A cell with a single set of chromosomes, such as a human egg or sperm, is described as haploid.
Missing Word
haploid
Haploid cells, written n, contain one set of chromosomes. Human gametes are haploid with 23 chromosomes.
Category: The Genome
Question 2
Human body cells are described as diploid because they contain two matched sets of chromosomes.
Missing Word
diploid
Diploid cells, written 2n, carry two sets of chromosomes, one from each parent. Human somatic cells are diploid with 46 chromosomes.
Category: The Genome
Question 3
The specific position on a chromosome where a particular gene is found is called its locus.
Missing Word
locus
A locus is the location of a gene on a chromosome. Homologous chromosomes carry genes for the same traits at the same loci.
Category: The Genome
Question 4
An image of a cell's chromosomes arranged in pairs by length is called a karyotype.
Missing Word
karyotype
A karyotype displays an organism's chromosomes sorted into homologous pairs, ordered by size. It is used to count chromosomes and spot large abnormalities.
Category: The Genome
Question 5
In a bacterium, the region of cytoplasm that holds the circular chromosome, with no surrounding membrane, is the nucleoid.
Missing Word
nucleoid
The nucleoid is where a prokaryote's chromosome is concentrated. Unlike a nucleus, it is not enclosed by a membrane.
Category: Prokaryotic Division
Question 6
A small ring of DNA in some bacteria, separate from the main chromosome and not needed for normal growth, is a plasmid.
Missing Word
plasmid
Plasmids are small, circular DNA molecules found in addition to the main bacterial chromosome. They can carry useful genes but are not essential for ordinary growth.
Category: The Genome
Question 7
The long stage of the cell cycle in which a cell grows and copies its DNA, made up of G1, S and G2, is interphase.
Missing Word
interphase
Interphase covers G1, S and G2, the period between divisions when the cell grows, replicates its DNA and prepares to divide.
Category: Interphase and Checkpoints
Question 8
After S phase, a duplicated chromosome consists of two identical sister copies, each called a chromatid.
Missing Word
chromatid
A chromatid is one of the two identical DNA copies of a replicated chromosome. Sister chromatids stay joined until they separate in anaphase.
Category: Interphase and Checkpoints
Question 9
The constricted region where a replicated chromosome's two identical halves are held together is the centromere.
Missing Word
centromere
The centromere joins sister chromatids, and kinetochores assemble on it to attach the chromosome to spindle microtubules.
Category: Mitosis
Question 10
Animal centrosomes contain a pair of rod-shaped structures set at right angles, each called a centriole.
Missing Word
centriole
Centrioles are rod-like structures within animal centrosomes that help organize cell division. Plants and most fungi lack them.
Category: Mitosis
Question 11
A protein complex on each chromosome that links it to spindle microtubules during mitosis is a kinetochore.
Missing Word
kinetochore
A kinetochore assembles at the centromere of each sister chromatid. It attaches the chromosome to spindle microtubules so the chromatids can be pulled to opposite poles.
Category: Mitosis
Question 12
Chromosomes line up single file along the cell's equatorial plane during the phase called metaphase.
Missing Word
metaphase
In metaphase the condensed chromosomes align at the center of the cell, with sister chromatids still joined and attached to spindle fibers from both poles.
Category: Mitosis
Question 13
Division of the cytoplasm that follows nuclear division, producing two separate daughter cells, is cytokinesis.
Missing Word
cytokinesis
Cytokinesis splits the cytoplasm after the nucleus has divided. Animal cells pinch in two with a cleavage furrow, while plant cells build a cell plate.
Category: Cytokinesis
Question 14
If DNA damage cannot be repaired, p53 can trigger programmed cell death, a process called apoptosis.
Missing Word
apoptosis
Apoptosis is a controlled self-destruction of a cell. It removes cells whose DNA is too damaged to fix, and cancer cells with faulty p53 often escape it.
Category: Cancer and Cell Cycle
Question 15
In binary fission, the partition of new membrane and wall that grows inward between the two chromosome copies is the septum.
Missing Word
septum
The septum forms at the FtsZ ring and grows from the cell's edge to its center. When the new walls are complete, the two daughter cells separate.
Category: Prokaryotic Division