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41 Cards in this Set
- Front
- Back
What are the 3 patterns of human inheritance
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single gene with two alleles
single gene with multiple alleles many genes that act together |
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what is an example of a trait controlled by a single gene with two alleles
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widow's peak (dominant over straight)
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what is an example of a trait controlled by a a single gene with multiple alleles
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Blood type:
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what is an example of a trait controlled by many genes?
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Height
Skin color |
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How many alleles control the inheritance of blood type? what are they?
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Three alleles:
type A written IA (codominant with B) type B written IB (codominant with A) Type O written i (recessive) |
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What are the possible blood types?
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Type A- IAIA or IAi
Type B- IBIB or IBi Type AB- IAIB Type O- ii |
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How many pairs of chromosomes in each body cell?
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23 pairs
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What is different about Sex chromosome pairs?
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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
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What are sex linked genes
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Genes whose alleles are passed from parent to child on a sex chromosome (X or Y chromosome)
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what are sex linked traits?
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Traits controlled by sex linked genes.
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what is an example of a sex-linked trait?
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color blindness
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What is a carrier?
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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.
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Why are males more likely to have sex-link traits controlled by a recessive allele?
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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.
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Can both males and females be carriers of color blindness?
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No. Only females can be carriers of a sex-linked trait.
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If a child has blood type O and his parents are both AB, what can you tell about this child?
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He is adopted!
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What are the functions of the sex chromosomes?
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The sex chromosomes carry genes that determine whether a person is male or female. The also carry genes that determine other traits.
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Are a person's characteristics determined by genes alone?
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No. Many characteristics are determined by an interaction between genes and the environment.
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Give examples of characteristics affected by environment.
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Height/weight-- affected by nutrition.
Ability to play a sport or musical instrument- requires physical traits and learning. |
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What is a genetic disorder?
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An abnormal condition that a person inherits through genes or chromosomes
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What are the two major causes of genetic disorders in humans?
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Mutations in the DNA of genes.
Changes in the overall structure of chromosomes or number of chromosomes. |
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What is cystic fibrosis?
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A genetic disorder in which the body produces abnormally thick mucus in the lungs making it hare to breathe.
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What causes cystic fibrosis?
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a recessive allele on one chromosome that is a result of a mutation in which 3 bases are removed from a DNA molecule.
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What is Sickle-Cell Disease?
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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.
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What is hemophilia?
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A genetic disorder in which a person's blood clots very slowly or not at all.
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What causes hemophilia?
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A recessive allele on the X-chromosome. Because it is sex linked, it occurs more frequently in males.
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What causes Down Syndrome?
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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.
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What tool do geneticists use to trace the inheritance of traits in humans?
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A pedigree
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What is a pedigree?
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A chart or a family tree that tracks which members of a family have a particular trait.
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How are males and females represented in a pedigree?
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A male is a square, a female is a circle.
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What is a karyotype?
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A picture of all of the chromosomes in a cell.
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How are karyotypes used?
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To help diagnose genetic disorders.
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What can you tell from a karyotype?
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You can tell if a person has the correct number of chromosomes.
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What do genetic counselors do? What tools do they use?
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They helps couples understand their chances of having a child with a particular disorder. They use Punnett squares, pedigree charts and karyotypes.
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How are people with genetic disorders helped?
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Through medical care, education, job training and other methods.
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How is cystic fibrosis treated?
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With physical therapy to help remove mucus from the lungs.
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How is sickle-cell disease treated?
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People take folic acid to help their bodies make red blood cells
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A ____________gene is masked if it is paired with a dominant gene.
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Recessive
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Of the two sex chromosomes, which has the fewer genes?
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The Y chromosome
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A female has two _______________.
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X chromosomes
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The traits that are visible in an organism determine its _____________.
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phenotype
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A sex cell is called a _____________.
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Gamete
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