Unit 28

Fertilized eggs are known as ____________________.

zygotes

Pairs of genes that are homozygous are ____________________, while those that are different are called ____________________.

alike, heterozygous

A group of animals having common ancestors and similar characteristics that are passed on to their offspring is called a:

breed

A cow's vagina is separated from the uterine horn by the:

cervix

Once an egg has been fertilized, cell ____________________ occur and the embryo begins to grow.

divisions

Genetic ____________________ is the process of transferring genes from one individual to another by inserting them in the chromosomes of the new individual or organism.

engineering

An embryo going through the co-culture process must have more than how many cells by the third day to be a good candidate for implanting into a surrogate (donor) ewe?

8

Offspring resulting from the crossbreeding of animals are called:

hybrids

Genetic engineering has increased or improved what three production traits?

Genetic engineering has made it possible to increase resistance to diseases, improve production, and improve efficiency of animals.

Describe the difference between mitosis and meiosis

In mitosis, each chromosome splits in two. The wall of the nucleus disappears, and the chromosomes move to opposite sides of the cell wall in pairs. Then a new nucleus wall forms around each pair of chromosomes. The walls on opposite sides of the original cell then move toward each other until they divide the cell into two new cells complete with nuclei and pairs of chromosomes. With meiosis, the chromosomes separate and move individually to the cell walls. When new cells are formed, each cell contains only one of each chromosome pair rather than both chromosomes. When the egg is fertilized, the sperm contributes the other chromosome. In animals, meiosis occurs only in the reproductive organs. When an egg is fertilized, the sperm contributes one half of each chromosome pair; the egg contributes the other.

____________________ is the mating of unrelated animal families within the same breed.

outcrossing

Where does in vitro mating occur?

outside the body

Animals are often selected based on their ancestry or ____________________, which appears on the registration papers of purebred animals.

pedigree

Comparative dairy judging includes evaluating:

the overall appearance of four different animals

Polled means naturally or genetically:

Hornless

___________________ is the process of placing sperm in a female animal in close proximity with female reproductive cells.

Artificial insemination

Define artificial insemination, and tell why it is important

Artificial insemination (AI) is the process of placing sperm in a female animal in close proximity with female reproductive cells, called eggs or ova, by a method other than natural mating. Sperm consists of male reproductive cells. AI allows for use of a superior male animal to father many times more offspring than would be possible naturally. This process has allowed for more improvement in milk production in the last 50 years than had occurred in the previous 200 years.

Explain embryo transfer.

Embryo transfer is a process that removes fertilized eggs, or zygotes, from a female animal and places them in another female animal to be carried and nurtured until birth.

Embryo co-culture is the union of two different species of animal

False

Rabbits make ideal receptacles for gene-implanted embryos.

False

Ribosomes are responsible for storing proteins.

False

When an embryo is implanted into the uterus of a cow that is not the embryo's biological mother, some DNA is shared and the calf takes on some of the traits of the surrogate mother.

False

List the two major criteria for selecting animals.

Selection methods fall into two major types: selection based on physical appearance and selection based on performance or production of either the individual or its progeny

What term is used to describe a genetic change or accident, such as the polled trait?

These genetic accidents or changes in genes are called mutations.

Another term for identical individuals is clones.

True

Color blindness is an example of a sex-linked trait.

True

Meiosis is the division or duplication of egg and sperm cells.

True

Mitosis is the process of division or duplication of a typical cell.

True

Sheep embryos can now be kept alive outside the ewe's oviduct for up to six days.

True