Life Science Ch. 8

gene mutation

a change in the sequence of nucleotides in a gene; a change in the sequence of bases in the segment of DNA that makes up a gene; when a cell uses mutated DNA segment to make messenger RNA, the RNA will contain the wrong code; many human genetic disorders are believed to be gene mutations

chromosomal change

a change involving the number of chromosomes or the number or location of genes on a chromosome; this could be considered a mutation in the broadest sense of the word; unlike a gene mutation, this does not directly involve the formation of different proteins; this may cause an organism to have some different traits. these traits can sometimes cause disorders, or they may just cause different variations in organisms; as with gene mutations, a chromosomal change may be somatic or occur in a gamete

Down Syndrome

a human disorder that is caused by a change in ploidy; people with down syndrome have three of the 21st (or sometimes the 22nd) chromosomes instead of two; this gives them a total of 47 chromosomes rather than the typical 46; characteristics include: a lower than average mentality, short stature, stubby hands and feet, and an extra fold of skin on the eyelids; about 1 in every 600 babies born in the USA has Down Syndrome

crossbreeding

aka hybridization; another method to produce animals with desirable traits; this involves breeding individuals from different varieties to produce offspring that have the traits of both parents; for example, a variety of wheat that survives cold temperatures is bred with another variety of wheat that resists a certain fungal disease. the offspring, called Marquis wheat, has both of these traits; it is hard to get hybrids that will produce offspring like themselves because the offspring will have a different gene combination that its parent did

mutation

any change in a organism's genetic material; can happen at any time; usually occur randomly in the genetic material; a cell can usually divide thousands to millions of time before one mutation takes place; not always harmful; many cause death though

Albinism

caused by a mutation that affects the pigment producing cells in the skin; when a person's genes are purebred for complete albinism, his/her body does not make pigments. without pigments, the person's skin and hair are white; of the eyes do not have pigments, the irises appear pink because there are no pigments to block the color of blood vessels in the iris. People with this can live nearly normal lives but exposure to sunlight can be especially harmful to the eyes and skin of those who do not have normal pigments

Tay-Sachs

caused by a recessive gene; seem normal until about 6 months; children with this lack a special enzyme that breaks down fatty substances; when this enzyme is missing, fatty substances begin to collect in the nervous system causing the death of neurons ; the child suffers brain damage, seizures, blindness, paralysis, and finally death

malignant hyperthermia

caused by dominant gene; where typical anesthesia triggers server reactions that cause sudden and extremely hight body temperatures (one woman's body reached 112F!); most people do not know they have this until undergoing anesthesia; without treatment, 60% of those with the disease die if they undergo typical anesthesia; today the mortality rate is less than 10%

selective breeding

choosing certain organisms with desirable traits to breed in the hope that their offspring will also have the desired traits

ploidy

chromosome changes that result in an unusual number of chromosomes are sometimes referred to as changes in __________

fraternal twins

develop from different zygotes so so each ____ has different genetic makeup. they are NOT members of a clone

banana plant

has a chromosome mutation that prevents it from producing seeds; this is a desirable mutation; to reproduce seedless ________, the farmers cut up the plant's corm and planted the pieces; using this form of asexual reproduction, farmers can produce whole plantations of seedless __________ ___________

unsuccessful hybrid

in 1927 Karpechenko experimented to crossbreed radish and cabbage because radish roots are edible and cabbage leaves are edible he wanted to make a vegetable hybrid; after many experiments, he got a hybrid that would produce seeds; the hybrid plants grew quickly and were strong but they had the leaves of radish and the roots of cabbage. the opposite of what K had wanted; this was an ____________ _________

20 years

in the past ____ _________ man's knowledge of genetics has increased remarkably

hemophilia

known as "bleeder's disease" or "disease of royalty" is one of the first diseases caused by heredity rather than an infection; although rare (1 in every 10,000 males) this sex-linked disease is well known because of the unusual symptoms; a hemophiliac does not have a certain blood clotting chemical in his blood; since blood clots in a hemophiliac do not form quickly, broken blood vessels may continue to bleed for a long time. without treatment, a hemophiliac could bleed to death from a minor injury

lethal mutations

mutations that cause death; many of these mutations cause the organism to die before it is born, while others kill the organism after it is born

somatic mutations

mutations that occur in body cells (cells that do not make gametes); these mutations are not passed on to further generations; for example, if a mutation that changes a gene in a skin cell would not affect your children because skin cells don't produce gametes

germ mutations

mutations that occur in gametes or in the cells that form gametes are called this; this type of mutation may not affect the organism in which it occurs, but it can affect the organism's offspring; if an offspring develops from a mutated gametes, all of the cells will receive the mutated gene. fortunately, most gene mutations are recessive and since most organism's have two of every gene, normal genes will dominate the recessive genes; although the offspring will still have the mutated genes, it will probably appear normal

