Unit 4 Summary 1

Question 1

Chromosome

Answer 1

Dark staining thread-like structure in the nucleus; composed of DNA and proteins and contains genetic information in the form of genes arranged in a linear order. Found in constant numbers in body cells of organisms from a particular species

Question 2

DNA

Answer 2

(Deoxyribonucleic acid) A nucleic acid made up of a sequence of deoxyribose sugars and bases (adenine, cytosine, guanine and thymine) linked by phosphate bonds. It is the carrier of genetic information in all cellular organisms and most viruses; found in chromosomes (and mitochondria and chloroplasts)

Question 3

Histones

Answer 3

Small protein; any of a group of basic proteins found in chromatin.

Question 4

Prokaryotes

Answer 4

A microscopic single-celled organism which has neither a distinct nucleus with a membrane nor other specialised organelles, including the bacteria and cyanobacteria.

Question 5

Binary fission

Answer 5

A type of asexual reproduction common among prokaryotes wherein a cell divides giving rise to two cells, each having the potential to grow to the size of the original cell.

Question 6

Eukaryotes

Answer 6

Organism composed of one or more cells that contain distinct membrane bound nuclei and many organelles; including protists, fungi, plants and animals.

Question 7

Cell cycle

Answer 7

The cycle of changes during the life of a cell that are involved with replication

Question 8

Interphase

Answer 8

The phase in the cell cycle where the cell is not undergoing mitosis

Question 9

DNA replication

Answer 9

Mechanism by which DNA can be copied

Question 10

Mitosis

Answer 10

(I for identical) Cellular division resulting in two cells genetically identical to the parent cell. -growth and repair, esexual reproduction. Two diploid cells.
PMAT: Prophase Metaphase Anaphase Telophase

Question 11

Centrioles

Answer 11

Small cylindrical structure composed of microtubules; occurs in pairs and involved in separation of chromosomes in animal cells.

Question 12

Spindle fibres

Answer 12

Microtubules that attaches to centromeres and is involved in the separation of each member of a chromosome pair to opposite poles of the cell during cell division

Question 13

Chromatids

Answer 13

One of the two daughter strands of a replicated chromosome which are joined by a single centromere; separates and becomes a daughter chromosome

Question 14

Centromere

Answer 14

Point on a chromosome at which chromatids are held together and to which the spindle fibres attach during cell division. Visible during cell division as a constriction along the along the length of a contracted chromosome.

Question 15

Kinetochore

Answer 15

another term for centromere / a specialized structure on the centromere to which the microtubular spindle fibers attach during mitosis and meiosis

Question 16

Cytokinesis

Answer 16

The division of cytoplasm during mitosis or meiosis, as distinct from the division of the nucleus

Question 17

Sexual reproduction

Answer 17

Formation of offspring by the fusion of haploid gametes from two different organisms

Question 18

Asexual reproduction

Answer 18

Reproduction in which offspring are clones of the parent

Question 19

Meiosis

Answer 19

(ei for Every Individual) Cellular division that reduces the number of chromosomes in the parent cell by half and produces four haploid daughter cells; the products of meiosis are gametes or spores.

Question 20

Haploid

Answer 20

Having a single unpaired set (n) of chromosomes; the chromosome number of gametes

Question 21

Diploid

Answer 21

Having two (paired) sets of chromosomes (2n)

Question 22

Sex cells/gametes

Answer 22

Haploid cells that fuse to form a zygote during sexual reproduction; sperm and egg cells

Question 23

Homologous chromosomes

Answer 23

Matching pairs of chromosomes in a diploid organism

Question 24

Crossing over

Answer 24

The exchange of chromosomal material between members of a chromosome pair during meiosis

Question 25

Chiasma

Answer 25

(pl. chiasmata) Point of crossing of strands of non-sister chromatids observed during the final stage of meiosis

Question 26

Recombination

Answer 26

(principle of independent assortment) Mendel’s second law, which states that each pair of factors sorts out independently of other pairs at gamete formation. This means that either factor of a pair can combine with either factor of another pair. The law applies to characteristics on different chromosomes.

Question 27

Nondisjuntion

Answer 27

Lack of separation (segregation) of members of a chromosome pair during meiosis.

Question 28

Trisomy

Answer 28

A condition in which an extra copy of a chromosome is present in the cell nuclei, causing developmental abnormalities.

Question 29

Polyploidy

Answer 29

Having more than one copy of the full complement of chromosomes, e.g. diploid (two copies) triploid and tetraploid