Question 1

What is the cell cycle?

Accepted Answer

The ordered sequence of events that a cell passes through between one cell division and the next.

Question 2

What is a centromere?

Accepted Answer

The region at which sister chromatids are bound together; a constricted area in condensed chromosomes.

Question 3

What is a chromatid?

Accepted Answer

A single DNA molecule of two strands of duplicated DNA and associated proteins held together at the centromere.

Question 4

What does it mean to be diploid?

Accepted Answer

A cell, nucleus, or organism containing two sets of chromosomes (2 n ).

Question 5

What is a gamete?

Accepted Answer

A haploid reproductive cell or sex cell (sperm, pollen grain, or egg).

Question 6

What is a gene?

Accepted Answer

The physical and functional unit of heredity, a sequence of DNA that codes for a protein.

Question 7

What is a genome?

Accepted Answer

The total genetic information of a cell or organism.

Question 8

What does it mean to be haploid?

Accepted Answer

A cell, nucleus, or organism containing one set of chromosomes.

Question 9

What is a histone?

Accepted Answer

A histone is one of several similar, highly conserved, low molecular weight, basic proteins found in the chromatin of all eukaryotic cells; associates with DNA to form nucleosomes.

Question 10

What are homologous chromosomes?

Accepted Answer

Chromosomes of the same morphology with genes in the same location; diploid organisms have pairs of homologous chromosomes (homologs), with each homolog derived from a different parent.

Question 11

What is a locus?

Accepted Answer

The position of a gene on a chromosome.

Question 12

What is a nucleosome?

Accepted Answer

A subunit of chromatin composed of a short length of DNA wrapped around a core of histone proteins.

Question 13

How is DNA organized in prokaryotes?

Accepted Answer

In prokaryotes, the genome is composed of a single, double-stranded DNA molecule in the form of a loop or circle. The region in the cell containing this genetic material is called a nucleoid.

Question 14

What are plasmids?

Accepted Answer

Some prokaryotes have smaller loops of DNA called plasmids that are not essential for normal growth. Bacteria can exchange these plasmids with other bacteria, sometimes receiving beneficial new genes that the recipient can add to their chromosomal DNA. Antibiotic resistance is one trait that often spreads through a bacterial colony through plasmid exchange.

Question 15

How is DNA organized in eukaryotes?

Accepted Answer

In eukaryotes, the genome consists of several double-stranded linear DNA molecules. Each species of eukaryotes has a characteristic number of chromosomes in the nuclei of its cells.

Question 16

How many chromosomes do humans have?

Accepted Answer

Human body cells have 46 chromosomes, while human gametes (sperm or eggs) have 23 chromosomes each.

Question 17

What is the difference between human somatic cells and gametes?

Accepted Answer

A typical body cell, or somatic cell, contains two matched sets of chromosomes, a configuration known as diploid. Human cells that contain one set of chromosomes are called gametes, or sex cells; these are eggs and sperm, and are designated 1 n , or haploid.

Question 18

How can chromosomes be viewed?

Accepted Answer

The condensed chromosomes can be removed from a cell in mitosis and spread out on a slide, and artificially arranged according to length; an arrangement like this is called a karyotype. The chromosomes are exposed to fluorescent stains for differentiation of the different chromosomes. A method of staining called “chromosome painting” employs fluorescent dyes that highlight chromosomes in different colors.

Question 19

How are homologous chromosomes different from each other?

Accepted Answer

Each copy of a homologous pair of chromosomes originates from a different parent; therefore, the genes themselves are not identical. The variation of individuals within a species is due to the specific combination of the genes inherited from both parents. Even a slightly altered sequence of nucleotides within a gene can result in an alternative trait.

Question 20

How is blood type determined by homologous chromosomes?

Accepted Answer

For example, there are three possible gene sequences on the human chromosome that code for blood type: sequence A, sequence B, and sequence O. Because all diploid human cells have two copies of the chromosome that determines blood type, the blood type (the trait) is determined by which two versions of the marker gene are inherited. It is possible to have two copies of the same gene sequence on both homologous chromosomes, with one on each (for example, AA, BB, or OO), or two different sequences, such as AB.

Question 21

How much of a difference is there between homologous chromosomes?

Accepted Answer

Minor variations of traits, such as blood type, eye color, and handedness, contribute to the natural variation found within a species. However, if the entire DNA sequence from any pair of human homologous chromosomes is compared, the difference is less than one percent.

Question 22

What is the exception to homologous chromosome uniformity?

Accepted Answer

The sex chromosomes, X and Y, are the single exception to the rule of homologous chromosome uniformity: Other than a small amount of homology that is necessary to accurately produce gametes, the genes found on the X and Y chromosomes are different.