identical twins

natural human clones; as the father's sperm fertilizes the female's ovum, the newly formed zygote splits before it begins to develop ; since both of these cells develop into two individuals with identical genes, they are members of a clone

sex-linked

not all disorders are this; many are caused by recessive genes; a person with a recessive disorder lacks normal genes and has only the mutated genes for that trait

biotechnology

not new; it merely uses living organisms to make new, more desirable organisms or products; what had really changed in this is the vast increase and knowledge and improved laboratory procedure

therapeutic cloning

producing clones to be used in medical research to find cures for disease; many people believe that this is acceptable because its purpose is to treat those who are ill. However to create another human clone and then destroy it during research is the same as murder. even if a perfect human clone could be produced, destroying life in order to save life is unacceptable. another problem is that many possible deformities and weaknesses that may occur before "good" ones are produced. if a deformed human clone were produced, who would care for it? also, human clones would not have the benefit of family and since they would be considered property of state, they could not be taught to love and serve the Lord; also, man are not a part of the animal kingdom and are not to abuse our bodies or mistreat other humans

Cystic Fibrosis

recessive trait and is a major killer of children; patients with this used to die around 14 but now are living into adulthood; if a person is hybrid for this( a normal gene and a gene for cystic fibrosis), he will not suffer from the disorder but will be a carrier; this disease affects the mucus and sweat glands in the body- instead of producing free flowing mucus, a child with this produces thick sticky mucus that plugs the glands; lungs and pancreas are very affected

Duchenne muscular dystrophy

sex-linked disorder; most wide spread form of _________ ___________; this disorder causes muscles first to enlarge and swell and then shrink and waste away; a person with this gradually loses their ability to walk, stand, and sit, and eventually dies in his early teens

inbreeding

the mating of of an organism with its close relatives or in the case of plants, with itself (called self pollination); during this, a breeder again chooses particular plants and animals for reproduction because they have certain desirable traits; through this the breeder hopes to get a group of organisms that are purebred for these desired traits and produce offspring with the same traits

corm

thick, underground stem

genetic engineering

using special techniques to control the genetic makeup of an organism is called this; one area of this involves isolating individual genes and transferring them to other cells; for example, scientists have taken the gene that codes for human insulin and placed it inside a bacterium; as the bacterium divides, it forms a colony of insulin producing bacteria; when the colony becomes large enough, the scientists kill the bacteria and remove the insulin; this helps supply insulin for people whose bodies do not produce it; through genetic engineering, man can select and design genes for organisms

Santa Gertrudis

was very costly and took many years to create this breed; in the early 1900's, many Texas ranchers raised shorthorn cattle from England that produced a lot of meat, but could not withstand the heat. one Texas ranch began to crossbreed shorthorns with Brahman cattle, which are resistant to high temps; it took 30 yrs to develop this combination into a pure breed

The Human Genome Project

a project where researchers are studying all 23 pairs of human chromosomes; by April 2003, they had found and located all the genes on the chromsomes

diploid

an organism or cell that has two sets of chromosomes

reproductive cloning

producing human clones for people who are unable to have children naturally

achondroplasia

a dominant genetic disorder; causes the long bones in arms and legs to stop growing before they should; a person with this has a normal sized head and body, normal intelligence, but very short arms and legs; many people we refer to as dwarfs have this

hybrid vigor

a greater strength, productivity, or health that sometimes occurs in offspring produced by crossbreeding

clone

a group of genetically identical organisms that were produced by asexual reproductions (this can also refer to each individual in the group); usually man __________ an organism because its genetic makeup produces some desirable trait

breed

a group of organisms that is purebred for certain characteristics

genetic engineering problems

genetic engineering can has some potentially serious problems' if a scientist made a small mistake while working with a virus, he might form a disease organism that could destroy many living things; or a genetically engineered plant may grow so well that it becomes a weed; other scientist are concerned about health risks of consuming genetically engineered crops; many countries do not import genetically engineered crops

animal cloning

Animals that naturally clone by asexual reproduction are invertebrates such as sponges, planarians, and jellyfish; to clone a frog, a scientist divides the embryo (which normally produces one individual) into two cells. each of these cells may grow into a separate frog. since the frog has the same genes, they are both members of a clone; if the zygote is separated too many times, the cells will die; scientists have also cloned mammals such as sheep, pigs, and cats; they remove the nucleus of a cell from an adult animal and place it into an unfertilized ovum (egg cell) whose nucleus has also been removed; at first it was exciting but as these animals grew up, they often had disorders that were fatal and never lived to adulthood