Mutations

What percentage of our DNA causes differences among humans?

0.1%

Chances are very small that a change in human DNA will have a noticeable effect. Why?

95% of human DNA is non-coding DNA.

What percent of our DNA is the same for all humans?

99.9%

What is a genetic disorder?

A disease or condition that results from mutations that affect the normal functioning of the cells.

How do mutations occur?

An error can occur when DNA is copied, Or exposure to environmental factors, such as harmful chemicals, x-rays, or UV radiation can damage DNA.

What is a mutation?

Any change in DNA.

How can a mutated gene have a beneficial effect?

Beneficial - when the mutated gene increases the organism's ability to survive.

What is a common disease that is caused by a mutated gene that drastically increases how fast cells divide?

Cancer

What effect does cancer have on the cell cycle of a cancerous cell?

Cancer causes cells to divide continuously, upsetting the normal life cycle of the cell.

In what type of cell would a mutation to a gene have the greatest effect?

Egg or sperm cell

How can a mutation be harmful?

Harmful - can cause Disease or genetic disorders that reduce an organism's likelihood of survival.

How are pedigrees used to follow a genetic disease through a family?

If the genotypes of the people in the family are known, then the pedigree can be used to show who has the disease or carries the allele for the disease.

Identify causes of genetic disorders and give an example of each.

Inherited (passed on from one generation to another). Examples: sickle cell disease, cystic fibrosis, albinism Tendency (may happen depending on certain other factors) Examples: diabetes, glaucoma, Alzheimer's disease Environmental (happen during a person's lifetime): Examples: smoking increases risk of lung cancer and emphysema.

A mutation in a triplet code that ends up coding for the same amino acid is referred to as a silent mutation. In what sense is it silent?

It has no effect on the protein produced, so the cell functions normally.

From which disease does a sickle cell allele give some protection?

Malaria

How can a mutated gene have a minor effect?

Minor - a mutated gene that changes one's appearance but doesn't affect important bodily functions, such as skin color.

How can a mutated gene have no effect?

No effect - sometimes only one gene is mutated in a pair of genes, the "normal gene' can still provide the good instructions.

Are all mutations harmful?

No, some have no effect, some may be beneficial.

What percentage of the DNA in a human cell are in the genes that code for RNA and proteins?

Only 5%

What diagram shows patterns of inheritance among family relationships?

Pedigree

What does it mean that DNA is non-coding?

Segments of DNA are not part of a gene and do not code for RNA or protein.

On a pedigree chart, what do the horizontal lines connecting males and females represent?

Sexual reproduction between the two.

Why are genetic diseases carried within genes on the X chromosome more common in male offspring than female offspring?

Since a male only has one X chromosome, if there is a disease gene on his X chromosome, it will be expressed. However, a female has two X chromosomes; even if one X chromosome has the disease gene, the other may not.

Name some things that can damage DNA.

Ultra violet radiation, X-rays, Toxic chemicals

What is a characteristic of all cancers?

Uncontrolled division of cells.