
crossing over of chromosomes normally takes place during which process? (mitosis, meiosis I, meiosis II)
meiosis I
during which process do homologous pairs of chromosomes align adjacent to one another at the metaphase plate of a cell?
metaphase I of meiosis
in which process of meiosis do centromeres split and sister chromatids migrate to opposite poles of the cell?
anaphase II
in which process does independent assortment of chromosomes occur?
in meiosis II only
independent assortment: random arrangement and segregation of homologous chromosomes along the metaphase plate