Question 23

How large is human DNA compared to the size of an average cell?

Accepted Answer

If the DNA from all 46 chromosomes in a human cell nucleus was laid out end to end, it would measure approximately two meters; however, its diameter would be only 2 nm, compared to the size of a typical human cell which is about 10 µm (100,000 cells lined up to equal one meter).

Question 24

How is eukaryotic DNA organized in a cell?

Accepted Answer

DNA must be tightly packaged to fit in the cell’s nucleus. At the same time, it must also be readily accessible for the genes to be expressed. During some stages of the cell cycle, the long strands of DNA are condensed into compact chromosomes. There are a number of ways that chromosomes are compacted.

Question 25

What is the first level of compaction of chromatin?

Accepted Answer

In the first level of compaction, short stretches of the DNA double helix wrap around a core of eight histone proteins at regular intervals along the entire length of the chromosome. The DNA-histone complex is called chromatin. The beadlike, histone DNA complex is called a nucleosome, and DNA connecting the nucleosomes is called linker DNA. A DNA molecule in this form is about seven times shorter than the double helix without the histones, and the beads are about 10 nm in diameter, in contrast with the 2-nm diameter of a DNA double helix.

Question 26

What is the second level of compaction of chromatin?

Accepted Answer

The next level of compaction occurs as the nucleosomes and the linker DNA between them are coiled into a 30-nm chromatin fiber. This coiling further shortens the chromosome so that it is now about 50 times shorter than the extended form.

Question 27

What is the third level of compaction of chromatin?

Accepted Answer

In the third level of packing, a variety of fibrous proteins is used to pack the chromatin. These fibrous proteins also ensure that each chromosome in a non-dividing cell occupies a particular area of the nucleus that does not overlap with that of any other chromosome.

Question 28

What are sister chromatids?

Accepted Answer

DNA replicates in the S phase of interphase. After replication, the chromosomes are composed of two linked sister chromatids. When fully compact, the pairs of identically packed chromosomes are bound to each other by cohesin proteins. The connection between the sister chromatids is closest in a region called the centromere. The conjoined sister chromatids, with a diameter of about 1 µm, are visible under a light microscope. The centromeric region is highly condensed and thus will appear as a constricted area.

Question 29

What is anaphase?

Accepted Answer

The stage of mitosis during which sister chromatids are separated from each other.

Question 30

What is a cell plate?

Accepted Answer

A structure formed during plant cell cytokinesis by Golgi vesicles, forming a temporary structure (phragmoplast) and fusing at the metaphase plate; ultimately leads to the formation of cell walls that separate the two daughter cells.

Question 31

What is a centriole?

Accepted Answer

A rod-like structure constructed of microtubules at the center of each animal cell centrosome.

Question 32

What is a cleavage furrow?

Accepted Answer

Constriction formed by an actin ring during cytokinesis in animal cells that leads to cytoplasmic division.

Question 33

What is condensin?

Accepted Answer

Proteins that help sister chromatids coil during prophase.

Question 34

What is cytokinesis?

Accepted Answer

Division of the cytoplasm following mitosis that forms two daughter cells.

Question 35

What is the G0 phase?

Accepted Answer

A phase distinct from the G1 phase of interphase; a cell in G0 is not preparing to divide.

Question 36

What is the G1 phase?

Accepted Answer

The first phase of interphase centered on cell growth during mitosis. AKA first gap.

Question 37

What is the G2 phase?

Accepted Answer

The third phase of interphase during which the cell undergoes final preparations for mitosis. AKA second gap.

Question 38

What is interphase?

Accepted Answer

The period of the cell cycle leading up to mitosis; includes G1, S, and G2 phases (the interim period between two consecutive cell divisions).

Question 39

What is karyokinesis?

Accepted Answer

Mitotic nuclear division.

Question 40

What is a kinetochore?

Accepted Answer

A protein substructure associated with the centromere of each sister chromatid that attracts and binds spindle microtubules during prometaphase.

Question 41

What is the metaphase plate?

Accepted Answer

Equatorial plane midway between the two poles of a cell where the chromosomes align during metaphase.

Question 42

What is metaphase?

Accepted Answer

The stage of mitosis during which chromosomes are aligned at the metaphase plate.

10: Cell Reproduction Flashcards

Cell Division, the Cell Cycle, Control of the Cell Cycle, Cancer and the Cell Cycle, Prokaryotic Cell Division

Brainscape's Knowledge GenomeTM

10: Cell Reproduction Flashcards

Cell Division, the Cell Cycle, Control of the Cell Cycle, Cancer and the Cell Cycle, Prokaryotic Cell Division

Brainscape's Knowledge Genome^TM