Chemistry Reference
In-Depth Information
somes
, which are made up of linear segments of DNA. All cells in any given
living organism contain the same number of chromosomes; in different
plant and animal species, however, the number of chromosomes varies (see
Table 62).
The cytoplasm of plants and animals is a gelatinous fluid that
includes discrete membrane-surrounded structures, collectively known as
organelles
, which perform specialized functions in the life of a cell. The
lysosomes
,
ribosomes
,
mitochondria
, and the
endoplasmatic reticulum
and
the
Golgi apparatus
, for example, are all organelles. The function of the
lysosomes
is to break down substances taken up by the cell. Proteins and
other substances required by the cell are synthesized in the
ribosomes
and
endoplasmatic reticulum
. In the
mitochondria
, sugars are broken down to
keep the cell supplied with energy. A difference between plant and animal
cells is that the plant cell also contains a
vacuole
(a fluid containing cavity),
which controls pressure in the cell, and
chloroplasts
, in which
photosyn-
thesis
, the biosynthesis of sugars, takes place.
TABLE 62 Number of Chromosomes in the Cells
of Living Organisms
Living organism
Common name
Genus and species
Chromosomes
Animals
Cat
Felix maniculata
38
Cattle
Bos taurus
60
Dog
Canis familiaris
78
House fly
Musca domestica
12
Human
Homo sapiens
46
Mosquito
Culex pipiens
6
Rat
Rattus norvegicus
42
Vegetables
Clover (white)
Trifolium repens
32
Corn (maize)
Zea mays
20
Oak
Quercus robur
24
Onion
Allium cepa
16
Pine tree (yellow)
Pinus ponderosa
24
Potato
Solanum tuberosum
48
Tomato
Lycopersicon esculentum
12
