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41 Cards in this Set

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  • Back
What are the 3 patterns of human inheritance
single gene with two alleles
single gene with multiple alleles
many genes that act together
what is an example of a trait controlled by a single gene with two alleles
widow's peak (dominant over straight)
what is an example of a trait controlled by a a single gene with multiple alleles
Blood type:
what is an example of a trait controlled by many genes?
Height
Skin color
How many alleles control the inheritance of blood type? what are they?
Three alleles:
type A written IA (codominant with B)
type B written IB (codominant with A)
Type O written i (recessive)
What are the possible blood types?
Type A- IAIA or IAi
Type B- IBIB or IBi
Type AB- IAIB
Type O- ii
How many pairs of chromosomes in each body cell?
23 pairs
What is different about Sex chromosome pairs?
The only chromosomes that do not always match: In a girl, they match (XX). In a boy, they do not (XY). The Y chromosome is smaller than the X
What are sex linked genes
Genes whose alleles are passed from parent to child on a sex chromosome (X or Y chromosome)
what are sex linked traits?
Traits controlled by sex linked genes.
what is an example of a sex-linked trait?
color blindness
What is a carrier?
A person who has one recessive allele for a trait and one dominant allele. They are a carrier because they do not have the trait but can pass it on to off-spring.
Why are males more likely to have sex-link traits controlled by a recessive allele?
Because females have two X chromosomes, a recessive allele on the X chrom. may be masked by a dominant allele on the other X chromosome, but a male only has one X chromosome and if it carries a recessive allele, the male will have the trait.
Can both males and females be carriers of color blindness?
No. Only females can be carriers of a sex-linked trait.
If a child has blood type O and his parents are both AB, what can you tell about this child?
He is adopted!
What are the functions of the sex chromosomes?
The sex chromosomes carry genes that determine whether a person is male or female. The also carry genes that determine other traits.
Are a person's characteristics determined by genes alone?
No. Many characteristics are determined by an interaction between genes and the environment.
Give examples of characteristics affected by environment.
Height/weight-- affected by nutrition.
Ability to play a sport or musical instrument- requires physical traits and learning.
What is a genetic disorder?
An abnormal condition that a person inherits through genes or chromosomes
What are the two major causes of genetic disorders in humans?
Mutations in the DNA of genes.

Changes in the overall structure of chromosomes or number of chromosomes.
What is cystic fibrosis?
A genetic disorder in which the body produces abnormally thick mucus in the lungs making it hare to breathe.
What causes cystic fibrosis?
a recessive allele on one chromosome that is a result of a mutation in which 3 bases are removed from a DNA molecule.
What is Sickle-Cell Disease?
A disesase that affect hemoglobin, a protein in red blood cells that carry oxygen. Sickle shaped red blood cells clog blood vessels and connot carry as much oxygen as other cells.
What is hemophilia?
A genetic disorder in which a person's blood clots very slowly or not at all.
What causes hemophilia?
A recessive allele on the X-chromosome. Because it is sex linked, it occurs more frequently in males.
What causes Down Syndrome?
A person's cells have an extra copy of chromosome 21. Instead of a pair of chromosomes, that person has 3 chromosomes. This occurs most often when chromosomes fail to separate properly during meiosis.
What tool do geneticists use to trace the inheritance of traits in humans?
A pedigree
What is a pedigree?
A chart or a family tree that tracks which members of a family have a particular trait.
How are males and females represented in a pedigree?
A male is a square, a female is a circle.
What is a karyotype?
A picture of all of the chromosomes in a cell.
How are karyotypes used?
To help diagnose genetic disorders.
What can you tell from a karyotype?
You can tell if a person has the correct number of chromosomes.
What do genetic counselors do? What tools do they use?
They helps couples understand their chances of having a child with a particular disorder. They use Punnett squares, pedigree charts and karyotypes.
How are people with genetic disorders helped?
Through medical care, education, job training and other methods.
How is cystic fibrosis treated?
With physical therapy to help remove mucus from the lungs.
How is sickle-cell disease treated?
People take folic acid to help their bodies make red blood cells
A ____________gene is masked if it is paired with a dominant gene.
Recessive
Of the two sex chromosomes, which has the fewer genes?
The Y chromosome
A female has two _______________.
X chromosomes
The traits that are visible in an organism determine its _____________.
phenotype
A sex cell is called a _____________.
Gamete