somatic cell
Any cell in a multicellular organism except a sperm or egg cell.
diploid cell
A cell containing two sets of chromosomes (2n), one set inherited from each parent.
chromosome
A threadlike, gene-carrying structure found in the nucleus. Each chromosome consists of one very long DNA molecule and associated proteins. See chromatin.
meiosis
A two-stage type of cell division in sexually reproducing organisms that results in cells with half the chromosome number of the original cell.
haploid cell
A cell containing only one set of chromosomes (n).
gamete
A haploid cell, such as an egg or sperm. Gametes unite during sexual reproduction to produce a diploid zygote.
fertilization
The union of haploid gametes to produce a diploid zygote.
zygote
The diploid product of the union of haploid gametes in conception; a fertilized egg.
homologous chromosomes
Chromosome pairs of the same length, centromere position, and staining pattern that possess genes for the same characters at corresponding loci. One homologous chromosome is inherited from the organism’s father, the other from the mother
sister chromatids
Replicated forms of a chromosome joined together by the centromere and eventually separated during mitosis or meiosis II.
sexual reproduction
A type of reproduction in which two parents give rise to offspring that have unique combinations of genes inherited from the gametes of the two parents.
asexual reproduction
A type of reproduction involving only one parent that produces genetically identical offspring by budding or by the division of a single cell or the entire organism into two or more parts.
gene
A discrete unit of hereditary information consisting of a specific nucleotide sequence in DNA (or RNA, in some viruses)
mitosis
A process of nuclear division in eukaryotic cells conventionally divided into five stages: prophase, prometaphase, metaphase, anaphase, and telophase. Mitosis conserves chromosome number by equally allocating replicated chromosomes to each of the daughter nuclei.
A single individual is reproducing.
asexual reproduction
Human gametes are produced by _____.
meiosis
Normal human gametes carry _____ chromosomes.
23
A diploid organism whose somatic (nonsex) cells each contain 32 chromosomes produces gametes containing _____ chromosomes
16
What is the best evidence telling you whether a cell is diploid or haploid?
Only diploid cells contain two sets of chromosomes, one maternal and one paternal.
Genetic variation occurs when chromosomes are shuffled in fertilization and what other process?.
meiosis
How are sister chromatids and homologous chromosomes different from each other?
Homologous chromosomes contain the same gene loci but may have different alleles of a particular gene. Sister chromatids are identical copies of each other produced during DNA replication. One homologous chromosome comes from the father, and the other comes from the mother. Sister chromatids are identical copies of each other.
In which types of cell would mitosis occur?
skin cells
If a cell has 24 chromosomes before S phase and undergoes one normal cycle of mitosis and cytokinesis, how many chromosomes will each new daughter cell have?
24. Mitosis produces daughter cells that are exact copies of the parent cell.
After the division of the nuclei by mitosis or meiosis, _______ separates the cytoplasm to form separate daughter cells.
cytokinesis
Colchicine is a drug that interferes with normal meiotic chromosome segregation. Treated cells will often produce many diploid gametes. If a diploid gamete is fertilized by a normal gamete, what is the resulting offspring’s ploidy?
(3n) triploid. When a diploid gamete (2n) combines with a normal haploid gamete (n), a triploid offspring results
In alternation of generations, what is the diploid stage of a plant that follows fertilization called?
The sporophyte is the diploid, multicellular stage of the plant that produces haploid spores by meiosis
Identify all possible products of meiosis in plant and animal life cycles.
Gametes and spores.
What is the ploidy of organisms that have two sets of chromosomes?
An organism that has two sets of chromosomes has a ploidy of 2n
What information can not be obtained from an individual’s karyotype?
The sequence of bases of a particular gene
True or false? A haploid organism has one pair of homologous chromosomes.
False. A haploid organism only has one set of chromosomes, so it has no homologous chromosomes.
If a cell has 24 chromosomes, how many chromosomes would each of its four daughter cells have after meiosis?
12. Meiosis is a reduction division that reduces the number of chromosomes passed on to daughter cells by one-half.
Which structure is directly correlated with the production of genetic variability in the daughter cells produced during meiosis?
The chiasma is an X-shaped structure formed from the crossing over of homologous chromosomes, which can then exchange segments at the crossover sites.
Heritable variation is required for which of the following?
Variation is the raw material of evolution
For what purpose(s) might a karyotype be prepared?
for prenatal screening, to determine if a fetus has the correct number of chromosomes, to determine whether a fetus is male or female, to detect the possible presence of chromosomal abnormalities such as deletions, inversions, or translocations
_____goes on continuously in most parts of the body, whereas _____takes place only in the gonads.
Mitosis, meiosis
_____ is the only time that chromosomes line up by homologous pairs.
meiosis I only
The _____ is the point of attachment between two duplicated chromosomes
centromere
What number and types of chromosomes are found in a human somatic cell?
44 autosomes and 2 sex chromosomes. Human somatic cells contain 22 pairs of autosomes and either two X chromosomes (in females) or an X and a Y chromosome (in males)
Meiosis I produces _____ cells, each of which is _____.
two … haploid
Meiosis II typically produces _____ cells, each of which is _____.
four … haploid
During _____ tetrads align along the metaphase plate.
metaphase l
Synapsis, the pairing of homologous chromosomes, occurs during _____
prophase I
During _____ sister chromatids remain attached at their centromeres, and homologous chromosomes move to opposite poles
anaphase I
During _____ chromosomes align single file along the equator of a haploid cell.
metaphase II
At the end of _____ and cytokinesis there are four haploid cells.
telophase II
